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Home My WebLink About20053247.tiff GEOLOGIC AND PRELIMINARY GEOTECHNICAL INVESTIGATION PORTION OF WHITHAM PROPERTY 4ORTHEAST OF COLORADO HIGHWAY 119 AND COUNTY ROAD NO. 3'/a WELD COUNTY, COLORADO r CTL/THOMPSON , INC . CONSULTING ENGINEERS 2005-3247 GEOLOGIC AND PRELIMINARY GEOTECHNICAL INVESTIGATION PORTION OF WHITHAM PROPERTY NORTHEAST OF COLORADO HIGHWAY 119 AND COUNTY ROAD NO. 3'/s WELD COUNTY, COLORADO Prepared For: Pulte Home Corporation 100 Inverness Terrace East, Suite 200 Englewood, Colorado 80112 Attention: Mr. Jim Miller Job No. FC-1044 August 11, 1998 PULTE HOME CORPORATION WHITHAM PROPERTY CLT/T PC-1044 L l TABLE OF CONTENTS SCOPE 1 SUMMARY OF CONCLUSIONS 1 SITE 2 PROPOSED DEVELOPMENT - 3 SITE GEOLOGY AND GEOLOGIC HAZARDS 4 SUBSURFACE CONDITIONS 6 SITE DEVELOPMENT 9 Ground Water 9 Grading 11 Slope Stability and Erosion 13 Utility Construction 13 Pavements 14 RESIDENTIAL CONSTRUCTION CONSIDERATIONS 15 Foundations 15 Slab-on-Grade and Basement Floor Construction 16 Basements 17 SURFACE DRAINAGE 18 CONCRETE 19 LIMITATIONS AND ADDITIONAL INVESTIGATION 19 FIG. 1 - LOCATIONS OF EXPLORATORY BORINGS FIG. 2 - ESTIMATED BEDROCK DEPTH FIG. 3 - ESTIMATED BEDROCK ELEVATION FIG. 4 - ESTIMATED GROUND WATER DEPTH FIG. 5 - ESTIMATED GROUND WATER ELEVATION FIGS. 6 THROUGH 8 - SUMMARY LOGS OF EXPLORATORY BORINGS FIGS. 9 THROUGH 19 - SWELL CONSOLIDATION TEST RESULTS FIG. 20 -TYPICAL SEWER UNDERDRAIN DETAIL FIG. 21 - SANITARY SEWER MAIN UNDERDRAIN DETAIL TABLE I - SUMMARY OF LABORATORY TEST RESULTS APPENDIX A - GUIDE SITE GRADING SPECIFICATIONS fa- PULTE HOME CORPORATION WHITHAM PROPERTY CLT/T FC-1044 6 SCOPE This report presents the results of our geologic and preliminary geotechnical investigation for the south about one-half (parcel) of the Whitham Property, located northeast of the intersection of Colorado Highway 119 and County Road No. 3% in Weld County, Colorado (Fig. 1). The Pulte Home Corporation is considering purchase and plans to develop the parcel as a subdivision for single-family residences. We investigated the geology and subsurface conditions at the parcel to evaluate the affect of the geology,the soils,the bedrock and the ground water on the proposed development of the parcel and the design and construction of residences in the proposed subdivision. This report presents the results of our field and laboratory studies and our conclusions, opinions and recommendations regarding the proposed development and the design and construction of the residences from the geotechnical viewpoint. Our conclusions are summarized below. SUMMARY OF CONCLUSIONS 1. The ground under the parcel is a thin (2 feet to 3 feet thick) layer of windblown clays over sedimentary (claystone, sandstone, siltstone) bedrock. Ground water is shallow (3 feet to 7 feet deep depending on location and day). The clays showed little tendency to swell in our tests. The bedrock showed low swell (expansion) in our tests. 2. The ground water depth is above typical residence basement depth (measured from existing grade) over nearly the entire parcel. The parcel surface elevations could be raised using engineered fill to increase the depth to ground water from the ground surface so basement floors can be placed at least 3 feet above the expected ground water surface or a parcel wide subdrain could be installed to lower the ground water surface to at least 3 feet below basement floors. A combination of the two alternatives might be the more feasible. Draining the subdrain system by gravity will be difficult, if possible, because of topographic constraints. This suggests lift stations might be needed to lower the ground water using a subdrain. In addition to a form of parcel-wide subdrain the proposed residences will need foundation drains connected to the parcel-wide subdrain. PULTE HOME CORPORATION WHITHAM PROPERTY 1 CLT/T PC-1044 L J 3. A successful parcel wide subdrain will tend to lower the ground water elevation under Oligarchy Ditch (aligned approximately parallel to the boundary of the parcel we investigated) just north of the parcel. The affect on Oligarchy Ditch will need consideration when evaluating the decision to install a parcel wide subdrain. 4. The clays at the site can be characterized as nil to low expansive and the bedrock as low expansive. We believe footings can be the foundations for the residences proposed for the subdivision if the final lot grades are at or above the existing natural grades. The finally selected site grading plan will determine if the foundation strata for a given residence foundation will be footings bearing on clays or footings bearing on the bedrock. The tendency for swell in the bedrock will cause the footing design criteria to include criteria for a minimum dead load for both bearing strata. Much lowering of the final grades below the existing natural grades will probably result in drilled piers as the preferred foundation for 10 percent of the residences. 5. The natural clays and bedrock can be the subgrade for slab-on-grade basement floors. Considerations for slab-on-grade basement floors are discussed in "Slabs-on-Grade and Basement Floor Construction" subsection. 6. The natural clays are a weaker subgrade for pavements. Residential streets will probably require full-depth asphaltic concrete pavement thicknesses of the order of 6 inches (4 inches of asphaltic concrete over 8 inches of the compacted base course) and thicker pavement sections for collector and arterial streets. These sections could be thinned by strengthening the subgrade with lime or other strengthener. 7. Control of the surface water will influence the performance of foundations, slab-on-grade floors and pavements. Surface ground contours and drainage structures must cause rapid runoff of surface water away from structures and removal of the water from the area. SITE The site (parcel) is approximately 250 acres located northeast of the intersection of Colorado Highway 119 and County Road No. 31/2 in Weld County, Colorado (Fig. 1). The parcel is currently planted with corn and hay. From a local high point at the northwest corner of the parcel, the ground surface slopes down gradually to the south and east. No significant erosional features were observed. The improvements on the parcel are fences and a graveled road extending from the PULTE HOME CORPORATION WHITHAM PROPERTY CLT/i FC-1044 2 southeast corner through the middle of the parcel toward its north end. The parcel is irrigated through main ditches around the perimeter and a network of interior, lateral ditches. County Road No. 31 and Colorado Highway 119 bound the parcel on the west and north, respectively. An unpaved frontage road parallels Highway 119. Residences are located across County Road 3 1/2 to the west. Single-family residences are completed and under construction in a subdivision to the east. Highway 119 is higher than the parcel. The subdivision to the east is graded to drain to a detention pond to the north. The ground to the south and west is irrigated farm land. Oligarchy Ditch is located about 600 feet north of the parcel. It is aligned about parallel to the north boundary of the parcel. Calkins Lake is located about one-half mile northwest of the parcel. The St. Vrain River/Boulder Creek confluence is south of Highway 119, about one-half mile east of the parcel. PROPOSED DEVELOPMENT Plans envision the 250 acre parcel will be a single-family residence subdivision. The conceptual plat showed streets, cul-de-sacs and lots. A park was shown near the center of the parcel, a commercial area was located in the southwest corner and a detention pond in the southeast corner. We have seen no grading plans as of the writing of this report. Utilities for servicing the residential lots and commercial area will be buried under the streets. We have assumed for this analysis the residences that will be built in the proposed subdivision will be mostly two-story wood frame structures with full basements. Typically these kinds of residences will have some stone and/or masonry veneer on the exteriors. PULTE HOME CORPORATION WHITHAM PROPERTY CLT/T FC-1044 3 L J SITE GEOLOGY AND GEOLOGIC HAZARDS The parcel is located within the Colorado Piedmont section of the Great Plains physiographic province. The Piedmont is a broad erosional trench which separates the Southern Rocky Mountain from the High Plains. Mapping by R.B. Colton (USGS Map I-855-G, Geologic Map of the Boulder-Fort Collins-Greeley Area, Colorado 1978) indicates the surface of the parcel is Eolian (Qe) deposits consisting of olive-brown- gray windblown clay, silt and sand. The underlying bedrock consists of the Upper Transition Zone of the Pierre Shale (Kptz), which is described as interbedded sandstone and shale with hard sandstone ledges and water with high sulfate content. The thickness of the Pierre Shale is about 2,800 feet. We believe the Pierre Shale dips gently to the east in the area of the parcel. Our field exploration generally confirmed the conditions described by published maps. This section discusses geologic hazards that we believe could affect land planning and zoning. Specific requirements of Colorado House Bill 1041 "Areas and Activities of State Interest" and Colorado Senate Bill 35 "County Planning and Building Codes" are addressed. This section was reviewed by our Engineering Geologist, Mr. David A. Glater, PE, CPG. The claystone phases of the bedrock are expansive. This can result in more or less damage to improvements or structures depending upon the characteristics of the claystones and the increase in moisture that occurs. Engineered design of pavements, foundations, slabs-on-grade and surface drainage can mitigate the effects of expansive bedrock. The soils and bedrock under this parcel are not expected to be unusually corrosive to metal but may have sulfate concentrations that can affect concrete. Natural slopes are gentle and appear to be stable. Significant faulting and structural discontinuities are not expected in the bedrock at this site. The soil and bedrock units are not expected to respond r—. unusually to seismic activity. The area is considered by the most recent editions of the Uniform Building Code (UBC) as Zone 1, its least active zone designation. Maximum bedrock accelerations at 4 to 7.5 percent of gravity are probable during PULTE HOME CORPORATION WHITHAM PROPERTY 4 CLTR EC-1044 L J major earthquakes in the area. Only minor damage to relatively new, properly designed and built residences would be expected. Regarding the potential for radioactive substances on the parcel, it is normal in the Front Range of Colorado and nearby eastern plains area to find significant accumulations of radon gas in poorly ventilated spaces (i.e., full-depth residential basements) in contact with soil or bedrock. Radon 222 gas has been shown to be a health hazard and is just one of several radioactive products with a short half-life in the chain of the natural decay of uranium into stable lead. There is no geologic property of the soils and bedrock at this parcel that would make radon gas any more likely than other areas of the Front Range of Colorado. The amount of radon gas that can accumulate in an area is a function of many factors, including the radionuclide activity of the soil and bedrock, construction methods and materials, soil gas pathways, and accumulation areas. Typical mitigation methods consist of sealing soil gas entry areas and ventilation of below-grade spaces. Radon rarely accumulates to significant levels in above-grade living spaces. The parcel does not appear to be flood prone. There are no highly-developed, incised drainages on the parcel.The very gentle topography of the parcel indicates little, if any, water would be expected to flow onto the parcel from outside the boundaries and there is no geologic indication of periodic flooding as evidenced by the absence of recent quaternary alluvium. The erosion potential on the parcel is considered low, due to gentle slopes. The erosion potential can be expected to increase during construction, but should return to pre-construction rates or less if proper grading practices, surface drainage design and revegetation efforts are implemented. We do not believe the parcel is located above underground mines or is located in a subsidence hazard zone. The bedrock below the parcel is the Pierre Shale formation which does not contain significant coal beds. There is no evidence of past mining activities on the parcel. r PULTE HOME CORPORATION WHITHAM PROPERTY 5CUMFC-1044 No economically important mineral deposits are expected on this parcel or are known to occur nearby. We do not expect ground subsidence related to natural or mining processes. The borings we drilled on the parcel showed ground water was shallow under the parcel. It was above typical basement depth (measured from the existing ground surface). The development strategy for a parcel with shallow ground water usually includes consideration of a parcel-wide subdrain, foundation drains around basements, raising the natural ground elevations with engineered fill to provide the needed distance above ground water for basements and probably other mitigating measures. No geologic hazards which would preclude the proposed development were noted on the subject tract. The shallow ground water will require attention. We believe the geologic hazards can be mitigated with proper engineering design and t'` construction practices, as discussed in this report. SUBSURFACE CONDITIONS Clays overlaying sedimentary, interlayered claystone, sandstone and siltstone; claystone; and sandstone bedrock were penetrated by the 12 borings we drilled to investigate the parcel subsurface. The approximate boring locations are shown on Fig. 1. Our borings were drilled with a 4-inch diameter, continuous flight auger and a truck-mounted drill rig. The drilling operations were observed by our field representative who logged the soils and obtained samples for laboratory testing. Graphic logs of the soils found in our borings including results of field penetration resistance tests are shown in Figs. 6 through 8. Samples obtained during drilling were returned to our laboratory where they were visually classified and selected for testing. The results of our laboratory tests are on Figs. 9 through r 19 and summarized in Table I. PLILTE HOME CORPORATION WHITHAM PROPERTY 6 CLTA FC4o44 Clays. The upper subsoils found in our borings generally consisted of very moist, medium stiff, sandy clay that was at depths of 2 to 13 feet. The clays are comparatively weak so foundations bearing on the clays will need to be designed for lower bearing pressures. We selected 3 samples of the clays for swell-consolidation tests. The samples exhibited low swell (0.2 percent)when wetted, as shown in Table A below. These samples represented the stiffer clays. We believe the majority of the clays possess nil to low expansion potential. The majority are more likely compressible because they are wind blown (lower natural density) and have higher moisture contents. The clay samples tested had moisture contents of 19 to 30 percent, liquid limits of 34 to 39 percent, plasticity indices of 21 to 25 percent, and contained 67 to 77 percent silt and clay size particles (passing No. 200 sieve). Bedrock. The bedrock found in our borings underlying the clays at 2 to 13 feet deep was claystone, sandstone and interbedded claystone, siltstone and sandstone. The interbedded bedrock was predominant. A cemented sandstone lense was encountered in boring TH-12 at about 8 feet, and site geology indicates discontinuous lenses of bedrock may be cemented. Our estimated depth to bedrock contours are shown on Fig. 2 and our estimated bedrock surface elevation contours are shown on Fig. 3. The upper 2 to 3 feet of the bedrock in 3 of the borings was weathered to a stiff clay. The underlying bedrock was hard to very hard. The weathered claystone,sandstone,and interbedded claystone,siltstone and sandstone bedrock is judged to be nil to low expansive. Eleven samples of these materials were swell tested in our laboratory and exhibited slight compression to low swell when wetted under an applied load of 1,000 psf. The shallower claystone samples tested were moist due to the shallow ground water conditions and exhibited lower swell. The deeper claystone samples tested were less moist and exhibited low to moderate swell (see Table A below). Samples of the shallower claystone had moisture contents of 12 to 33 percent with an average of 19 percent. Deeper claystone samples had moisture contents between 13 and 20 percent with an average of 15 percent. Claystone samples tested had liquid limits of 36 and 42 PULTE HOME CORPORATION WHITHAM PROPERTY 7 CLTJT FC-1044 L _ r percent, plasticity indices of 19 and 25 percent and 73 and 96 percent silt and clay size particles (passing No. 200 sieve). Table A - Summary of Swell Test Results. The following table reviews and compares the swell behavior of the samples we tested. No Range of Measured Swell (%) Compressed Movement Upon Soil Type Wetting Very Due to Low Moderate High High Wetting 0 to <2 2 to <4 4 to <6 6 Number and Percent of Samples Clay 0 0 3 0 0 0 Sand Y Y 0% 0% 100% 0% 0% 0% Weathered 1 0 0 0 0 0 Claystone 100% 0% 0% 0% 0% 0% ---- Interbedded 1 3 5 0 0 0 Sandstone/ 11% 33% 56% 0% 0% 0% Claystone Shallow 1 1 1 0 0 0 Claystone 33% 33% 33% 0% 0% 0% Deeper 0 0 2 1 0 0 Claystone 0% 0% 67% 33% 0% 0% 1 0 0 0 0 0 Sandstone 100% 0% 0% 0% 0% 0% 4 4 11 1 0 0 Overall 20% 20% 55% 5% 0% 0% Ground Water. Free ground water was encountered in 10 of our 12 borings at depths from 7 to 32 feet at the time of drilling and in all borings at depths of 3 to 7.5 feet when checked several weeks after drilling. Measurements were taken in June and July and ground water levels did not change appreciably between measurements. The parcel was being irrigated while we were drilling our borings and during the time we made subsequent ground water depth measurements. We believe the irrigation was started during the week between the staking of our boring locations and drilling. We believe water was turned into Oligarchy Ditch shortly PULTE HOME CORPORATION WHITHAM PROPERTY 8 CLT/T FC-1044 before we started drilling and we believe it is probable that at least part of the rise in ground water between the time we drilled our borings and the subsequent measurements was due to the irrigation. However, we further believe that this simulated the affect of future lawn irrigation when the vicinity is fully developed. Fig. 4 shows our estimate of the depth to ground water and Fig. 5 shows our estimate of the contours of the elevation of the ground water surface using our interpretation of the June and July, 1998 measurements. The behavior of the ground water at this parcel is not yet well understood. Calkins Lake is about one-half mile northwest of the parcel. Though we believe it remote, it is possible Calkins Lake influences the ground water in the vicinity of the parcel. We recommend continuing measurements of ground water depth in the borings we drilled to better understand the ground water behavior. Temporary perforated, plastic casings were placed in borings TH-2, TH-3,TH-5 and TH-7 through TH-11 to facilitate future ground water depth measurements. SITE DEVELOPMENT We have identified no geologic or geotechnical conditions that should preclude development of this parcel. The ground water is shallow, above typical basement floor depth (measured from existing, natural grade). The clays overlying the bedrock are lower strength and phases of the bedrock have lower expansion. We have discussed our opinions and recommendations regarding each of these issues below. We have also discussed site grading, pavement construction, utility installation and construction of permanent slopes for long term stability and protection against erosion. S+round Water Present plans are to build residences with basements. The ground water depths we measured in our borings are at or above typical basement depths if the existing ground surface in the proposed subdivision is not altered much during PULTE HOME CORPORATION WHITHAM PROPERTY 9 CLTR FC-1044 grading. This says something will need to be done to make basements feasible. In our opinion, two alternatives seem technically feasible, namely: a. Install a parcel wide subdrain system to lower the ground water under the parcel so it will be at least 3 feet below the basement floor elevations at the residence locations and provide foundation drains around all residences. Figure 20 shows conceptually this alternative; or b. Raise the ground surface elevations enough that basement floor elevations at the residence locations will be at least 3 feet above the depths to ground water shown on Figure 3 and provide foundation drains around all residences; or c. A combination of (a) and (b) above. Subdrain. Two complications we can visualize for the area wide subdrain are topographic constraints and Oligarchy Ditch. It will be difficult at best to drain a subdrain by gravity. This suggests lift stations may be needed to drain the subdrain. Regarding Oligarchy Ditch,the subdrain will tend to lower the ground water elevation under the ditch also and may influence leakage from the ditch. These complications will need to be reviewed when deciding to install a parcel-wide subdrain. Additional investigation may prove needed to finally decide for and design a parcel wide subdrain. Such an investigation would be aimed at better identifying the possible sources of ground water, and measuring the permeability of the soil and bedrock to finally recommend a drain configuration and drain sizing. The parcel wide subdrain we envision will be a combination of an interceptor drain along most of the west, the north and a part of the east side of the parcel and an underdrain under all the sanitary sewer mains under the streets. The invert elevation of the interceptor, it appears to us, will be dictated by the elevation of the bedrock (Figure 5) near the midpoint of the north property boundary where the elevation is lower compared to the northwest and northeast corners. It is important that the invert of the interceptor everywhere be at least one foot below the bedrock surface but it must also be sloped from its high point to drain. The underdrain system installed under the sanitary sewer mains will supplement the interceptor and serve as an outlet for individual residence foundation drains (see "Basements" PULTE HOME CORPORATION WHITHAM PROPERTY CLT/T FC4044 10 r subsection). The underdrains should be provided with cleanouts so they can be regularly maintained. If the sewer district will not maintain underdrains, the home owners' association should be empowered to provide maintenance and be provided copies of"as-built" plans. The underdrains would be of an appropriately graded filter material surrounding a pipe. The pipe should be sized for the flow determined after the recommended ground water investigation is completed. The drain pipe should consist of smooth, perforated or slotted rigid PVC pipe laid at a grade of at least 0.5 percent. The filter material should have a cross-section of at least 2 square feet. A typical sewer underdrain detail is shown on Fig. 21. A positive cutoff collar (concrete) should be constructed around the sewer pipe and underdrain pipe immediately downstream of the point the underdrain pipe leaves the sewer trench. Solid pipe should be used down gradient of this collar to the daylight or collection point. The underdrain should be designed to discharge to a gravity outfall or to a series of lift stations. If lift stations or any system that could temporarily fail are used, we recommend a check valve be placed on the underdrain service to each house, and cutoff collars be constructed to prevent backflow through the filter gravels. We further recommend backup pumps for each lift station pump and backup, on-site, electricity generators that will automatically turn on when the subdivision power fails. Oligarchy Ditch. The effect of the parcel subdrain on Oligarchy Ditch needs to be investigated during the recommended ground water investigation. Should the study show a probable increase in leakage from the ditch we believe the ditch will need to be lined. Several liners are available but we believe the more feasible is probably Portland cement concrete. This needs to be confirmed during the investigation to determine if the ditch will be affected by the subdrain. Grading Overlot grading should be engineered fill that is compacted. Areas to receive grading fill need to be cleared, grubbed and stripped of all vegetation, organic PULTE HOME CORPORATION WHITHAM PROPERTY CLT7T PC-1044 11 topsoil and other deleterious matter. The cleared, grubbed and stripped materials should be discarded or placed in areas that will never be under structures, utilities, sidewalk, curbs and gutters, driveways or pavements. After stripping, the resulting subgrade should be scarified, moisture conditioned to 0 to 3 percent above optimum and compacted to obtain a firm platform for fill placement. Our borings indicate some soft soils exist on the parcel. Where soft soils are encountered, they can be stabilized prior to placing fill. Stabilization of soft subgrade soils is often accomplished by removal and replacement, scarifying and drying, utilizing geosynthetics or "crowding" crushed rock into the subgrade until a firm surface is achieved. The properties of the fill will affect the performance of foundations, slab-on- grade floor and pavements. The soils from the parcel are suitable for use as grading fill. Claystones should be broken down before placing as fill. If imported materials are necessary, they should consist of sandy clays that are low plastic and low expansion like the on-site clays. A sample of all soils proposed for import for fill should be submitted to our office for classification and approval prior to hauling them to the site. Fill should be placed in thin loose lifts, moisture conditioned to 0 to 3 percent above optimum moisture content and compacted to at least 95 percent of standard Proctor maximum dry density (ASTM D 698). Guide specifications for overlot grading are in Appendix A. Placement and compaction of the grading fill should be observed and tested by a representative of our firm. For the most part, the soils and bedrock at this parcel are nil to low expansive. In addition the shallow ground water appears to have "pre-wetted" and decreased the swell potential of the upper approximately 10 feet of soils and bedrock. The deeper claystone bedrock in one of our borings was moderately expansive. If the existing grades are lowered by cutting, this claystone will begin to influence structure foundation type. If possible, site grading should be planned to provide at .-. least 4 feet of nil to low expansive clays or fill above the claystone bedrock so that special foundations can be avoided. PULTE HOME CORPORATION WHITHAM PROPERTY 12 CLTrTFC-1044 Preliminary data shows that if the natural ground grades are lowered the claystone bedrock would affect the choice of foundation type for our estimated 10 percent of the parcel area. The claystone under the parcel is not steeply dipping but it is low to moderate expansion. Residences built in areas of expansive soils and bedrock are susceptible to damage from heave caused by wetting and swelling of expansive soils and bedrock. Special precautions are needed in the construction of foundations and other elements to mitigate the effects of swelling soils/bedrock. In our experience these techniques can and have reduced the damages to residences when the expansive soils/bedrock like those on this parcel get wet. Slope Stability and Erosion We observed no evidence of slope instability or significant erosion on the parcel. For the type of soils present at this parcel, we believe permanent slopes should be 3:1 (horizontal:vertical) or flatter. Surface drainage should not be allowed to sheet flow across slopes or pond at the crest of slopes. Slopes should be revegetated as soon as possible to reduce potential for erosion problems. Localized slopes enclosing retention/detention ponds should be designed by a qualified Civil Engineer with erosion control and slope stability in mind. Utility Construction The bedrock penetrated by our borings was hard to very hard and included cemented, very hard sandstone lenses. We believe most of the materials can be excavated with either heavy duty trenchers or large backhoes, however, ripping or other means may be required to loosen the cemented, bedrock lenses. Medium stiff clays and hard interbedded sandstone, claystone and siltstone are predominant. We believe the clay soils on this parcel can be classified as Type C, and bedrock as Type A or Type B based on the Occupational Safety and Health r-. Administration (OSHA) standards governing excavations. Type C soils require maximum slope inclination of 1.5:1 (horizontal:vertical), Type B soils require maximum slope inclination of 1:1 (horizontal:vertical) and Type A soils require a PULTE HOME CORPORATION WHITHAM PROPERTY 13 1 CLT/T FC4044 1-64-1 maximum slope of 3/4:1 (horizontal:vertical). The contractor's competent person on site should identify the soils encountered in excavations and refer to OSHA standards to determine appropriate slopes. Excavations deeper than 20 feet should be designed by a professional engineer. Ground water will be encountered during utility excavation. The clays and bedrock at this parcel are expected to be low to moderately permeable. Ground water seepage will be slow to moderate. We anticipate trench dewatering may be accomplished by sloping the trench bottom to collection areas where water can be removed by pumping, however large, heavy duty pumps should be anticipated. Some zones of sandier clays and more permeable sandstone bedrock may exist requiring the occasional use of well points or other means to lower ground water and allow for excavation. Water and sewer lines are usually constructed beneath paved roads. Compaction of trench backfill will have significant effect on the life and serviceability of pavements. We recommend trench backfill be placed in thin, loose lifts, moisture conditioned to 0 to 3 percent above optimum moisture content and compacted to at least 95 percent of standard Proctor maximum dry density (ASTM D 698). The placement and compaction of fill and backfill should be observed and tested by a representative of our firm during construction. Pavements The surficial soils found on-site have fair to poor pavement support qualities. For preliminary planning purposes, we suggest assuming 6 inches of full depth asphaltic concrete paving will be needed for local residential streets. A section using asphaltic concrete and compacted base course would be 4 inches of asphaltic concrete over 8 inches of base course. Thicker pavements will be needed for collector and arterial streets. A subgrade investigation and pavement design should be performed after overlot grading is complete. PULTE HOME CORPORATION WHITHAM PROPERTY CLT/T FC-4044 14 L�J The softer clays we found may rut and "pump" during subgrade preparation. Should this occur they can be stabilized using lime or by "crowding" crushed rock into the soft soils until they firm and will support construction equipment. Geofabric can also be used. RESIDENTIAL CONSTRUCTION CONSIDERATIONS Two-story residences with full basements are planned for the proposed subdivision. Ground conditions and characteristics across the parcel include very moist, medium stiff sandy clays near the surface underlain by claystone, sandstone or interbedded claystone, siltstone and sandstone bedrock. The strata at foundation level will depend upon finally selected finished grades. The following discussions are preliminary and are not intended for design or construction. After grading is completed, a detailed soils and foundation investigation should be performed on a lot specific basis. Foundations The foundations that can be used to found the proposed residences will depend upon how the parcel is graded. In our opinion, if the parcel finished grades are at or above the existing natural grades at the residence locations the residences can be founded with footings bearing on the soils/bedrock at footing elevation. Some of the residences will likely be founded with footings bearing on the natural clays and/or compacted overlot fill and others will be founded with footings bearing on the bedrock. We expect the maximum design bearing capacity for footings bearing on the clay will prove to be of the order of 1,500 pounds per square foot(psf) and the bearing capacity for footings bearing on the bedrock will prove to be of the order of 8,000 psf. It will be prudent to design all footings for a minimum dead load of the order of 30 percent of the maximum design bearing capacity. �-. A grading plan that results in finished grades lower than the existing natural ground elevation we estimate will result in needing to found at least 10 percent of the residences with drilled piers penetrating the bedrock. We expect the maximum end PULTE HOME CORPORATION WHITHAM PROPERTY 15 CLTlr FC-1044 bearing pressure for piers will prove to be of the order of 35,000 psf and the side shear value in the bedrock 10 percent of the maximum end bearing capacity. The minimum design dead load pressure will be of the order of 1000 psf. The minimum penetration for piers into bedrock will probably prove to be 6 feet, the minimum length for piers will probably prove to be 16 feet and 4-inch void spaces will likely be needed under grade beams between the piers. There is the possibility some piers will need to be cased to dewater and clean the pier holes due to the ground water found under the parcel. Slab-on-Grade and Basement Floor Construction Slabs-on-grade are typically used for basement floors on lots with soil conditions similar to this parcel. Our firm generally recommends structurally supported basement floors for high (4 to less than 6 percent) and very high (6 percent or greater) swell potentials. Preliminary data indicate structural basement floors will not be required on any of the lots on this parcel. Site grading cuts in areas where bedrock is shallowest should be avoided to keep basement floors above the bedrock or as far up in the more moist, lower swelling portions of the bedrock as possible. The following precautions will not eliminate slab-on-grade movement but will reduce the potential for damage due to movement of slabs: 1. Isolation of the slabs from foundation walls, columns or other slab penetrations; 2. Voids under interior partition walls to allow for slab movement without transferring the movement to the structure; 3. Flexible water and gas connections to allow for slab movement. A flexible duct above furnaces may also be required; and 4. Proper surface grading and foundation drain installation to reduce water availability to slab subgrade and foundation soils. r PULTE HOME CORPORATION WHITHAM PROPERTY CLT/T FC-1044 16 Basements Free ground water was shallow in our borings drilled during this investigation and will affect basement construction. Control of ground water levels below basements will be needed for basements. A parcel-wide subdrain is discussed above. Foundation drains will be needed around all crawl spaces and basements. This requirement will hold regardless of the finally selected finished grade elevations. We suggest foundation drains be connected to the sewer underdrain system with a piped connection. A typical detail for a connection from the foundation drain to the underdrain is provided on Fig. 21. Sump pits with pumps should be installed as a backup if underdrains do not perform as intended. We discussed drainage systems for control of ground water under the parcel and the possible limiting affects of ground water conditions on providing basements for the proposed residences. Typically, foundation drains are comparatively shallow relative to the bottom of a slab-on-grade floor or the floor of a crawl (air) space under a structural floor. Where the ground water is likely to within 3 or 4 feet of a floor we recommend an underslab gravel layer and deeper foundation drains. Further, we recommend basement floors be at least 3 feet above the anticipated ground water surface. If a parcel-wide subdrain is installed the 3 feet should be measured from the ground water level that will result from the subdrain design. Basement excavations that penetrate the ground to near the ground water surface may require dewatering and the soils in the excavation floor may be soft. Should soft soils be encountered, the excavation floor may need to be stabilized so it will support traffic. Basement and crawl space walls will be subjected to lateral pressure from the wall backfill. Such walls should be designed to resist the higher "at rest" lateral earth pressure because they are not free to rotate and develop the internal strength of the backfill. We expect the backfill will be the clays from required excavations for PULTE HOME CORPORATION WHITHAM PROPERTY 1 T CLT/T PC-1044 L the residences and suggest assuming for preliminary designs an equivalent fluid density of 50 pcf for backfill in design calculations. SURFACE DRAINAGE The performance of improvements in this development will be influenced by surface drainage. When developing an overall drainage scheme, consideration should be given to drainage around each residence. Drainage should be planned so that surface runoff is directed away from foundations and is not allowed to pond adjacent to or between structures or over pavements. We recommend slopes of at least 12 inches where possible in the first 10 feet for the areas surrounding all residences or buildings. In areas between houses which are less than 20 feet apart, the slope should be at least 10 percent toward the swale used to convey water out of these areas. Slopes marginally less steep than those recommended may be necessary at the back of the houses on lots which drain to the front. Roof downspouts and other water collection systems should discharge well beyond the limits of all backfill around structures. Proper control of surface runoff is also important to control the erosion of surface soils. Sheet flow should not be directed over unprotected slopes. Water should not be allowed to pond at the crest of slopes. Permanent slopes should be revegetated to reduce erosion. Attention should be paid to compact the soils behind curb and gutter adjacent to streets and parking areas and in utility trenches during development. If surface drainage between preliminary development and construction phases is neglected, performance of the roadways, flatwork and foundations will be poor. When considering landscaping of common areas, we recommend the use of xeriscaping which requires little initial or long-term watering. PULTE HOME CORPORATION WHITHAM PROPERTY CLT/T FC-1044 18 CONCRETE We measured soluble sulfate concentrations for representative samples of the subsoils from our borings. Sulfate concentrations from this parcel ranged from 0.10 to 3.00 percent. Based on ACI standards, water soluble sulfate concentrations in this range represent a severe to very severe sulfate exposure. ACI recommends using a cement meeting the requirements for Type V (sulfate resistant) cement, with a maximum water-cement ratio of 0.45 and air entrainment of 5 to 7 percent for concrete exposed to soils with this level of soluble sulfates. We understand Type V cement may not be readily available locally. As an alternative, we believe cement which meets ASTM C 150 Type II requirements and contains 20 percent fly ash can be used to provide similar resistance. The fly ash should meet ASTM C 618 Class F requirements. The fly ash can be reduced to 15 percent in cold weather months. LIMITATIONS AND ADDITIONAL INVESTIGATIONS We based the discussions in this report on our understanding of the proposed development and residences, conditions disclosed by exploratory drilling, review of geologic maps,site observation, results of our laboratory tests,engineering analysis of field and laboratory data and our experience. The criteria presented in this report are intended for aid in purchase decisions and preliminary planning purposes. Future geotechnical engineering investigations and analysis are required to formulate design criteria for a parcel-wide subsurface drain system to lower ground water, geotechnical design criteria for residence, foundations and floors, and street pavement sections. Our borings were widely spaced. In our opinion, the boring pattern provided us the needed picture of the underground to provide the above report intended to aid Pulte Home Corporation in their purchase decision regarding the parcel that is the subject of this report and the planning and development of this parcel. Variations between the borings will occur. We recommend continuing to measure the depth to ground water in the borings we drilled to better understand the behavior of the ground water under the parcel and to guide future decisions regarding installing and then designing a parcel-wide, subsurface drain to lower the ground water under the parcel. A representative of our firm should be present during site grading and utility trench backfilling to observe fill placement and perform compaction tests. Detailed PULTE HOME CORPORATION WHITHAM PROPERTY 1 g CLT/T FC-1046 1 investigations should be performed for design of residence foundations and slab-on- grade floors and street pavement sections after overlot grading has been completed. We should review the final grading plans prior to construction to look for potential geotechnical problems. We believe this investigation was conducted in a manner consistent with that level of care and skill ordinarily used by geotechnical engineers practicing in this area at this time. No other warranty, express or implied, is made. If we can be of further service in discussing the contents of this report or analyses of the influence of subsurface conditions on the design of the proposed development, residences and streets, please call. CTL/THOMPSON, INC Howar. Perko Proje. E gineer i1t4 C, : Revie X4)0 E `P Fr. . J F . . PE- �,4; 1 E Princ'.al ANKJ. HOLLIDAY P:FJH;bl. 5 copies se t) PULTE HOME CORPORATION WHITHAM PROPERTY 20 CLTrT FC-1046 a ) )' SCALE: 1"=400' °c 6 O C P ? I II 1 IC gl l i g of ii u. �I it C HIGHWAY 119 \ COUNTY ROAD 3 12 BM VIOINo�TY MAP • • • • TH-10 TH-1 TH-4 TH-7 Q) .-- I I Q _ • TH-11 I I I • TH-8 LEGEND: 0 • • TH-5 TH-2 0 CC •TH-1 INDICATES APPFOAWTE O I I LOCATION OF E[PLORATORT J BORING a 0 J 9 TEMPORARY BENCHMARK, • TH-3 TH-6 TH-9 TeM WATER WIRY Mw MOLE • •_ (ASSUMED EL = lOO.0) TH-12 Locations of Exploratory PULTh HOW '"" Borings i Job No.FO-1044 F'10. 1 ) SCALE: 1"=400' COUNTY ROAD 3 '/2 TH-10 TH-1 TH-47 2 )-- 1 I10 LEGEND: CD I 9 TH-11 / / INDICATES OF EXPLORATORYMELON/GORY Q TH-B BORING o • TH-5 Q TH-2 (Y X13_ MDIGTES ESTIW1Bp DEPM 0 TO BEDROCK(FRT) 0 U \\ s TH- • TH-6 7_ 7Hy7g l • TH-12 Estimated Bedrock nBL.E NAME aoW'onAllCi+ Depth VoNOWA DI!•BY Job No. 6 Flp. 2 JOE NO.F104L F--- at SCA'F: 1"=400' Vag)g o o 40\/ COUITY ROAD 3 1/2 • • • TH-10 m /9TH-1 l TH-4 TH-7 r y OP S LEGEND: __ _ • TH-11 IND A1FS APPROXIMATE 0 /� •TH-1• TH-8�-141 LOCAllON OF EXPLORATORE Q / • • TH-5 , BORING CC TH-2 120 O _ INDICATES S N m _ I � ^�gs 710 —100 BEDROCK ESTIMATN Mt Iiii U 105 \\ Ji - • TH-3 • TH-8 TH— \ OO. \ TH-12 Estimated PULlE Bedrock KAM "°""E°°""°"""°" Elevation Jab No.FO-104.4 Fl0. 3 -®� E I� SCALE: 1"=400' \----( COUNTY ROAD 3 1/2 / / • TH-10 TH-1 - TH-4/ c-7 0) 4 5 4 3I }- v Q '4\ •TH-1 LEGEND: _ TH-11 CD INDICATES APPROXIMATE LOGTbN OF IXPl➢RATORY O • • TH- 8 BORING 0 TH-2 Q INDICATES ESTIMATED OEM (C —5 TO GROUND WATER (FWII _I 7._____-_,N, I O \U • TH-3 •TH-6 TH-9 `.� 8�• TH-12 Estimated Ground Water RAZE HOME CORPORATN]IJ Job Depth 4 _ ? L� SCALE: 1”=400' \:") COUNTY ROAD 3 1/2 - • H— \--Ab • TH-10 5 TH-1 TH-4 T 125 p1 100 105 110 115 120 QLEGEND: _ • TH-11 12\1\ INDICATES APPROXIMATE _ • TH 8 •TH—1 LOCATION or EXPLORATORY U TH-5 BORING O H-2 _t00 INDICATES ISTNATEO GROUND 0_ - 110 115 INDICATE-5 — FIEVAIN]N OW) GROUND 105 O 5 U 1• TH-3\ • TH-6 100\ \l • TH-12 Estimated Ground Water Elevation PULIE%w HOME � 'M" "`°" °" MM(IrAN mown No.FO-1044 FW 6 ) rV LEGEND: 130 TH-11 130- CLAY. SANDY, SILTY, MEDIUM STIFF, MOIST TO WET, BROWN (CL). (EL.=125.7) TH-12 - i (EL.=124.9) S = _ ® CLAY, SANDY, STIFF, MOIST, OLIVE, BROWN (WEATHERED 10112 50/12 CLAYSTONE). 11/12 120 :E 50/12 120- R - Z `- ' INTERBEDDED CLAYSTONE, SILTSTONE AND SANDSTONE, HARD TO VERY 25/12 _ \ HARD, SLIGHTLY MOIST, BROWN, RUST (BEDROCK). ■50/5 - CLAYSTONE, HARD TO VERY HARD, SLIGHTLY MOIST, BROWN, RUST 50112 110 ■50/2 (BEDROCK). 110- 50/11 \050/4 - SANDSTONE, VERY HARD, SLIGHTLY MOIST, BROWN (BEDROCK). w 100 505 \\250/2 100 W W LL I; SANDSTONE, CEMENTED LENSE, VERY HARD, SLIGHTLY MOIST, BROWN (BEDROCK). Fz o h DRIVE SAMPLE. THE SYMBOL 0/12 INDICATES THAT 8 BLOWS OF A ? I- Irl 140-POUND HAMMER FALLING 30 INCHES WERE REQUIRED TO DRIVE A w W 2.5 INCH D.O. SAMPLER 12 INCHES. J• 0 90 J W - V INDICATES WATER LEVEL MEASURED AT THE TIME OF DRILLING. Y INDICATES WATER LEVEL MEASURED ON JUNE 22, 1998. O 80 4 INDICATES WATER LEVEL MEASURED ON JULY 10, 1998. NOTES: 1. THE TEST HOLES WERE DRILLED ON TUNE 18 AND 19, 1998 USING A TRUCK-MOUNTED DRILL RIG AND 4-INCH DIAMETER, CONTINUOUS FLIGHT AUGER. 70 70 2. THESE LOGS ARE SUBJECT TO THE EXPLANATIONS, LIMITATIONS AND CONCLUSIONS IN THIS REPORT. 3. BORING ELEVATIONS ARE APPROXIMATE AND SURVEYED WITH RESPECT TO THE TEMPORARY BENCHMARK SHOWN ON FIG. 4. O 60 0 SUMMARY LOGS OF EXPLORATORY BORINGS FIG. 8 JOB NO. FC-1044 V 130 130 TH-4 _ (EL.='119) 120 120 / _ / /,]6/12 - / ,J 4/12 TH-5 - _ 2- / (EL.=110.6) - 110 ,\]50/6 110 I 8/12 TH-2 4=r'■8/12 - (EL. =102.8) `7 50/6 - \ TH-1 '•50/12 f- E- 100 (EL.=98.4) _�� 3/12 TH-3 k 50/7 \ \ 100 w w w _ ,. 14/12(EL.=95.6) 2 . 50/2 - i t ,]8/12 `�/\ z z = \\ 50/4 _o H x]6/12 ,\\�50/8 y 12/12 I- 4 / \ 38/12 90 id w w 0 /]6/12 ,\� 50/6 • \`‘.\ \ 50/12 .•:..50/1 - �750/2 j50/12 ,\\a 50/5 _ 50/6 80 0 \ 50/6 \• 50/4 ` 50/5 , \ 50/4 \\\ _ \ 50/3 - 70 70 50/0 - 60 0 50 1 � 0 SUMMARY LOGS OF EXPLORATORY BORINGS JOB NO. FC-1044 FIG. 6 V .- TH-10 (EL. =129.2) 130 130 Y JUG/i? TH 7 — • 3/12 — (EL.=121.8) TH-8 7 — (EL.=119.3) \\ 120 I• 14/12 \•50/12 120 \ _ II 8/12 40/12 4- 50/6 \• 50/3 _ t �E 50/12 TH-9 \ \ — \ 3 (EL.=108.6) "' 110 \ = 50/6 \■50/3 110 — TH 6 \\E 50/12 / \\ — (EL.=103.9) \ x]10/12 \ \ 50/6 dr114/12 \•50/2 — \ ■ 50/6 — 7/12 \ — = H w 100 7/12 .\ 2 50/5 7 50/3 100 w i _ \\■ 50/2 Q -z z H 50/12 50/6 50/4 H0 H H �., ¢ - W w 0 50/7 50/2 90 w 50/6 50/2 - 0 50/5 80 50/1 - 70 70 0 60 f--- 0 50 SUMMARY LOGS OF EXPLORATORY BORINGS JOB NO. FC-1044 FIG. 7 1-1 • i NdMOVEMENT DUE TO z WETTING O 0 y ; O -2 to eL• -3 0-a 5 O a 01 to 10 100 APPLIED PRESSURE -KSF Sample of INTERBEDDED CLAYSTONE/SANDSTONE NATURAL DRY UNIT WEIGHT= 108 PCP From TH - 1 AT 14 FEET NATURAL MOISTURE CONTENT= 18.3 To 3 2 EXPANSION UNDER CONSTANT --PRESSURE-DUETOWETTING--- z 0 O a• _1 - X w Z -z 0 y U, w a. .3 _______ a O • -4 0.1 1.0 10 100 i^ APPLIED PRESSURE-KSF Sample of INTERBEDDED CLAYSTONESANDSTONE NATURAL DRY UNIT WEIGHT= 121 PCF From TH-2 AT 9 FEET NATURAL MOISTURE CONTENT= 12.2 Swell Consolidation JOB NO. FC-1044 Test Results FIG. 9 Lij 2 1 Z 0 O ADDIT ONAL COMPRESSION a 1 L L UNDEGLCONSTANTFIRFSSUR ___ DUE TO WETTING a , z .2 O w o a' -3 a O U -4 0 00 0.1 1.0 APPLIED PRESSURE-KSF Sample of CLAYSTONE NATURAL DRY UNIT WEIGHT= 108 PCF From TH-3 AT 4 FEET NATURAL MOISTURE CONTENT= 17.2 3 2 EXPANSION UNDER CONSTANT ____ __ _ _ __ -,PRESSURE-DUETOWETTING- -- - o O y X Z -2 O U) 1n w - De -3 _ a O , 0.1 0 10 100 APPLIED PRESSURE-KSF Sample of CLAYSTONE NATURAL DRY UNIT WEIGHT= 120 PCF From TH-3 AT 14 FEET NATURAL MOISTURE CONTENT= 12.9 % Swell Consolidation InR Mn Fr-,nag Test Results FIG. 10 H 11-1 2 EXPANSION UNDER CONSTANT PRESSURE DUE tOWETTING--- - O ° a• -1 0 Z• -2 - ----- --- ------ ----- - --- --,—•- - - - -- -- --- - F co W 0- -3 a O U -4 0.1 1.0 10 100 APPLIED PRESSURE-KSF Sample of INTERBEDDED CLAYSTONE/SANDSTONE NATURAL DRY UNIT WEIGHT= 115 PCF From TH-4 AT 9 FEET NATURAL MOISTURE CONTENT= 15.5 3 2 Z 0 Z13 ADDITIONAL COMPRESSION UNp (CONSTANT PRESSURE= X 1 D'UETO WETTING Z -2 O to a. 4 0.1 1.0 10 100 i-. APPLIED PRESSURE -KSF Sample of INTERBEDDED CLAYSTONE/SANDSTONE NATURAL DRY UNIT WEIGHT= 109 PCF From TH-4 AT 19 FEET NATURAL MOISTURE CONTENT= 13.8 Swell Consolidation Inn Nn FC_1n44 Test Results FIG. 11 I -IIli 7 5 ---- ---_------- - ------ __ ____ __ _ --------------- ------ -- - - - - - ----. 4 3 L L L 2 1 0 ADDITIONAL COMPRESSION UNDER _QON$TANT Pf ESSSIRE_DUE TO WETTIN-G__ _ _ _2 -3 ___ __ _ _ _____ _ _____________ --------- _ 2 O in-4 2 0 a X 6 0-6 Co w w O. O. O U -8 100 o 6 10 APPLIED PRESSURE -KSF Sample of WEATHERED CLAYSTONE NATURAL DRY UNIT WEIGHT= 101 PCF From TH-5 AT 4 FEET NATURAL MOISTURE CONTENT= 23.0 Swell Consolidation JOB NO- FC-1044 Test Results FIG. 12 7 6 5 _________ ______ ___ __ _----__--- --___ _ _ ____ 4 3 I t A i 2 EXPANSION UNDER CONSTANT PRESSURE DUE TO WgTTINC} _2 -3 O a X 5 "/- 0 (7)0 co w a 2 -7 0 U -6 0.1 1.0 10 100 APPLIED PRESSURE - KSF Sample of CLAY,SANDY(CL) NATURAL DRY UNIT WEIGHT= 91 PCF From TH-6 AT 2 FEET NATURAL MOISTURE CONTENT= 27.4 Swell Consolidation JOB NO. FC-1044 Test Results FIG. 13 3 2 EXPANSION UNDER CONSTANT -- VRESGURE DUE to WETTING o ° fA , • , X W • • z _2 0 y rn W • -3 a. 0 U -4 0.1 10 10 100 APPLIED PRESSURE -KSF Sample of CLAYSTONE NATURAL DRY UNIT WEIGHT= 122 PCF From TH-6 AT 9 FEET NATURAL MOISTURE CONTENT= 13.6 3 2 EXPANSION UNDER CONSTANT PRESSURE-DUETOWETTING---z ° O N X• -1 - - - Z -2 O N 1n 0- 0 4 0.1 1.0 10 100 APPLIED PRESSURE-KSF Sample of CLAYSTONE NATURAL DRY UNIT WEIGHT= 117 PCF From TH-6 AT 14 FEET NATURAL MOISTURE CONTENT= 12.8 % Swell Consolidation Ina No FC-1044 Test Results FIG. 14 � -1 3 2 EXPANSION UNDER CONSTANT TIREIJRE DUE TO WETTING O 0 , ii:x rn R' -3 2 O a 10 100 0.1 1.0 APPLIED PRESSURE -KSF Sample of CLAY, SANDY(CL) NATURAL DRY UNIT WEIGHT= 105 PCF From TH-7 AT 2 FEET NATURAL MOISTURE CONTENT= 20.5 3 2 EXPANSION UNDER CONSTANT PRESSURE-DUETOWEfTING---T - Z o O -, a Z -2 0 1n re -3 r -- a O -O _ 10 100 01 1.0 APPLIED PRESSURE -KSF Sample of INTERBEDDED CLAYSTONE/SANDSTONE NATURAL DRY UNIT WEIGHT= 121 PCF From TH-7 AT 9 FEET NATURGI MOISTURE CONTENT= 13.6 Swell Consolidation ,no ^,n ,n^^ Test Results FIG. 15 3 2 EXPANSION UNDER CONSTANT 1 ---------- - -' ------- `PRESSURE DUE TOWI=TTING- Z o T O N 2 < \Ns.:: W e 2 O h w te -3 a 5 O V 0 10 100 0.1 1.0 ,0 ,, APPLIED PRESSURE-KSF Sample of INTERBEDDED CLAYSTONE/SANDSTONE NATURAL DRY UNIT WEIGHT= 113 PCF From TH-7 AT 14 FEET NATURAL MOISTURE CONTENT= 15.7 3 2 Z 0 O y ADDITIONAL COMPRESSION Z UNPFR CONSTANT PRESSPJRR X -1 --DUE-TO-WETTING W Z0 -z 7) in a 2 0 O A 01 1.0 10 100 APPLIED PRESSURE-KSF Sample of SANDSTONE NATURAL DRY UNIT WEIGHT= 107 PCF From TH-8 AT 4 FEET NATURAL MOISTURE CONTENT= 15.5 Swell Consolidation ,,,- ,,,, — ,M„ Test Results FIG. 16 11 2 EXPANSION UNDER CONSTANT 1 P'RES-g0RE DUE TOWETTING- O ° z -2 N a -3 a O a 10 100 0.1 1.0 APPLIED PRESSURE-KSF Sample of CLAY,SANDY(CL) NATURAL DRY UNIT WEIGHT= 103 PCF From TH-9AT 2 FEET NATURAL MOISTURE CONTENT= 18.6 °/ 3 2 EXPANSION UNDER CONSTANT 1 PRESSURE-DUETO WETTING--- O ° w Z -2 O N rn Ce -3 O -O 0.1 1.0 10 100 APPLIED PRESSURE -KSF Sample of INTERBEDDED CLAYSTONE/SANDSTONE NATURAL DRY UNIT WEIGHT= 117 PCF From TH- 10 AT 9 FEET NATURAL MOISTURE CONTENT= 14.2 Swell Consolidation ,^n ^,n Cr, ,n44 Test Results FIG. 17 3 2 NO MOVEMENT DUE TO 'WETTING O ° X 1 Z _2 __ O fn rn W Et -3 a. O -4 0.1 1.0 10 100 APPLIED PRESSURE-KSF NATURAL DRY UNIT WEIGHT= 116 PCF Sample of INTERBEDDED CLAYSTONE/SANDSTONE NATURAL MOISTURE CONTENT= 13.9 i From TH- 10 AT 14 FEET 3 2 NkO A(1QVEMENT DUE TO iNETT NG z a• x Z -2 O U) a O O 4 ° 100 0.1 1.0 APPLIED PRESSURE -KSF Sample of CLAYSTONE NATURAL DRY UNIT WEIGHT= 123 PCF From TH-11 AT 9 FEET NATURAL MOISTURE CONTENT= 11.9 % Swell Consolidation ,eNn , r„ ,r1^A Test Results FIG. 18 • L J 3 2 EXPANSION UNDER CONSTANT --- P RES-S IJ RE DUE TO WETTING - oz 0 to a Z .z - - - - -- - O fA f!7 Q -3 O 4 10 100 0.1 1.0 APPLIED PRESSURE-KSF ' a- NATURAL DRY UNIT WEIGHT= 109 PCF Sample of CLAYSTONE From TH- 11 AT 14 FEET NATURAL MOISTURE CONTENT= 19.8 3 2 EXPANSION UDDER CONSTANT 1 ,-- PRESSURE-DUETOWETING---T - Z o O . • Z -2 O U) y L1.1 C- OU -4 _ to 100 0.1 1.0 APPLIED PRESSURE-KSF Sample of INTERBEDDED CLAYSTONE/SANDSTONE NATURAL DRY UNIT WEIGHT= 117 PCF From TH- 10 AT 9 FEET NATURAL MOISTURE CONTENT= 14.2 Swell Consolidation Test Results FIG. 19 ino ton Cl"_1(IAA ) IliNO SCALE Z 5 o hi CONNECT UNDERDRAIN SERVICE TO FOUNDATION DRAIN FIRST FLOOR STREET BASEMENT CRAWL SANITARY SEWER SERVICE - TOP OF BASEMENT - a SANITARY SEWER MAIN \ FLOOR 3' MM YRawl Sa wSon" '1/2 `� ,'t: V MIN aynum Sloes - - �- 'y FIRST FLOOR -UNDERDRAI IN UNDERDRAIN SERVICE --- BOTTOM OF EXCAVATION GROUNDWATER SURFACE VARIES. FOR POSSIBLE STRUCTURAL eaelmnl ACTUAL GROUND WATER SURFACE MUST BASEMENT FLOOR I--- BE CONFIRMED AFTER UNDERDRAIN ---r\ ° Cheek :� SYSTEM IS INSTALLED. M K Deaa°Vaeglaa ••: "I ° SLAB-ON-GRADE OR STRUCTURAL (yam^♦' `_ ., =r,T FLOOR DEPENDING ON DESIGN 21,... ^ r- ''"., '.. `r `-:.l. Of Eixavatlon a3 c I•.... Draln Nahml\ 51 pipe `Sons 0 w Cut-off Collar "1 1 p) 1 m = r N O L J ,--, • \SANTARY SEWER 4" PERFORATED CORRUGATED POLYETHYLENE-\\ 0 PIPE (ASTM F 405) CONNECTION TO } RESIDENCE e- IJl FOUNDATION DRAIN I • PROVIDE •; " '�'r MIRAFI 140N 6"MIN ` '' .6"MIN. i- A,, 6"MI ' 4e • • e A ..:n.- „ le -4" .4.. PVC PERFORATED SUBDRAIN PIPE SIZE VARIES SPECIFIED TRENCH 3/8" PERFORATIONS AT 5", WASHED ROCK WIDTH 2 ROWS AT 60' FROM VERTICAL PVC PIPE AND FITTINGS MAXIMUM SIZE: 1" CONFORMING TO ASTM D 3034, LESS THAN 3% PASSING SDR 35 THE NO. 200 SIEVE NOTE: NOT TO SCALE I r Sanitary Sewer g. Main InrInrdrain - - - JOB NO. FC-1044 TABLE I SUMMARY OF LABORATORY TEST RESULTS NATURAL ATTERBERG LIMITS UNCONFINED SOLUBLE PASSING BORING DEPTH NATURAL DRY SWELL` LIQUID PLASTICITY COMPRESSIVE SULFATE NO.200 SOIL TYPE MOISTURE DENSITY LIMIT INDEX STRENGTH CONTENT SIEVE (ft) (%) (Pcf) (%) (%) (%) (psf) (%) (%) TH-1 4 24.7 111 34 21 _ 67 CLAY, SANDY(CL) TH-1 9 27.8 91 CLAY, SANDY (CL) TH-1 14 18.3 108 0.0 INTERBEDDED CLAYSTONE/SANDSTONE TH-2 4 21.3 106 0.1 CLAY, SANDY (CL) TH-2 9 12.2 121 0.9 INTERBEDDED CLAYSTONE/SANDSTONE TH-3 2 21.2 105 WEATHERED CLAYSTONE TH-3 4 17.2 108 -0.1 CLAYSTONE TH-3 9 33.3 101 42 25 96 CLAYSTONE TH-3 14 12.9 120 0.4 CLAYSTONE TH-4 9 15.5 115 0.2 INTERBEDDED CLAYSTONE/SANDSTONE TH-4 19 13.8 109 -0.1 INTERBEDDED CLAYSTONE/SANDSTONE TH-5 4 23.0 101 -0.1 WEATHERED CLAYSTONE TH-6 2 27.4 91 0.2 CLAY, SANDY (CL) TH-6 9 13.6 122 0.6 CLAYSTONE TH-6 14 12.8 117 0.4 CLAYSTONE _ TH-7 2 20.5 105 0.2 CLAY, SANDY (CL) J TH-7 4 23.5 101 CLAY, SANDY (CL) TH-7 9 13.6 121 0.5 INTERBEDDED CLAYSTONE/SANDSTONE TH-7 14 15.7 113 0.5 INTERBEDDED CLAYSTONE/SANDSTONE TH-8 4 15.5 107 -0.1 SANDSTONE TH-9 2 18.6 103 0.2 CLAY, SANDY (CL) TH-9 4 19.3 103 CLAY, SANDY (CL) TH-9 14 16.2 31 6 40 INTERBEDDED SILTSTONE/SANDSTONE TH-10 4 28.6 39 25 77 CLAY, SANDY (CL) TH-10 9 14.2 117 0.2 INTERBEDDED CLAYSTONE/SANDSTONE TH-10 14 13.9 116 0.0 INTERBEDDED CLAYSTONE/SANDSTONE TH-11 2 24.2 100 CLAY, SANDY (CL) TH-11 4 29.5 92 3.0 CLAY, SANDY (CL) TH-11 9 11.9 123 0.0 CLAYSTONE TH-11 14 19.8 109 2.0 CLAYSTONE " - Swell due to wetting at an applied pressure of 1,000 psf. Negative values indicate consolidation. PAGE 1 OF 2 JOB NO. FC-1044 TABLE I SUMMARY OF LABORATORY TEST RESULTS • NATURAL ATTERBERG LIMITS UNCONFINED SOLUBLE PASSING BORING DEPTH NATURAL DRY SWELL* LIQUID PLASTICITY COMPRESSIVE SULFATE NO. 200 SOIL TYPE MOISTURE DENSITY LIMIT INDEX STRENGTH CONTENT SIEVE (ft) (%) (pcf) (%) (%) (%) (psf) 1%) (%) TH-11 19 12.5 125 36 19 - 73 'CLAYSTONE TH-12 19 16.8 105 0.0 INTERBEDDED CLAYSTONE/SANDSTONE * -Swell due to wetting at an applied pressure of 1,000 psf. Negative values indicate consolidation. PAGE 2 OF 2 APPENDIX A r GUIDE SITE GRADING SPECIFICATIONS WHITHAM PROPERTY NORTHEAST OF COLORADO HIGHWAY 119 AND COUNTY ROAD NO. 3 1/2 WELD COUNTY, COLORADO PULTE HOME CORPORATION WHITHAM PROPERTY CLT/T FC-1044 es- GUIDE SITE GRADING SPECIFICATIONS WHITHAM PROPERTY WELD COUNTY, COLORADO 1. DESCRIPTION This item shall consist of the excavation, transportation, placement and compaction of materials from locations indicated on the plans, or staked by the Engineer, as necessary to achieve preliminary street and overlot elevations. These specifications shall also apply to compaction of materials that may be placed outside of the project. 2. GENERA) The Soils Engineer shall be the Owner's representative. The Soils Engineer shall approve fill materials, method of placement, moisture content and percent compaction, and shall give written approval of the completed fill. 3. CLEARING JOB SITE The Contractor shall remove all trees, brush and rubbish before excavation or fill placement is begun. The Contractor shall dispose of the cleared material to provide the Owner with a clean, neat appearing job site. Cleared material shall not be placed in areas to receive fill where the material will support structures of any kind. 4. SCARIFYING AREA TO BE FILLED All topsoil and vegetable matter shall be removed from the ground surface upon which fill is to be placed. The resulting surface shall then be plowed or scarified until the surface is free from ruts, hummocks or other uneven features which would prevent uniform compaction by the equipment to be used. 5. COMPACTING AREA TO BE FILLED After the foundation for the fill has been cleared and scarified, it shall be disked or bladed until it is free from large clods, brought to the proper moisture content, (0 to 3 percent above optimum) and compacted to obtain a firm platform for fill placement. 6. FILL MATERIALS Fill soils shall be free from vegetable matter or other deleterious substances, and shall not contain rocks having a diameter greater than six (6) inches. Fill materials shall be obtained from cut areas shown on the plans or staked in the field by the Engineer or imported to the parcel. Concrete, asphalt, and other deleterious materials or debris shall not be used as fill. Import materials shall be similar to on site soils. PULTE HOME CORPORATION WHITHAM PROPERTY A_1 CLT/T PC-1044 7. MOISTURE CONTENT Fill materials shall be moisture treated to within 0 to 3 percent above optimum moisture content as determined by the Standard Proctor Compaction Test (ASTM D 698). Sufficient laboratory compaction tests shall be made to determine the optimum moisture content for the various soils encountered in borrow areas or imported to the parcel. The Contractor may be required to add moisture to the excavation materials in the borrow area if, in the opinion of the Soils Engineer, it is not possible to obtain uniform moisture content by adding water on the fill surface. The contractor will be required to rake or disk the fill soils to provide uniform moisture content through the soils. The application of water to fill materials shall be made with any type of watering equipment approved by the Soils Engineer, which will give the desired results. Should too much water be added to any part of the fill, such that the material is too wet to permit the desired compaction from being obtained, rolling and all work on that section of the fill shall be delayed until the material has been allowed to dry to the required moisture content. The Contractor will be permitted to rework wet material in an approved manner to hasten its drying. 8. COMPACTION OF FILL AREAS Selected fill material shall be placed and mixed in evenly spread layers. After each fill layer has been placed, it shall be uniformly compacted to not less than 95 percent of standard Proctor maximum dry density(ASTM D 698). Fill materials shall be placed such that the thickness of loose material does not exceed 8 inches and the compacted lift thickness does not exceed 6 inches. Compaction, as specified above, shall be obtained by the use of sheepsfoot rollers, multiple-wheel pneumatic-tired rollers, or other equipment approved by the Soils Engineer for soils classifying as CL, CH, or SC. Granular fill shall be compacted using vibratory equipment or other equipment approved by the Soils Engineer. Compaction shall be accomplished while the fill material is at the specified moisture content. Compaction of each layer shall be continuous over the entire area. 9. COMPACTION OF SLOPE SURFACES Fill material shall be compacted by means of sheepsfoot rollers or other suitable equipment. Compaction operations shall be continued until slope surfaces are stable, but not too dense for planting, and there is no appreciable amount of loose soil on the slope surfaces. Compaction of slope surfaces may be done progressively in increments of three to five feet (3' to 5') in height or after the fill is brought to its total height. Permanent fill slopes shall not exceed 3:1 (horizontal:vertical). PULTE HOME CORPORATION WHITHAM PROPERTY A-2, CLT/T FC-1044 10. DENSITY TESTS Field density tests shall be made by the Soils Engineer at locations and depths of his choosing. Where sheepsfoot rollers are used, the soil may be disturbed to a depth of several inches. Density tests shall be taken in compacted material below the disturbed surface. When density tests indicate the density or moisture content of any layer of fill or portion thereof is below that required, the particular layer or portion shall be reworked until the required density or moisture content has been achieved. Observation by the Soils Engineer shall be full time during the placement of fill and compaction operations so that they can declare the fill was placed in general conformance with specifications. All inspections necessary to test the placement of fill and observe compaction operations will be at the expense of the Owner. 11. COMPLETED PRELIMINARY GRADES All areas, both cut and fill, shall be finished to a level surface and shall meet the following limits of construction: A. Overlot cut or fill areas shall be within plus or minus 0.2 of one /^^ foot. B. Street grading shall be within plus or minus 0.1 of one foot. The civil engineer, or duly authorized representative, shall check all cut and fill areas to confirm that the work is in accordance with the above limits. 12. SUPERVISION AND CONSTRUCTION STAKING All construction staking will be provided by the Civil Engineer or his duly authorized representative. Initial and final grading staking shall be at the expense of the owner. The replacement of grade stakes through construction shall be at the expense of the contractor. 13. SEASONAL LIMITS No fill material shall be placed, spread or rolled while it is frozen, thawing, or during unfavorable weather conditions. When work is interrupted by heavy precipitation,fill operations shall not be resumed until the Soils Engineer indicates the moisture content and density of previously placed materials are as specified. 14. NOTICE REGARDING START OF G�DING The contractor shall submit notification to the Soils Engineer and Owner advising them of the start of grading operations at least three (3) days in advance of the starting date. Notification shall also be submitted at least 3 days in advance of PULTE HOME CORPORATION WHITHAM PROPERTY A-3 CLT/T FC4044 any resumption dates when grading operations have been stopped for any reason other than adverse weather conditions. 15. REPORTING OF FIELD DENSITY TESTS Density tests made by the Soils Engineer, as specified under "Density Tests" above, shall be submitted progressively to the Owner. Dry density, moisture content and percentage compaction shall be reported for each test taken. 16. DECLARATION REGARDING COMPLETED FILL The Soils Engineer shall provide a written declaration stating that the parcel was filled with acceptable materials, or was placed in general accordance with the specifications. 17. DEC ARATION REGARDING GOh"PLETED GRADE ELEVATIONS A registered Civil Engineer or licensed Land Surveyor shall provide a declaration stating that the site grading has been completed and resulting elevations are in general conformance with the accepted detailed development plan. r PULTE HOME CORPORATION WHITHAM PROPERTY A-4 CLT/T FC-1044 CTUThompson, Inc. 1971 West 12th Avenue Denver, Colorado 80204 (303) 825-0777 Commercial Testing Laboratories, Inc. 22 Lipan Street Denver, Colorado 80223 (303) 825-0777 CTUThompson, Inc. 5240 Mark Dabling Blvd. Colorado Springs, Colorado 80918 (719) 528-8300 CTL/Thompson, Inc. 234 Center Dr. Glenwood Springs, Colorado 81601 (970) 945-2809 CTUThompson, Inc. 375 E. Horsetooth Rd. The Shores Office Park Building 3, Suite 100 Ft. Collins, Colorado 80525 (970) 206-9455 CTUThompson, Inc. 4718 N. Elizabeth Street, Suite C-2 Pueblo, Colorado 81008 (719) 595-1287 r GEOLOGIC AND PRELIMINARY GEOTECHNICAL INVESTIGATION LIFEBRIDGE PLANNED URBAN DEVELOPMENT SOUTHWEST OF COUNTY ROAD 26 AND COUNTY ROAD NO. 31/ WELD COUNTY, COLORADO Prepared For: LIFEBRIDGE CHRISTIAN CHURCH 10345 Ute Highway Longmont, Colorado 80504 Attention: Mr. Bruce Grinnell Job No. FC-2442 September 6, 2002 CTL/THOMPSON, INC. CONSULTING ENGINEERS 375 E. HORSETOOTH RD. • THE SHORES OFFICE PARK ■ BLDG.3, SUITE 100 ■ FT. COLLINS, CO 80525 (970)206-9455 TABLE OF CONTENTS SCOPE 1 SUMMARY OF CONCLUSIONS 1 SITE 2 PROPOSED DEVELOPMENT 3 PREVIOUS INVESTIGATION 3 SITE GEOLOGY AND GEOLOGIC HAZARDS 3 SUBSURFACE CONDITIONS 6 Slightly Sandy to Sandy Clay 7 Silty Sand 7 Sandstone Bedrock 7 Claystone Bedrock 8 Groundwater 8 SITE DEVELOPMENT 9 Groundwater 9 Grading 11 Slope Stability and Erosion 12 Utility Construction 12 Pavements 14 RESIDENTIAL CONSTRUCTION CONSIDERATIONS 14 Foundations 14 Slab-on-Grade and Basement Floor Construction 15 Basements 15 SURFACE DRAINAGE 16 CONCRETE 17 LIMITATIONS AND ADDITIONAL INVESTIGATION 18 FIG. 1 - LOCATIONS OF EXPLORATORY BORINGS FIG. 2 - SUMMARY LOGS OF EXPLORATORY BORINGS FIG. 3 - ESTIMATED BEDROCK DEPTH FIG. 4 - ESTIMATED BEDROCK ELEVATION FIG. 5 - ESTIMATED GROUNDWATER DEPTH FIG. 6 - ESTIMATED GROUNDWATER ELEVATION FIGS. 7 AND 8 - SWELL CONSOLIDATION TEST RESULTS TABLE I - SUMMARY OF LABORATORY TEST RESULTS APPENDIX A- GUIDE SITE GRADING SPECIFICATIONS LIFEBRIDGE CHRISTIAN CHURCH LIFEBRIDGE PUD CTL/T FC-2442 SCOPE This report presents the results of our geologic and preliminary geotechnical investigation for the Lifebridge Christian Church Property, located southwest of the intersection of County Road 26 and County Road No. 31/2 in Weld County, Colorado (Figure 1). The Lifebridge Christian Church plans to develop the parcel as a subdivision for single-family residences. We investigated the geology and subsurface conditions at the parcel to evaluate the affect of the geology, the soils, the bedrock and the groundwater on the proposed development of the parcel and the design and construction of residences in the proposed subdivision. This report presents the results of our field and laboratory studies and our conclusions, opinions and recommendations regarding the proposed development and the design and construction of the residences with respect to geotechnical engineering. Our conclusions are summarized below. SUMMARY OF CONCLUSIONS 1. The parcel is underlain by slightly sandy to sandy clay and claystone and sandstone bedrock. Samples of the overburden clay exhibited low swell potential when tested in the laboratory. Isolated layers of clay with moderate or high swell potential should be anticipated in some areas of the parcel. Sandstone bedrock was encountered in three of our seven borings at depths ranging from approximately 8 to 22 feet. Claystone bedrock was encountered in one boring at a depth of approximately 25 feet. 2. Groundwater was encountered within our borings at depths ranging from approximately 6 to 21 feet below the existing ground surface. Groundwater should be anticipated above typical basement depths in the southern portions of the site based on the current surface topography. In addition, groundwater elevations are likely to rise seasonally or in response to higher precipitation amounts in the project area. Basement floors should be placed at least 3 feet above the expected groundwater surface. LIFEBRIDGE CHRISTIAN CHURCH LIFEBRIDGE PUD 1 CTUT FC-2442 r- 3. Site grading or installation of a parcel wide subdrain system, or a combination of these methods could be used to mitigate areas of shallow water. The proposed residences will also need foundation drains. 4. The clays and sandstone bedrock at the site can be characterized as nil to low expansive. Claystone bedrock encountered at comparatively deep depths may have a moderate to high swell potential. We believe footings will be the predominate foundation type for the residences proposed for the subdivision if the final lot grades are at or above the existing natural grades. The finally selected site grading plan will determine if the foundation strata for a given residence foundation will be footings bearing on clays or footings bearing on the bedrock. The tendency for swell in the bedrock will cause the footing design criteria to include criteria for a minimum deadload for both bearing strata. 5. The natural clays and bedrock can be the subgrade for slab-on-grade basement floors. Considerations for slab-on-grade basement floors are discussed in"Slabs-on-Grade and Basement Floor Construction" subsection. 6. The natural clays are a weaker subgrade for pavements. Residential streets will probably require full-depth asphaltic concrete pavement thicknesses of the order of 6 inches(or 4 inches of asphaltic concrete over 8 inches of compacted base course) and thicker pavement sections for collector and arterial streets. 7. Control of the surface water will influence the performance of foundations, slab-on-grade floors and pavements. Surface ground contours and drainage structures must cause rapid runoff of surface water away from structures and removal of the water from the area. SITE The site (parcel) is located southwest of the intersection of County Road 26 and County Road No. 31/2 in Weld County, Colorado (Figure 1). The irregularly shaped site is bound to the south by the Great Western Railway and to the east by Weld County Road 31/2. A single residence is present at the northeast corner of the parcel. From the northeast corner of the parcel, the ground surface slopes down gradually to the south and west. No significant erosional features were observed. Surface improvements were not visible at the site. L IFEBRIDGE CHRISTIAN CHURCH 2 L IFEBRIDGE PUD CTUT FC-2442 PROPOSED DEVELOPMENT This parcel will be a single-family residential subdivision that will adjoin additional development proposed on the adjacent land to the south and east. Grading plans were not available at the writing of this report, however a plan showing the existing topography was provided by Rocky Mountain Consultants, Inc. We have assumed for this analysis the residences that will be built in the proposed subdivision will be mostly two-story wood frame structures with full basements. Typically these kinds of residences will have some stone and/or masonry veneer on the exteriors. PREVIOUS INVESTIGATION The parcel of land currently under consideration adjoins two parcels previously considered by Pulte Homes. CTUThompson, Inc. conducted geologic and preliminary geotechnical investigations for those sites. Details regarding our investigations, observations, conclusions and recommendations are presented in our reports dated August 11, 1998 (FC-1044) and November 17, 1998 (FC-1107). Information from our previous exploratory borings, laboratory testing and engineering analyses were used in preparation of this report, as appropriate. SITE GEOLOGY AND GEOLOGIC HAZARDS The parcel is located within the Colorado Piedmont section of the Great Plains physiographic province. The Piedmont is a broad erosional trench which separates the Southern Rocky Mountain from the High Plains. Mapping by R.B. Colton (USGS Map I-855-G, Geologic Map of the Boulder-Fort Collins-Greeley Area, Colorado 1978) indicates the surface of the parcel is Eolian (Qe) deposits consisting of olive-brown-gray windblown clay, silt and sand. The underlying LIFEBRIDGE CHRISTIAN CHURCH LIFEBRIDGE PUD 3 CTL/T FC-2442 bedrock consists of the Upper Transition Zone of the Pierre Shale (Kptz), which is described as interbedded sandstone and shale with hard sandstone ledges and water with high sulfate content. The thickness of the Pierre Shale is about 2,800 feet. Locally the Pierre Shale dips towards the south. However on a larger scale, we believe the general regional dip is towards the east. Our field exploration generally confirmed the conditions described by published maps and our previous reports. This section discusses geologic hazards that we believe could affect land planning and zoning. Specific requirements of Colorado House Bill 1041 "Areas and Activities of State Interest" and Colorado Senate Bill 35 "County Planning and Building Codes" are addressed. The claystone phases of the bedrock are expansive. This can result in damage to improvements or structures depending upon the characteristics of the claystone and the increase in moisture content that occurs. Engineered design of pavements, foundations, slabs-on-grade and surface drainage can mitigate the effects of expansive bedrock. The soils and bedrock under this parcel are not expected to be unusually corrosive to metal but may have sulfate concentrations that can affect concrete. Natural slopes are gentle and appear to be stable. Significant faulting and structural discontinuities are not expected in the bedrock at this site. The soil and bedrock units are not expected to respond unusually to seismic activity. The area is considered by the most recent editions of the Uniform Building Code (UBC) as Zone 1, its least active zone designation. Only minor damage to relatively new, properly designed and built residences would be expected during an earthquake. Regarding the potential for radioactive substances on the parcel, it is normal in the Front Range of Colorado and nearby eastern plains area to find significant accumulations of radon gas in poorly ventilated spaces (i.e., full-depth residential LIFEBRIDGE CHRISTIAN CHURCH LIFEBRIDGE PUD 4 CTLIT FC-2442 basements) in contact with soil or bedrock. Radon 222 gas has been shown to be a health hazard and is just one of several radioactive products with a short half-life in the chain of the natural decay of uranium into stable lead. There is no geologic property of the soils and bedrock at this parcel that would make radon gas any more likely than other areas of the Front Range of Colorado. The amount of radon gas that can accumulate in an area is a function of many factors, including the radionuclide activity of the soil and bedrock, construction methods and materials, soil gas pathways, and accumulation areas. Typical mitigation methods consist of sealing soil gas entry areas and ventilation of below-grade spaces. Radon rarely accumulates to significant levels in above-grade living spaces. The parcel does not appear to be flood prone. There are no highly- developed, incised drainages on the parcel. The very gentle topography of the parcel indicates little, if any, water would typically be expected to flow onto the parcel from outside the boundaries and there is no geologic indication of periodic flooding as evidenced by the absence of recent quaternary alluvium. Union Reservoir is adjacent to the property to the northwest and could present a hazard in the event of catastrophic storms. The erosion potential on the parcel is considered low, due to gentle slopes. The erosion potential can be expected to increase during construction, but should return to pre-construction rates or less if proper grading practices, surface drainage design and revegetation efforts are implemented. We do not believe the parcel is located above underground mines or is located in a subsidence hazard zone. The bedrock below the parcel is the Pierre Shale formation which does not contain significant coal beds. There is no evidence of past mining activities on the parcel. No economically important mineral deposits are expected on this parcel or are known to occur nearby. We do not expect ground subsidence related to natural or mining processes. LIFEBRIDGE CHRISTIAN CHURCH LIFEBRIDGE PUD 5 CTL/T FC-2442 r The borings we drilled on the parcel showed groundwater was shallow under some areas of the parcel. We believe these groundwater elevations may be deeper than normal based on the recent drought conditions in Colorado. We anticipate groundwater will be encountered above typical basement depth(measured from the existing ground surface) in some areas of the site. The development strategy for a parcel with shallow groundwater usually includes consideration of a parcel-wide subdrain, foundation drains around basements, raising the natural ground elevations with engineered fill to provide the needed distance above groundwater for basements and other mitigating measures. Very hard sandstone bedrock was encountered on the southern and western part of the property. Special excavation equipment and techniques may be needed if deep excavations are planned. No geologic hazards which would preclude the proposed development were noted on the subject tract. The shallow groundwater will require mitigation. We believe the geologic hazards can be mitigated with proper engineering design and construction practices, as discussed in this report. SUBSURFACE CONDITIONS Seven borings were drilled with a 4-inch diameter, continuous flight auger and a truck-mounted drill rig at the approximate locations shown on Figure 1. The drilling operations were observed by our field representative who logged the soils and obtained samples for laboratory testing. Graphic logs of the soils found in our borings including results of field penetration resistance tests are shown in Figure 2. Samples obtained during drilling were returned to our laboratory where they were visually classified and selected for testing. The results of our laboratory tests r are on Figures 7 through 8 and summarized in Table I. LIFEBRIDGE CHRISTIAN CHURCH LIFEBRIDGE PUD 6 CTLIT FC-2442 Slightly sandy to sandy clay overlying claystone and sandstone bedrock were penetrated by our borings. The following paragraphs provide general descriptions of the soil and bedrock types encountered. Slightly Sandy to Sandy ClaV Natural slightly sandy to sandy clay was encountered in our seven borings from the ground surface to depths ranging from approximately 6 to 22 feet deep. Swell-consolidation tests performed by wetting four samples after application of a 1,000 psf pressure indicate the samples tested had a negligible to low swell potential. Samples of the clay tested in the laboratory contained between 92 and 96 percent clay-and silt-sized particles (passing the No. 200 sieve), had liquid limits ranging from 45 to 52 percent, and plasticity indices ranging from 29 to 34 percent. The highly plastic properties of some of these samples indicates layers of clay with moderate to high swell potential are likely in localized areas on the site. The thickness and extent of such soils should be determined as part of lot specific, design level geotechnical investigations performed after site grading. Silty Sand A thin layer of silty sand was encountered underlying the overburden clay in one of the borings. The sand is non-plastic. Similar thin layers of sand should be anticipated intermixed with the sandy clays underlying the site. The silty sand is not anticipated to significantly impact project development. Sandstone Bedrock Sandstone bedrock was encountered underlying the overburden soils in three of our seven borings at depths of approximately 8, 9, and 22 feet. Samples of the sandstone tested were found to be non-plastic. The sandstone is non- LIFEBRIDGE CHRISTIAN CHURCH LIFEBRIDGE PUD 7 CTVT FC-2442 swelling and will not significantly impact foundation design. The hard to very hard sandstone may require extra effort and/or special equipment or blasting to complete deep excavations at the site particularly along the southern property boundary and near the southwest corner of the property. Contours illustrating the approximate depth to bedrock are shown on Figure 3, and the approximate elevation of the bedrock surface is shown on Fig. 4. Claystone Bedrock Claystone bedrock was encountered in one of our borings at a depth of approximately 25 feet. The claystone is anticipated to have variable swell potential. At the depth encountered, the claystone is not anticipated to significantly impact design or construction of the proposed residences. However, lenses of claystone may be encountered within the sandstone bedrock at shallower depths in other areas of the site. Contours illustrating the approximate depth to bedrock are shown on Figure 3, and the elevation of the bedrock surface is shown on Fig. 4. Groundwater Groundwater was encountered in 4 of our 7 borings at depths ranging from approximately 7 to 21 feet at the time of drilling and in all of our borings at depths of 7 to 24 feet when checked several weeks after drilling. Our investigation suggests water is generally flowing from north to south beneath the property. Based on current topography, groundwater will impact residential construction on about 30 to 40 percent of the site. Figure 5 shows our estimate of the depth to groundwater and Figure 6 shows our estimate of the elevation of the groundwater surface. We anticipate these groundwater levels may rise significantly should drought conditions in Colorado ease. s-� LIFEBRIDGE CHRISTIAN CHURCH LIFEBRIDGE PUD CTL)T FC-2442 SITE DEVELOPMENT We have identified no geologic or geotechnical conditions that should preclude development of this parcel. Geotechnical constraints we identified for the property include the following: • The groundwater is shallow in some areas of the site, above typical basement floor depth (measured from existing, natural grade); • Clay with low swell potential was encountered at the site; • Relatively shallow sandstone bedrock was encountered underlying the clay in some areas of the site. Discussions of these constraints and of site grading, pavement construction, utility installation and construction of permanent slopes for long term stability and protection against erosion are included below. Groundwater Present plans are to build residences with basements. The groundwater depths we measured in some of our borings are at or above typical basement depths if the existing ground surface in the proposed subdivision is not altered much during grading. Therefore, changes to the existing condition will be necessary to make basements feasible. In our opinion, two alternatives seem technically feasible: a. Install a parcel wide subdrain system to lower the groundwater under the parcel so it will be at least 3 feet below the basement floor elevations at the residence locations and provide foundation drains around all residences; or b. Raise the ground surface elevations enough that basement floor elevations at the residence locations will be at least 3 feet above the groundwater and provide foundation drains around all residences; or c. A combination of (a) and (b) above. LIFEBRIDGE CHRISTIAN CHURCH LIFEBRIDGE PUD 9 CTL/T FC-2442 Subdrain. Topographic constraints may complicate installation of a subdrain. Topography may not allow for gravity flow of the subdrain necessitating the use of pump stations. Additional investigation may be needed if a parcel wide subdrain is a selected alternative. Such an investigation would be aimed at better identifying the possible sources of groundwater, and measuring the permeability of the soil and bedrock to recommend a drain configuration and drain sizing. The parcel wide subdrain we envision will be an underdrain below the sanitary sewer mains that will serve as an outlet for individual residence foundation drains(see"Basements"subsection)and will help to maintain the water level below the planned basement floor elevations. The underdrains should be provided with cleanouts so they can be regularly maintained. If the sewer district will not maintain underdrains, the home owners' association should be empowered to provide maintenance and be provided copies of "as-built" plans. t"1 The underdrains would be an appropriately graded filter material surrounding a pipe. The pipe should be sized for the flow determined after the recommended ground water investigation is completed. The drain pipe should consist of smooth, perforated or slotted rigid PVC pipe laid at a grade of at least 0.5 percent. The filter material should have a cross-section of at least 2 square feet. A positive cutoff collar(concrete)should be constructed around the sewer pipe and underdrain pipe immediately downstream of the point the underdrain pipe leaves the sewer trench. Solid pipe should be used down gradient of this collar to the daylight or collection point. The underdrain should be designed to discharge to a gravity outfall or to a series of lift stations. If lift stations or any system that could temporarily fail are used,we recommend a check valve be placed on the underdrain service to each house, and cutoff collars be constructed to prevent backflow through the filter gravels. We further recommend backup pumps for each lift station pump and backup, on-site, electricity generators that will automatically turn on when the subdivision power fails. LIFEBRIDGE CHRISTIAN CHURCH LIFEBRIDGE PUD 10 CTL/T FC-2442 Grading Overlot grading should be engineered fill that is compacted under controlled conditions. Areas to receive grading fill need to be cleared, grubbed and stripped of all vegetation, organic topsoil and other deleterious matter. The cleared, grubbed and stripped materials should be discarded or placed in areas that will never be under structures, utilities, sidewalk, curbs and gutters, driveways or pavements. After stripping, the resulting subgrade should be scarified, moisture conditioned to 0 and 3 percent above optimum moisture content and compacted to obtain a firm platform for fill placement. Our borings indicate some very moist, weak soils exist on the parcel. Where such soils are encountered, they can be stabilized prior to placing fill. Stabilization of soft subgrade soils is often accomplished by removal and replacement, scarifying and drying, utilizing geosynthetics or "crowding" crushed rock into the subgrade until a firm surface is achieved. The properties of the fill will affect the performance of foundations, slab-on- grade floors and pavements. The soils from the parcel are suitable for use as grading fill. Claystone should be broken down before placing it as fill. If imported materials are necessary, they should consist of sandy clays that have low plasticity and low swell potential similar to the on-site clays. A sample of soils proposed for importing as fill should be submitted to our office for classification and approval prior to hauling them to the site. Fill should be placed in thin loose lifts, moisture conditioned to between 0 and 3 percent above optimum moisture content and compacted to at least 95 percent of standard Proctor maximum dry density (ASTM D 698). Guide specifications for overlot grading are in Appendix A. Placement and compaction of the grading fill should be observed and tested by a representative of our firm. LIFEBRIDGE CHRISTIAN CHURCH LIFEBRIDGE PUD CTLR FC-2442 11 For the most part, the soils and bedrock at this parcel have negligible to low swell potential. Deeper claystone bedrock was moderately expansive under the adjacent parcel. If the existing grades are lowered by cutting, this claystone will begin to influence structure foundation type. If possible, site grading should be planned to provide at least 4 feet of nil to low expansive clays or fill above the claystone bedrock so that deep foundations can be avoided. Residences built in areas of expansive soils and bedrock are susceptible to damage from heave caused by wetting and swelling of expansive soils and bedrock. Special precautions are needed in the construction of foundations and other elements to mitigate the effects of swelling soils/bedrock. In our experience these techniques can and have reduced the damages to residences when the expansive soils/bedrock like those on this parcel get wet. Slope Stability and Erosion We observed no evidence of slope instability or significant erosion on the parcel. For the type of soils present at this parcel, we believe permanent slopes should be 3:1 (horizontal:vertical) or flatter. Surface drainage should not be allowed to sheet flow across slopes or pond at the crest of slopes. Slopes should be revegetated as soon as possible to reduce the potential for erosion problems. Localized slopes enclosing retention/detention ponds should be designed by a qualified Civil Engineer with erosion control and slope stability in mind. Utility Construction The bedrock penetrated by our borings was hard to very hard and included cemented, very hard sandstone lenses. We believe most of the materials can be excavated with either heavy duty trenchers or large backhoes, however, ripping or �—. other means may be required to loosen the cemented, bedrock lenses. LIFEBRIDGE CHRISTIAN CHURCH LIFEBRIDGE PUD 12 CTL/T FC-2442 Medium stiff clays and hard interbedded sandstone, claystone and siltstone are predominant. We believe the clay soils on this parcel can be classified as Type C, and bedrock as Type A or Type B based on the Occupational Safety and Health Administration (OSHA) standards governing excavations. Type C soils require maximum slope inclination of 1.5:1 (horizontal:vertical), Type B soils require maximum slope inclination of 1:1 (horizontal:vertical) and Type A soils require a maximum slope of 3/4:1 (horizontal:vertical). The contractor's competent person on site should identify the soils encountered in excavations and refer to OSHA standards to determine appropriate slopes. Excavations deeper than 20 feet should be designed by a professional engineer. Groundwater will be encountered during utility excavation. The clays and bedrock at this parcel are expected to be low to moderately permeable. Groundwater seepage will be slow to moderate. We anticipate trench dewatering may be accomplished by sloping the trench bottom to collection areas where water can be removed by pumping, however large, heavy duty pumps should be anticipated. Some zones of sandier clays and more permeable sandstone bedrock may exist requiring the occasional use of well points or other means to lower groundwater and allow for excavation. Water and sewer lines are usually constructed beneath paved roads. Compaction of trench backfill will have significant effect on the life and serviceability of pavements. We recommend trench backfill be placed in thin, loose lifts, moisture conditioned between 0 and 3 percent above optimum moisture content and compacted to at least 95 percent of standard Proctor maximum dry density(ASTM D 698). The placement and compaction of fill and backfill should be observed and tested by a representative of our firm during construction. LIFEBRIDGE CHRISTIAN CHURCH LIFEBRIDGE PUD 13 CTLIT FC-2442 r-� Pavements The surficial soils found on-site have fair to poor pavement support qualities. For preliminary planning purposes, we suggest assuming 6 inches of full depth asphaltic concrete paving will be needed for local residential streets. A section using asphaltic concrete and compacted base course would be 4 inches of asphaltic concrete over 8 inches of base course. Thicker pavements will be needed for collector and arterial streets. A subgrade investigation and pavement design should be performed after overlot grading is complete. The softer clays we found may rut and "pump" during subgrade preparation. Should this occur they can be stabilized as described above so that they will support construction equipment. RESIDENTIAL CONSTRUCTION CONSIDERATIONS Two-story residences with full basements are planned for the proposed subdivision. Ground conditions and characteristics across the parcel include very moist, medium stiff sandy clays near the surface underlain by claystone, sandstone or interbedded claystone, siltstone and sandstone bedrock. The strata at foundation level will depend upon finally selected finished grades. The following discussions are preliminary and are not intended for design or construction. After grading is completed, a detailed soils and foundation investigation should be performed on a lot specific basis. Foundations The foundations that can be used to found the proposed residences will depend upon how the parcel is graded. In our opinion, if the parcel finished grades are at or above the existing natural grades at the residence locations, the residences can be founded with footings bearing on the soils/bedrock at footing LIFEBRIDGE CHRISTIAN CHURCH LIFEBRIDGE PUD 14 CTL T FC-2442 elevation. Some of the residences will likely be founded with footings bearing on the natural clays and/or compacted overlot fill and others will be founded with footings bearing on sandstone bedrock. We expect the maximum design bearing capacity for footings will prove to be of the order of 1,500 to 3,000 pounds per square foot (psf) depending on the bearing stratum. In areas where moderately to highly swelling clays or claystones are encountered at or near foundation elevations,drilled piers may be recommended. Piers will likely have maximum end bearing pressure on the order of 35,000 psf and the side shear value in the bedrock 10 percent of the maximum end bearing capacity. Typical lengths will likely be in the 20 to 25 foot range. There is the possibility some piers will need to be cased to dewater and clean the pier holes due to the ground water found under the parcel. Slab-on-Grade and Basement Floor Construction Slabs-on-grade are typically used for basement floors on lots with soil conditions similar to this parcel. Our firm generally recommends structurally supported basement floors for high (4 to less than 6 percent) and very high (6 percent or greater) swell potentials. Preliminary data indicate structural basement floors will not be required on any of the lots on this parcel. Site grading cuts in areas where bedrock is shallowest should be avoided to keep basement floors above the bedrock or as far up in the more moist, lower swelling portions of the bedrock as possible. Basements Relatively shallow groundwater was encountered in our borings in some areas of the site and will affect basement construction. Control of groundwater levels below basements will be required. A parcel-wide subdrain is discussed above. Foundation drains will be needed around basements regardless of the site grading plan. We suggest foundation drains be connected to the sewer underdrain LIFEBRIDGE CHRISTIAN CHURCH LIFEBRIDGE PUD 15 CTL/T FC-2442 system with a piped connection. Sump pits and provisions for pumps should be installed as a backup if underdrains do not perform as intended. Typically,foundation drains are comparatively shallow relative to the bottom of a slab-on-grade floor or the floor of a crawl (air) space under a structural floor. Where the groundwater is likely to be within 3 or 4 feet of a slab-on-grade floor we recommend an underslab gravel layer and deeper foundation drains. Further, we recommend basement floors be at least 3 feet above the anticipated groundwater surface. If a parcel-wide subdrain is installed the 3 feet should be measured from the groundwater level that will result from the subdrain design. Basement excavations that penetrate the ground to near the groundwater surface may require dewatering and the soils in the excavation floor may be soft. Should soft soils be encountered, the excavation floor may need to be stabilized so it will support traffic. Basement and crawl space walls will be subjected to lateral pressure from the wall backfill. Such walls should be designed to resist the higher"at rest" lateral earth pressure because they are not free to rotate and develop the internal strength of the backfill. We expect the backfill will be the clays from required excavations for the residences and suggest assuming for preliminary designs an equivalent fluid density of 50 pcf for backfill in design calculations. SURFACE DRAINAGE The performance of improvements in this development will be influenced by surface drainage. When developing an overall drainage scheme, consideration should be given to drainage around each residence. Drainage should be planned so that surface runoff is directed away from foundations and is not allowed to pond adjacent to or between structures or over pavements. We recommend slopes of at least 12 inches where possible in the first 10 feet for the areas surrounding all LIFEBRIDGE CHRISTIAN CHURCH LIFEBRIDGE PUD 16 CTUT FC-2442 residences or buildings. In areas between houses which are less than 20 feet apart, the slope should be at least 10 percent toward the swale used to convey water out of these areas. Slopes marginally less steep than those recommended may be necessary at the back of the houses on lots which drain to the front. Roof downspouts and other water collection systems should discharge well beyond the limits of all backfill around structures. Proper control of surface runoff is also important to control the erosion of surface soils. Sheet flow should not be directed over unprotected slopes. Water should not be allowed to pond at the crest of slopes. Permanent slopes should be revegetated to reduce erosion. Attention should be paid to compact the soils behind curb and gutter adjacent to streets and parking areas and in utility trenches during development. If surface drainage between preliminary development and construction phases is neglected, performance of the roadways, flatwork and foundations will be poor. When considering landscaping of common areas, we recommend the use of xeriscaping which requires little initial or long-term watering. CONCRETE We measured soluble sulfate concentrations for representative samples of the subsoils from our borings. The water soluble sulfate concentration was 0.04 percent. Sulfate concentrations ranging from 0.1 to 3.7 percent were measured on the adjacent parcels. Based on ACI standards,water soluble sulfate concentrations in this range represent a severe to very severe sulfate exposure. ACI recommends using a cement meeting the requirements for Type V(sulfate resistant)cement,with a maximum water-cement ratio of 0.45 and air entrainment of 5 to 7 percent for concrete exposed to soils with this level of soluble sulfates. We understand Type V cement may not be readily available locally. As an alternative,we believe cement which meets ASTM C 150 Type 11 requirements and contains 20 percent fly ash can LIFEBRIDGE CHRISTIAN CHURCH LIFEBRIDGE PUD 17 CTL/r FC-2442 be used to provide similar resistance. The fly ash should meet ASTM C 618 Class F requirements. The fly ash can be reduced to 15 percent in cold weather months. LIMITATIONS AND ADDITIONAL INVESTIGATIONS We based the discussions in this report on our understanding of the proposed development and residences, conditions disclosed by exploratory drilling, review of geologic maps, site observation, results of our laboratory tests, engineering analysis of field and laboratory data and our experience. The criteria presented in this report are intended for aid in purchase decisions and preliminary planning purposes. Future geotechnical engineering investigations and analysis are required to formulate design criteria for a parcel-wide subsurface drain system to lower ground water, geotechnical design criteria for residence foundations and floors, and street pavement sections. r Our borings were widely spaced. In our opinion,the boring pattern provided us the needed picture of the underground to provide the above report intended to aid in planning the development of the parcel that is the subject of this report. Variations between the borings will occur. We recommend continuing to measure the depth to ground water in the borings we drilled to better understand the behavior of the ground water under the parcel and to guide future decisions regarding installing and then designing a parcel-wide,subsurface drain to lower the ground water under the parcel. A representative of our firm should be present during site grading and utility trench backfilling to observe fill placement and perform compaction tests. Detailed investigations should be performed for design of residence foundations and slab- on-grade floors and street pavement sections after overlot grading has been completed. We should review the final grading plans prior to construction to look for potential geotechnical problems. LIFEBRIDGE CHRISTIAN CHURCH LIFEBRIDGE PUD 18 CTL/T FC-2442 We believe this investigation was conducted in a manner consistent with that level of care and skill ordinarily used by geotechnical engineers practicing in this area at this time. No other warranty, express or implied, is made. If we can be of further service in discussing the contents of this report or analyses of the influence of subsurface conditions on the design of the proposed development, residences and streets, please call. CTUTHAMPSON, INC Juan C. Sorensen, PE Project Engineer Reviewe • p0 R G `EOF PROFESS,_ t" H 10504 Cc\ 11— 33848 r MPG Thomas A. t;CPS Q c �vy Associate Engin6ev,;L eoPAS A. CX" JCS:TAC:by (6 copies sent) LIFEBRIDGE CHRISTIAN CHURCH LIFEBRIDGE PUD 19 CTLIT FC-2442 • `.-�''TH-i \ i SITE Jr Sri / TH-5 �APPROXIMATE SCALE: • • • UNION ' D RESERVOIR / • I%• VICINITY MAP ILON N TAR EA) NOSCALE TH-3 • • / TH-7 ' . �O OOVN ?PPP /. '/. '(\NO' •'/'' -�' siAS /. •TH-1 TH-4 /' •—' LEGEND : a ��,, K TH-1 INDICATES APPROXIMATE • LOCATION OF EXPLORATORY �, BORING Z Z ' %- 0 r.. .., INDICATES APPROXIMATE BOUNDARY /• ,cakrP' 3 Lj OF INVESTIGATED SITE I i #0' z I TH-2 N • w $ Locations of & Exploratory i p Borings q LIFEBRIDGE CHRISTIAN CHURCH FIGURE k JOB NO.FC-2442 �1 TH-2 TH-3 TH-4 TH-5 TH-6 ) TH-7E ) �- 966 El.4955 El.4986 EL 4969 El.4993 EL 4990 I.4972 --4995 4995 - / - / //10112 // LEGEND: -4985 7 // /,J 11/12 4985 7 CLAY,SLIGHTLY SANDY TO SANDY.MEDIUM STIFF TO STIFF,MOIST.BROWN(CL). - / // 111112 // _ / / 16/12 / / // // 11912 -'?SAND,SLIGHTLY CLAYEY.MEDIUM DENSE TO DENSE,MOIST.LIGHT BROWN TO BROWN / // // %/(SC). //112112 / - -4975 / ._ /.fl 13/12 4975- SANDSTONE,SLIGHTLY CLAYEY TO CLAYEY,MEDIUM HARD TO HARD,SLIGHTLY MOIST - / i .. 120/12 // TO MOIST,BROWN,RUST,GRAY,OCCASIONALLY WEATHERED AT THE SURFACE _ (BEDROCK). q[ // // CLAYSTONE,SLIGHTLY SANDY TO SANDY,SLIGHTLY MOIST TO MOIST,MEDIUM HARD TO / / / 19/12 III HARD,BROWN,RUST.GRAY(BEDROCK). - A16/7 = / / 4965 9/12 '120112 // 4965- DRIVE SAMPLE. THE SYMBOL 12/12 INDICATES THAT 12 BLOWS OF A 140-POUND HAMMER 112/12 //18/12 — FALLING 30 INCHES WERE REQUIRED TO DRIVE A 2.1-INCHOD.SAMPLER 12 INCHES. 08 / /715112 V WATER LEVEL MEASURED AT TIME Of DRILLING. i 5/12 2_ —4955 II ]son 1 // 4955--w _ / Z WATER LEVEL MEASURED SEVERAL DAYS AFTER DRILLING, 5/12 / z- 4/12 4 / z / Oz >_ q- //330/12 w-4945 325/12 - 4945--w 50/1 50/0 - NOTES: 50/7 - 1. THE BORINGS WERE DRILLED ON AUGUST 26,2002 USING A 4-INCH DIAMETER CONTINUOUS FLIGHT AUGER AND A TRUCK MOUNTED DRILL RIG. -4935 4935- 50/6 2. BORING LOCATIONS WERE IDENTIFIED IN THE FIELD BY A REPRESENTATIVE OF 50/4 - CTL/THOMPSON,INC. - 3. BORING ELEVATIONS WERE ESTIMATED FROM TOPOGRAPHIC SURVEY INFORMATION --4825 4925- PROVIDED BY ROCKY MOUNTAIN CONSULTANTS,INC. 4. THESE LOGS ARE SUBJECT TO THE EXPLANATIONS AND CONCLUSIONS IN THIS REPORT. -4915 4915- _ SUMMARY LOGS OF EXPLORATORY BORINGS -4905 4905- LIFEBRIDGE CHRISTIAN CHURCH FIGURE 2 JOB NO.FC-2442 I lalill • Aif' ' • PPROXIMATE SCALE: SCALE: 300' / • % •`- 25' TH-6 / TH-5 • • \ 25 / I UNION • I RESERVOIR /7 / I LEGEND : • TH-3 • I I TH-t INDICATES APPROXIMATE • LOCATION OF EXPLORATORY /� T I • BORING elf 7 I''1' .t.(FL°� ./- r-1 INDICATES APPROXIMATE rCJ- O��`-O O°uN /--/ •/ 20' L"-"J BORINGLOCATION TIN OF EXPLORATORY �Xtgt\N 20' ..0""". TH-t TH-4 t5'•—•— • •-- -10' t0'�` ESTIMATED DEPTH • en TO BEDROCK Q t5' -- 0 NOTE: THIS ESTIMATE IS BASED ON A >>- SUBJECTIVE ANALYSIS OF DRILL F HOLE DATA,AND MAY NOT - Z REFLECT LOCAL VARIATIONS. I ��N - 0 ILI 10' -•��SS• E z I TH-2 -- P co • - w Estimated Depth i to Bedrock 3 LIFEBRIDGE CHRISTIAN CHURCH FIGURE 3 p JOB NO.FC-2442 LU lair 77 • i APPROXIMATE SCALE: 1' = 300' i1/.. T�6UNION4975RES�EFRVOIR •• TH-3 4970 i I % • \965 hP� Oi h TH-7LEGEND : �ppp2 / 4 TH-1 INDICATES APPROXIMATE ppV O / LOCATION OF EXPLORATORY j\Np��p /,, 99iy. V BORING OS / TH-��y S TH-4 • v _ �. • 9vs 49'SO • n r.. ..1 INDICATES APPROXIMATE �' m LOCATION OF EXPLORATORY I 4940 • p BORING Q 0 K , ,- CONTOUR OF APPROXIMATE Z494-0-- BEDROCK SURFACE ELEVATION • �\W0P' 0 5��1 _I NOTE: THIS ESTIMATE IS BASED ON A '( w SUBJECTIVE ANALYSIS OF DRILL /� �j d'I R. REFLECT LOCAL VARIATIONS. HOLE DATA,AND MAY NOT OC Z I TH-2 • . N • x w 4 9i Approximate Elevation A LIFEBRIDGE CHRISTIAN CHURCH of Bedrock S�.Il facie !f JOB NO.FC-2442 FIGURE 4 )L If TX APPROXIMATE SCALE: • / ` 25' „,...---1. \-- -' TH-6 % TH-5 •I • ' 25' • UNION RESERVOIR • I /'• TH-3 LEGEND : • • I• TH-1 INDICATES APPROXIMATE 15' • LOCATION OF EXPLORATORY {� `� T 7JI BORING -�` J1S('I ROpO26 /' / ` . / r.. "- INDICATES APPROXIMATE G Af1E\-O GC 1‘.11.4-r( , L" "J BORNG LOCATION OF EXPLORATORY EY`\`'Z\N -/.'�T� 1 T•-4 • I 20 __ 15' £I 1 D,�` ESTIMATED DEPTH 10' r , 10' m TO GROUNDWATER O ...""..' CC NOTE: THIS ESTIMATE IS BASED ON A SUBJECTIVE ANALYSIS OF DRILL Z HOLE DATA,AND MAY NOT .•9010 0 REFLECT LOCAL VARIATIONS. \V U �g�0N -J 0 I / G\LEP z TH-2 'I• w • /. E � Estimated Depth S LIFEBRIDGE CHRISTIAN CHURCH to Groundwater k JOB NO.FC-2442 FIGURE 5 1 4r)r f ---_--I. , . . ,.. _''TH-6 APPROXIMATE SCALE: / TH-5 •Ii 1' = 300' x • / • 015 UNION • RESERVOIR / / 'kl • p •--•-------/ --- -TH-3� I • 4965 LEGEND : TH-7 ' • • JI TH-1 INDICATES APPROXIMATE { µ0p02 ./, 4960 �/ • BORING OF EXPLORATORY GON314 ./ G�E�D /'' EY,1st1N /�'TH-1 TH-4 0• /' L- INDICATES APPROXIMATE —- �\ ' • • LOCATION OF EXPLORATORY \\ BORING • co 4955 CONTOUR OF APPROXIMATE /,, —4945- GROUNDWATER SURFACE ,' re ELEVATION • Z 49Sp /,GPO O NOTE: THIS ESTIMATE IS BASED ON A 0 SUBJECTIVE ANALYSIS OF GRILL i O HOLE DATA,AND MAY NOT /''�SSµN W REFLECT LOCAL VARIATIONS. / GpFA��N z TH-2 •/ I y I x 4g45 i / w i Approximate Elevation 9i of Groundwater Surface 1 LIFEBRIDGE CHRISTIAN CHURCH FIGURE 6 JOB NO.FC-2442 3 2 1 EXPANSION UNDER ON TANT ?RESSURE DUE TO ING z o O 0 cn CI- _1 X w 0 Ce -3 a 2 0 -4 0.1 1.0 10 100 APPLIED PRESSURE-KSF Sample of CLAY,SANDY(CL) NATURAL DRY UNIT WEIGHT= 106 PCF From TH-1 AT 4 FEET NATURAL MOISTURE CONTENT= 18.4 % 3 2 1 ADDITIONAL COMPRESSION z UNDER CONS-ANT PRESSURE O DUE TO WETT,NG x -1 x z 2 0 U) w IX -3 a 2 0 O I I I I -4 0.1 1.0 10 100 APPLIED PRESSURE-KSF Sample of CLAYSTONE NATURAL DRY UNIT WEIGHT= 116 PCF From TH-2 AT 9 FEET NATURAL MOISTURE CONTENT= 16.7 Swell Consolidation Test Results FIG. 7 LIFEBRIDGE CHRISTIAN CHURCH LI--I LI] 3 2 1 0 v) EXPANSION UNDER CONSTANT PRESSURE DUE TO WETTING a _1 x z _2 O uz cc -3 2 O U -4 0.1 1.0 10 100 �..� APPLIED PRESSURE-KSF Sample of CLAY, SANDY(CL) NATURAL DRY UNIT WEIGHT= 107 PCF From TH-3 AT 9 FEET NATURAL MOISTURE CONTENT= 19.4 % 3 - - I 2 - ' EXPANSION UNDER CONSTANT FbRE°SURE DUE TO WETTING 0 - a O a x _1 w 0 -2 IX -3 a O V _4 �,..� 0.1 1.0 10 100 APPLIED PRESSURE-KSF Sample of CLAY,SANDY(CL) NATURAL DRY UNIT WEIGHT= 114 PCF From TH-6 AT 9 FEET NATURAL MOISTURE CONTENT= 14.3 % Swell Consolidation Test Results FIG. 8 LIFEBRIDGE CHRISTIAN CHURCH ) ) ) TABLE I SUMMARY OF LABORATORY TEST RESULTS NATURAL SWELL TEST DATA SOIL ATTERBERG LIMITS UNCONFINED SOLUBLE PASSING HOLE DEPTH NATURAL DRY SWELL APPLIED SUCTION LIQUID PLASTICITY COMPRESSIVE SULFATES NO.200 SOIL TYPE MOISTURE DENSITY PRESSURE VALUE LIMIT INDEX STRENGTH SIEVE (FEET) (%) (PCF) (°/0) (PSF) (pF) (%) (%) (PSF) (%) (%) . TH-1 4 18.4 106 1.5 1,000 CLAY, SANDY(CL) TH-2 4 25.1 96 45 29 92 CLAY, SLIGHTLY SANDY(CL) TH-2 9 16.7 116 -0.4 1,000 CLAYSTONE TH-3 9 19.4 107 1.0 1,000 CLAY, SANDY(CL) TH-4 9 13.7 109 NL NP 1,400 SANDSTONE _ TH-5 4 52 34 96 CLAY, SLIGHTLY SANDY(CH) _ TH-6 9 14.3 114 1.4 1,000 CLAY, SANDY(CL) TH-7 4 15.9 49 31 0.040 CLAY, SANDY(CL) LIFEBRIDGE CHRISTIAN CHURCH JOB NO. FC-2442 Page 1 of 1 r APPENDIX A GUIDE SITE GRADING SPECIFICATIONS LIFEBRIDGE PUD SOUTHWEST OF COUNTY ROAD 26 AND COUNTY ROAD NO. 3 ' WELD COUNTY, COLORADO LIFEBRIDGE CHRISTIAN CHURCH LIFEBRIDGE PUD CTU!FC-2442 r GUIDE SITE GRADING SPECIFICATIONS LIFEBRIDGE PUD WELD COUNTY, COLORADO 1. DESCRIPTION This item shall consist of the excavation, transportation, placement and compaction of materials from locations indicated on the plans, or staked by the Engineer, as necessary to achieve preliminary street and overlot elevations. These specifications shall also apply to compaction of materials that may be placed outside of the project. 2. GENERAL The Soils Engineer shall be the Owner's representative. The Soils Engineer shall approve fill materials, method of placement, moisture content and percent compaction, and shall give written approval of the completed fill. 3. CLEARING JOB SITE The Contractor shall remove all trees, brush and rubbish before excavation or fill placement is begun. The Contractor shall dispose of the cleared material to provide the Owner with a clean, neat appearing job site. Cleared material shall not be placed in areas to receive fill where the material will support structures of any kind. 4. SCARIFYING AREA TO BE FILLED All topsoil and vegetable matter shall be removed from the ground surface upon which fill is to be placed. The resulting surface shall then be plowed or scarified until the surface is free from ruts, hummocks or other uneven features which would prevent uniform compaction by the equipment to be used. 5. COMPACTING AREA TO BE FILLED After the foundation for the fill has been cleared and scarified, it shall be disked or bladed until it is free from large clods, brought to the proper moisture content, (0 to 3 percent above optimum) and compacted to obtain a firm platform for fill placement. 6. FILL MATERIALS Fill soils shall be free from vegetable matter or other deleterious substances, and shall not contain rocks having a diameter greater than six (6) inches. Fill materials shall be obtained from cut areas shown on the plans or staked in the field by the Engineer or imported to the parcel. Concrete, asphalt, and other deleterious materials or debris shall not be used as fill. Import materials shall be similar to on site soils. LIFEBRIDGE CHRISTIAN CHURCH LIFEBRIDGE PUD CTUT FC-2442 A-1 r 7. MOISTURE CONTENT Fill materials shall be moisture treated to within 0 to 3 percent above optimum moisture content as determined by the Standard Proctor Compaction Test (ASTM D 698). Sufficient laboratory compaction tests shall be made to determine the optimum moisture content for the various soils encountered in borrow areas or imported to the parcel. The Contractor may be required to add moisture to the excavation materials in the borrow area if, in the opinion of the Soils Engineer, it is not possible to obtain uniform moisture content by adding water on the fill surface. The contractor will be required to rake or disk the fill soils to provide uniform moisture content through the soils. The application of water to fill materials shall be made with any type of watering equipment approved by the Soils Engineer, which will give the desired results. Should too much water be added to any part of the fill, such that the material is too wet to permit the desired compaction from being obtained, rolling and all work on that section of the fill shall be delayed until the material has been allowed to dry to the required moisture content. The Contractor will be permitted to rework wet material in an approved manner to hasten its drying. 8. COMPACTION OF FILL AREAS Selected fill material shall be placed and mixed in evenly spread layers. After each fill layer has been placed, it shall be uniformly compacted to not less than 95 percent of standard Proctor maximum dry density (ASTM D 698). Fill materials shall be placed such that the thickness of loose material does not exceed 8 inches and the compacted lift thickness does not exceed 6 inches. Compaction, as specified above, shall be obtained by the use of sheepsfoot rollers, multiple-wheel pneumatic-tired rollers, or other equipment approved by the Soils Engineer for soils classifying as CL, CH, or SC. Granular fill shall be compacted using vibratory equipment or other equipment approved by the Soils Engineer. Compaction shall be accomplished while the fill material is at the specified moisture content. Compaction of each layer shall be continuous over the entire area. 9. COMPACTION OF SLOPE SURFACES Fill material shall be compacted by means of sheepsfoot rollers or other suitable equipment. Compaction operations shall be continued until slope surfaces are stable, but not too dense for planting, and there is no appreciable amount of loose soil on the slope surfaces. Compaction of slope surfaces may be done progressively in increments of three to five feet (3' to 5') in height or after the fill is brought to its total height. Permanent fill slopes shall not exceed 3:1 (horizontal:vertical). LIFEBRIDGE CHRISTIAN CHURCH LIFEBRIDGE PUD CTLIT FC-2442 A-2 10. DENSITY TESTS Field density tests shall be made by the Soils Engineer at locations and depths of his choosing. Where sheepsfoot rollers are used, the soil may be disturbed to a depth of several inches. Density tests shall be taken in compacted material below the disturbed surface. When density tests indicate the density or moisture content of any layer of fill or portion thereof is below that required, the particular layer or portion shall be reworked until the required density or moisture content has been achieved. Observation by the Soils Engineer shall be full time during the placement of fill and compaction operations so that they can declare the fill was placed in general conformance with specifications. All inspections necessary to test the placement of fill and observe compaction operations will be at the expense of the Owner. 11. COMPLETED PRELIMINARY GRADES All areas, both cut and fill, shall be finished to a level surface and shall meet the following limits of construction: A. Overlot cut or fill areas shall be within plus or minus 0.2 of one foot. B. Street grading shall be within plus or minus 0.1 of one foot. The civil engineer, or duly authorized representative, shall check all cut and fill areas to confirm that the work is in accordance with the above limits. 12. SUPERVISION AND CONSTRUCTION STAKING All construction staking will be provided by the Civil Engineer or his duly authorized representative. Initial and final grading staking shall be at the expense of the owner. The replacement of grade stakes through construction shall be at the expense of the contractor. 13. SEASONAL LIMITS No fill material shall be placed, spread or rolled while it is frozen, thawing, or during unfavorable weather conditions. When work is interrupted by heavy precipitation, fill operations shall not be resumed until the Soils Engineer indicates the moisture content and density of previously placed materials are as specified. LIFEBRIDGE CHRISTIAN CHURCH LIFEBRIDGE PUD A-3 CTL/T FC-2442 r 14. NOTICE REGARDING START OF GRADING The contractor shall submit notification to the Soils Engineer and Owner advising them of the start of grading operations at least three (3) days in advance of the starting date. Notification shall also be submitted at least 3 days in advance of any resumption dates when grading operations have been stopped for any reason other than adverse weather conditions. 15. REPORTING OF FIELD DENSITY TESTS Density tests made by the Soils Engineer, as specified under "Density Tests" above, shall be submitted progressively to the Owner. Dry density, moisture content and percentage compaction shall be reported for each test taken. 16. DECLARATION REGARDING COMPLETED FILL The Soils Engineer shall provide a written declaration stating that the parcel was filled with acceptable materials, or was placed in general accordance with the specifications. 17. DECLARATION REGARDING COMPLETED GRADE ELEVATIONS rte, A registered Civil Engineer or licensed Land Surveyor shall provide a declaration stating that the site grading has been completed and resulting elevations are in general conformance with the accepted detailed development plan. LIFEBRIDGE CHRISTIAN CHURCH LIFEBRIDGE PUD CTL/T FC-2442 A-4 JUL-01-2002 M0N 02: 28 PM . Ul[IRMO • • GEOLOGIC AND PRELIMINARY GEOTECHNICAL INVESTIGATION PORTION OF WHITHAM PROPERTY(NORTH HALF) SOUTHEAST OF COUNTY ROAD 26 AND COUNTY ROAD NO. 3% WELD COUNTY, COLORADO Prepared For: Pulte Home Corporation 100 Inverness Terrace East, Suite 200 Englewood, Colorado 80112 Attention: Mr. Jim Miller Job No. FC-1107 November 17, 1998 PULTE HOME CORPORATION WHRHAM PROPERTY(NORTH HALF) CLTIT FC•1107 P. 01 1/056 TABLE OF CONTENTS SCOPE 1 SUMMARY OF CONCLUSIONS 1 SITE 2 PROPOSED DEVELOPMENT 3 PREVIOUS INVESTIGATION 3 SITE GEOLOGY AND GEOLOGIC HA7ARDS 4 SUBSURFACE CONDITIONS 6 SITE DEVELOPMENT 9 Ground Water 9 Grading 11 Slope Stability and Erosion 13 UtilIty Construction 13 Pavements 14 RESIDENTIAL CONSTRUCTION CONSIDERATIONS 14 Foundations 15 Slab-on-Grade and Basement Floor Construction 16 Basements 16 SURFACE DRAINAGE 17 CONCRETE 18 LIMITATIONS AND ADDITIONAL INVESTIGATION 19 FIG. 1 - LOCATIONS OF EXPLORATORY BORINGS FIG. 2 - ESTIMATED BEDROCK DEPTH FIG. 3 - ESTIMATED BEDROCK ELEVATION FIG.4- ESTIMATED GROUND WATER DEPTH FIG. 5- ESTIMATED GROUND WATER ELEVATION FIGS. 6 THROUGH 8 -SUMMARY LOGS OF EXPLORATORY BORINGS FIGS. 9 THROUGH 16 -SWELL CONSOLIDATION TEST RESULTS FIG. 17 -GRADATION TEST RESULTS FIG. 18 -TYPICAL SEWER UNDERDRAIN DETAIL FIG. 19 -SANITARY SEWER MAIN UNDERDRAIN DETAIL TABLE I -SUMMARY OF LABORATORY TEST RESULTS APPENDIX A-GUIDE SITE GRADING SPECIFICATIONS PULTE HOME CORPORATION WHnMAM PROPERTY(NORTH HALM CLTIT FGT107 JUL-Ill-ZUUZ MU6 UZ:Zy YM A. V` r SCOPE This report presents the results of our geologic and preliminary geotechnical investigation for the north about one-half(parcel) of the Whitham Property, located southeast of the intersection of County Road 26 and County Road No. 31% in Weld County, Colorado(Fig.1). The Puite Home Corporation is considering purchase and plans to develop the parcel as a subdivision for single-family residences. We investigated the geology and subsurface conditions at the parcel to evaluate the affect of the geology,the soils,the bedrock and the ground water on the proposed development of the parcel and the design and construction of residences in the proposed subdivision. This report presents the results of our field and laboratory studies and our conclusions, opinions and recommendations regarding the proposed development and the design and construction of the residences from the geotechnical viewpoint. Our conclusions are summarized below. SUMMARY OF CONCLUSIONS 1. The ground under the parcel Is a thin to thicker(2 feet to 28 feet thick) layer of wind blown clays over sedimentary (claystone, sandstone, siltstone) bedrock. Ground water is comparatively shallow to deep (3 feet to 24 feet deep depending on location). The clays showed no tendency to swell (expansion)and slight potential for consolidation in our tests. The bedrock showed low swell In our tests. 2. The ground water depth Is above typical residence basement depth (measured from existing grade) under the south and east sides of the parcel. The parcel surface elevations could be raised using engineered fill to increase the depth to ground water from the ground surface so basement floors can be placed at least 3 feet above the expected ground water surface or a parcel wide subdrain could be Installed to lower the ground water surface to at least 3 feet below basement floors. A combination of the two alternatives might be the more feasible. Draining the subdrain system by gravity will be difficult, if possible, because of topographic constraints. This suggests lift stations might be needed to lower the ground water using a subdrain. In addition, to a form of parcel-wide subdrain the proposed residences will need foundation drains connected to the parcel-wide subdrain. PULTE HOME CORPORATION WHr(HAM PROPERTY(NORTH HALF) CM FU110T vl Low. mvo UL. L rM P. 013/056 3. A successful parcel wide subdrain will tend to lower the ground water elevation under Oligarchy Ditch which bisects the parcel near the south boundary. The affect on Oligarchy Ditch will need consideration when evaluating the decision to Install a parcel wide subdrain. 4. The clays at the site can be characterized as nil to low expansive and the bedrock as low expansive. We believe footings can be the foundations for the residences proposed for the subdivision if the final lot grades are at or above the existing natural grades. The finally selected site grading plan will determine if the foundation strata for a given residence foundation will be footings bearing on clays or footings bearing on the bedrock. The tendency for swell in the bedrock will cause the footing design criteria to include criteria for a minimum dead load for both bearing strata. Much lowering of the final grades below the existing natural grades will probably result In drilled piers as the preferred foundation. 5. The natural clays and bedrock can be the subgrade for slab-on-grade basement floors. Considerations for slab-on-grade basement floors are discussed in "Slabs-on-Grade and Basement Floor Construction" subsection. 6. The natural clays are a weaker subgrade for pavements. Residential streets will probably require full-depth asphaltic concrete pavement thicknesses of the order of 6 inches (4 Inches of asphaltic concrete over 8 inches of the compacted base course) and thicker pavement sections for collector and arterial streets. These sections could be thinned by strengthening the subgrade with lime or other strengthener. 7. Control of the surface water will Influence the performance of foundations, slab-on-grade floors and pavements. Surface ground contours and drainage structures must cause rapid runoff of surface water away from structures and removal of the water from the area. SITE The site (parcel) Is located southeast of the intersection of County Road 26 and County Road No.3% in Weld County, Colorado (Fig. 1). The parcel is currently planted with corn. From the northwest corner of the parcel, the ground surface slopes down gradually to the south and east. No significant erosional features were observed. The Improvements on the parcel are fences and a graveled road extending from the southeast corner through the middle of the parcel toward its north end. Storage tanks for oil and gas production are located near the center of the site, and PULTE NOME CORPORATION wnrtHAM►ROPERTY(NORTH HALF) CTUT FC-0107 2 JUL-01-2002 M0N 02:29 PM P. 014/056 a pipeline connects the tanks with another pipeline that trends east-west along the south property boundary. The parcel is irrigated by a series of ditches. County Road No. 3% and County Road 26 bound the parcel on the west and north, respectively. Residences are located southwest of the site across County Road 31/2. Single-family residences are completed and under construction in a subdivision to the east. Highway 119 is located approximately 1/2 mile south of the site. The subdivision to the east is graded to drain to a detention pond to the north. The ground to the south is irrigated farm land. Oligarchy Ditch Is located near the south boundary of the parcel and flows from west to east. Calkins Lake is located northwest of the parcel. The St. Vrain River/Boulder Creek confluence is south of Highway 119, about one-half mile south east of the parcel. PROPOSED DEVELOPMENT - This parcel will be a singie4amily residence subdivision that will adjoin additional development proposed on the adjacent land to the south. We have seen no grading plans as of the writing of this report. Utilities for servicing the residential lots and commercial area will be buried under the streets. We have assumed for this analysis the residences that will be built in the proposed subdivision will be mostly two-story wood frame structures with full basements. Typically these kinds of residences will have some stone and/or masonry veneer on the exteriors. PREVIOUS INVESTIGATION The parcel of land currently under consideration adjoins a 250 acre parcel previously considered by Putts Homes. CTLiThompson, Inc. conducted a geologic and preliminary geotechnical investigation at that site. Details regarding our PULTE NOME CORPORATION WMITHAM PROPERTY(NORTH MAL?) CTL./T PC-1707 .wu ,,. LUUL mvn UL.DU rM P. 015/050 investigations, observations, conclusions and recommendations are presented in our report no. PC-1044, dated August 11. 1938. Information from our previous exploratory borings, laboratory testing and engineering analyses were used in preparation of this report, as appropriate. The locations of the previously considered site and three of our exploratory borings for that investigation are shown on Fig. 1 (attached). Exploratory borings for this Investigation are numbered sequentially following those of the previous Investigation, and elevations are referred to the same temporary benchmark to facilitate comparisons between the two projects. SITE GEOLOGY AND GEOLOGIC HAZARDS The parcel is located within the Colorado Piedmont section of the Great Plains . physiographic province. The Piedmont is a broad erosional french which separates the Southern Rocky Mountain fromthe High Plains. Mapping by R.B. Colton (USGS Map 1-855-G, Geologic Map of the Boulder-Fort Collins-Greeley Area, Colorado 1978) Indicates the surface of the parcel is Eolian (Cie) deposits consisting of olive-brown- gray windblown clay, silt and sand. The underlying bedrock consists of the Upper Transition Zone of the Pierre Shale (Kptz), which is described as Interbedded sandstone and shale with hard sandstone ledges and water with high sulfate • content. The thickness of the Pierre Shale is about 2,800 feet. We believe the Pierre Shale dips gently to the east in the area of the parcel. Our field exploration generally confirmed the conditions described by published maps. This section discusses geologic hazards that we believe could affect land planning and zoning. Specific requirements of Colorado House Bill 1041 "Areas and Activities of State Interest" and Colorado Senate Bill 35 "County Planning and Building Codes"are addressed. The claystone phases of the bedrock are expansive. This can result in more or less damage to improvements or structures depending upon the characteristics of the claystones and the increase in moisture that occurs. Engineered design of POLTE HOME CORPORATION WHITHAM PROPERTY(NORTH HALF) CTLR PC4107 4 JUL-01-2002 M0N 02:30 PM P. 016/056 pavements, foundations, slabs-on-grade and surface drainage can mitigate the effects of expansive bedrock. The soils and bedrock under this parcel are not expected to be unusually corrosive to metal but may have sulfate concentrations that can affect concrete. Natural slopes are gentle and appear to be stable. Significant faulting and structural discontinuities are not expected in the bedrock at this site. The soil and bedrock units are not expected to respond unusually to seismic activity. The area is considered by the most recent editions of the Uniform Building Code (UBC) as Zone 1, its least active zone designation. Maximum bedrock accelerations at 4 to 7.5 percent of gravity are probable during major earthquakes in the area. Only minor damage to relatively new, properly designed and built residences would be expected. Regarding the potential for radioactive substances on the parcel, it is normal in the Front Range of Colorado and nearby eastern plains area to find significant accumulations of radon gas in poorly ventilated spaces (i.e., full-depth residential basements) in contact with soil or bedrock. Radon 222 gas has been shown to be a health hazard and is just one of several radioactive products with a short half-life in the chain of the natural decay of uranium into stable lead. There is no geologic property of the soils and bedrock at this parcel that would make radon gas any more likely than other areas of the Front Range of Colorado. The amount of radon gas that can accumulate in an area is a function of many factors, including the radionuclide activity of the soil and bedrock, construction methods and materials, soil gas pathways, and accumulation areas. Typical mitigation methods consist of sealing soil gas entry areas and ventilation of below-grade spaces. Radon rarely accumulates to significant levels In above-grade living spaces. The parcel does not appear to be flood prone. There are no highly-developed, incised drainages on the parcel.The very gentle topography of the parcel indicates little, if any, water would be expected to flow onto the parcel from outside the boundaries and there is no geologic indication of periodic flooding as evidenced by the absence of recent quaternary alluvium. The erosion potential on the parcel is considered low, due to gentle slopes. The erosion potential can be expected to PULTE NOME CORPORATION WHITMAN PROPERTY(NORTH HALFI S C LJT FC-110T P. 011/056 increase during construction, but should return to pre-construction rates or lass if proper grading practices, surface drainage design and revegetatlon efforts are implemented. We do not believe the parcel is located above underground mines or is located in a subsidence hazard zone. The bedrock below the parcel is the Pierre Shale formation which does not contain significant coal beds. There Is no evidence of past mining activities on the parcel. No economically important mineral deposits are expected on this parcel or are known to occur nearby. We do not expect ground subsidence related to natural or mining processes. The borings we drilled on the parcel showed ground water was shallow under the parcel. It was above typical basement depth (measured from the existing ground surface). The development strategy for a parcel with shallow ground water usually Includes consideration of a parcel-wide subdraln, foundation drains around basements, raising the natural ground elevations with engineered fill to provide the needed distance above ground water for basements and probably other mitigating measures. No geologic hazards which would preclude the proposed development were noted on the subject tract. The shallow ground water will require attention. We believe the geologic hazards can be mitigated with proper engineering design and construction practices, as discussed in this report. SUBSURFACE CONDITIONS Clays and sands overlying sedimentary, interiayered claystone, sandstone and slitstone; claystone; and sandstone bedrock were penetrated by the 9 borings we drilled to Investigate the parcel subsurface and the 3 borings for our report no. FC-1044. The approximate boring locations are shown on Fig. 1 and are labeled PULTE HOME CORPORATION WNITNAM PROPERTY(NORTH HALF) CTLIT PC-11n7 a JUL-01-2002 MON 02: 30 PM P. 018/056 TH-10 through TH-21. Our borings were drilled with a 4-Inch diameter, continuous flight auger and a truck-mounted drill rig. The drilling operations were observed by our field representative who logged the soils and obtained samples for laboratory testing. Graphic logs of the soils found in our borings including results of field penetration resistance tests are shown in Figs. B through 8. Samples obtained during drilling were returned to our laboratory where they were visually classified and selected for testing. The results of our laboratory tests are on Figs. 9 through 17 and summarized in Table I. F_i11. Two of our borings,TH-14 and TH-16, contained approximately 1 foot of man-placed fill that consists of clayey sand and gravel mixed with sandy, silty clays. The fill is base course placed on and adjacent to an existing road on the property. Clays. The upper subsoils found in our borings generally consisted of very moist, medium stiff, sandy clay that was at depths of 2 to 28 feet. The clays are comparatively weak so foundations bearing on the clays will need to be designed for lower bearing pressures. We selected several samples of the clays for swell- consolidation tests. The samples consolidated when wetted under an applied load of 1,000 psf; as shown in Figs. 9 through 16. We believe the majority of the clays possess nil to low expansion potential. The majority are more likely compressible because they are wind blown (lower natural density) and have higher moisture contents.The clay samples tested had moisture contents of 16 to 29 percent, liquid limits of 30 to 39 percent, plasticity indices of 12 to 25 percent, and contained 83 percent silt and clay size particles (passing No.200 sieve). Sand- One of our borings, TH-21, penetrated 3 feet of moist, medium dense, silty sand at a depth of 10 feet. This strata was identified near the northeast corner of the site and suggests a change in the subsurface toward the northeast. PULTE HOME CORPORATION WHRHAM PROPERTY(NORTH HALF) 7 CTLR PC-1107 VL.JI P. 019/056 Bedrock. The bedrock found In our borings underlying the clays at 2 to 28 feet deep was claystone, sandstone and interbedded claystone, slitstone and sandstone. The interbedded bedrock was predominant, however, the site geology Indicates discontinuous lenses of bedrock may be cemented. A cemented sandstone lense was encountered in boring TH-12 at about 8 feet. Our estimated depth to bedrock contours are shown on Fig.2 and our estimated bedrock surface elevation contours are shown on Fig.3. The upper 1 to 2 feet of the bedrock in 2 of the borings was weathered to a stiff clay. The underlying bedrock was hard to very hard. The weathered claystone,sandstone,and interbedded claystone,slltstone and sandstone bedrock is judged to be nil to low expansive. Samples of these materials were swell tested in our laboratory and exhibited slight compression to low swell when wetted under an applied load of 1,000 psf. The shallower claystone samples tested were moist due to the shallow ground water conditions and exhibited lower swell. The deeper claystones were less moist and can be expected to show low to • moderate swell potential. Samples of the claystone had moisture contents of about 14 percent. r;rn,ind Water Free ground water was encountered in 9 of our 12 borings at depths from 7 to 18 feet at the time of drilling and In all of our borings at depths of 2 to 24 feet when checked several weeks after drilling. Measurements were taken June and July In boring TH-10 through TH-12, and in October when ground water levels in the area tend to be comparatively low In borings TH-13 through TH-21. The parcel was not being irrigated while we were drilling our borings TH-13 through TH- 21 and during the time we made subsequent ground water depth measurements in these borings. However,future lawn irrigation,paving and development will likely increase the local ground water elevations when the vicinity is fully developed. Fig. 4 shows our estimate of the depth to ground water and Fig. 5 shows our estimate of the contours of the elevation of the ground water surface using our interpretation of both our June and July 1998 and our October, 1998 measurements. The behavior of the ground water at this parcel is not yet well understood. Calkins Lake is about one-half mile northwest of the parcel. Though we believe it remote, It is possible Calkins Lake Influences the ground water in the vicinity of the PULTE HOME CORPORATION WHITMAN PROPERTY(NORTH HAEF) CTUTFc4tW 8 JUL-01-2002 M0N 02:31 PM P. 020/056 parcel. We recommend continuing measurements of ground water depth in the borings we drilled to better understand the ground water behavior. Temporary perforated, plastic casings were placed In the borings to facilitate future ground water depth measurements. SITE DEVELOPMENT We have identified no geologic or geotechnical conditions that should preclude development of this parcel. The ground water is shallow, above typical basement floor depth (measured from existing, natural grade). The clays overlying the bedrock are lower strength and phases of the bedrock have lower expansion potential. We have discussed our opinions and recommendations regarding each of these issues below. We have also discussed site grading,pavement construction, utility installation and construction of permanent slopes for long term stability and protection against erosion. Around Water Present plans are to build residences with basements. The ground water depths we measured In our borings are at or above typical basement depths if the existing ground surface in the proposed subdivision is not altered much during grading. Therefore, changes to the existing condition will be necessary to make basements feasible. In our opinion, two alternatives seem technically feasible, namely: a. Install a parcel wide subdrain system to lower the ground water under the parcel so it will be at least 3 feet below the basement floor elevations at the residence locations and provide foundation drains around all residences. Fig. 18 shows conceptually this alternative; or b. Raise the ground surface elevations enough that basement floor elevations at the residence locations will be at least 3 feet above the depths to ground water shown on Figure 3 and provide foundation drains around all residences; or c, A combination of(a) and (b) above. PULTE HOME CORPORATION WHRHAM PROPERTY(NORTH HALF] CM PC-1107 JuL-ut-zuuz m0N 02:31 PM P. 021/056 Subdraln. Two complications we can visualize for the area wide subdrain are topographic constraints and the Oligarchy Ditch. It will be difficult at best to drain a subdrain by gravity. This suggests lift stations may be needed to drain the subdrain. Regarding the Oligarchy Ditch,the subdrain will tend to lower the ground water elevation under the ditch also and may Influence leakage from the ditch. These complications will need to be reviewed as part of the decision to install a parcel-wide subdrain. Additional Investigation may be needed If a parcel wide subdraln is a selected alternative. Such an investigation would be aimed at better Identifying the possible sources of ground water, and measuring the permeability of the soli and bedrock to recommend a drain configuration and drain sizing. The parcel wide subdrain we envision will be a combination of an interceptor drain along most of the west,the north and a part of the east side of the parcel and an underdrain below all the sanitary sewer mains under the streets. The invert . elevation of the interceptor, it appears to us,will be dictated by the elevation of the bedrock(Fig. 5) near the southeast corner of the property, near the midpoint of the south property boundary and the east boundary where the elevation is lower compared with the remainder of the parcel. It Is important that the invert of the interceptor everywhere be at least one foot below the bedrock surface but it must also be sloped from its high point to drain. The underdrain system installed below the sanitary sewer mains will supplement the interceptor and serve as an outlet for individual residence foundation drains (see "Basements" subsection). The underdrains should be provided with cleanouts so they can be regularly maintained. If the sewer district will not maintain underdrains, the home owners' association should be empowered to provide maintenance and be provided copies of"as-built" plans. The underdrains would be an appropriately graded filter material surrounding a pipe. The pipe should be sized for the flow determined after the recommended ground water investigation is completed.The drain pipe should consist of smooth, perforated or slotted rigid PVC pipe laid at a grade of at least 0.5 percent. The filter material should have a cross-section of at least 2 square feet. A typical sewer underdrain detail is shown on Fig. 19. A positive cutoff collar(concrete) should be ^. PULYQ NOME CORPORATION WNITNAl.I PROPQRTY 1NORTN NALF) CTLjFC470T 10 JUL-01-2002 M0N 02:32 PM P. 022/056 r1 constructed around the sewer pipe and underdrain pipe immediately downstream of the point the underdrain pipe leaves the sewer trench. Solid pipe should be used down gradient of this collar to the daylight or collection point The underdrain should be designed to discharge to a gravity outfall or to a series of lift stations, if lift stations or any system that could temporarily fail are used, we recommend a check valve be placed on the underdrain service to each house, and cutoff collars be constructed to prevent backflow through the filter gravels. We further recommend backup pumps for each lift station pump and backup, on-site, electricity generators that will automatically turn on when the subdivision power fails. Oligarrhy Ditch. The effect of the parcel subdrain on Oligarchy Ditch needs to be Investigated during the recommended ground water investigation. Should the study show a probable Increase in leakage from the ditch we believe the ditch will need to be lined. Several liners are available but we believe the more feasible Is f \ probably Portland cement concrete. This needs to be confirmed during the investigation to determine if the ditch will be affected by the subdrain. Grading Overiot grading should be engineered fill that Is compacted under controlled conditions. Areas to receive grading fill need to be cleared, grubbed and stripped of all vegetation,organic topsoil and other deleterious matter. The cleared, grubbed and stripped materials should be discarded or placed in areas that will never be under structures, utilities, sidewalk, curbs and gutters, driveways or pavements. After stripping, the resulting subgrade should be scarified, moisture conditioned to 0 to 3 percent above optimum and compacted to obtain a firm platform for fill placement. Our borings indicate some soft soils exist on the parcel. Where soft soils are encountered, they can be stabilized prior to placing fill. Stabilization of soft subgrade soils is often accomplished by removal and replacement, scarifying and drying, tilizing geosynthetics or "crowding" crushed rock into the subgrade until a firm surface is achieved. r PULTE HOME CORPORATION WHITHAM PROPERTY(NORTH HALF) 11 CTLR FC.110T P. 023/056 The properties of the fill will affect the performance of foundations, slab-on- grade floor and pavements. The soils from the parcel are suitable for use as grading fill. Claystones should be broken down before placing as fill. If imported materials are necessary, they should consist of sandy clays that are low plastic and low expansion like the on-site clays. A sample of all soils proposed for Import for fill should be submitted to our office for classification and approval prior to hauling them to the site. Fill should be placed in thin loose lifts, moisture conditioned to 0 to 3 percent above optimum moisture content and compacted to at least 95 percent of standard Proctor maximum dry density (ASTM D 698). Guide specifications for overlot grading are In Appendix A. Placement and compaction of the grading fill should be observed and tested by a representative of our firm. For the most part,the soils and bedrock at this parcel are nil to low expansive. In addition the shallow ground water appears to have"pre-wetted" and decreased the swell potential of the upper approximately 10 feet of soils and bedrock. Deeper claystone bedrock was moderately expansive under the adjacent parcel. If the existing grades are lowered by cutting, this claystone will begin to influence structure foundation type. If possible,site grading should be planned to provide at least 4 feet of nil to low expansive clays or fill above the claystone bedrock so that special foundations can be avoided. Preliminary data shows that if the natural ground grades are lowered the claystone bedrock may affect the choice of foundation type for our estimated 10 percent of the parcel area. The claystone under the parcel is not steeply dipping but It has swell potential. Residences built in areas of expansive soils and bedrock are susceptible to damage from heave caused by wetting and swelling of expansive soils and bedrock, Special precautions are needed in the construction of foundations and other elements to mitigate the effects of swelling soils/bedrock. In our experience these techniques can and have reduced the damages to residences when the expansive soils/bedrock like those on this parcel get wet. PULTE HOME CORPORATION WHITHAM PROPERTY(NORTH HALF) CTLlr FC•N07 12 JUL-01-2002 M0N 02:32 PM F. D24/056 Slnpp Stability antErosion We observed no evidence of slope instability or significant erosion on the parcel. For the type of soils present at this parcel, we believe permanent slopes should be 3:1 (horizontal:vertical) or flatter. Surface drainage should not be allowed to sheet flow across slopes or pond at the crest of slopes. Slopes should be revegetated as soon as possible to reduce potential for erosion problems. Localized slopes enclosing retention/detention ponds should be designed by a qualified Civil Engineer with erosion control and slope stability In mind. • Utility Construction The bedrock penetrated by our borings was hard to very hard and included cemented, very hard sandstone lenses. We believe most of the materials can be excavated with either heavy duty trenchers or large backhoes, however, ripping or other means may be required to loosen the cemented, bedrock lenses. Medium stiff clays and hard Interbedded sandstone, claystone and siltstone are predominant. We believe the clay soils on this parcel can be classified as Type C, and bedrock as Type A or Type S based on the Occupational Safety and Health Administration (OSHA) standards governing excavations. Type C soils require maximum slope inclination of 1.5:1 (horizontal:vertical), Type B soils require maximum slope inclination of 1:1 (horizontal:vertical) and Type A soils require a maximum slope of 3/4:1 (horizontal:vertical). The contractors competent person on site should identify the soils encountered in excavations and refer to OSHA standards to determine appropriate slopes. Excavations deeper than 20 feet should be designed by a professional engineer. Ground water will be encountered during utility excavation. The clays and bedrock at this parcel are expected to be low to moderately permeable. Ground water seepage will be slow to moderate. We anticipate trench dewatering may be accomplished by sloping the trench bottom to collection areas where water can be removed by pumping, however large, heavy duty pumps should be anticipated. PULTE HOME CORPORATION 13 WHRHAM PROPERTY(NORTH HALF) Cn1T FC-1107 •�.. y1 LUVL MAY UL. DL rm P. 025/056 Some zones of sandier days and more permeable sandstone bedrock may exist requiring the occasional use of well points or other means to lower ground water and allow for excavation. Water and sewer lines are usually constructed beneath paved roads. Compaction of trench backfill will have . significant effect on the life and serviceability of pavements. We recommend trench backfill be placed in thin, loose lifts, moisture conditioned to 0 to 3 percent above optimum moisture content and compacted to at least 95 percent of standard Proctor maximum dry density (ASTM D 698). The placement and compaction of fill and backfill should be observed and tested by a representative of our firm during construction. Pavernn m} • The surficial soils found on-site have fair to poor pavement support qualities. For preliminary planning purposes, we suggest assuming 8 Inches of full depth asphaltic concrete paving will be needed for local residential streets.A section using asphaltic concrete and compacted base course would be 4 inches of asphaltic concrete over 8 inches of base course. Thicker pavements will be needed for collector and arterial streets. A subgrade Investigation and pavement design should be performed after overlot grading Is complete. The softer clays we found may rut and"pump"during subgrade preparation. Should this occur they can be stabilized as described above so that they will support construction equipment. RESIDENTIAL CONSTRUCTION CONSIDERATIONS Two-story residences with full basements are planned for the proposed subdivision. Ground conditions and characteristics across the parcel include very moist, medium stiff sandy clays near the surface underlain by claystone,sandstone or interbedded claystone,siltstone and sandstone bedrock. The strata at foundation level will depend upon finally selected finished grades. The following discussions PULlE HOME CORPORATION WMnKAN PROPERTY!NORTH HALF) CTLR FC.1107 14 JUL-01-2002 M0N 02:33 PM P. 026/055 are preliminary and are not intended for design or construction. After grading is completed,a detailed soils and foundation investigation should be performed on a lot specific basis. poundatinne The foundations that can be used to found the proposed residences will depend upon how the parcel Is graded. In our opinion, If the parcel finished grades are at or above the existing natural grades at the residence locations the residences can be founded with footings bearing on the soils/bedrock at footing elevation. Some of the residences will likely be founded with footings bearing on the natural clays and/or compacted overlot fill and others will be founded with footings bearing on the bedrock. We expect the maximum design bearing capacity for footings bearing on the clay will prove to be of the order of 1.500 pounds per square foot (psf) and the bearing capacity for footings bearing on the bedrock will prove to be of the order of 8,000 psf. The maximum design capacity for footings in areas where the bedrock is deeper may be of the order of 3,000 psf. It will be prudent to design all footings for a minimum dead load of the order of 30 percent of the maximum design bearing capacity. A grading plan that results In finished grades lower than the existing natural ground elevation we estimate will result In needing to found at least 10 percent of the residences with drilled piers penetrating the bedrock. We expect the maximum end bearing pressure for piers will prove to be of the order of 35,000 psf and the side shear value in the bedrock 10 percent of the maximum end bearing capacity. The minimum design dead load pressure will be of the order of 1000 psf.The minimum penetration for piers Into bedrock will probably prove to be 6 feet, the minimum length for piers will probably prove to be 16 feet and 4-inch void spaces will likely be needed under grade beams between the piers. There is the possibility some piers will need to be cased to dewater and clean the pier holes due to the ground water found under the parcel. P0LTE NOME CORPORATION WN(TNAM PROPERTY(NORTH HALF) 15 CTLIT PC-110T JuL—ui—LUUL MUN uz:3i rat P. 027/056 ' Slab-nnaasi&and Rasentpnt Flnnr Cnnatructlort Slabs-on-grade are typically used for basement floors on lots with soil conditions similar to this parcel. Our firm generally recommends structurally supported basement floors for high (4 to less than 6 percent) and very high (6 percent or greater) swell potentials. Preliminary data indicate structural basement floors will not be required on any of the lots on this parcel. Site grading cuts In areas where bedrock is shallowest should be avoided to keep basement floors above the bedrock or as far up In the more moist, lower swelling portions of the bedrock as possible. The following precautions will not eliminate slab-on-grade movement but will reduce the potential for damage due to movement of slabs: • 1. Isolation of the slabs from foundation walls, columns or other slab penetrations; 2. Voids under interior partition walls to allow for slab movement without transferring the movement to the structure; 3. Flexible water and gas connections to allow for slab movement. A flexible duct above furnaces may also be required; and 4. Proper surface grading and foundation drain Installation to reduce water availability to slab subgrade and foundation soils. placements Free ground water was shallow in our borings drilled during this investigation and will affect basement construction. Control of ground water levels below basements will be needed for basements. A parcel-wide subdraln is discussed above. Foundation drains will be needed around all crawl spaces and basements. This requirement will hold regardless of the finally selected finished grade elevations. We suggest foundation drains be connected to the sewer underdraln system with a piped connection. A typical detail for a connection from the foundation drain PULTE HOME CORPORATION WHnHAM PROPERTY(NORTH HALF) CTUT Fc-1107 16 JUL-01-2002 M0N 02:33 PM Y. UZ8/Ubb to the underdrain is provided on Fig. 19. Sump pits with pumps should be Installed as a backup if underdrains do not perform as intended. We discussed drainage systems for control of ground water under the parcel and the possible limiting affects of ground water conditions on providing basements for the proposed residences. Typically,foundation drains are comparatively shallow relative to the bottom of a slab-on-grade floor or the floor of a crawl (air) space under a structural floor. Where the ground water is likely to within 3 or 4 feet of a floor we recommend an underslab gravel layer and deeper foundation drains. Further, we recommend basement floors be at least 3 feet above the anticipated ground water surface. If a parcel-wide subdrain is installed the 3 feet should be measured from the ground water level that will result from the subdrain design. Basement excavations that penetrate the ground to near the ground water surface may require dewatering and the soils In the excavation floor may be soft Should soft soils be encountered,the excavation floor may need to be stabilized so it will support traffic. Basement and crawl space walls will be subjected to lateral pressure from the wall backflll. Such walls should be designed to resist the higher "at rest" lateral earth pressure because they are not free to rotate and develop the internal strength of the backfill. We expect the backfill will be the clays from required excavations for the residences and suggest assuming for preliminary designs an equivalent fluid density of 50 pcf for backfill in design calculations. SURFACE DRAINAGE The performance of improvements In this development will be Influenced by surface drainage. When developing an overall drainage scheme, consideration should be given to drainage around each residence. Drainage should be planned so that surface runoff is directed away from foundations and is not allowed to pond adjacent to or between structures or over pavements. We recommend slopes of at least 12 inches where possible in the first 10 feet for the areas surrounding all PULTE HOME CORPORATION WHITHAM PROPERTY(NORTH HALF? 17 OM Fc-1107 JUL-U1-2UU2 M0N 02:34 PM P. 029/056 residences or buildings. In areas between houses which are less than 20 feet apart, the slope should be at least 10 percent toward the swale used to convey water out of these areas. Slopes marginally less steep than those recommended may be necessary at the back of the houses on lots which drain to the front. Roof downspouts and other water collection systems should discharge well beyond the limits of all backfill around structures. Proper control of surface runoff Is also Important to control the erosion of surface soils. Sheet flow should not be directed over unprotected slopes. Water should not be allowed to pond at the crest of slopes. Permanent slopes should be revegetated to reduce erosion. Attention should be paid to compact the soils behind curb and gutter adjacent to streets and parking areas and in utility trenches during development. If surface • drainage between preliminary development and construction phases Is neglected, performance of the roadways, flatwork and foundations will be poor. When considering landscaping of common areas,we recommend the use of xerlscaping which requires little Initial or long-term watering. CONCRETE We measured soluble sulfate concentrations for representative samples of the subsoils from our borings. Sulfate concentrations from this and the adjacent parcel ranged from 0.1 to 3.7 percent. Based on ACI standards,water soluble sulfate concentrations in this range represent a severe to very severe sulfate exposure. ACI recommends using a cement meeting the requirements for Type V(sulfate resistant) cement, with a maximum water-cement ratio of 0.45 and air entrainment of 5 to 7 percent for concrete exposed to soils with this level of soluble sulfates. We understand Type V cement may not be readily available locally. As an alternative, we believe cement which meets ASTM C 150 Type II requirements and contains 20 percent fly ash can be used to provide similar resistance. The fly ash should meet ASTM C 618 Class F requirements. The fly ash can be reduced to 15 percent in cold weather months. PULTE HOME CORPORATION WHf'HAM PROPERTY(NORTH HALF) 18 JUL-01-2002 M0N 02:34 PM r. u3U/UUU LIMITATIONS AND ADDITIONAL INVESTIGATIONS We based the discussions In this report on our understanding of the proposed development and residences, conditions disclosed by exploratory drilling, review of geologic maps,site observation,results of our laboratory tests,engineering analysis of field and laboratory data and our experience. The criteria presented in this report are intended for aid in purchase decisions and preliminary planning purposes. Future geotechnical engineering investigations and analysis are required to formulate design criteria for a parcel-wide subsurface drain system to lower ground water, geotechnical design criteria for residence,foundations and floors, and street pavement sections. Our borings were widely spaced. In our opinion,the boring pattern provided us the needed picture of the underground to provide the above report intended to aid Pulte Home Corporation In their purchase decision regarding the parcel that is the subject of this report and the planning and development of this parcel. Variations between the borings will occur. We recommend continuing to measure the depth to ground water in the borings we drilled to better understand the behavior of the ground water under the parcel and to guide future decisions regarding installing and then designing a parcel-wide, subsurface drain to lower the ground water under the parcel. A representative of our firm should be present during site grading and utility trench backfilling to observe fill placement and perform compaction tests. Detailed Investigations should be performed for design of residence foundations and slab-on- grade floors and street pavement sections after overlot grading has been completed. We should review the final grading plans prior to construction to look for potential geotechnlcal problems. r PULTE HOME CORPORATION WHrrHAM PROPERTY(NORTH HALF) 19 CTLR FC-7107 • L.UVL ..,V,. UL.JY M P. 031/056 We believe this Investigation was conducted in a manner consistent with that level of care and skill ordinarily used by geotechnical engineers practicing In this area at this time. No other warranty, express or Implied, is made. If we can be of further service In discussing the contents of this report or analyses of the influence of subsurface conditions on the design of the proposed development, residences and streets, please call. CTUTHOhAPS©N, INC Tho as • . Chapel • ProJ= gineer Revi- =d by: • ' rev Fra J. H•I'day, P C ''�''`�f{.7 r ' i 4 II P.y .i EnInver P sip g CC J 3 Y , � � , i . ;,. : �: , •:.. • . JH;bic w. i (5 copies sent) PRANK 3.HOLL!DIY POLTE NOME CORPORATION WHITMAN PROPERTY(NORTH HALF) 20 CM FCd107 a F GFii ii ppxaE �' p an cwmm Ram 3 K1111 III 'll I 3 it al mwic ow a a n nny.n g • • m COUNTY ROAD 26 •• H • r to co a• 7 • • a T • n • • r . • • I II in i Q ft I 7It a U I i II 0 iil ..1 w COLORADO HIGHWAY 119 Ili g ...,.•• • 9S0/Z50 'd Yid 66':ZO HON Z00Z-l0-111f ) } fn m --0--- n_. SCUP 1x500' �. I • 1H-10 r vewj . wma mininm10 12 • TH-13 MCA=PRISM COUNTY ROAD 3 1/2 4 :m.,w,,. 4We • 24 n • O TH-10 �° -4— ;: : eTau O e a O = H if d n \ 1 20 1Z 1 28 14 18 28 CO T1ir 4 1• TH- • • M-12 TH 17 22 -15 18 I ft 1� 18 If 10 4 4 E$ Depth I Ww WowOw � Estimatedc Job ma.10771n TO Bedrock RQ. 2 R i 111 it ri i g 6!, !' !!' 'I' o 4 h r COUNTY ROAD 28 2t. R g 1 / • $; pp N S g n 151 8 g a • /Ca a • 0 • fr- ,,-.-_ I I I fn cc I U j i I Its COLORADO HIGHWAY 119 i lit Qcv4cn 7 lid 56:Z0 NOW ZOOZ-l0-1111 11 e Dll i III Iil di I! Oil ill hi ii al 2 - 0 aAiL I ; m COUNTY ROAD 28 1 ��3 ' w � n � o h • m • tl a N I:: I •C 04 rf'`.2041:• i i .. 4.4 f "\ n oF ,..,...7"re � 4 40, n ' • o y n r ' tl i w n gf Mtlk I n j i i i gg 7 111° i II z s COLORADO HIGHWAY 119 s 4 V at/u 1tY Y 950/5E0 'd e 11a t rui 2O k� Pch Id W li Oil ghh III w 3 59 I o n a Im • . COUNTY ROAD 28 16!t -- j........„.....-------9 55 160 12 F w 160 15C 145 140 14 r 36 i• 30 • • NO. 140 1 fl n n • / • ;41•o e N S 43 zI I n 3 z I o I o U j i) k A Its COLORADO HIGHWAY 119 la 4Gn/qcn 7 V9d 56'ZO HO ZODZ-(O-inf •._ �. LUUL .fiVi. VLJJ rN P. 037/056 U 1 3 • • • • , • . o 1 2 d ' W :C o .2 A - -- eDltibNAI:COMPRESSION•UNDER IN BS , CONSTANT PRESSURE DUE TO inigin7NG c. i L i l. L ri I l i M I U ; .4 0.1 1.0 10 100 APPLIED PRESSURE.KSF Sample of CLAY,SANDY(CL) • NATURAL DRY UNIT WEIGHT= 88 PCF "� From TH-1 B AT 8 FEET NATURAL MOISTURE CONTENT= 18.0 % 3 ' • 2 I. NO MOVE ION;IT NE TO WEYTING z la H N W a. 0 4 0.1 1.0 10 too APPLIED PRESSURE-KSF Sample of CLAYSTONE NATURAL DRY UNIT WEIGHT= 112 PCF From 1N-17 AT 14 FEET NATURAL MOISTURE CONTENT,' 13.9 % Swell Consolidation JOB NO. FC-1107 Test Results FIG, 14 JUL-U1-ZUUZ MUN UZ: b I'M 0 2 L L L EXPANSION UNDER CONSTANT PRESSURE (iUE TO WEtINC; , ZO0 __r_r_r-.r•--- __ __.- •-r",-r r-- ------- ------- -- - - __T Q I I I i I W X O• 3 - U1 00 a -3 a r r L 1 I • O ' 4 0.1 1.0 10 100 APPLIED PRESSURE•KSF Sample of CLAYSTONE NATURAL DRY UNIT WEIGHT= 119 PCP From TS-18 AT 9 FEET NATURAL MOISTURE CONTENT= 14.0 % 3 I I • • D , y z I a 4 ADDITIONAL COMPRESSION UNDER CONtDAN7 PRESSURE-D[1g Td W6">'t'NG-- 0, I Z a - 0. 0 0 O 4 0.1 1.0 10 100 APPLIED PRESSURE-KSF Sample of CLAY, SANDY(CL) NATURAL DRY UNIT WEIGHT= 108 PCP From TH-19 AT 8 FEET NATURAL MOISTURE CONTENT= 18.2 % Swell Consolidation JOB NO. FC-1107 Test Results FIG. 15 JUL UI LUUL ,1LU11 UL.JO FM P. 039/056 V --, • v , , , 8 11 L 1 , • • 2 CIDITJOf4AR.OCAUFRESSIOt4 UNDER, C0NSTAKIT'PRESSURE DUE TO'JETTING-- , - 0 ' t �` , : : . , 4 -.--.. .. • ....... ...... • - • Qi ; C. I • ' I ' II I 0 MI 2 4 r.. ._r.r__ ..r....... ....... •- --r--♦ rr W I , IX QMa £ %. L `......-1------. 0 a 4 0.1 1.0 10 100 APPLIED PRESSURE-KSF Sample of CLAY,SANDY(CL) NATURAL DRY UNIT WEIGHTS 99 PCF From TH-21 AT 4 FEET NATURAL MOISTURE CONTEND. 22.8 % Swell Consolidation JOB NO. FC-1107 Test Results FIG. 16 JUL-01-2002 M0N 02: 36 PM r, U4U/UDo r. 1 HYDROMETER ANALYSIS I SIEVE ANALYSIS 1 24 HR 7 FR RUE REUOINOS US.STANDARD MIS CLEARSQUARE OPENING'S 46 MIN. 16 MIN, 60 MIN.19 MIN. 4 MIN. 1M1µ 000 M00 '50'40'90 '16 '10-0 '4 Sir SW lH' r 5'r C O 100 . .. �r - " .__ fj . .. — . f0 60 - . . " J 7I 40. . _ . . .. .-. _ r so 6 b .. . . ` _.._ r 1. ..... . .. .. .7 ; ' . ' 70 . . . .. . .�. ._ _ . . __. . " . ."_ __. 20 .. . " . .. . .. . . . . . . .... .. . J . . . ... 00 . . "_ . . . .140 2670600; 1 _ .. . . -. ._ ... ... -::2 152 0.001 0.002 .006 .000 010 .057 .074 .10 7,.01]6 A75 0.62 iat 05.1 Tax 127 200 DIAMETER OF PARTICLE IN MIW METERS SANDS GRAVEL CLAY IPNBTICI TD GILT INDNatASnLT FINE 1 MEDIUM I C01AR66 PINE I commix I cO6m9/3 Sample of CLAY,SANDY(CL) GRAVEL 0 % SAND 38 % ,i^ From TH-21AT9FEET SILTS Can% LIQUID LIMIT 30 % • PLASTICITY INDEX 12 % I NYDRCMETER ANALYSIS ( SIEVE ANALYSIS I 26 a TM. TIME REAANG6 U.S.STANDARD SERIES CLEAR SCUBA OPIEN1NW Al..aµ 16 MIN. 10 M01 10 MIN. 4M1µ 1MIN. '160 •100 •BD•40 wan -NI •10•6 •4 K 5/4• 1W r TO'r 100 ' _-. L . _ .t - 0 _ e0 . _ ... . . . . .. . . . .. 00 1111 .- . _. --_ __ .. . so .. ... 5 . ; .. . .. ... . . . - -r LLL 60 . .. . .... . . .. .... . .. . \ ii 40 _. ._. . M • --I . ' " . . . .- - . . . .: I. . . . . . _ . . . .. __ . . . .L•., ._ .'. 1 : I . : 7;. . 100 .001 (Lou ,DDS .000 .019 .057 .074 .141 297 0.42.610 1.10 20 2.50 4.74 6.62 10.1 56.1 782 •127�7D0 DIAMETER OF PARR0.E IN MILLIMETERS ;MPS GRAVEL CLAY IPWRC)T09 •PU LT lNONSTIC) I FWE I MEDIVM (CLAR6E_ MS I DDARSS Ico6elFs Sample of GRAVEL % SAND % From SILTS CLAY % LIQUID LIMIT_V PLASTICITY INDEX % Gradation Job No. FC-1107 Test Results Fig. 17 a. t►nanta tV»/r `r C • i r. c IINO SCALE nc. • 333 c A J 4 a V f CONNECT UNDERORNN SERVICE TO FOUNDATION DRAIN FIRST FLOOR STREET BASEMENT CRAWL SANITARY SEWER SERVICE TOP OF BASEMENT la 1 r SANITARY SEWER MAIN FLOOR 3,MIN swop. •L.,----- — — Ord T MIN te: Sots an I°Bsiiinsta want . FIRST FLOOR NDERDRA N UNDERDRAIN SERVICE BOTTOM OF EXCAVATION GROUNDWATER SURFACE VARIES. FOR POSSIBLE STRUCTURAL _� ACRIAL GROUND WATER SURFACE MUST BASEMENT FLOOR �; BE CONFIRMED AFTER UNDERDRNN i r ..• 'clrgi • SYSTEM IS INS ALLED. SLAB-ON-GRADE OR STRUCTURAL ;� ��J•• FLOOR DEPENDING ON DESIGN -�co W a d — ! Baawn Camels c' fM-A Collor T In 0. ---- C ra .� 0 CO 0 • of `I 1 1 1 / / JUL-01-2002 MON 02:37 PM P. 042/056 NSANITARY S 4" PERFORATED CORRUGATED POLYETHYLENE -\\ 0 . PIPE (ASTM F 405) CONNECTION TO RESIDENCE •• • • FOUNDATION .4 DRAIN •' PROVIDE MIRAFI 140N 6"MIN 4 • '• ♦SHIN• • � , d r ' : CS" ' d 4• . • a ' . •. • . . 4 . . • S . A . . ,v 4" 4.rr PVC PERFORATED SUBDRAIN PIPE I SIZE VARIES SPECIFIED TRENCH 3/8" PERFORATIONS AT 5", 2 ROWS AT 50' FROM VERTICAL WASHED ROCK WIDTH PVC PIPE AND FITTINGS MAXIMUM SIZE: 1' CONFORMING TO ASTM D 3O34, LESS THAN 3% PASSING SDR 35 THE NO. 200 SIEVE NOTE: NOT TO SCALE Sanitary Sewer Main _- Underdrain Job No. FC-1907 Fig. 'I 1 . C r JOB NO.FC-1107 e TABLE I C C SUMMARY OF LABORATORY TEST RESULTS I NATURAL ATTERBERG LIMITS UNCONFINED SOLUBLE PASSING ti BORING DEPTH NATURAL DRY SWELL LIQUID PLASTICITY COMPRESSIVE SULFATE NO.200 SOIL TYPE MOISTURE DENSITY LIMIT INDEX STRENGTH CONTENT SIEVE (n} (%) (t>c1) (%L %) (%) (F80) (%) (%) TH-10 4 28.6 L 39 25 77 CLAY,SANDY(CL) TN-10 9 14.2 117 0.2 INTERBEDDED CLAYSTONEISANDSTONE TH-10 14 13.9 116 0.0 INTERBEDDED CLAYSTONEISANDSTONE TH-11 2 24.2 100 CLAY,SANDY(CL) TN-11 4 29.5 92 3.00 CLAY,SANDY(CL) TH-11 9 11$ 123 0.0 CLAYSTONE TH-11 14 19.8 r 109 2.0 CLAYSTONE TH-11 19 125 I• 125 36 19 73 CLAYSTONE TH-12 19 16.6 105 0.0 INTERBEDDED CLAYSTONFISANDSTONE' 111-13 4 18.9 103 0.3 CLAY,SANDY(CL) TH-14 4 22.4 100 1 -02 CLAY,SANDY(CL) TH-14 9 22.6 103 0.0 _ CLAY,SANDY(CL) TH-14 14 12.9 123 0.11 CLAYSTONE TH-15 4 182 105 36 23 83 CLAY,SANDY(CL) TH-15 9 20.6 100 0.0 CLAY,SANDY(CL) TH-16 4 17.4 102 3.70 CLAY,SANDY(CL) _ TH-16 9 18.0 99 4.7 CLAY,SANDY(CL) TH-17 9 25.0 96 1796 CLAY,SANDY(CL} TH-17 14 13.9 112 0.0 CLAYSTONE TH-18 9 14.0 119 ' 0.6 CLAYSTONE TFI-19 9 18.2 108 -0.1 CLAY,SANDY(CL) TH-20 4 13.9 105 1.20 CLAY,SANDY(CL) TH-21 4 228 99 -0.1 CLAY,SANDY(CL) 111-21 9 r 23.4 102 30 12 CLAY,SANDY(CL) I -o C a w 0 cn -Swell due to wetting at an applied pressure o11,000 psf. Negallve values Indicate consolldafon. PAGE 1 OF 1 co I JUL-01-2002 M0N 02:37 PM P. 044/056 • • • APPENDIX A GUIDE SITE GRADING SPECIFICATIONS WHITHAM PROPERTY(NORTH HALF) SOUTHEAST OF COUNTY ROAD 26 AND COUNTY ROAD NO. 3 1/2 WELD COUNTY, COLORADO PULTE HOME CORPORATION WHITHAM PROPERTY(NORTH HALF) CTLJT FC4107 P. 045/056 • GUIDE SITE GRADING SPECIFICATIONS WHITHAM PROPERTY(NORTH HALF) WELD COUNTY, COLORADO 1. DESCRIPTION This Item shall consist of the excavation, transportation, placement and compaction of materials from locations indicated on the plans, or staked by the Engineer,as necessary to achieve preliminary street and overlot elevations. These specifications shall also apply to compaction of materials that may be placed outside of the project. 2. GENERA' The Soils Engineer shall be the Owner's representative. The Soils Engineer shall approve fill materials, method of placement, moisture content and percent compaction, and shall give written approval of the completed fill. 3. BLEARING JOB E The Contractor shall remove all frees,brush and rubbish before excavation or fill placement Is begun. The Contractor shall dispose of the cleared material to provide the Owner with a clean, neat appearing job site. Cleared material shall not be placed In areas to receive fill where the material will support structures of any kind. 4. SCARIEYItQAREA TO BE FILI ED All topsoil and vegetable matter shall be removed from the ground surface upon which fill is to be placed. The resulting surface shall then be plowed or scarified until the surface is free from ruts, hummocks or other uneven features which would prevent uniform compaction by the equipment to be used. 5. COMPACTING AREA TO BE FILLED After the foundation for the fill has been cleared and scarified, It shall be disked or bladed until it is free from large clods, brought to the proper moisture content, (0 to 3 percent above optimum) and compacted to obtain a firm platform for fill placement. 6. FiLl MATFRIAI R Fill soils shall be free from vegetable matter or other deleterious substances, and shall not contain rocks having a diameter greater than six (6) Inches. Fill materials shall be obtained from cut areas shown on the plans or staked in the field by the Engineer or imported to the parcel. Concrete, asphalt, and other deleterious materials or debris shall not be used as fill. Import materials shall be similar to on site soils. PULSE NOME CORPORATION WHITHAM PROPERTY(NORTH HARP) clur FO-1107 A-1 JUL-01-2002 MON 02:37 °M P. 046/Obb 7. MOISTURE CONTENT Fill materials shall be moisture treated to within 0 to 3 percent above optimum moisture content as determined by the Standard Proctor Compaction Test (ASTM D 698). Sufficient laboratory compaction tests shall be made to determine the optimum moisture content for the various soils encountered In borrow areas or Imported to the parcel. The Contractor may be required to add moisture to the excavation materials in the borrow area if, in the opinion of the Soils Engineer, it is not possible to obtain uniform moisture content by adding water on the fill surface. The contractor will be required to rake or disk the fill soils to provide uniform moisture content through the soils. The application of water to fill materials shall be made with any type of watering equipment approved by the Soils Engineer, which will give the desired results. Should too much water be added to any part of the fill, such that the material is too wet to permit the desired compaction from being obtained, rolling and all work on that section of the fill shall be delayed until the material has been allowed to dry to the required moisture content The Contractor will be permitted to rework wet material in an approved manner to hasten Its drying. 8. COMPACTION OF PI! I ARFAR Selected fill material shall be placed and mixed In evenly spread layers. After each fill layer has been placed, It shall be uniformly compacted to not less than 95 percent of standard Proctor maximum dry density (ASTM D 698). Fill materials shall be placed such that the thickness of loose material does not exceed 8 Inches and the compacted lift thickness does not exceed 6 Inches. Compaction, as specified above, shall be obtained by the use of sheepsfoot rollers, multiple-wheel pneumatic-tired rollers, or other equipment approved by the Soils Engineer for soils classifying as CL, CH, or SC. Granular ill shall be compacted using vibratory equipment or other equipment approved by the Soils Engineer. Compaction shall be accomplished while the fill material Is at the specified moisture content Compaction of each layer shall be continuous over the entire area. 9. COMPACTION OF SLOPE SURFACES Fill material shall be compacted by means of sheepsfoot rollers or other suitable equipment Compaction operations shall be continued until slope surfaces are stable, but not too dense for planting, and there Is no appreciable amount of loose soil on the slope surfaces. Compaction of slope surfaces may be done progressively In Increments of three to five feet (3' to 5') in height or after the fill is brought to its total height. Permanent fill slopes shall not exceed 3:1 (horlzontal:vertical). ontal:vert i ca I). es", PULTE NOME CORPORATION WNITNAM PROPERTY(NORTH HALF) A-2 CM PC-1107 P. 047/056 10. DENSITY TESTS Field density tests shall be made by the Soils Engineer at locations and depths of his choosing. Where sheepsfoot rollers are used,the soil may be disturbed to a depth of several Inches. Density tests shall be taken in compacted material below the disturbed surface. When density tests Indicate the density or moisture content of any layer of fill or portion thereof is below that required, the particular layer or portion shall be reworked until the required density or moisture content has been achieved. Observation by the Solis Engineer shall be full time during the placement of fill and compaction operations so that they can declare the fill was placed In general conformance with specifications. All inspections necessary to test the placement of fill and observe compaction operations will be at the expense of the Owner, 11. COMPLETED PRELIMINARY r;RADFR All areas, both cut and fill, shall be finished to a level surface and shall meat the following limits of construction: A. Overlot cut or fill areas shall be within plus or minus 0.2 of one foot. B. Street grading shall be within plus or minus 0.1 of one foot. The civil engineer, or duly authorized representative,shall check all cut and fill areas to confirm that the work Is In accordance with the above limits. 12. SUPERVISION AND ONSTR Cfph STAKING All construction staking will be provided by the Civil Engineer or his duly authorized representative, Initial and final grading staking shall be at the expense of the owner. The replacement of grads stakes through construction shall be at the expense of the contractor. 13. RFARONAL I IMrrs No fill material shall be placed, spread or rolled while It Is frozen,thawing, or during unfavorable weather conditions. When work is interrupted by heavy precipitation,fill operations shall not be resumed until the Soils Engineer indicates the moisture content and density of previously placed materials are as specified. 14. NOTIe,F REGARDING START OF GRADING The contractor shall submit notification to the Soils Engineer and Owner advising them of the start of grading operations at least three (3) days In advance of the starting date. Notification shall also be submitted at least 3 days in advance of PULTE HOME CORPORATION WH(IHAM PROPERTY(NORTH HALF) CTL1T FC-1167 A-3 JUL-01-2002 MON 02:38 PM P. 048/0b • any resumption dates when grading operations have been stopped for any reason other than adverse weather conditions. 1$, REPORTING OF FIFI O 0FNSITY TFST4 Density tests made by the Soils Engineer,as specified under"Density Tests" above,shall be submitted progressively to the Owner. Dry density, moisture content and percentage compaction shall be reported for each test taken. • 16 Wert ARATION RFr3ARDING COMPLETED FILL The Solis Engineer shall provide a written declaration stating that the parcel was filled with acceptable materials, or was placed in general accordance with the specifications. 17. DECLARATIO►SEGARDING COMPI ETED GRADE ELEVATIONS A registered Civil Engineer or licensed Land Surveyor shall provide a declaration stating that the site grading has been completed and resulting elevations are in general conformance with the accepted detailed development plan. PULTE HOME CORPORATION WHITHAM PROPERTY(NORTH HALF) A-4 CTUT FC•1H 07 P. 049/056 Imo .. 200 200-- 180 180-- 160 180- 140 LL TH-10 140-+�+ EL. 1299 TH-11 TH-12 _ 9-3.22 _ 128 EL. 125 120 -:sera R 1�%1 li ®-u 50/3 50/12 25/12 - 50/5 -G 50/3 50/2 50/11 50/2 50/4 _ 100 50/5 50/2 100- - 0 80- - 0 60- 0 40- SUMMARY LOGS OF EXPLORATORY BORINGS JOB NO. FC-1107 FIG. 6 JUL-01-2002 EN 02:38 PM P. 050/056 V 200— 200 180— 180 - TH-i6 TH-17 150 180 EL. 155 EL. 154 _ 114-13 TH-14 - EL. 145 EL. 146 20/12 '15/12 - 14/12 4 -7/12 11/12 '� F v. -.,50/10 140—y 140 rt::: .r ""2 LH i5 50/12 �-50/e i � El. 130 � - z \\50/2 �.- 50/8 50/6 ?_50/6 _t \-50/8 \- 50/4 12/12 50/8 \ -u \- 50/3 120—G 120 -50/6 5/12 50/3 - N\\-50/3 50/2 - 50/11 50/0 - 50/0 - 100 50/2 100-- 80— 0 60— 0 I 40� 0 SUMMARY LOGS OF EXPLORATORY BORINGS FIG. 7 JOB NO. FC-1107 "- �� CVVL WVI1 UL.3O fN P.051/056 • • I I l l 11 I I i l 1 1 1 1 I 1 I .L"win?"' [ I I- .j i ! I i i 1 i i i ..I iA ad a • w B N F .r5 � R N N N N • g ! C4 � e N N N N neri a ELEVATION - FEET Eli f4 s e w v ER ® tom` I:4 c#2 'qag m" aPt VIvg M wtl QI 1eU gg in' gi p P PO g dlFf ti r In a � � P &IIII ;JP . g�vffl � N � K P m K I o � m pCg III s e �' n • .Q !!I Ii1;;; 4 I `q • IR a L R JUL-01-2002 M0N 02:39 PM Y. Uh'l,lUhb V 3 . z ' EXPANSION UNDER CONSTANT PRESSURE I. bUE TO WETTING 1 O• n 1-.-. N , Q J.... .-l. J a1 ------- L L LJ.L L. J I O -2 Vi IX -1 T J 0. O 0 -4 1c 100 0.1 1.0 APPLIED PRESSURE-KSF Sample of INTERBEDDED CLAYSTONE/SANDSTONE NATURAL DRY UNIT WEIGHT P 117 PCF From TH-10 AT 9 FEET NATURAL MOISTURE CONTENT' 14.2 3 ....J , L t NO MOVEMFNTOliE TO WEtTINO ..J.........1 .... .J.... .....J-.-J-L_ E -, ti O .= d.. .l.L..LJ.......J — V1 N O. O (7 100 0,1 1.0 10 APPLIED PRESSURE•KSF 118 FOE ,�... Sample of INTERBEDDED CIAYSTONEISANDSTONE NATURAL DRY UNIT WEIGHT= From TH-10 AT 14 FEET NATURAL MOISTURE CONTENT= 13.9 Y= Swell Consolidation Test Results FIG. 9 JOB NO. FC-1107 „VIII 114.3i TM P. 053/056 Ig ----.., I I I ” 41 J L rT L z + 4 L L LA_L N • d c. * NO MOVEMENT DUE TO WETTING 0 -2 N to 'I ' I i I W I ' m 4 -------1.... a }..1.... .t 3I L J 1 J 1 . f J r U .4 0.1 1.0 10 - APPLIED PRESSURE-KSF 100 Sample of CLAYSTONE NATURAL DRY UNIT WEIGHT,. 123 POP From TH-11 AT 9 FEET NATURAL MOISTURE CONTENT= 11.9 % 3 2 , I I I EXFl1NSION UNDERONST{1tyT + ;PIREEBURE DUE TO WETTING 0 0 ..J. L. .1...L J iJ LL!j - --------t"" W X -3 A. 2 0 O 0.1 7.0 70 APPLIED PRESSURE-KSF 100 Sample of CLAYSTONE NATURAL DRY UNIT WEIGHT= PCF Porn TH-11 AT 14 FEET 109 NATURAL MOISTURE CONTENre 7 @,g %% --� Swell Consolidation JOB NO. FC-110T Test Results FIG. 10 Y. U54/05b JUL-01-2002 MON 02.39 PM r^ ® I 9 ' I i .1 2 _______1....L • 1 2 G _ _-. ....r.. ..r. ..r 2 a i '-�_ -J- -.6J-------i_-__ _ .1 0'` _~ENO MOVEMENT DUE TO WETTING Z -, - - ._ O a a ca isi i Q.C. •J 5 ' O 100 ✓ p t0 0.1 Lo APPUED PRESSURE-KSF PCF CLAYSTONE NATURAL DRY UNIT WEIGHT= 105 Y Sample of NATURAL MOISTURE CONTENT= 18.8 From TH-12 AT 19 FEET 3 i a.. a_ a.__.......J- .....J_j""1 EXPANSION UNDER ON;STe.NT PRESSURE DUE TOWETT1NG:r, y__ W• -1 S -�J�____________ ___t._._.__a._ 0 I .. . ... "" 10 100 G.5 APPLIED PRESSURE-KSF PCP NATURAL DRY UNIT WEIGHT= 103 ,•-. Sample of CLAY SANDY(CL) 18.9 % NATURAL MOISTURE CONTENT' From TH- IjA7 4 FEET Swell Consolidation Test Results FIG. 11 JOB NO.FC-1107 P. 055/056 S I • 1 • i ; I 1 1 I 4 L L J•J. ..LJ............L_. ....L..... • 3 1 2 ,• I (} • 1 I ' I , 1 1 L ....4.. J J J.J-a__i. J.... ..J•_L. .I J.L 11 I 1 1 1 1 UNDER •• CDNSTNT'P�assaREDUETO VETTING -2 .........J......_J..__ . • • • • • , i i I : .4 ' I 4 7.. O 1.4 4 t r 2 • yya� yy -7 .___r..•.-.-.-I- J _.1_ .I• J....0 2 ir¢L^S{ 1 1 I 1 1 I 1 •� QJ.LJ J • 1J J.... _.J..L.t.4 J._ C, -10 0.1 1.0 t0 100 APPLIED PRESSURE-KSF Sample of CLAY,SANDY(CL) NATURAL DRY UNIT WEIGHT= 100 PCF From TN-14 AT 4 FEET NATURAL MOISTURE CONTENT= 22.4 % Swell Consolidation JOB NO.FO-1107 Test Results FIG.12 JUL-01-2002 M0N 02:40 PM P. 056/056 Eg l l 1 Z 1 ` r.. O ....r.. ..r. . ... r...:r r.r. ..r� r .r. r. w D MDVEIdENT ZUE TO WETTING X 0 z r . En co `a a ' U ' 0.7 7.0 10 100 F'''''', APPLIED PRESSURE-KSF Sample of CLAY,SANDY(CL) • NATURAL DRY UNIT WEIGHT= 103 PCF From Ti-I-14 AT 9 FEET NATURAL MOISTURE CONTENT= 226 % I I t i 4 J t._ rr-- 1 NO MOVEM4N4,t E TO WETTING to O0j K a a. Z 0 U c., ,A 10 1DD APPLIED PRESSURE-KSF Sample of CLAY,SANDY(CL) NATURAL DRY UNR WEIGHT= 100 PCF From TH-15 AT 9 FEET NATURAL MOISTURE CONTENT= 20.5 % Swell Consolidation JOB NO. FC-1107 Test Results FIG. 13 Hello