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Home My WebLink About20110470.tiff N • GEOTECHNICAL ENGINEERING REPORT PROPOSED CUSTOM HOME & ISDS LOT 9 - HIGHLAND FARMS PUD WELD COUNTY, COLORADO TERRACON PROJECT NO. 22075109 September 6, 2007 Prepared for: • Balmes Homes 6480 Weld County Road 5 Erie, Colorado 80516 Attn: Mr. Greg Balmes Prepared by: Terracon Consultants, Inc. 1242 Bramwood Place, Suite 2 Longmont, Colorado 80501 Phone: 303-776-3921 Fax: 303-776-4041 • 2011-0470 lierracon • lierracon • Consulting Engineers & Scientists September 6, 2007 1242 Bramwood Place e p Longmont, Colorado 80501 Phone 303.776.3921 Fax 303.776.4041 Mr. Greg Balmes www.terracon.com Balmes Homes 6480 Weld County Road 5 Erie, Colorado 80516 RE: Geotechnical Engineering Report Proposed Custom Home & ISDS Lot 9 — Highland Farms PUD Weld County, Colorado Terracon Project No. 22075109 As requested, Terracon has completed a geotechnical engineering exploration for the proposed custom home and individual sewage disposal system (ISDS) to be located at Lot 9 of the Highland Farms PUD. This study was performed in general accordance with our proposal number G2207120 dated August 23, 2007. • The results of our engineering study, including the boring location diagram, test boring records, laboratory test results and the geotechnical recommendations needed to aid in the design and construction of foundations and other earth connected phases of this project are attached. Expansive bedrock is present on this site. This report provides recommendations to help mitigate the effects of soil movement/heave associated with swelling soils/bedrock. However, even if these procedures are followed, some movement and cracking in the structure is possible. The severity of cracking and other damage such as uneven on-grade slabs and pavements will probably increase if modification of the site results in excessive wetting or drying of the expansive materials. Eliminating the risk of movement and distress is probably not feasible, particularly for on grade slabs and pavements, but it may be possible to further reduce the risk of movement if significantly more expensive measures are used during construction. Some of these options are discussed in this report. We would be pleased to discuss other construction alternatives with you upon request. Other design and construction recommendations, based upon geotechnical conditions, are presented in the report. We appreciate being of service to you in the geotechnical engineering phase of this project, and are prepared to assist you during the construction phases as well. • Delivering Success for Clients and Employees Since 1965 More Than 80 Offices Nationwide Balmes Homes lferracon • Proposed Custom Home 8 ISDS Lot 9—Highland Farms PUD Weld County,Colorado Terracon Project No.22075109 If you have any questions concerning this report or any of our testing, observation, design and consulting services, please do not hesitate to contact us. Sincerely, TERRACON CONSULTANTS, INC. 00 LIC4ili .0000 lili ��O��No:oy ysFoh/ .rC. . S�h 4. Cs. • .• •�S.iNi 1 41250 S 277'1I 7 ; '1 •0. °ems % % 1.4 0, 1 7 L, 1 ,i tII fre'.........•G l 1111 ' .•F ' \N11�! t i S810NAIENr 11`a....%% Glenn D. Ohlsen, P.E. Eric S. Willis, P.E. Project Engineer Geotechnical Department Manager Copies to: Addressee (3) ` N.•_` 1 9• _FG/ 11 v;. .ip� s� 1 • J 111 • • c /� • U' 77 1 • / I i 7 i 111 •, llh . .111 i, �[: ; 111 "1 ' ` , ` • iii Balmes Homes lierrcacon • Proposed Custom Home&ISDS Lot 9—Highland Farms PUD Weld County,Colorado Terracon Project No.22075109 TABLE OF CONTENTS Page No. Letter of Transmittal ii INTRODUCTION 1 PROJECT DESCRIPTION 1 SITE EXPLORATION PROCEDURES 2 Field Exploration 2 Laboratory Testing 2 SITE CONDITIONS 3 SUBSURFACE CONDITIONS 3 Soil and Bedrock Conditions 3 • Field and Laboratory Test Results 3 Groundwater Conditions 4 ENGINEERING RECOMMENDATIONS 4 Geotechnical Considerations 4 Foundation Recommendations 5 Basement Construction 7 Floor Slab Design and Construction 8 Septic System Construction 9 Excavation 11 General Earthwork 11 Underground Utility Systems 12 Corrosion Protection (Concrete) 12 Surface Drainage 12 GENERAL COMMENTS 13 • iv • Balmes Homes lierracon Proposed Custom Home& ISDS Lot 9—Highland Farms PUD Weld County,Colorado Terracon Project No.22075109 TABLE OF CONTENTS (Cont'd) APPENDIX A Boring Location Diagram Al Logs of Borings A2 to A4 APPENDIX B Swell-Consolidation Test Curves B1 to B6 Grain Size Distribution/Soil Classification Curve B7 Percolation Test Results Form B8 APPENDIX C: General Notes: Drilling & Exploration Cl Unified Soil Classification C2 Rock Classification C3 • • v GEOTECHNICAL ENGINEERING REPORT PROPOSED CUSTOM HOME & ISDS LOT 9 - HIGHLAND FARMS PUD WELD COUNTY, COLORADO TERRACON PROJECT NO. 22075109 September 6, 2007 INTRODUCTION This report contains the results of our geotechnical engineering exploration for the proposed custom home and individual sewage disposal system (ISDS) to be located at Lot 9 in the Highland Farms PUD. The site is located in the Northwest 1/4 of Section 5, Township 1 North, Range 68 West of the 6th Principal Meridian in Weld County, Colorado. • The purpose of these services is to provide information and geotechnical engineering recommendations relative to: • Subsurface soil and bedrock conditions • Groundwater conditions • Foundation design and construction • Basement construction • Floor slab design and construction • Individual sewage disposal systems • General earthwork considerations • Site drainage considerations The recommendations contained in this report are based upon the results of field and laboratory testing, engineering analyses, experience with similar soil conditions and structures, and our understanding of the proposed project. PROJECT DESCRIPTION We understand that the proposed project will include the construction of a single family residence at the subject site. The proposed residence will be a two-story, wood frame • structure with a walkout basement and an attached garage. We understand that fill will be used to raise the site to achieve walk-out basement construction and that maximum basement 1 Balmes Homes lierracon • Proposed Custom Home&ISDS Lot 9—Highland Farms PUD Weld County,Colorado Terracon Project No.22075109 cuts will be on the order of 2 to 3 feet below current site grades. Considering the size and type of construction planned, we anticipate maximum wall and column loads will be on the order of 3% kips per lineal foot (klf) and 40 kips, respectively. Other site development considerations will include the construction of an individual sewage disposal system (ISDS) in accordance with Weld County regulations. If foundation loads or type or depth of construction vary from those outlined above or if location of construction changes, we should be contacted to confirm and/or modify our recommendations accordingly. SITE EXPLORATION PROCEDURES Field Exploration: Three test borings were drilled on August 28, 2007. The borings were drilled to depths of about 10 to 35 feet at the approximate locations shown on the Boring Location Diagram, Figure 1. Two borings were drilled within or near the footprint of the proposed residence. One soil profile boring and six percolation test holes were drilled in the location of the proposed septic system. Percolation tests were conducted in general accordance with Weld County requirements. Borings were advanced with a truck-mounted • drilling rig, utilizing 4 and 6-inch diameter solid stem auger. The borings were located in the field, with the client, by measurements with a mechanical surveying wheel using property boundaries and/or existing site features as a reference. Right angles for locating the borings were estimated. Approximate ground surface elevations at each boring location were obtained by measurements with an engineer's level and rod from a temporary bench mark (TBM) shown on the Boring Location Diagram. The accuracy of boring locations and elevations should only be assumed to the level implied by the methods used. A geotechnical engineer recorded lithologic logs of each boring during the drilling operations. At selected intervals, samples of the subsurface materials were taken by means of driving California barrel samplers. Penetration resistance measurements were obtained by driving the California barrel into the subsurface materials with a 140-pound hammer falling 30 inches. The penetration resistance value is a useful index in estimating the consistency, relative density, or hardness of the materials encountered. In addition, groundwater levels were recorded in each boring at the time of site exploration and one day after completion of drilling. Laboratory Testing: Samples retrieved during the field exploration were returned to the laboratory for observation by the project geotechnical engineer and were visually classified • in general accordance with the Unified Soil Classification System described in Appendix C. 2 • Balmes Homes llrerraacort • Proposed Custom Home&ISDS Lot 9—Highland Farms PUD Weld County,Colorado Terracon Project No.22075109 Samples of bedrock were classified in accordance with the general notes for Rock Classification. An applicable laboratory testing program was formulated to determine engineering properties of the subsurface materials, after which, the field descriptions were confirmed or modified as necessary. Boring logs were prepared and are presented in Appendix A. Laboratory tests were conducted on selected samples and are presented in Appendix B. The test results were used for the geotechnical engineering analyses and the development of foundation and earthwork recommendations. Laboratory tests were performed in general accordance with applicable local standards or other accepted standards. Selected samples were tested for the following engineering properties: • Water Content • Grain Size Distribution • Dry Unit Weight • Atterberg Limits • Swell-Consolidation Potential • Water Soluble Sulfate Content • • Unconfined Compressive Strength SITE CONDITIONS The site is currently a vacant lot in a residential subdivision and has been used for agricultural purposes in the recent past. An existing residence was observed to the north, while agricultural land or vacant lots were observed in the other directions. The ground surface was relatively even with a downward slope to the west and north. Vegetation consisted of cut grasses and weeds. SUBSURFACE CONDITIONS Soil and Bedrock Conditions: As presented on the Logs of Boring, a vegetative soil layer was observed at the surface of our borings and was overlying about 2'/ to 8'% feet of sandy lean clay. Siltstone/claystone and claystone bedrock were observed below the clays and extended to the depths explored. For a more detailed description of the subsurface conditions, please refer to the individual boring logs. Field and Laboratory Test Results: Field test results indicate that the clay soils are very stiff in consistency. The bedrock varies from weathered to very hard in hardness. • Laboratory test results indicate that the clays have low swell potential. The dry density of the clays varied between 91 to 95 pcf at moisture contents ranging from 4 to 12 percent. 3 • Balmes Homes lierracan Proposed Custom Home& ISDS Lot 9—Highland Farms PUD Weld County, Colorado Terracon Project No.22075109 Swell-consolidation test results indicate that the bedrock is moderately to highly expansive. Field test results indicate the soils in the area of the proposed septic system have good percolation characteristics. A summary of the percolation test results is included in the Appendix of the report. Groundwater Conditions: Groundwater was not observed in any test boring at the time of the field exploration. However, when checked one day after drilling, groundwater was measured in Boring 2 at a depth of about 31 feet. The other borings were dry at that time. These observations represent groundwater conditions at the time of the field exploration, and may not be indicative of other times, or at other locations. Groundwater levels can be expected to fluctuate with varying seasonal and weather conditions. In addition, zones of perched and/or trapped groundwater, where not already present, may also occur at times in the subsurface soils overlying bedrock, on top of the bedrock surface or within permeable fractures in the bedrock materials. The location and amount of perched water is dependent upon several factors, including hydrologic conditions, type of site • development, irrigation demands on or adjacent to the site, fluctuations in water features, seasonal and weather conditions. ENGINEERING RECOMMENDATIONS Geotechnical Considerations: We believe that the primary geotechnical condition that will impact residential construction is the moderate to high swelling claystone bedrock encountered on the site. The risks associated with swelling bedrock can be mitigated by careful design, construction and maintenance practices; however, it should be recognized that these procedures will not necessarily eliminate the risk. The builder and future homeowner(s) should be aware and understand that slabs-on-grade and, in some instances foundations, may be affected by the swelling bedrock present on this site. This concern and other site development considerations are briefly discussed in the following sections. Considering the size and type of construction planned and the subsurface conditions encountered in our test borings (moderate to high swelling claystone) we believe that the use of straight shaft piers (caissons) drilled into bedrock are appropriate for support of the proposed residence. This type of system extends the foundation elements through expansive materials that are subjected to wetting and swelling and can place them in materials that are not as likely to experience significant moisture changes and resulting volume change. At the same time drilled piers better concentrate building dead loads to resist uplift forces caused by • expansive materials. 4 Balmes Homes lferracon • Proposed Custom Home&ISDS Lot 9—Highland Farms PUD Weld County,Colorado Terracon Project No.22075109 Swell-consolidation tests indicate that the soils/bedrock likely to influence slab on grade performance have variable swell potential, ranging from moderate to high. These materials are judged to be in the "Moderate to High" slab performance risk categories as defined by the Colorado Association of Geotechnical Engineers (CAGE). For this site, we estimate slab heave could be on the order of 3 to 4 inches, or more. Accordingly, we recommend the use of a structural floor with a void beneath it for basement areas of this residence. If a suspended structural floor system is chosen, the crawlspace area below the floor should be well ventilated to help control humidity and to facilitate moisture release. All grades must provide effective drainage away from the residence during and after construction. Water permitted to pond next to the residence can result in greater soil movements than those discussed in this report. These greater movements can result in unacceptable differential slab movements, cracked slabs and walls, and other structural or architectural defects. Estimated movements described in this report are based on effective drainage for the life of the structure and cannot be relied upon if effective drainage is not maintained. • Recommendations for the design and construction of foundations, floor slabs and foundation drainage are discussed in the following paragraphs. Foundation Recommendations: Considering the size and type of construction planned and the subsurface conditions encountered in our test borings (moderate to high swelling bedrock) we recommend that the proposed residence be supported by grade beams and straight shaft piers (caissons) drilled into bedrock. Straight shaft piers, drilled a minimum of 10 feet into firm or harder bedrock, with shaft lengths of at least 25 feet are recommended. For axial compression loads, piers may be designed for a maximum allowable end-bearing pressure of 20,000 pounds per square foot (psf), and skin friction of 2,000 psf for the portion of the pier in firm or harder bedrock. In addition, our boring data indicates that comparatively soft lignite layers may be present within the bedrock unit. Drilled piers should not "bottom-out" on these materials. If lignite layers are encountered during drilling, additional penetration into the competent bedrock may be required. This could result in pier lengths greater than anticipated. • 5 • Balmes Homes lierrecon Proposed Custom Home&ISDS Lot 9—Highland Farms PUD Weld County,Colorado Terracon Project No. 22075109 Required pier penetration should be balanced against potential uplift forces due to expansion of the subsoils and bedrock on the site. For design purposes, the uplift force on each pier can be determined on the basis of the following equation: Up = 50xD Where: Up = the uplift force in kips, and D= the pier diameter in feet Uplift forces on piers should be resisted by a combination of structure dead-load and skin friction resistance from pier penetration below a depth of at least 10 feet below the bottom of the grade beam and in the competent bedrock. Piers should be reinforced full depth for the applied axial, lateral and uplift stresses imposed. The amount of reinforcing steel for expansion should be determined by the tensile force created by the uplift force on each pier, with allowance for dead-load. To reduce potential uplift forces on piers, small diameter piers and long grade beam spans, which increase • individual pier loading, are recommended. For this project, a minimum pier diameter of 10 inches is recommended. A 6-inch or greater void space should be provided beneath grade beams between piers. The void material should be of suitable strength to support the weight of fresh concrete used in grade beam construction and to avoid collapse when foundation backfill is placed. Based on the subsurface conditions, it appears that pier drilling should be possible with appropriate sized caisson drill rigs. Groundwater was not encountered in the borings immediately after drilling; however, water developed in a boring when checked one day later. This condition indicates that trapped groundwater is likely present within permeable fractures within the bedrock formation. Accordingly, we anticipate that at least some of the piers will require the use of a concrete pump truck with a tremie extension in order to control water infiltration. Where dry or relatively dry conditions are encountered during pier drilling, it will probably be possible to construct piers using "drill and pour" construction methods. Pier concrete with slump in the range of 5 to 7 inches is recommended and should be designed to achieve its 28-day design strength at these higher slumps. Free-fall concrete placement in piers will only be acceptable if the pier holes are adequately dewatered and provisions are taken to avoid striking the concrete on the sides of the hole or reinforcing • steel. 6 Balmes Homes iferracon • Proposed Custom Home&ISDS Lot 9—Highland Farms PUD Weld County,Colorado Terracon Project No.22075109 The construction of drilled piers should be observed by a representative of Terracon in order to identify the appropriate bearing strata, observe the construction methods being used and to confirm that subsurface conditions are consistent with those encountered in our test borings. Basement Construction: Groundwater was measured in Boring 2 at a depth of about 31 feet below the ground surface. Therefore, full-depth basement construction is considered acceptable on the site. However, surface water can penetrate backfill adjacent to the residence and collect at the bottom of the excavations resulting in a perched groundwater condition. To reduce the potential for perched water to impact foundation/slab soils and enter the basement of the structure, installation of a perimeter drainage system is recommended. The drain trench and pipe should be constructed around the exterior perimeter of the basement foundation, and sloped at a minimum 1 percent ('%" drop per foot of drain) to a suitable outlet, such as an underdrain system (if available), a positive gravity outfall or to a • sump where water can be removed by pumping. The drainage system should consist of a minimum 4-inch diameter perforated pipe, embedded in free-draining gravel, placed in a trench at least 12-inches in width. The invert of the drain pipe, at its high-point, should be placed at least 2-inches below the bottom of the grade beam void space. Gravel should extend a minimum of 2-inches beneath the bottom of the pipe, and at least 6-inches above the drain pipe. The system should be underlain with a polyethylene moisture barrier, sealed to the foundation wall/grade beam and extended at least to the edge of the backfill zone. Gravel beneath the drain pipe could be eliminated if the pipe is placed directly on the polyethylene sheeting. The gravel should be covered with drainage fabric prior to placement of foundation backfill. If a suspended floor system with a crawl space is selected, the drain trench and pipe can be constructed around the interior perimeter of the basement foundation, and sloped at a minimum 1 percent (%" drop per foot of drain) to a suitable outlet, such as an underdrain system (if available), a positive gravity outfall or to a sump where water can be removed by pumping. Lateral lines placed at regular intervals should also be considered to help drain the interior area of the basement. The drainage system should consist of a minimum 4-inch diameter perforated pipe, embedded in free-draining gravel, placed in a trench at least 12- inches in width. The invert of the drain pipe, at its high-point, should be placed at least 4- inches below the bottom of the grade beam void space. Gravel should surround the pipe • 7 Balmes Homes lierracon • Proposed Custom Home&ISDS Lot 9—Highland Farms PUD Weld County, Colorado Terracon Project No.22075109 and extend a minimum of 2-inches beneath the bottom of the pipe. The gravel should be covered with drainage fabric. Basement walls should be designed for the lateral earth pressures imposed by the soil backfill. Claystone bedrock should not be used for wall backfill due to the expansive nature of these materials. The on-site clay soils should be stockpiled separately during excavation for use as wall backfill. We suggest basement walls be designed for an equivalent fluid pressure of 60 pounds per cubic foot (pcf) for the on-site clay or similar imported soils approved by Terracon. This value assumes the backfill will not become saturated during the life of the structure and therefore proper surface drainage should be maintained. In addition, the above value assumes some wall deflection and therefore minor cracking could occur. For the subsoil conditions similar to this site, experience indicates most basement walls designed with an equivalent fluid pressure of 60 pcf have performed satisfactorily. If little wall deflection is desired, higher design values may be appropriate. Fill against foundation walls should be moistened at or above optimum and should be well • compacted. Compaction of each lift adjacent to walls should be accomplished with hand- operated tampers or other lightweight compactors. Over-compaction may cause excessive lateral earth pressures that could result in wall movement. Floor Slab Design and Construction: Swell-consolidation tests indicate that the bedrock likely to influence slab on grade performance has variable swell potential, ranging from moderate to high. These materials are judged to be in the "Moderate to High" slab performance risk categories as defined by the Colorado Association of Geotechnical Engineers (CAGE). For this site, we estimate slab heave could be on the order of 3 to 4 inches, or more. Accordingly, we recommend the use of a structural floor with a void beneath it for basement areas of this residence. Building codes should be followed for clear space requirements below structurally supported floors with crawl space areas and will depend, in part, upon the type of materials used to construct the floor as well as the volumetric expansion potential of the underlying soil/bedrock. Clear spaces for these types of floors normally range from 18 to 24 inches. Where other floor support systems and materials are used, we recommend a minimum clear space/void of 8 inches be maintained between the underside of the structural floor system and the surface of the subgrade/exposed earth. If a suspended structural floor system is chosen, the crawlspace area below the floor should be well ventilated to help control humidity and facilitate moisture • release. 8 • Balmes Homes lferracon Proposed Custom Home 8 ISDS Lot 9—Highland Farms PUD Weld County,Colorado Terracon Project No.22075109 Garage slabs, driveway and sidewalks are normally constructed as slabs-on-grade. The performance of conventional slabs-on-grade on expansive soils is erratic and these features will likely heave to some degree and could crack when the underlying soils become elevated in moisture content. If movement of these features can not be accepted or must be reduced, we are available to discuss heave mitigation techniques, upon your request. To reduce slab movements, carefully planned and maintained surface drainage will be critical. We recommend the following precautions be observed for on-grade slabs. These precautions will not eliminate slab movement but they tend to reduce damage when movement occurs. • A minimum 3-inch void space should be constructed above, or below non-bearing partition walls placed on the floor slab. Special framing details and/or connections should be provided at door-jambs, stairwells and heating/air-conditioning units to allow vertical movement. • • Positive separations and/or isolation joints should be provided between slabs and foundations, columns or utility lines to allow independent movement. • Frequent control joints should be provided in slabs to reduce problems associated with shrinkage cracking and curling. We support the use of an additional joint about 3 to 5 feet away from and parallel to foundation walls. • Fill/backfill placed beneath slabs should be compacted in accordance with recommended specifications outlined below. • If moisture sensitive floor coverings are used on interior slabs, consideration should be given to the use of barriers to minimize potential vapor rise through the slab. • Floor slabs should not be constructed on frozen subgrade. • Other design and construction considerations, as outlined in the ACI Design Manual, Section 302.1R are recommended. Septic System Construction: Field test results indicate that a standard septic system and leach field (soil absorption bed) is feasible for construction on the site at the location of • percolation test holes P-1 through P-6. The system should be constructed in accordance with applicable state and county requirements and should be located at the minimum 9 Balmes Homes lierracon • Proposed Custom Home&ISDS Lot 9—Highland Farms PUD Weld County,Colorado Terracon Project No.22075109 distances from all pertinent ground features described in Weld County regulations. We believe that a percolation rate of 60 minutes per inch is a reasonable value for sizing the absorption bed. No groundwater was encountered in our soil profile boring, located at the proposed soil absorption bed. However, bedrock was encountered in the soil profile boring at a depth of about 8% feet. Accordingly, the bottom of the leach field should not be constructed below a depth of about 4%feet from existing site grade. Additional design criteria for septic system construction are as follows: • Based upon the proposed residence containing 5 bedrooms, the proposed soil absorption bed should include a minimum of 3,235 square feet in plan view. • A minimum 1,500-gallon capacity septic tank should be used in the design • and construction. • The bottom of the bed should be excavated level and should be scarified and roughened prior to placement of the gravel media. • Distribution lines within the soil absorption bed should consist of 3 or 4-inch diameter perforated plastic or similar pipe approved in governing regulations. Distribution lines should be placed the full length of the proposed absorption bed or trench and should not exceed 100-feet in length. Distribution lines should be spaced at a maximum of 6-feet on center with the perimeter lines placed within 3 feet of all sides in the absorption bed. • Absorption beds should be backfilled with a minimum 12-inch thickness of clean graded gravel ranging in size from 1/4 to 2'/ inches in diameter. The gravel should extend a minimum of 6-inches below and 2-inches above the distribution pipes. • The gravel bed should be completely covered with untreated building paper prior to final soil cover. Final soil cover should be a minimum of 12-inches and not more than 24-inches in thickness and suitable for vegetative growth. • The surface of the soil cover should be graded for positive surface drainage and to reduce the possibility of surface water infiltration. 10 • Balmes Homes lferraeon Proposed Custom Home&ISDS Lot 9—Highland Farms PUD Weld County,Colorado Terracon Project No.22075109 Excavation: Excavations into the on-site materials will likely encounter sandy clays overlying claystone and siltstone/claystone bedrock. Groundwater seepage into excavations is not expected. However, if seepage occurs or rain or snow-melt water develops, it should be removed as soon as possible. Control of water in the excavation (if any) should be feasible with sump pits and pumps. The individual contractor(s) is responsible for designing and constructing stable, temporary excavations, as required, to maintain stability of the excavation sides and bottom, as well as adjacent structures. Excavations should be sloped or shored in the interest of safety following local and federal regulations, including current OSHA excavation and trench safety standards. As a safety measure, it is recommended that vehicles and soil piles be kept to a minimum lateral distance from the crest of the slope equal to no less than the slope height. The exposed slope face should be protected against the elements. General Earthwork: Strip and remove existing vegetation, debris and other unsuitable materials from proposed building and pavement areas. Stripped materials consisting of • vegetation and organic materials should be wasted from the site, or used to re-vegetate landscaped areas. Clean on-site soils or approved imported materials may be used as fill and/or backfill on the site. Claystone bedrock should not be used for wall backfill. The on-site clay soils should be stockpiled separately during excavation for use as wall backfill. Foundation wall backfill should be moistened at or above optimum and should be well compacted. Particular attention should be paid to proper compaction of backfill soils that will support sidewalks, patios and other exterior concrete slabs in order to reduce movement. In those locations where movement of exterior slabs cannot be tolerated or must be reduced, consideration should be given to constructing slabs with a stem or key-edge a minimum of 6 inches in width and at least 18 inches below grade, supporting keys or stems on drilled piers or providing structural exterior slabs supported on foundations similar to the building. Compaction of each lift adjacent to wails should be accomplished with hand-operated tampers or other lightweight compactors. Over-compaction may cause excessive lateral earth pressures that could result in wall movement. New fill placed beneath slabs or other structural elements should be moisture conditioned within 1 percent below to 3 percent above optimum moisture and compacted to at least 95 percent of the standard Proctor • maximum dry density (ASTM D698). 11 Balmes Homes lferraacor1 • Proposed Custom Home&ISDS Lot 9—Highland Farms PUD Weld County,Colorado Terracon Project No.22075109 Underground Utility Systems: Underground piping within or near the proposed structure should be designed and constructed so deviations in alignment do not result in breakage or distress. Utility knockouts in foundation walls should be oversized to accommodate differential movements. Corrosion Protection (Concrete): We measured the soluble sulfate concentration for a representative sample of the subsoils which will likely be in contact with structural concrete. The sulfate concentration measured in the sample was 1,150 parts per million (ppm). ACI rates the measured concentrations as being a moderate risk of concrete sulfate attack. ACI recommends the use of Type II cement, or equivalent, and a maximum water cement ratio of 0.50 for construction concrete. Foundation concrete should be designed in accordance with the provisions of the ACI Design Manual, Section 318, Chapter 4. Surface Drainage: Grades must be adjusted to provide positive drainage away from the structure during construction and maintained throughout the life of the proposed residence. Maintenance of surface drainage is imperative subsequent to construction and becomes the • responsibility of the homeowner. Infiltration of water into utility or foundation excavations must be prevented during and after construction. Landscaped irrigation adjacent to the foundation system should be minimized or eliminated. Exposed ground should be sloped at approximately 10 percent grade for at least 10 feet beyond the perimeter of the building, where practicable. Between structures which are less than 20 feet apart, the slope should be at least 10 percent to the swale used to convey water out of these areas. The ground surface should be sloped in such a manner that water will not pond between or adjacent to structures. Backfill against exterior walls and in utility and sprinkler line trenches should be well compacted and free of construction debris to reduce moisture infiltration. After building construction and prior to project completion, we recommend that verification of final grading be performed to document that positive drainage, as described above, has been achieved. Water permitted to pond near or adjacent to the perimeter of the structure (either during or post-construction) can result in higher soil movements than those discussed in this report. As a result, estimations of potential movement described in this report cannot be relied upon if positive drainage is not obtained and maintained, and water is allowed to infiltrate the fill and/or subgrade. • 12 Balmes Homes lrerrcacor1 • Proposed Custom Home&ISDS Lot 9—Highland Farms PUD Weld County,Colorado Terracon Project No. 22075109 Flatwork and pavements will be subject to post-construction movement. Maximum grades practical should be used for paving and flatwork to prevent areas where water can pond. Where paving or flatwork abuts the structure, care should be taken that joints are properly sealed and maintained to prevent the infiltration of surface water. Planters located adjacent to the structure should preferably be self-contained. Sprinkler mains and spray heads should not be installed or allowed to discharge within 10 feet of foundation walls. Roof drains should discharge on pavements or be extended away from the structure a minimum of 10 feet through the use of splash blocks or downspout extensions. Additional suggestions to reduce potential movements can be obtained from the Colorado Geologic Survey (CGS) in "A Guide to Swelling Soils for Colorado Homebuyers and Homeowners", Publication No. SP-43. GENERAL COMMENTS Terracon should be retained to review the final design plans and specifications so • comments can be made regarding interpretation and implementation of our geotechnical recommendations in the design and specifications. Terracon also should be retained to provide testing and observation during excavation, grading, foundation and construction phases of the project. The analysis and recommendations presented in this report are based upon the data obtained from the borings performed at the indicated locations and from other information discussed in this report. This report does not reflect variations that may occur between borings, across the site, or due to the modifying effects of weather. The nature and extent of such variations may not become evident until during or after construction. If variations appear, we should be immediately notified so that further evaluation and supplemental recommendations can be provided. The scope of services for this project does not include either specifically or by implication any environmental or biological (e.g., mold, fungi, bacteria) assessment of the site or identification or prevention of pollutants, hazardous materials or conditions. If the owner is concerned about the potential for such contamination or pollution, other studies should be undertaken. This report has been prepared for the exclusive use of our client for specific application to the project discussed and has been prepared in accordance with generally accepted • geotechnical engineering practices. No warranties, express or implied, are intended or 13 Balmes Homes lierracon • Proposed Custom Home&ISDS Lot 9—Highland Farms PUD Weld County,Colorado Terracon Project No. 22075109 made. Site safety, excavation support, and dewatering requirements are the responsibility of others. In the event that changes in the nature, design, or location of the project as outlined in this report are planned, the conclusions and recommendations contained in this report shall not be considered valid unless Terracon reviews the changes and either verifies or modifies the conclusions of this report in writing. • • 14 r • T-- rr �o D it p TSM - N.BONNET BOLT OF FIRE HYDRANT—P" (ASSUMED ELEVATIONrl00.0') P-4 P-5 — P-6 \--________ TB-3 PROPOSED SEPTIC FIELD I P-3 P-2 P-1 TB-I PROPOSED RESIDENCE O TB-2 I N , 100 00 00 LEGEND APPROXIMATE LOCATION OF I BALMES HOMES 9 TEST BORING DRILLED ON PROPOSED CUSTOM NOME AUGUST 2S,2001 LOT 9 - NIC 1-(LAND FARMS LONGMONT, COLORADO APPROXIMATE LOCATION FIGURE I: BORING LOCATION DIAGRAM OF PERCOLATION HOLES Project Manager, r Project No TESTED AUGUST 29,2001 GDO22O151O9 Bran By GDO l t'�r r� o n scales = I0 ilill R2 CEB 4-24-01 Checked By. EJP 122 Branrood Place Date, S/eta/mZ DIAGRAM IS FOR GENERAL LOCATION ONLY,AND IS RI CEB 5-19-99 Longmont, Colorado 80501 NOT INTENDED FOR CONSTRUCTION PURPOSES RO CHS 4-22-98 Approved By EJP 303-776-3921 Sheet Ho I of 1 • LOG OF TEST BORING NO. TB-1 Page 1 of 1 CLIENT • Balmes Homes SITE Lot 9 - Highland Farms PUD PROJECT Weld County, Colorado Proposed Custom Home SAMPLES TESTS O Z wN O p - o> a co U Dw DESCRIPTION p z�? O�[ U r Y w �c z Z zF- a U=o m O wu, WH ED O0-w JU a cs w w w C ED >- w w o <O �3 zoo wjo Approx. Surface Elev.: 96.0 ft o z F- a 0_3 SO o a D O uW (n VEGETATIVE SOIL LAYER 5 5 .j Clayey soil with vegetation and root • penetration. 2.5 SANDY LEAN CLAY 93.5 CB 30/12 9 _ \brown, beige, rust, grey, very stiff, porous. _ SILTSTONE/CLAYSTONE -- trace sand, brown, beige, olive-grey, rust, 5 weathered to medium hard, with iron — CB 41/12 8 concretions. 7 89 CLAYSTONE grey, olive-grey, brown, rust, medium hard —_ to hard, varies slightly lignitic, with thin Siltstone beds with depth. CB 50/11 19 108 +3.8/500 10 CB 50/8 20 102 +1.8/1000 15 CB 50/9 21 100 +0.6/1000 20 -- -- ------- - z5 71 — CB 50/11 23 99 14820 25 Bottom of Test Boring 0 z 0 Q ll F The stratification lines represent the approximate boundary lines between soil and rock types: in-situ,the transition may be gradual. WATER LEVEL OBSERVATIONS,ft BORING STARTED 8-28-07 WL ? Dry 8/28/07 1 Dry 8/29/07 NG WL 2 llerracon RIIGRICOMPLETED Deidrich D-55 FOREMAN 8-28-07 GO Y w WL APPROVED EJP JOB# 22075109, • • LOG OF TEST BORING NO. TB-2 Page 1 of 1 CLIENT Balmes Homes ID SITE Lot 9 - Highland Farms PUD PROJECT Weld County, Colorado Proposed Custom Home SAMPLES TESTS J O J C z 111"6 O p O o H p> a <ow 0 DESCRIPTION >-cc (1)1-± o a _ f (/) w > F'c d'W Z Zi7 Uo F- (C m W O W w W H Z O0-w JOp �Z >- OO W�Q W (O/) D H W Wo ¢O Oa Z OH o Approx. Surface Elev.: 98.0 ft o ❑ Z H e_a o o a D O O) (D rn J 0.5 VEGETATIVE SOIL LAYER 97.a Clayey soil with vegetation and root 4 \penetration. J CL CB 21/12 7 95 +1.3/250 3s SANDY LEAN CLAY 94.5 ...■ brown, beige, rust, grey, very stiff, silty, porous. 5 CB 45/12 11 116 +5.1/500 CLAYSTONE grey, olive-grey, brown, rust, weathered to very hard, varies silty, with lignite lenses. 0 CB 50/10 15 116 _ +2.8/500 s CB 50/10 19 107 20 CB 50/5 16_ 25 CB 50/7 24 30 Iii 50/6 16 105 X35 63 35 CB 50/2 10 Bottom of Test Boring F- oo O U a p W H The stratification lines represent the approximate boundary lines g between soil and rock types: in-situ, the transition may be gradual. 1101 WATER LEVEL OBSERVATIONS, ft BORING STARTED 8-28-07 Nur WL V Dry 8/28/07 s 31 8/29/iii �rr�con BORING COMPLETED 8-28-07 o WL 2 RIG Deidrich D-55 FOREMAN GO oWL APPROVED EJP JOB# 22075109 ` LOG OF TEST BORING NO. TB-3 Page 1 of 1 CLIENT • Balmes Homes SITE Lot 9 -Highland Farms PUD PROJECT Weld County, Colorado Proposed Custom Home SAMPLES TESTS J zU' O a F 0> O. O W DESCRIPTION a H in(7) o`� w > � c fw Z Zflz J'S S O aH rn m W O Z3 FZ > 0W w�< Approx. Surface Elev.: 92.0 ft o Z X [LTD-o° S.° o a D O1- o N 0 5 VEGETATIVE SOIL LAYER 91 5 (Clayey soil with vegetation and root penetration. SANDY LEAN CLAY brown, beige, rust, very stiff, porous, trace j fine Gravel, trace lignite, with Clayey Silty _ CL CB 24/12 4 97 Sand lenses. • % 5 CL CB 23/12 12 91 8.5 83.5 _ SILTSTONE/CLAYSTONE trace sand, brown, beige, rust, tan, CB 34/12 7 - 10 \weathered to firm. 82 10 • Bottom of Test Boring 0 0 z z O U K W H 25- The stratification lines represent the approximate boundary lines st between soil and rock types: in-situ,the transition may be gradual. 10 WATER LEVEL OBSERVATIONS, ft BORING STARTED 8-28-07 WL V o WL y Dry 8/28/07 7 Dry 8/29/07 1 -07 erracon RIG BORING COMPLETED8 28 Deidrich D-55 FOREMAN GO o WL APPROVED EJP JOB# 22075109 aS • 8 6 4 2 • z o -2 0 a O o -4.. • -6 -8 - - -10 0.1 1 10 100 APPLIED PRESSURE, ksf Specimen Identification Classification Y3, pcf WC,% • TB-1 9.0ft CLAYSTONE 108 19 0 Notes: Water Added to Sample at 500 psf. • z SWELL/CONSOLIDATION TEST Project: Proposed Custom Home lierraccin Site: Lot 9 - Highland Farms PUD Weld County, Colorado o Job #: 22075109 U F Date: 9-4-07 10 • I 8 f- - - - 6 4 J W • -2 i Q J -4 O • -6 -8 -10 0.1 1 10 100 APPLIED PRESSURE,ksf Specimen Identification Classification 7d, pcf WC,% a • TB-1 14.0ft CLAYSTONE 102 20 Notes. Water Added to Sample at 1,000 psf. • N z SWELUCONSOLfDATION TEST ir e rr 7COn Project: Proposed Custom Home Site: Lot 9- Highland Farms PUD Weld County, Colorado o Job#: 22075109 0 Date: 9-4-07 • a 6 i I I _1 I 11 1 I II I 4 [l{ Oa- -7- o -2 H 0 J 0 z -4 1 0 U • -6 -8 -10 .. 0.1 1 10 100 APPLIED PRESSURE,ksf Specimen Identification Classification Yd, pcf WC,% • TB-1 19.0ft CLAYSTONE 100 21 Notes: Water Added to Sample at 1,000 psfce ce C7 • " SWELUCONSOLIDATION TEST Z Project: Proposed Custom Home 1 parr acon Site: Lot 9- Highland Farms PUD Weld County, Colorado o Job#: 22075109 Date: 9-4-07 • • 6 --' ' 4 IL' U) 2 - - -_ -- • -2 O en U • -s -- • - • -10 0.1 1 10 100 APPLIED PRESSURE,ksf Specimen Identification Classification Yd, pcf WC,% - r • TB-2 2.0ft SANDY LEAN CLAY(CL) 95 7 0 Notes: Water Added to Sample at 250 psf. a C7 of • Z" SWELUCONSOLIDATION TEST cc Project: Proposed Custom Home 1 ue rr acon Site: Lot 9- Highland Farms PUD Weld County, Colorado o Job#: 22075109 U Date: 9-4-07 10. • 6 4 2 -- IIIII�� 1 III 1111111 ail Z _ I �� li I X1111111 o -2 �11i11 z -4 ��IIIIII X111111 X1111111 • X1111111 -6 ��IIIiI I��IIIII -8 1111 -10 _ 11111 _ 0.1 1 10 100 APPLIED PRESSURE, ksf Specimen Identification Classification Yd, pcf WC,% • TB-2 5.0ft CLAYSTONE 116 11 O C� 0 O Notes: Water Added to Sample at 500 psi. CC CC W La- CO • = SWELL/CONSOLIDATION TEST N Project: Proposed Custom Home iluerraccin Site: Lot 9 - Highland Farms PUD Weld County, Colorado o Job #: 22075109 O Date: 9-4-07 k • 8 6 4 U) • 2 • z o -2 k= O J U 0z -4 • -6 -8 - — -- — 1 - -10 — 0.1 1 10 100 APPLIED PRESSURE,ksf Specimen Identification Classification Yd, pcf WC,% F • TB-2 9.Oft CLAYSTONE 116 15 Notes: Water Added to Sample at 500 psf. I • " _ SWELLICONSOLIDATION TEST ,;'D Project: Proposed Custom Home Kerr acon Site: Lot 9 - Highland Farms PUD Weld County, Colorado o Job#: 22075109 Date: 9-4-07 F U.S.SIEVE OPENING IN INCHES I U.S.SIEVE NUMBERS I HYDROMETER 6 4 3 2 15 1 3/4 1/2 ,, 3 6 610 1416 20 30 40 50 60 100 140 200 100 1 1 I I Y MM -- 95 - _ - • ::iii_i 11■ 1!:IIII■ II ■■111111■■II•IIII :1■ IIII■® !1 • 8 ■■11111 _ 1111111 80 • • i■■1111111■ IIl1 i1■■flip 1■ II IIII■■lllil ■ 75 • • 70 • soII • 11■■11111 w • 111111■■11111 ■■I1•III■■■1111111■■ 50 • I- 45 w • ° 40 a 35 • • ° 2 11■■111111 lull' �■ 11111 I■■11 IIII ■1111111■ • • 20 • • 15 i:111 11■■11:1111■: 11111: 1 ■11111 : ■■1111111■ 1111111■■ ■I! IIII■®111111■■■ III .- ■■1! 1111■■111111 ■� 0 100 10 1 0.1 0.01 0.001 GRAIN SIZE IN MILLIMETERS COBBLESF. GRAVEL SAND ■ SILT OR CLAY coarse fine coarse medium fine Specimen Identification Classification LL PL PI Cc Cu •1 TB-1 5.0ft SILTSTONE/CLAYSTONE,trace SAND 51 20 31 Specimen Identification D100 D60 D30 D10 %Gravel %Sand %Silt %Clay • TB-1 5.0ft 9.5 0.1 3.5 96.4.9'73C7 of GRAIN SIZE DISTRIBUTION/SOIL CLASSIFICATION Project: Proposed Custom Home lierracon Site: Lot 9 - Highland Farms PUD Weld County, Colorado Job #: 22075109 O Date: 9-4-07 PERCOLATION TEST RESULTS Client/Project: Balmes Homes/ Proposed Custom Home Project No.: 22075109 Location: Lot 9 - Highland Farms Tester: KPL Legal Description: NW 1/4 Section 5, Township 1 North, Range 68 West Test Date: 8/30/2007 Soil Description: Sandy Lean Clay(CL) P - 1 P - 2 P - 3 Depth: 33" Diameter: 7" Depth: 29" Diameter:6" Depth: 31" Diameter:6" Change in Change Percolation Change in Change Percolation Change in Change Percolation Reading Height in Time Rate Reading Height in Time Rate Reading Height in Time . Rate 17 1/4 - - - 15 - - - 15 3/8 - - - 18 7/16 1 3/16 30 25 16 5/16 1 5/16 30 23 16 7/16 1 1/16 30 28 19 1/2 1 1/16 30 28 17 5/16 1 30 30 17 5/16 7/8 30 34 20 3/8 7/8 30 34 18 1/8 13/16 30 37 18 11/16 30 44 21 1/4 7/8 30 34 18 3/4 5/8 30 48 1811/16 11/16 30 44 22 1/16 13/16 30 37 19 5/16 9/16 30 53 19 3/8 11/16 30 44 22 3/4 11/16 30 44 19 7/8 9/16 30 53 1915/16 9/16 30 53 Hole Perc. Rate: min./in. Hole Perc. Rate: min./in. Hole Perc. Rate: min./in. P - 4 P - 5 P - 6 Depth:29" Diameter:7" Depth: 32" Diameter: 6" Depth:29" Diameter: 7" Change in Change Percolation Change in Change Percolation Change in Change Percolation Reading Height in Time Rate Reading Height in Time Rate Reading Height in Time Rate 15 1/8 - - - 16 - - - 15 1/4 - - - 16 7/8 30 34 17 3/8 1 3/8 30 22 17 9/16 2 5/16 30 13 16 3/4 3/4 30 40 18 7/16 1 1/16 30 28 19 3/16 1 5/8 30 18 17 3/8 5/8 30 48 19 1/4 13/16 30 37 20 7/16 1 1/4 30 24 1715/16 9/16 30 53 20 3/4 30 40 21 9/16 1 1/8 30 27 18 1/2 9/16 30 53 20 3/4 3/4 30 40 22 7/16 7/8 30 34 19 1/2 30 60 21 3/8 5/8 30 48 23 3/16 3/4 30 40 Hole Perc. Rate: min./in. Hole Perc. Rate: min./in. Hole Perc. Rate: min./in. • 1242 Bramwood Place, Longmont, Colorado 80501 llerracon • GENERAL NOTES DRILLING&SAMPLING SYMBOLS: • SS: Split Spoon- 1'/e" I.D., 2"O.D., unless otherwise noted HS: Hollow Stem Auger ST: Thin-Walled Tube—2.5"O.D., unless otherwise noted PA: Power Auger RS: Ring Sampler-2.42"I.D., 3"O.D., unless otherwise noted HA: Hand Auger CB: California Barrel- 1.94"I.D.,2.5"O.D., unless otherwise noted RB: Rock Bit BS: Bulk Sample or Auger Sample WB: Wash Boring or Mud Rotary The number of blows required to advance a standard 2-inch O.D. split-spoon sampler(SS) the last 12 inches of the total 18-inch penetration with a 140-pound hammer falling 30 inches is considered the "Standard Penetration" or "N-value". For 2.5" O.D. California Barrel samplers (CB)the penetration value is reported as the number of blows required to advance the sampler 12 inches using a 140-pound hammer falling 30 inches, reported as "blows per inch," and is not considered equivalent to the "Standard Penetration"or"N-value". WATER LEVEL MEASUREMENT SYMBOLS: WL: Water Level WS: While Sampling WCI: Wet Cave in WD: While Drilling DCI: Dry Cave in BCR: Before Casing Removal AB: After Boring ACR: After Casing Removal Water levels indicated on the boring logs are the levels measured in the borings at the times indicated. Groundwater levels at other times and other locations across the site could vary. In pervious soils,the indicated levels may reflect the location of groundwater. In low permeability soils,the accurate determination of groundwater levels may not be possible with only short-term observations. DESCRIPTIVE SOIL CLASSIFICATION: Soil classification is based on the Unified Classification System. Coarse Grained Soils have more than 50%of their dry weight retained on a#200 sieve;their principal descriptors are: boulders, cobbles, gravel or sand. Fine Grained Soils have less than 50% of their dry weight retained on a#200 sieve; they are principally described as clays if they are plastic, and silts if they are slightly plastic or non-plastic. Major constituents may be added as modifiers and minor constituents may be added according to the relative proportions based on grain size. In addition to gradation, coarse-grained soils are defined on the basis of their in-place relative density and fine-grained soils on the basis of their consistency. • FINE-GRAINED SOILS COARSE-GRAINED SOILS BEDROCK (CB) fSS) fCIB Relative (CBI fSS) Blows/Ft. Blows/Ft. Consistency Blows/Ft. Blows/Ft. Density Blows/Ft. Blows/Ft. Consistency < 3 <2 Very Soft 0-5 <3 Very Loose < 24 <20 Weathered 3-4 2-3 Soft 6-14 4-9 Loose 24-35 20-29 Firm 5-7 4-6 Medium Stiff 15-46 10-29 Medium Dense 36-60 30-49 Medium Hard 8-15 7-12 Stiff 47-78 30-49 Dense 61-96 50-79 Hard 16-32 13-26 Very Stiff > 78 >49 Very Dense > 96 >79 Very Hard > 32 > 26 Hard RELATIVE PROPORTIONS OF SAND AND GRAIN SIZE TERMINOLOGY GRAVEL Descriptive Terms of Percent of Major Component Other Constituents Dry Weight of Sample Particle Size Trace < 15 Boulders Over 12 in. (300mm) With 15-29 Cobbles 12 in.to 3 in. (300mm to 75 mm) Modifier >30 Gravel 3 in.to#4 sieve(75mm to 4.75 mm) Sand #4 to#200 sieve (4.75mm to 0.075mm) Silt or Clay Passing#200 Sieve(0.075mm) RELATIVE PROPORTIONS OF FINES PLASTICITY DESCRIPTION Descriptive Terms of Percent of Other Constituents Dry Weight Term Plasticity Index Trace <5 Non-plastic 0 With 5-12 Low 1-10 Modifiers > 12 Medium 11-30 High 30+ • lierracon UNIFIED SOIL CLASSIFICATION SYSTEM • Criteria for Assigning Group Symbols and Group Names Using Laboratory Tests" Soil Classification Group Symbol Group Name° Coarse Grained Soils Gravels Clean Gravels Cu≥4 and 1 s Cc s 3° GW Well graded graver - More than 50%retained More than 50%of coarse Less than 5%foes` Cu<4 and/or 1 >Cc>3° GP Poorly graded gravel` fraction retained on on No.200 sieve No.4 sieve Gravels with Fines Fines classify as ML or MH GM Silty graver-Q" • More than 12%fines` Fines classify as CL or CH GC Clayey graver." Sands Clean Sands Cu≥6 and 1 5 Cc 5 3` SW Well graded sand' 50%or more of coarse Less than 5%fines° Cu<6 and/or 1>Cc>3r SP Poorly graded sand' fraction passes No.4 sieve Sands with Fines Fines classify as ML or MH SM Silty sand`"' More than 12%foes° Fines classify as CL or CH SC Clayey sand`"' Fine-Grained Soils Silts and Clays Inorganic PI>7 and plots on or above"A"line' CL Lean clay*" 50%or more passes the Liquid limit less than 50 PI<4 or plots below"A"line' ML Silti " No.200 sieve Organic Liquid limit-oven Organic clay"`"-N dried <0.75 OL Liquid limit-not Organic silt"--"° dried Silts and Clays Inorganic PI plots on or above"A"line CH Fat clay""-41 Liquid limit 50 or more PI plots below"A"line MH Elastic silt"`" Organic Liquid limit-oven dried <0.75 OH Organic clay"L"4` Liquid limit-not dried Organic silt4hr° Highly organic soils Primarily organic matter,dark in color,and organic odor PT Peat •ased on the material passing the 3-in. (75-mm)sieve "If fines are organic, add"with organic fines"to group name. If field sample contained cobbles or boulders, or both,add"with cobbles I If soil contains≥ 15%gravel,add'With gravel"to group name. or boulders,or both"to group name. J If Atterberg limits plot in shaded area,soil is a CL-ML, silty clay. cGravels with 5 to 12%fines require dual symbols: GW-GM well graded K If soil contains 15 to 29%plus No.200, add'With sand"or"with gravel with silt,GW-GC well graded gravel with clay, GP-GM poorly gravel,"whichever is predominant. graded gravel with silt, GP-GC poorly graded gravel with clay. L If soil contains≥30%plus No.200 predominantly sand, add °Sands with 5 to 12%fines require dual symbols: SW-SM well graded "sandy"to group name. sand with silt, SW-SC well graded sand with clay,SP-SM poorly graded m sand with silt, SP-SC poorly graded sand with clay If soil contains≥30%plus No.200, predominantly gravel, add"gravelly"to group name. (D3°)2 "PI≥4 and plots on or above"A"line. ECu =D6o/Dio Cc= Dio x Deo ° PI <4 or plots below"A"line. F If soil contains≥15%sand,add'With sand"to group name. °PI plots on or above"A"line. °If fines classify as CL-ML, use dual symbol GC-GM, or SC-SM. ° PI plots below"A"line. 60 - —I I I l— : ---- --- - - For classification of fine-grained soils and fine-grained fraction 60Ho f coarse-grained soils - ---woe- --- .\ce_ --- Equation of"A"-line i +J.{ •P 0- Horizontal at PI=4 to LL=25.5. 1 X 40 then P1=0.73(LL-20) — - 0� - - -- tL °( o Equation of"U" line ? ; 'veriicai at LL=16 to PI=7, G >- 30 then P1=0.9(LL-8) - O /J`ON. p , Ne G 0- - ' MH or OH • o I MLo / 1_ 4 OL o _ CLML 0 10 16 20 30 40 50 60 70 80 90 100 110 • LIQUID LIMIT(LL) llerra con ROCK CLASSIFICATION (Based on ASTM C-294) Sedimentary Rocks Sedimentary rocks are stratified materials laid down by water or wind. The sediments may be composed of particles of pre-existing rocks derived by mechanical weathering, evaporation or by chemical or organic origin. The sediments are usually indurated by cementation or compaction. Chert Very fine-grained siliceous rock composed of micro-crystalline or crypto- crystalline quartz, chalcedony or opal. Chert is various colored, porous to dense, hard and has a conchoidal to splintery fracture. Claystone Fine-grained rock composed of or derived by erosion of silts and clays or any rock containing clay. Soft massive; gray, black, brown, reddish or green and may contain carbonate minerals. Conglomerate Rock consisting of a considerable amount of rounded gravel, sand and cobbles with or without interstitial or cementing material. The cementing or interstitial material may be quartz, opal, calcite, dolomite, clay, iron oxides or other materials. Dolomite A fine-grained carbonate rock consisting of the mineral dolomite (CaMg • (CO3)21. May contain noncarbonate impurities such as quartz, chert, clay minerals, organic matter, gypsum and sulfides. Reacts with hydrochloric acid (HCL). Limestone A fine-grained carbonate rock consisting of the mineral calcite (CaCo3). May contain noncarbonate impurities such as quartz, chert, clay minerals, organic matter, gypsum and sulfides. Reacts with hydrochloric acid (HCL). Sandstone Rock consisting of particles of sand with or without interstitial and cementing materials. The cementing or interstitial material may be quartz, opal, calcite, dolomite, clay, iron oxides or other material. Shale Fine-grained rock composed of, or derived by erosion of silts and clays or any rock containing clay. Shale is hard, platy, or fissile may be gray, black, reddish or green and may contain some carbonate minerals (calcareous shale). Siltstone Fine grained rock composed of, or derived by erosion of silts or rock containing silt. Siltstones consist predominantly of silt sized particles (0.0625 to 0.002 mm in diameter) and are intermediate rocks between clays and sandstones, may be gray, black, brown, reddish or green and may contain carbonate minerals. • lierracon Hello