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Home My WebLink About20132820.tiffGEOTECIINICAL INVESTIGATION FOR PART OF THE NORTH'/: OF THE SOUTHWEST 'A OF SECTION 35, TOWNSHIP 8 NORTH, RANGE 65 WEST, WELD COUNTY, COLORADO FOR SELECT ENERGY SERVICES CDS ENGINEERING CORPORATION LOVELAND, COLORADO PROJECT NUMBER 13-6397 MAY 29, 2013 May 29, 2013 Project No. 13-6397 Mr. Jim Goddard SELECT ENERGY SERVICES 24246 Weld County Road 34 LaSalle, CO 80615 Dear Jim. Enclosed is the report you requested of the geotechnical exploration for the proposed building to be located on part of the North `L of the Southwest'/ of Section 35, Township 8 North, Range 65 West, Weld County, Colorado. The site appears to be suitable for the construction of the proposed structure, provided the design criteria and recommendations given in this report are followed. If you have any further questions concerning the information in this report, please contact this office. Respectfully, FOR AND ON BEHALF OF CDS ENGINEERING CORPORATION Kevin F. Becker, P Enclosures TABLE OF CONTENTS Pace Letter of Transmittal Table of Contents Scope Site Investigation Site Location and Description Subsurface Conditions Foundation Recommendations - Continuous Spread Footing and Isolated Pad Foundation Lateral Earth Pressures Slab Construction Conclusions ATTACHMENTS Location of Test Borings Symbols and Soil Properties Log of Borings Swell -Consolidation Test Results Summary of Test Results Post -Construction Site Preparation and Maintenance Placement of Compacted Fill Materials ii ii 1 3 3 3 4 Drawing No. 1 Figure No. 1 Figure No. 2 Figure Nos. 3 & 4 Table No. 1 Appendix I Appendix 3 SCOPE This report presents the results of a geotechnical exploration for the proposed facility to be located on part of the N'// of the SW"/ of Section 35, Township 8 North, Range 65 West of the 6`n P.M., Weld County, Colorado. The building is anticipated to be of typical steel frame construction. Slab -on -grade construction is anticipated for this structure, with the anticipated excavation depths to range from two (2) to four (4) feet below grades which existed at the time of this exploration. This exploration was conducted to provide recommendations pertaining to the type and depth of foundation system, allowable soil bearing pressures, groundwater conditions. and to identify any complications that may be encountered during or after construction due to subsurface conditions. SITE INVESTIGATION The field investigation performed on May 9, 2013, consisted of drilling, logging, and sampling two (2) test borings within the approximate building envelope at the site. The borings ranged in depth from twelve (12) to twenty (20) feet. The location of the Test Holes is shown on Drawing No. 1. Boring locations were established by a representative ofCDS Engineering Corporation based on a site plan provided by Wemsman Engineering. Distances from the referenced features were made by pacing and angles were estimated. Graphical logs of the borings are shown on Figure No. 2. The descriptions of the soils and/or bedrock strata are based, primarily, on visual and tactual methods which are subject to interpretation. The test borings were advanced using a truck mounted, four -inch (4") diameter, continuous flight auger drill rig. Laboratory samples were obtained by driving a two and one-half inch (2'G") diameter California Barrel Sampler twelve (12) inches (or as shown) into undisturbed soils with a 140 -pound hammer falling thirty (30) inches. Bag samples of auger cuttings may have also been collected. Laboratory tests performed were - Swell -Consolidation, Natural Moisture, Natural Dry Densities, Grain Size Analysis. Unconfined Compressive Strengths. and Atterberg Limits. All tests were conducted in accordance with .ASTM standards. A Summary of the Swell -Consolidation Test Results is shown on Figure Nos. 3 and 4. A Summary of Test Results is shown on Table No. 1. 2 SITE LOCATION AND DESCRIPTION The site is located east of Briggsdale. one mile south of highway 14, on the east side of County Road 105, Weld County. Colorado. The site is generally in a plains region and vegetation consists primarily of grasses and cacti. The site is relatively flat. No rock outcrops were observed at this site. SUBSURFACE CONDITIONS Refer to the Lou of Borings, Figure No. 2. The subsurface conditions appear uniform throughout the proposed building site. General descriptions of the soils and/or rock encountered are as follows: TOPSOIL — A thin layer of topsoil. approximately six (6) inches, overlies the site. The topsoil should not be used as foundation bearing material, structural fill, or backfill. It is suggested that the topsoil he stripped, stockpiled and used for landscaped areas. CLAY — Clays with slight to moderate amounts of sand were encountered in the upper nine (9) to ten and one-half (10'/) feet of Test Hole Nos. 1 and 2. The clays appear to be slightly moist. stiff to hard, and brown. The clays exhibit low to moderate bearing capacities with low swell potential detected in our tests. SANDSTONE - Sandstone bedrock strata with interbedded siltstone lenses, were encountered from below the upper soils to the depths explored. Claystone lenses were encountered from sixteen (16) feet to the depths explored. The competent sandstone exhibits high bearing capacities and are anticipated to have no to low swell potential. Groundwater levels were recorded as the borings were advanced, after completion of the drilling operations, and twenty-four (24) hours after drilling operations were complete. During our field exploration groundwater was not encountered in the test borings. The groundwater table should be expected to fluctuate throughout the year depending on seasonal moisture variations. 3 FOUNDATION RECOMMENDATIONS The type of foundation best suited for a particular building site is dependant not only on the characteristics of the soil and rock but also depends on the type of structure. depth to groundwater, the proposed depth of excavation, and owner preference. The recommendations that follow are primarily based on the type of soil encountered. Based on the conditions observed in the field and laboratory tests, we recommend the foundation be a continuous spread footing and isolated pad foundation. Continuous Spread Footing and Isolated Pad Foundation Where the foundation will bear less than four (4) feet below existing grade, the foundation should be designed for a maximum allowable bearing capacity of 1500 pounds per square foot (dead load plus full live load) and a minimum dead load of 500 pounds per square foot (psf) to help counteract the swelling should the subsoils become wetted. Where the foundation will bear deeper than four (4) feet below existing grades. the foundation should be designed for a maximum allowable bearing capacity of 1000 psf and a minimum dead load kept as high as practicable. If the foundation should bear on the sandstone footings should be designed for a maximum allowable bearing capacity of 2500 psf with a minimum dead load of 750 psf. If claystone is encountered in the excavation. alternate recommendations may be required. The foundation is to bear on the native, undisturbed soils or sandstone, and not on unapproved fill, topsoil, or frozen ground. The bottom of all foundation components should be kept at least thirty (30) inches (or per local code) below finished grade for frost protection. The open excavation should not be left open for an extended period of time or exposed to adverse weather conditions. The completed open excavation should be observed by a representative of CDS Engineering Corporation in order to verify the subsurface conditions from test hole data. LATERAL EARTH PRESSURES Lateral earth pressures are forces exerted on earth retaining structures by the soil. In residential applications this force is exerted on the foundation walls or retaining walls. The pressure exerted is influenced by wetting of the backfill soils, type and compaction of the backfill and the methods used to compact the backfill. We recommend that the foundation walls and other retaining structures be designed for a minimum equivalent fluid density of45 pcf (active). This value assumes positive drainage will be maintained and that the on -site soils will be used as backfill against foundation walls and retaining structures; also, that a below -grade perimeter drainage system will be installed. If there is opportunity for the backfill soils to become saturated, we shall be notified to revise the minimum equivalent fluid density. The design lateral earth pressure reported could also be revised if a backfill other than the on -site materials is utilized. SLAB CONSTRUCTION Changes in the moisture contents may result in consolidation or swelling of the subsoil, resulting in differential slab movement. The soils encountered and tested at this site exhibit low swell potential as moisture contents are increased. According to the Guideline for Slab Performance Risk Evaluation and Residential Basement Floor System Recommendations, developed by the Colorado Association of Geotechnical Engineers, slab performance risk at this site would he considered low. Slabs placed on the native, unaltered soils at this site may experience slight heaving and cracking, but should not be excessive. Where floor movement cannot be tolerated by the owner, structural floors could he constructed in place of slabs -on grade. Another alternative which could reduce the risk of potential slab movement would be to remove at least two (2) feet of soil beneath the slab and replace it with a moisture and density controlled fill approved by the engineer. If slabs -on -grade are chosen and the owner is willing to accept the risks of potential damage from slab movement, slabs should he constructed to he "free-floating" and isolated from all structural members of the foundation, utility lines, and partition walls. There should be a minimum two-inch (2") void constructed below partition walls located over slabs -on -grade. The void should be increased to four (4) inches for slabs placed on potentially expansive bedrock stratum. Eliminate under -slab plumbing where feasible. Where such plumbing is unavoidable, it should be pressure tested before and after slab construction to minimize leaks which would result in wetting of the subsoil. Failure to allow the slab to float independently could result in functional, structural. architectural, and utility line damage. All slabs should be scored into maximum 225 square foot areas or maximum dimensions of fifteen (15) feet with a minimum depth of one (1) inch to localize and control any cracking due to heaving. Slabs less than thirty (30) square feet should be scored at least once in each direction. The minimum slab thickness should be four (4) inches, with four (4) inches of clean, washed gravel under the slab. Slabs should be reinforced with welded wire fabric, or equivalent, to help control cracking and separation. Fiber mesh shall not be considered an equivalent substitute for the welded wire fabric. CONCLUSIONS The soils and rock encountered at this site low swell potential as moisture contents are increased. Future owners should be cautioned that there may be some risk of future damage caused by introduction of excess water to the soils and/or rock. All new and future owners should be directed to those items under "Post -Construction Site Preparation and Maintenance" in Appendix 1, included in this report. Our experience has shown that damage to foundations usually results from saturation of the foundation soils caused by improper drainage, excessive irrigation, poorly compacted backfills, and leaky water and sewer lines. The elimination of the potential sources of excessive water will great]) minimize the risks of construction at this site. The findings and recommendations of this report have been obtained in accordance with accepted professional engineering practices in the field of Geotcchnical Engineering. However, standard Geotcchnical Engineering practices and related government regulations are subject to change. The recommendations provided in this report are only valid as of the date of this report. If the construction is at a later date, we would be glad to review the information presented in this report with regard to updated governmental requirements or industry standards. There is no other warranty, either expressed or implied. We do not guarantee the performance of the project in any respect, hut only that our engineering work and judgments rendered meet the standard of care of our profession. This report applies only to the type of construction anticipated in the area tested. The current technology is not at a stage where a guarantee of"absolutely no damage" can be assured by design and construction practices. \ICINI Tv M1, (not to stole) Hwy '.4 L7 O / CR 85 tr U PTH-1 Pere Area PERCOLATION TEST LOCATION N 40.62571° W 104.06807° access road Client: Select Energy Services Project: Weitzel Ranch Facility Weld County, Colorado LOCATION OF TEST BOR NGS Approximate Scale: 1" = 300' Project No. 13-5397 CDS Engineering Corporation 165 2nd St. S.W. Loveland, CO 60537 Tele: (970) 667-8010 Dwg. No.: 1 S vm b o • v r FICUP: NO. PHI Gravel Sand Silt Silty Clay Clay Weathered Bedrock Siltstone Claystone Sandstone Limestone Igneous & Metamorphic N/12 CALIFORNIA N/12 SPLIT SPOON THIN WALLED (SHELBY) BAG SAMPLE II PITCHER SAMPLE Penetration Resistance and Strength Classifications are Based on The Standard Penetration Test Number of Blows Per foot (N)* 0-4 4-10 10-30 30-50 50+ Relative Density Cohesioniess Soils \/ery Loose Loose Medium Dense Very Dense • BLOWS PER FOOT - BLOWS OF 140 LB. HAMMER DROPPED 30 IN. TO DRIVE SPLIT SPOON OR CALIFORNIA SAMPLER 12" (IN.) (ASTM DL586-67) " EQUIVALENT TO PP/2 AND Qu/2 Consistency Approximate Cohesive Soils Cohesion ksf** Soft Firm Stiff Very Stiff Hard Less than 0.5 0.5-1.0 1.0-2.0 2.0-4.0 Greater than 4.0 CDS Engineering 165 2nd St. S.W. Loveland, CO 80537 Corporation Tele: (370) 667-8010 5 FT. 0 FT. 0 FT. 15 FT. 20 FT. 25 FT. 30 FT. 35 FT. —L TH-1 CLAY: sl. sandy, to sandy, sl. moist, stiff to hard, brown —2 SANDSTONE: wx. to competent, cicystone lenses, moist, hard, brown to cork gray PTF—I Pero Area 0 FT 5 F. 10 FT. 15 FT. 20 FT. 25 FT. 30 FT. Borings drilled 05/09/13 using a 4" diameter, continuous flight trucK mounted drilling rig. = Groundwater © drilling = Groundwater on 05/10/13 All soil and/or rock contacts shown on boring logs are approzimote and represent subsurface conditions at time of drilling. Boring loss and information presented on loos ore sub iect to discussion and limitations of this report. 35 FT. LOG OF BORINGS CLIENT: Select Energy Services PROJECT NO. 13-6397 PROJECT LOCATION Weitzel Ranch Facility Weld County, Colorado CDS Engineering Corporation Fig. No.: 2 155 2nd St. S.F,. Loveland, CO 80537 Tele: (970) 587-8010 SWELL / CONSOLIDATION TEST CURVES Client: Select Energy Services Project: Weitzel Ranch Facility Project No.: 13-6397 Boring: TH-1 Description: Lean Clay Depth, ft: 2 Water Content: 17.7% Swell (%):* IA Dry Density, pcf: 106.5 Approximate Swell Pressure. psf: 2700 on 6 4 Pressure, psf 1000 10000 I I ; Boring: TH-1 Description: Lean Clay Depth, ft: 6 Water Content: 10.3% Swell (%):* 0.7 Dry Density, pcf: 95.2 Approximate Swell Pressure, psf: 900 100 4 Pressure, psf 1000 10000 0• _ u -I _ R -4 -6 -7 1 "negative values indicate consolidation CPS Zngineering Corporation Figure 3 SWELL / CONSOLIDATION TEST CURVES Client: Select Energy Services Project: Weitzel Ranch Facility Project No.: 13-6397 Boring: TH-1 Description: Claystone Depth, ft: 20 Swell (°/0)* 1.6 4 u tc U 0• _ 0 1 _ r 100 Water Content: 25.6% Dry Density, pcf: 94.4 Approximate Swell Pressure, psf: 4200 Pressure, psf 1000 10000 -5 4 negative values indicate consolidation 'P5I ineerin9 Corporation Figure 4 M 0 Z U N O a Passing #4 / #200 Description Seive (%) T co U c N 0 J > W O c N U) -J I Silty Sandstone I Claystone with Coal Lenses Lean Clay > t0 U c ID C) J I Silty Sandstone • :. :.. LO 'Cr Q O) _.. Unconfined Compressive Strength" (psf) Unconfined Compressive Strength (psf) O O O N _.. Atterberg Limits c o N J J EL- Q Swell Pressure @ 1000 psf Surcharge Swell Pressure @ 500 psf Surcharge 2700 O. O 4200 c _ 3 . Q — r - O U r Natural Dry Density (Pcf) LL) 6 O N ui Q) c. Q a CO O Natural Moisture (%) co co # of blows/ penetration CV N CNI N NI O, 1: nj r) NO CO Up u r N t0 0c N N co m 0 0 a N 0 v TO J J 0, m a.) w Cu u a 0 O O a 0 m -o m 0 3 0 v D 3 O 0 O APPENDIX I POST -CONSTRUCTION SITE PREPARATION AND MAINTENANCE Backfill When encountering potentially expansive or consolidating soils, measures should be taken to prevent the soil from being wetted during and after construction. Generally. this can be accomplished by ensuring that the backfill placed around the foundation walls will not settle after completion of construction, and that this backfill material is relatively impervious. Water may need to be added to backfill material to allow proper compaction -- do not puddle or saturate. Backfill should he mechanically compacted to at least 95% of Standard Proctor around all structures, and 90% of Standard Proctor elsewhere. Compaction requirements should be verified with field tests by the Engineer. It is the contractor's responsibility to contact the engineer for such tests. Surface Drainage The final grade should have a positive slope away from the foundation walls on all sides. At minimum. the slope shall meet the requirements of the goveming Building Code. Where site grading allows, we recommend a minimum of six inches (6") in the first five feet (5'). Downspouts and sill cocks should discharge into splash blocks that extend beyond the limits of the backfill. Splash blocks should slope away from the foundation walls. The use of long downspout extensions in lieu of splash blocks is advisable. Surface drainage away from the foundation shall be maintained throughout the lifetime of the structure. Lawn Irrigation Do not install sprinkler systems next to foundation walls, porches, or patio slabs. If sprinkler systems are installed, the sprinkler heads should be placed so that the spray from the heads under full pressure does not fall within five feet (5') of foundation walls, porches, or patio slabs. Lawn irrigation must be carefully controlled. If the future owners desire to plant next to foundation walls. porches, or patio slabs. and are willing to assume the risk of structural damage, etc., then it is advisable to plant only flowers and shrubbery (no lawn) of varieties that require very little moisture. These flowers and shrubs should be hand watered only. Landscaping with a plastic covering around the foundation area is not recommended. Check with your local landscaper for fabrics which allow evaporation when inhibiting plant growth when a plastic landscape covering is desired. Experience shows that the majority of problems with foundations due to water conditions are generally due to the owner's negligence of maintaining proper drainage of water from the foundation area. The future owners should he directed to pertinent information in this report. REV 6/17/85 APPENDIX 3 GENERAL SPECIFICATIONS FOR THE PLACEMENT OF COMPACTED FILL MATERIAL Moisture -Density Determination Representative samples of the materials to be used for fill shall be furnished by the contractor at least seventy two (72) hours prior to compaction testing. Samples with higher moisture contents will require extra time for test results due to the required drying for sample preparation. Tests to determine the optimum moisture and density of the given material will he made using methods conforming to the most recent procedures of ASTM D698 (standard Proctor) or other approved methods, whichever may apply. Copies of the Proctor Curves will be furnished to the contractor. These test results shall be the basis of control for the field moisture/density tests. Materials The soils used for compacted fill shall be selected or approved by the Engineer. The material shall be free of vegetation. topsoil or any other deleterious materials. The material should be relatively impervious and non -swelling for the depth specified in the soils report with no material greater than six (6) inches in diameter. Site Preparation All timber, logs, trees. brush and rubbish shall be removed from the area and disposed in a manner approved by the local governing agency. All vegetation and a substantial amount of topsoil shall be removed from the surface upon which the fill is to be placed. Where applicable, the surface shall then be scarified to a depth of at least six (6) inches, moistened or dried as necessary to allow for uniform compaction by the equipment being used. The scarified surface shall be compacted to not less than 95% of maximum dry density based on ASTM D698. or to such other density as may be determined appropriate for the materials and conditions and acceptable to the Engineer. Fill shall not be placed on frozen or muddy ground. Moisture The fill material, while being compacted shall contain, as nearly as practical (typically +/- 2%), the optimum amount of moisture as determined by the Standard Proctor Test ASTM D698, or other approved method. The moisture shall be uniform throughout the fill material. The effort required for optimum compaction will be minimized by keeping soils near optimum moisture contents. Freezing temperatures and/or inclement weather conditions may impede moisture control and compaction operations. Placement of Fill The Geotechnical Engineer shall be retained to supervise the placement of fill material. The fill material shall be placed in uniform layers and be compacted to not less than 95% of maximum dry density based on ASTM D698, or to such other density as may be determined appropriate for the materials and conditions and acceptable to the Engineer. Prior to compacting, each layer shall have a maximum loose layer height of twelve (12) inches (or as dictated by the compaction equipment and/or soil conditions) with the surface relatively level. Test areas are recommended to determine the optimum layer thickness. Thinner lifts may he necessary in order to achieve the required compaction. Compacted layer thickness shall not exceed six (6) inches. Each twelve (12) inches of compacted fill shall he approved by the Engineer prior to placing succeeding lifts. Fill shall be compacted with machinery appropriate for the type of earthen material being installed. Granular materials shall be compacted with vibratory type machinery. Clay and silt material shall he compacted with a sheepsfoot or other segmented pad type compaction equipment. "Wheel rolling" is not considered an appropriate method to achieve the recommended compaction specifications. "Wheel rolling" is not recommended for extensive areas or depths and cannot be relied upon to give uniform results. Moisture and Density Testing It is the contractor's responsibility to contact the Engineer with a minimum of 24 -hours notice to schedule compaction testing. The density and moisture content of each layer of compacted fill will be determined by the Engineer, or qualified technician. in accordance with ASTM D6938 (nuclear method), or other approved method. If the tests show inadequate density, that layer, or portion thereof shall be reworked until the required conditions are obtained. Additional layers shall not be placed until each underlying lift has been approved. The results of all density tests will be furnished to both the owner and the contractor by the Engineer. Hello