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HomeMy WebLinkAboutEx 07b HP Kumar Subsoil Study 06.22.2018EXHIBIT 7 TO LIMITED IMPACT REVIEW FOR STORAGE AND FABRICATION FACILITY (Including Request for Subdivision Plat Amendment) Parcel ID No. 2393-274-01-004 Page 120 ot. hni Engin 'ng Materials Testing I Environ ntal ering _ • log 5020 County Roao 154 Glenwood Springs, CO 81601 Phone: (970) 945-7988 Fax: (970) 945-8454 Email: hpkglenwood@kumarusa,com Office Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, Summit County, Colorado SUBSOIL STUDY FOR FOUNDATION DESIGN PROPOSED STORAGE BUILDING 12744 HIGHWAY 82 GARFIELD COUNTY, COLORADO PROJECT NO. 18-7-367 JUNE 22, 2018 PREPARED FOR: GO SELF STORAGE ATTN: WES GRAMMER P.O. BOX 22876 KANSAS CITY, MISSOURI 64113 g amm sky .toy Page 121 TAB E OF CONTENTS PURPOSE AND SCOPE OF STUDY - 1 - PROPOSED CONSTRUCTION - 1 - SITE CONDITIONS - 1 - SUBSIDENCE POTENTIAL - 2 - FIELD EXPLORATION - 2 - SUBSURFACE CONDITIONS - 3 - DESIGN RECOMMENDATIONS - 3 - FOUNDATIONS - 3 - FOUNDATION AND RETAINING WALLS - 4 - FLOOR SLABS - 5 - UNDERDRAIN SYSTEM - 6 - SURFACE DRAINAGE - 6 - LIMITATIONS - 7 - FIIURE 1 - LOCATION OF EXPLORATORY BORINGS FIGURE 2 - LOGS OF EXPLORATORY BORINGS FII IURE 3 - LEGEND AND NOTES FIGURES 4 AND 5 - SWELL -CONSOLIDATION TEST RESULTS FIGURE 6 - GRADATION TEST RESULTS TABLE 1- SUMMARY OF LABORATORY TEST RESULTS Nam: 18-7-7 Page 122 PURPOSE AND SCOPE OF STUDY This report presents the results of a subsoil study for a proposed storage building to be located at 12744 Highway 82, Garfield County, Colorado. The project site is shown on Figure 1. The purpose of the study was to develop recommendations for the foundation design. The study was conducted in accordance with our proposal for geotechnical engineering services to GO Self Storage, dated May 11, 2018. A field exploration program consisting of exploratory borings was conducted to obtain information on the subsurface conditions. Samples of the subsoils obtained during the field exploration were tested in the laboratory to determine their classification, compressibility or swell and other engineering characteristics. The results of the field exploration and laboratory testing were analyzed to develop recommendations for foundation types, depths and allowable pressures for the proposed building foundation. This report summarizes the data obtained during this study and presents our conclusions, design recommendations and other geotechnical engineering considerations based on the proposed construction and the subsurface conditions encountered. PROPOSED CONSTRUCTION The proposed storage building will be a large, 3-story structure with a slab -on -grade ground floor. The ground floor will likely be close to the current ground surface. Grading for the structure is assumed to be relatively minor with cut depths between about 4 to 6 feet. We assume relatively light to moderate foundation loadings, typical of the proposed type of construction. If building loadings, location or grading plans change significantly from those described above, we should be notified to re-evaluate the recommendations contained in this report. SITE CONDITIONS The proposed building area is the site of the former "Planted Earth" tree nursery/storage area. The site is relatively flat and was created by shallow fill placed on the south side and a large cut H-PkiK MAR Project No. 18-7-367 Page 123 -2- on tfe north side. The southern fill area is south of the proposed building footprint and is retained by an MSE wall with masonry facing. The northern cut is retained with large, interlocking concrete blocks. Alluvial sand and gravel was exposed in a cut slope to the northeast of Boring 4. SUBSIDENCE POTENTIAL Bedrock of the Pennsylvanian age Eagle Valley Evaporite underlies the site. These rocks are a sequence of gypsiferous shale, fine-grained sandstone and siltstone with some massive beds of gypsum and limestone. There is a possibility that massive gypsum deposits associated with the Eagle Valley Evaporite underlie portions of the lot. Dissolution of the gypsum under certain conditions can cause sinkholes to develop and can produce areas of localized subsidence. During previous work in the area, several sinkholes were observed scattered throughout the Roaring Fork Valley. These sinkholes appear similar to others associated with the Eagle Valley Evaporite in areas of the Roaring Fork Valley. Sinkholes were not observed in the immediate area of the subject site. No evidence of cavities was encountered in the subsurface materials; however, the exploratory borings were relatively shallow, for foundation design only. Based on our present knowledge of the subsurface conditions at the site, it cannot be said for certain that sinkholes will not develop. The risk of future ground subsidence on this site throughout the service life of the proposed storage building, in our opinion, is low; however, the owner should be made aware of the potential for sinkhole development. If further investigation of possible cavities in the bedrock below the site is desired, we should be contacted. FIELD EXPLORATION The field exploration for the project was conducted on June 1, 2018. Four exploratory borings were drilled at the locations shown on Figure 1 to evaluate the subsurface conditions. The borings were advanced with 4 inch diameter continuous flight augers powered by a truck - mounted CME-45B drill rig. The borings were logged by a representative of H-P/Kumar. Samples of the subsoils were taken with 1% inch and 2 inch I.D. spoon samplers. The samplers were driven into the subsoils at variou depths with blows from a 140 pound haw - Auer falling 30 Page 124 -3- itches. This test is similar to the standard penetration test described by ASTM Method D-1586. The penetration resistance values are an indication of the relative density or consistency of the subsoils. Depths at which the samples were taken and the penetration resistance values are shown on the Logs of Exploratory Borings, Figure 2. The samples were returned to our laboratory for review by the project engineer and testing. SUBSURFACE CONDITIONS Graphic logs of the subsurface conditions encountered at the site are shown on Figure 2. Below up to 5 feet of organic clayey sand and gravel fill, the subsoils consist of about 17 to 22 ftmt of medium den se clayey silty; sand overlying rel tivelt dervm silty sand and gravel at depths of 22 to 261/2 feet down to the maximum depth drilled of 31 feet. Dense alluvial sand and gravel with cobbles and small boulders was encountered in Boring 4 below about 1 foot of fill. Drilling in the dense alluvial gravel soils with auger equipment was difficult due to the cobbles and boulders and drilling refusal was encountered in the deposit. Laboratory testing performed on samples obtained from the borings included natural moisture content, density, Atterberg limits and gradation analyses. Results of swell -consolidation testing performed on relatively undisturbed drive samples of the clayey sand soils, presented on Figures 4 and 5, indicate low to moderate compressibility under conditions of loading and wetting. Results of gradation analyses performed on a small diameter drive sample (minus 11/2 inch fraction) of the coarse granular subsoils from Boring 4 are shown on Figure 6. Atterberg limits testing indicates the clayey sand soils have low plasticity. The laboratory testing is summarized in Table 1. No free water was encountered in the borings at the time of drilling and the subsoils were slightly moist to moist. DESIGN RECOMMENDATIONS 1OUNDA IONS Considering the subsurfaceconditionmlnditiont encountered in the exploratory boring* and r e nature of the proposed construction, we recommend the storage building be founded with spread footings rP KU ProjcINA18-7-37 Page 125 -4- bearing on to natural clayey sand soils. Sub -excavation to below design bearing level may be needed along the downhill, south side of the building to completely remove unsuitable fill soils. The design and construction criteria presented below should be observed for a spread footing foundation system. 1) Footings placed on the undisturbed natural granular soils should be designed for an allowable bearing pressure of 2,000 psf. Based on experience, we expect settlement of footings designed and constructed as discussed in this section will be about 1 inch or less with additional settlement potential if the bearing soils are wetted. The footings should have a minimum width of 18 inches for continuous walls and 2 feet for isolated pads. 3) Exterior footings and footings beneath unheated areas should be provided with adequate soil cover above their bearing elevation for frost protection. Placement of foundations at least 36 inches below exterior grade is typically used in this area. 4) Continuous foundation walls should be reinforced top and bottom to span local anomalies such as by assuming an unsupported length of at least 12 feet. Foundation walls acting as retaining structures should also be designed to resist lateral earth pressures as discussed in the "Foundation and Retaining Walls" section of this report. 5) All existing fill, topsoil and any loose or disturbed soils should be removed and the footing bearing level extended down to the relatively firm natural clayey sand soils. The exposed soils in footing area should then be moistened and compacted. 6) A representative of the geotechnical engineer should observe all footing excavations prior to concrete placement to evaluate bearing conditions. FOUNDATION AND RETAINING WALLS Foundation walls and retaining structures which are laterally supported and can be expected to undergo only a slight amount of deflection should be designed for a lateral earth pressure computed on the basis of an equivalent fltnid unit weight of at least 50 pcf for back ill consisting of the on -site clayey sand soils. Cantilevered retaining structures which are separate from the storage building and can be expected to deflect sufficiently to moize tie full active earth Prcj No. 8-7-37 Page 126 -5- pressure condition should be designed for a lateral earth pressure computed on the basis of equivalent fluid unit weight of at least 40 pcf for backfill consisting of the on -site clayey sand soils. All foundation and retaining structures should be designed for appropriate hydrostatic and surcharge pressures such as adjacent footings, traffic, construction materials and equipment. The pressures recommended above assume drained conditions behind the walls and a horizontal backfill surface. The buildup of water behind a wall or an upward sloping backfill surface will increase the lateral pressure imposed on a foundation wall or retaining structure. An underdrain should be provided to prevent hydrostatic pressure buildup behind walls. Backfill should be placed in uniform lifts and compacted to at least 95% of the maximum standard Proctor density at a moisture content near optimum. Care should be taken not to overcompact t backfill or use large equip-errt near the wall, since this could cause excessive lateral pressure on the wall. Some settlement of deep foundation wall backfill should be e pected, even if the material is placed correctly, and could result in distress to facilities constructed on the backfill. Backfill should not contain organics, debris or rock larger than about 6 inches. The lateral resistance of foundation or retaining wall footings will be a combination of the sliding resistance of the footing on the foundation materials and passive earth pressure against the side of the footing. Resistance to sliding at the bottoms of the footings can be calculated based on a coefficient of friction of 0.35. Passive pressure of compacted backfill against the sides of the footings can be calculated using an equivalent fluid unit weight of 325 pcf. The coefficient of friction and passive pressure values recommended above assume ultimate soil strength. Suitable factors of safety should be included in the design to limit the strain which will occur at the ultimate strength, particularly in the case of passive resistance. Fill placed against the sides of the footings to resist lateral loads should be compacted to at least 95% of the maximum standard Proctor density at a moisture content near optimum. FLOOR SLABS The natural on -rite soil., exluri of topoil, arr suitablrto support lightly landed slab -on -grade construction. To reduce the effects of some differential movement, floor slabs should be separated from all bearing walls and columns with expansion joints which allow unrestrained H-P KUMAR roj 18-I-314 Page 127 -6- vertical movement. floor slab control joints should be used to reduce damage due to shrinkage cracking. The requirements for joint spacing and slab reinforcement should be established by the designer based on experience and the intended slab use. A minimum 4 inch layer of free - draining gravel should be placed beneath slabs for support. This material should consist of minus 2 inch aggregate with at least 50% retained on the No. 4 sieve and less than 2% passing the No. 200 sieve. Existing fill should be completely removed from beneath the building area. Fill materials for support of floor slabs should be placed and compacted to at least 95% of maximum standard Proctor density at a moisture content near optimum. Required fill can consist of the on -site soils devoid of vegetation, topsoil and oversized rock. UNDERDRAIN SYSTEM Although free water was not encountered during our exploration, it has been our experience in this area that local perched groundwater can develop during times of heavy precipitation or seasonal runoff. Frozen ground during spring runoff can also create a perched condition. We recommend below -grade construction, such as retaining walls and basement areas, be protected from wetting and hydrostatic pressure buildup by an underdrain system. The proposed slab -on - grade floor level should not need an underdrain. If installed, the drains should consist of drainpipe placed in the bottom of the wall backfill surrounded above the invert level with free -draining granular material. The drain should be placed at each level of excavation and at least 1 foot below lowest adjacent finish grade and sloped at a minimum 1% to a suitable gravity outlet. Free -draining granular material used in the underdrain system should contain less than 2% passing the No. 200 sieve, less than 50% passing the No. 4 sieve and have a maximum site of 2 inches. The drain gravel backfill should bt at least 11/2 feet deep. An impervious membrane such as 20 mil PVC should be placed beneath the drain gravel in a trough shape and attached to the foundation wall with mastic to prevent wetting of the bearing soils. SURFACE DRAINAGE The following drainage precautions should be observed during construction and maintained at all times after the storage building has been completed: Project No. 18-7-7 Page 128 -7- 1) Inundation of tl foundation; excaa ions and underslab areas should be avoided during construction. 2) Exterior backfill should be adjusted to near optimum moisture and compacted to at least 95% of the maximum standard Proctor density in pavement and slab areas and to at least 90% of the maximum standard Proctor density in landscape areas. 3) The ground surface surrounding the exterior of the building should be sloped to drain away from the foundation in all directions. We recommend a minimum slope of 6 inches in the first 10 feet in unpaved areas and a minimum slope of 21/ inches in the first 10 feet in paved areas. Free -draining wall backfill (if any) should be capped with about 2 feet of the on -site soils to re _-t e SUrfax water infiltration. 4) Roof downspouts and drains should discharge well beyond the limits of all backfill. 5) Landscaping which requires regular heavy irrigation should be located at least 10 feet from foundation walls. Consideration should be given to use of xeriscape to reduce the potential for wetting of soils below the building caused by irrigation. LIMITATIONS This study has been coducted in accordance with generally accepted geotechnical engineering principles and practices in this area at this time. We make no warranty either express or implied. The conclusions and recommendations sub itted in this report are based upon the data obtained from the exploratory borings drilled at the locations indicated on Figure 1, the proposed type of construction and our experience in the area. Our services do not include determining the presence, prevention or possibility of mold or other biological contaminants (MOBC) developing in the future. If the client is concerned about MOBC, then a professional in this special field of practice should be consulted. Our findings include interpolation and extrapolation of the subsurface conditions identified at the exploratory borings and variations in the subsurface conditionn may ot become evident until excavation is performed. If conditions encountered during construction appear different from those described in this report, we should be notified so that re-evaluation of the recommendations may be made. roject No. 18 7-3` Page 129 -8- This report Vas been prepared for the exclusive use by our client for design purposes. We are not responsible fol technical interpretations by others of our information. As the project evolves, we should provide continued consultation and field services during construction to review and monitor the implementation of our recommendations, and to verify that the recommendations have been appropriately interpreted. Significant design changes may require additional analysis or modifications to the recommendations presented herein. We recommend on -site observation of excavations and foundation bearing strata and testing of structural fill by a representative of the geotechnical engineer. Respectfully Submitted, H- K MA! Daniel E. Hardin, P. Reviewed by: ONAL Steven L. Pawlak, P.E. DEH/kac cc: The Land Studio — Doug Pratte ( stud @cor :a et) P Project N. 18-7-367 Page 130 2. `.3NI1123Vd 1V'LO1 OS MN MI MN APPROXIMATE SCALE —FEET JIBORING 3 y BORING 4 • 18-7-367 H-P%KUIVIAIR CATION OF EXPLORATORY BORINGS I Fig. 1 Page 131 BORING I BORING 2 (4) 15 20 9/12 wo=1O.0 DD=1uo 6/12 WC=11.7 OD=11J -2On=44 11/ 2 wC=1V.0 DD=1oO 9/12 wo=1s.1 oD=1oO -2oo=40 21/12 WC=17.4 DD=1O7 30 50/5.5 35 ` 0/12 9/12 WC=1D,J DD=11J 7/12 50/1 BORING 3 BORING 4 a/12 ~ 50/ ^ G/12 WC=1O.2 -20O=4b LL=22 F1=4 O/12 11/12 76/12 Wn=1.O +4=sS -2OO=7 U 5 10 15 20 2s 30 35 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 18-7-387 LOGS OF EXPLORATORY BORINGS Fig. 2 25 LEGEND (4) " BASECOURSE, THICKNESS IN INC ES SHOWN IN PARENTHESES TO LEFT OF THE LOG. BORING 1 ONLY. :o FILL: SAND AND GRAVEL, CLAYEY WITH ORGANICS, ROOTS, LOOSE, MOIST, BROWN. SAND (SC); CLAYEY, SILTY, MEDIUM STIFF TO MEDIUM DENSE, MOIST, BROWN. SAND AND GRAVEL (SM—GM); SILTY, WITH COBBLES, VERY DENSE, SLIGHTLY MOIST, BROWN. GRAVEL (GM —GP); SANDY, SLIGHTLY SILTY WITH COBBLES AND SMALL BOULDERS, DENSE, SLIGHTLY MOIST, LIGHT BROWN. BORING 4 ONLY. RELATIVELY UNDISTURBED DRIVE SAMPLE; 2—INCH I.D. CALIFORNIA LINER SAMPLE. 9/12 DRIVE SAMPLE BLOW COUNT. INDICATES THAT 9 BLOWS OF A 140—POUND HAMMER FALLING 30 INCHES WERE REQUIRED TO DRIVE THE CALIFORNIA OR SPT SAMPLER 12 INCHES. t PRACTICAL AUGER REFUSAL. NOTES 1. THE EXPLORATORY BORINGS WERE DRILLED ON JUNE 1, 2018 WITH A 4—INCH DIAMETER CONTINUOUS FLIGHT POWER AUGER. 2. THE LOCATIONS OF THE EXPLORATORY BORINGS WERE MEASURED APPROXIMATELY BY PACING FROM FEATURES SHOWN ON THE SITE PLAN PROVIDED. • THE LOCATIONS OF THE EXPLORATORY BORINGS WERE MEASURED APPROXIMATELY BY TAPING FROM FEATURES SHOWN ON THE SITE PLAN PROVIDED. 3. THE ELEVATIONS OF THE EXPLORATORY BORINGS WERE NOT MEASURED AND THE LOGS OF THE EXPLORATORY BORINGS ARE PLOTTED TO DEPTH. 4. THE EXPLORATORY BORING LOCATIONS SHOULD BE CONSIDERED ACCURATE ONLY TO THE DEGREE IMPLIED BY THE METHOD USED. 5. THE LINES BETWEEN MATERIALS SHOWN ON THE EXPLORATORY BORING LOGS REPRESENT THE APPROXIMATE BOUNDARIES BETWEEN MATERIAL TYPES AND THE TRANSITIONS MAY BE GRADUAL. 6. GROUNDWATER WAS NOT ENCOUNTERED IN THE BORINGS AT THE TIME OF DRILLING OR WHEN CHECKED # DAYS LATER. 7. LABORATORY TEST RESULTS: WC = WATER CONTENT (%) (ASTM D 2216); DD = DRY DENSITY (pcf) (ASTM D 2216); +4 = PERCENTAGE RETAINED ON NO. 4 SIEVE (ASTM D 422); —200= PERCENTAGE PASSING NO. 200 SIEVE (ASTM D 1140); LL = LIQUID LIMIT (ASTM D 4318); PI = PLASTICITY INDEX (ASTM D 4318). 18-7-367 H-PkKUMAR LEGEND AND NOTES Fig. 3 Page 133 CONSOLIDATION - SWELL —2 These teat results apply only to the samples tested. The testing report shall not he reproduced. except In full. without the written oppr000l of Kumar and Associates, Inc. Swell Consolidation testate performed In accordance with AS 0-4546. SAMPLE OF: Clayey Sand FROM: Boring 1 ® 5' WC = 16.0 %, DD = 108 pcf 1.0 APPLIED PRESSURE- KSF 10 SAMPLE OF: Clayey Sand FROM: Boring 1 CAA 15' WC = 10.0 %, DD = 108 pcf 1.0 APPLIED PRESSURE - KSF H-PvKUMAR ADDITIONAL COMPRESSION UNDER CONSTANT PRESSURE DUE TO WETTING 10 00 100 SWELL -CONSOLIDATION TEST RESULTS Fig. 4 Page 134 CONSOLIDATION - SWELL CONSOLIDATION - SWELL These test results opply only to the ample, tested. The testing report shall not be reproduced, except In full, without the written approval of Kumar and Assoelates, Inc. Swell Consolidation testing performed in OceordaDee with ASTI/ 0-4940. SAMPLE OF: Clayey Sand I FROM: Boring 2 ® 10' WC = 10.3 %, DD = 113 pcf ADDITIONAL COMPRESSION UNDER CONSTANT PRESSURE DUE TO WETTING 1.0 APPLIED PRESSURE - KSF 10 100 SAMPLE OF: Clayey Sand FROM: Boring 3 @ 15' WC = 10.2 % —200 = 46 %, LL = 22, PI = 1.0 APPLIED PRESSURE KSF 10 EXPANSION UNDER CONSTANT PRESSURE UPON WETTING 100 H-PtiKUMAR SWELL -CONSOLIDATION TEST RESULTS Fig. 5 Page 135 HYDROMETER ANALYSIS TIME READINGS U.S. STANDARD SERIES 24 HRS 100 4'IRS 7 5 1 M 70 60 a. 40 t...... 30 ,- 20 0 .001 .002 NIN 19MIN .005 .009 SIEVE ANALYSIS CLEAR SQUARE OPENINGS 4MIN 1NIN _,.A200 A100 400 40yk30 At 1'610 9 .075 .150 .300 1 .600 1.18 2.38 4.75 .425 2.0 DIAMETER OF PARTICLES IN MILLIMETERS 9.5 9 •6.. 8. 10 20 40 70 90 6 1 76.2 127 - 200 00 152 CLAY TO SILT SAND GRAVEL FINE MEDIUM COARSE FINE COARSE COBBLES GRAVEL 59 % LIQUID LIMIT SAMPLE OF: Slightly Silty Sandy Gravel SAND 34 X PLASTICITY INDEX SILT AND CLAY 7 % FROM: Boring 4 0 2.5' These test results apply only to the samplet which were teed. The testing report shall not be reproduced, except In full, without the written approval of Kumar & Associates, Inc. Sieve analysts testing Is performed In accordance with ASTM 0422, ASTM C136 and/or ASTM D1140. Fig. 6 Page 136 Project No. 18-7-367 0) cn >- 0) W H W F— ce 0 H Q w d' m 03 m I— J U. 0 >- 2 0) w a J_ O co Clayey Sand Clayey Sand Clayey Sand Clayey Sand Clayey Sand Clayey Silty Sand Clayey Sand Clayey Silty Sand Clayey Sand Slightly Silty Sandy Gravel I UNCONFINED COMPRESSIVE STRENGTH (psf) ATTERBERG LIMITS PLASTIC INDEX (%) d• LIQUID LIMIT (%) 22 PERCENT PASSING NO. 200 SIEVE 40 N O Q 0 Q CC (0 0 N M J W Q e ON In NATURAL DRY DENSITY (pcf) co O £II 108 oo 0 107 .M-I ,N-i NATURAL MOISTURE CONTENT (%) O VD N ,--- O Q ,-", 17.4 •--I .--1 10.3 N O Cl .-+ ,.O ,--i LOCATION DEPTH (ft) toAr N N 11N 0I 15 BORING ---4 N M d' Page137 GO Self Storage Limited Impact Review July 13, 2018 Conceptual Site and Drainage Plan, Sopris Engineering Page 138 S coO M3IA32J 10VdM 03111,111 000:10103'A1.Nf103013L IVO NOSIAI48f1S NOXI4 01332lVd 3EN O.LS d13S OJ ,-- 'f '1• // / f'_, , ell', r J \/ / \ / !- ,// l a ,�I Itl 1 \ 1 I \ ,/,//)/ If/ i /' // r—n 59 Page 139 GO Self Storage Limited Impact Review July 13, 2018 Conceptual Utility Plan, Sopris Engineering Page 140 M31A3a IOVdh 031V111 OaVN0100',uNl00GUANO NOSIAI08f1S NOXIQ 013023Vd 39VdaLS d13S OJ off i J ,, i;1.1 i��rE■,111;I';;, ■ --�' 11 Page 141