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HomeMy WebLinkAboutReports - Soils - 08/26/2023 400 North Link Lane | Fort Collins, Colorado 80524 Telephone: 970-206-9455 Fax: 970-206-9441 GEOLOGIC AND PRELIMINARY GEOTECHNICAL INVESTIGATION STRAUSS LAKE DEVELOPMENT FORT COLLINS, COLORADO Prepared For: ANDERSON CONSULTING ENGINEERS, INC. 375 East Horsetooth Road, Building 5 Fort Collins, Colorado 80525 Attention: Brian Smith Project No. FC08493-115 REV 5 October 1, 2018 (Revised October 8, 2018) (Revised November 6, 2018) (Revised November 7, 2018) (Revised February 20, 2023) (Revised August 26, 2023) i TABLE OF CONTENTS SCOPE ................................................................................................................................ 1 SUMMARY OF CONCLUSIONS ........................................................................................ 1 SITE DESCRIPTION .......................................................................................................... 2 PROPOSED DEVELOPMENT ........................................................................................... 2 SITE GEOLOGY ................................................................................................................. 2 GEOLOGIC HAZARDS ...................................................................................................... 3 Soft Soils ......................................................................................................................... 3 Groundwater .................................................................................................................... 4 Expansive Soils and Bedrock ......................................................................................... 4 Seismicity ........................................................................................................................ 4 Radioactivity .................................................................................................................... 5 FIELD AND LABORATORY INVESTIGATIONS ............................................................... 5 SUBSURFACE CONDITIONS ........................................................................................... 6 DEVELOPMENT RECOMMENDATIONS .......................................................................... 6 Site Grading .................................................................................................................... 6 Permanent Cut and Fill Slopes ....................................................................................... 7 Utility Construction .......................................................................................................... 7 Underdrain System ......................................................................................................... 9 Retaining Walls ............................................................................................................. 10 PRELIMINARY PAVEMENT RECOMMENDATIONS ..................................................... 10 Subgrade Preparation ................................................................................................... 10 Preliminary Pavement Thickness Design ..................................................................... 11 PRELIMINARY RECOMMENDATIONS FOR STRUCTURES ........................................ 11 Foundations ................................................................................................................... 11 Slabs-on-Grade and Basement Floor Construction ..................................................... 12 Below-Grade Construction ............................................................................................ 12 Surface Drainage .......................................................................................................... 12 General Design Considerations .................................................................................... 13 WATER SOLUBLE SULFATES ....................................................................................... 13 RECOMMENDED FUTU RE INVESTIGATIONS ............................................................. 14 LIMITATIONS ................................................................................................................... 14 ii TABLE OF CONTENTS cont’d FIGURE 1 – LOCATIONS OF EXPLORATORY BORINGS FIGURES 2 THROUGH 4 – SUMMARY LOGS OF EXPLORATORY BORINGS FIGURE 5 – GROUNDWATER ELEVATION CONTOURS FIGURES 6 THROUGH 8 – SEWER UNDERDRAIN DETAILS APPENDIX A – LABORATORY TEST RESULTS APPENDIX B – GUIDELINE SITE GRADING SPECIFICATIONS 1 ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL|T PROJECT NO. FC08493-115 REV 5 SCOPE This report presents the results of our Geologic and Preliminary Geotechnical Investigation. The purpose of our investigation was to identify geologic hazards that may exist at the site and to evaluate the subsurface conditions to assist in planning and budgeting for the proposed development. The report includes descriptions of site geology, our analysis of the impact of geologic conditions on site development, a d escription of subsoil, bedrock, and groundwater conditions found in our exploratory borings, and discussions of site development as influenced by geotechnical considerations. The scope was described in our Service Agreement (CTL Project No. FC-18-0242) dated June 6, 2018. This report was prepared based upon our understanding of the proposed use. The recommendations are considered preliminary and can be used as guidelines for further planning of development and design of grading. We should review development and grading plans to determine if additional investigation is merited, or if we need to revise our recommendations. Additional investigations will be required to design building foundations and pavements. A summary of our findings and recommendations is presented below. More detailed discussions of the data, analysis and recommendations are presented in the re port. SUMMARY OF CONCLUSIONS 1. The site contains geologic hazards that should be mitigated during planning and development. No geologic or geotechnical conditions were identified which would preclude development of this site. Shallow groundwater, expansive soils and bedrock, soft soils, and regional issues of seismicity and radioactivity are the primary geologic concerns pertaining to the development of the site . 2. The subsurface conditions encountered in our borings were variable across the site. In general, the soils and bedrock encountered in our borings consisted of 3 to 8 feet of fill over 0 to 12 feet of clayey sand or sandy clay, underlain by sand and gravel. Claystone bedrock was encountered in six of our borings at depths ranging from 17 to 23 feet below the existing ground surface. 3. Groundwater was encountered at depths ranging from 3½ to 12 feet below the existing ground surface. Groundwater levels will likely affect planned development at this site. A contour map of the groundwater surface is provided on Figure 5. 2 ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL|T PROJECT NO. FC08493-115 REV 5 4. We measured consolidation and low swell in samples of clayey sand, sandy clay, and the fill. Soils exhibited compression of up to 1.5 percent and swells of up to 2.0 percent. The bedrock was not tested for swell but is judged to have a minimal influence on the proposed construction. We anticipate footing or pad- type foundations will be appropriate for most structures. Slab-on-grade floors can likely be used. 5. Asphaltic pavement sections on the order of 4 to 6 inches over aggregate base course sections of 6 inches for streets, parking areas, and access drives are anticipated for preliminary planning purposes. SITE DESCRIPTION The site is located north of Horsetooth Road and east of Ziegler Road in Fort Collins, Colorado. During our investigation, the northern portion of the site was in use as a concrete plant. The southern portion of the site was vacant during our investigation. In 2014, excess material from the construction of the adjacent water storage reservoir project was use d to fill the southern portion of the site. Compaction testing of the fill was conducted by CTL|Thompson. Groundcover consisted of bare soils on the northern portion of the site and natural grasses and weeds on the southern portion of the site. The eastern boundary of the site is roughly the Boxelder Ditch. The building site on the 130+acre parcel has a general slope to the southeast. The Cache La Poudre River runs southeast approximately a mile east of the site. Rigden Reservoir is located east of the si te. PROPOSED DEVELOPMENT We understand the parcel is planned for development of single and/or multi-family residences. The single and multi-family residences will be 1 to 3-story, wood frame structures. Apartment structures will be 3 to 4 stories tall. Below grade areas such as basements or crawl spaces are likely but may be limited due to shallow groundwater. SITE GEOLOGY The geology of the site was investigated through review of mapping by Roger B. Colton (Geologic Map of the Boulder-Fort Collins-Greeley Area, Colorado, 1978). Our technician visited the site to assess whether field conditions are consistent with the geologic mapping and 3 ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL|T PROJECT NO. FC08493-115 REV 5 reports, evaluate specific site features and to look for other geologic concerns. Geology was further evaluated through review of con ditions found in exploratory borings, and our experience in the area. Referenced geologic mapping indicates the site contains primarily alluvial deposits of sand and gravel. The Upper unit of Pierre Shale was mapped as a narrow band across the southwest corner of the site and was encountered underlying the fill and alluvium. An area of eolian deposition is mapped west of the site and in the southwest corner of the site but was not encountered during drilling. GEOLOGIC HAZARDS Our investigation identified several geologic hazards that must be considered during the planning and development phases of this project. None of the geologic hazards identified will preclude development of the property. Planning should consider the geologic hazards discussed below. The hazards require mitigation which could include avoidance, non -conflicting use or engineered design and construction during site development. Geologic hazards at the site that need to be addressed include soft soils, shallow groundwater, flooding, expansive soils and bedrock, regional issues of seismicity, and radioactivity. The following sections discuss each of these geologic hazards and associated development concerns. Mitigation concepts are discussed below and in the DEVELOPMENT RECOMMENDAT IONS section of the report. Soft Soils Some of the soils encountered during drilling were very loose or medium-stiff. While mitigating groundwater levels may provide some improvement in the soil conditions, areas of soft or settling soils may still be encountered. Where encountered under proposed improvements, stabilization of soft soils can likely be achieved by removal and proper recompaction or crowding 1½ to 3 -inch nominal size crushed rock into the subsoils until the base of the excavation does not deform by more than about ½-inch when compactive effort is applied. 4 ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL|T PROJECT NO. FC08493-115 REV 5 Groundwater Groundwater was encountered at depths of 3½ to 12 feet during this investigation . Groundwater is expected to fluctuate seasonally, with changing water levels in nearby water bodies, and may rise due to site development. The depth to groundwater should be evaluated during Geotechnical Investigations at the site. In general, grading should be designed to raise the elevations in areas of shallow groundwater. Construction of underdrain systems with the sanitary sewer trenches is a commonly employed method to mitigate th e accumulation of shallow groundwater after construction. A minimum separation of 5 feet is desirable between the groundwater elevations and the lowest elevation of any below-grade structure. Expansive Soils and Bedrock The soils at this site include low-swelling fill and native sandy clays. Much of the bedrock formation below the site consists of claystone. Due to the depth of the bedrock and the level of groundwater above the bedrock, we believe the influence of potential swells of the bedrock will be minimal. We do not anticipate mitigation for expansive soils and bedrock will be required for the proposed construction. Seismicity This area, like most of central Colorado, is subject to a low degree of seismic risk. No indications of recent movements of any of the faults in the Larimer County area have been reported in the available geologic literature. As in most areas of recognized low seismicity, the record of the past earthquake activity in Colorado is somewhat incomplete. Based on the subsurface conditions encountered in our borings and our understanding of the geology, the site classifies as a Seismic Site Class D (2012 International Building Code). Only minor damage to relatively new, properly designed and built buildings would be expected. Wind loads, not seismic considerations, typically govern dynamic structural design in this area. 5 ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL|T PROJECT NO. FC08493-115 REV 5 Radioactivity It is normal in the Front Range of Colorado and nearby eastern plains to measure radon gas in poorly ventilated spaces in contact with soil or bedrock. Radon 222 gas is considered a health hazard and is one of several radioactive products in the chain of the natural decay of uranium into stable lea d. Radioactive nuclides are common in the soils and sedimentary rocks underlying the subject s ite. Because these sources exist on most sites, there is potential for radon gas accumulation in poorly ventilated spaces. The amount of soil gas that can accumulate is a function of many factors, including the radio-nuclide activity of the soil and bedrock, construction methods and materials, pathways for soil gas , and existence of poorly ventilated accumulation areas. It is difficult to predict the concentration of radon gas in finished construction. During our investigation, we did not detect any radiation levels above normal background levels for the area. We recommend te sting to evaluate radon levels after construction is completed. If required, typical mitigation methods for residential construction may consist of sealing soil gas entry areas and periodic ventilation of below-grade spaces and perimeter drain systems. It is relatively economical to provide for ventilation of perimeter drain systems or underslab gravel layers at the time of construction, compared to retrofitting a structure after construction. Radon rarely accumulates to significant levels in above -grade, heated, and ventilated spaces. FIELD AND LABORATORY INVESTIGATIONS Subsurface conditions were further investigated by drilling fifteen exploratory borings and three piezometers at the approximate locations shown on Figure 1. The borings and piezometers were drilled using a truck-mounted drill rig and with 4-inch diameter continuous- flight augers. Our field representative observed drilling, logged the soils found in the borings , and obtained samples. Three additional borings were drilled solely to monitor groundwater levels. Summary logs of the soils and bedrock found in the borings and field penetration resistance values are presented on Figures 2 through 4. 6 ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL|T PROJECT NO. FC08493-115 REV 5 Samples of soil and bedrock were obtained during drilling by driving a modified California-type sampler (2.5-inch O.D.) into the soils and bedrock using a 140-pound hammer falling 30 inches. Samples recovered from the borings were returned to our laboratory and visually classified by the geotechnical engineer. Laboratory testing included determination of moisture content and dry density, swell-consolidation characteristics, Atterberg limits, particle- size analysis, and water-soluble sulfate content. Laboratory test results are presented in Appendix A. SUBSURFACE CONDITIONS Subsurface conditions encountered in our borings were variable across the site. In general, the soils and bedrock encountered in our borings consisted of 3 to 8 feet of fill over 0 to 12 feet of clayey sand or sandy clay, underlain by sand and gravel. Claystone bedrock was encountered in six of our borings at 17 to 23 feet to the depths explored. Soils exhibited compression of up to 1.5 percent and swells of up to 2.0 percent. The bedrock was not tested for swell but is judged to have a minimal influence on the proposed construction . Groundwater was encountered at depths ranging from 3½ to 12 feet below the existing ground surface. Groundwater levels will likely affect planned development at this site. A more detailed description of the subsurface conditions is presented on our boring logs and in our laboratory testing. A map of groundwater elevation contou rs is presented on Figure 5. DEVELOPMENT RECOMMENDATIONS Site Grading At the time of this inv estigation, site grading plans were not available for review in conjunction with this subsurface exploration program. It is important that deep fills (if planned) be constructed as far in advance of surface construction as possible. It is our experience that fill compacted in accordance with the compaction recommendations in this report may settle about 1 to 2 percent of its height under its own weight. Most of this settlement usually occurs during and soon after construction. Some additional settlement is possible after development and landscape irrigation increases soil moisture . Delaying construction of structures up to one year where located on deep fills is recommended. 7 ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL|T PROJECT NO. FC08493-115 REV 5 The existing onsite soils are suitable for re-use as fill material provided debris or deleterious organic materials are removed. The existing onsite soils are suitable for re-use as fill material provided debris or deleterious organic materials are removed. If import material is used, it should be tested and approved as acceptable fill by CTL|Thompson. In general, import fill should meet or exceed the engineering qualities of the onsite soils. Prior to fill placement, all debris should be removed from fill areas and properly disposed. The ground surface in areas to be filled should be stripped of vegetation, topsoil, and other deleterious materials, scarified to a depth of at least 8 inches, moisture conditioned, and compacted as recommended below. Site grading fill should be placed in thin, loose lifts, moisture conditioned and compacted. In areas of deep fill, we recommend higher compaction criteria to help reduce settlement of the fill. The placement and compaction of fill should be observed, and density tested during construction. Compaction and moisture requirements are presented in Appendix B. Permanent Cut and Fill Slopes We recommend permanent cut and fill slopes be designed with a maximum inclination of 3:1 (horizontal to vertical). Where fills will be placed on slopes exceeding 20 percent (5:1) the slope should be benched. Structures should be setback from the top or bottom of cut and fill slopes. If site constraints (property boundaries and streets) do not permit constr uction with recommended slopes, we should be contacted to evaluate the subsurface soils and steep er slopes. Utility Construction We believe excavations for utility installation in the overburden soils can be performed with conventional heavy-duty trenchers or large backhoes. The excavation contractor should anticipate water in excavations. Dewatering may be accomplished by sloping excavations to occasional sumps where water can be removed by pumping . 8 ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL|T PROJECT NO. FC08493-115 REV 5 Utility trenches should be sloped or shored to meet local, State, and federal safety regulations. Based on our investigation, we believe the sand and gravel classifies as Type C soil, the clay and fill as Type B, and the bedrock classifies as Type A soil based on OSHA standards. Excavation slopes specified by OSHA are dependent upon soil types and groundwater conditions encountered. Seepage and grou ndwater conditions in trenches may downgrade the soil type. Contractors should identify the soils encountered in the excavation and refer to OSHA standards to determine appropriate slopes. Excavations deeper than 20 feet should be designed by a professional engineer. The width of the top of an excavation may be limited in some areas. Bracing or “trench box” construction may be necessary. Bracing systems include sheet piling, braced sheeting, and others. Lateral loads on bracing depend on the depth of excavation, slope of excavation above the bracing, surface loads, hydrostatic pressures, and allowable movement. For trench boxes and bracing allowed to move enough to mobilize the strength of the soils, with associated cracking of the ground surface, th e “active” earth pressure conditions are appropriate for design. If movement is not tolerable, the “at rest” earth pressures are appropriate. We suggest an equivalent fluid density of 40 pcf for the “active” earth pressure condition and 55 pcf for the “at rest” earth pressure condition, assuming level backfill. These pressures do not include allowances for surcharge loading or for hydrostatic conditions. We are available to assist further with bracing design if desired. Water and sewer lines are usually constructed beneath paved roads. Compaction of trench backfill can have significant effect on the life and serviceability of pavements. We believe trench backfill should be placed in thin, loose lifts, and moisture conditioned to between optimum and 3 percent above optimum content for clay soils and within 2 percent of optimum moisture content for sand. Trench backfill should be compacted to at least 95 per cent of maximum dry density (ASTM D 698). The placement and compaction of fill and backfill shou ld be observed and tested by our firm during construction. If deep excavations are necessary for planned utilities, the compaction requirements provided in Appendix B. 9 ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL|T PROJECT NO. FC08493-115 REV 5 Underdrain System The use of underdrain systems below sewer mains and services is a common method to control groundwater in response to development. We recommend an underdrain system be incorporated into sanitary sewer and sewer collection sy stems. Underdrains should also be installed below sewer service lines to each residence planned in this area with connection to residence foundation drains. The underdrain should consist of free-draining gravel surrounding a rigid PVC pipe. The pipe should be sized for anticipated flow. Guidelines for underdrain sizing are shown in Table A. The line should consist of smooth, perforated or slotted rigid PVC pipe laid at a grade of at least 0.5 percent. A gravel cross-section of at least 2 square feet s hould be placed around the pipe. A positive cutoff collar (concrete) should be constructed arou nd the sewer pipe and underdrain pipe immediately downstream of the point the underdrain pipe leaves the sewer trench. Solid pipe should be used down gradient of this collar to the daylight point. Clean-outs should be provided along the system. The enti ty responsible for maintenance should be identified and guidelines developed for maintenance. The underdrain should be designed to discharge to a gravity outfall provided with a permanent concrete headwall and trash rack, or to a storm sewer with a check valve to control water backing up into the underdrain system. Sewer underdrain details are shown on Figures 6 through 8. The underdrain system should be designed by a professional engineer that is licensed in the State of Colorado. Table A provides a general guideline for sizing the underdrain system. 10 ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL|T PROJECT NO. FC08493-115 REV 5 TABLE A UNDERDRAIN SIZING Slope = 0.005 (0.5 percent) Pipe Size (inches) 4 6 8 Maximum Number of Residences 50 100 200 Slope = 0.01 (1.0 percent) Pipe Size (inches) 4 6 8 Maximum Number of Residences 75 150 300 Slope = 0.02 (2.0 percent) Pipe Size (inches) 4 6 - Maximum Number of Residences 100 300 - Note: Minimum slopes of the underdrains will govern pipe sizes and maximum number of residences serviced. Retaining Walls Site retaining walls can generally be constructed on footing foundations, however, some movement is possible for walls constructed on fill or expansive soil. Due to the preliminary status of the design process for this project, wall locations have not yet been identified . Once wall structure locations and configurations have been identified, CTL|Thompson should be contacted to perform appropriate subsurface explorations and provide de sign recommendations. PRELIMINARY PAVEMENT RECOMMENDATIONS Subgrade Preparation Based on the borings, the near surface soils on this site will consist of low-swelling sandy clay fill. Mitigation for swell is not likely. The subgrade soils will likely be moderately to highly plastic and will provide relatively poor subgrade support below the pav ements. Lime or fly ash stabilization of these soils may be recommended to improve subgrade support characteristics, in addition to enhancing the workability of the clays and reducing water infiltration into the underlying subgrade and the potential movements under the pavements. 11 ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL|T PROJECT NO. FC08493-115 REV 5 Preliminary Pavement Thickness Design Preliminary guidelines for pavement systems on this site are provided. Final pavement sections should be determined based a design level geotechnical investigation and anticipated frequency of load applications on the pavement during the desired design life. Flexible hot mixed asphaltic concrete pavement (HMAC) over Aggregate Base Course (ABC) or rigid Portland cement concrete (PCC) pavements can be used at this site for automobil e and light truck traffic use. Rigid pavements are recommended in any areas subject to heavy truck traffic. We anticipate asphalt pavement sections for local residential streets will be on the order of 4 to 6 inches thick. ABC sections will be on the order of 6 inches thick. Portland cement concrete (PCC) pavement is recommended in areas subject to any heavy truck traffic such as garbage pickup and/or dumpster trucks , and any heavy delivery trucks. We anticipate the use of 5 inches of PCC for general area pavements which are not subject to truck traffic. A minimum 6-inch-thick section is anticipated in main drives and any areas subject to some moderately heavy truck traf fic. Any areas subject to frequent heavy trucks should be designed based on frequency and whee l loads. PCC pavements in this area are typically reinforced due to the underlying active clays. Properly designed control joints and other joints systems are required to control cracking and allow pavement movement. PRELIMINARY RECOMMENDATIONS FOR STRUCTURES The property is currently planned for residential construction. Our field and laboratory data indicate the soil and bedrock conditions vary across the site. The following discussions are preliminary and are not intended for design or constructi on. After grading is completed, a detailed soils and foundation investigation should be performed. Foundations Our geologic and preliminary geotechnical inves tigation for this site indicates structures may be founded on shallow foundations. A design level geotechnical investigation may identify potential hazards (i.e., higher swelling soils) for specified areas not indicated by our borings which may suggest the need for a deeper foundation system or mitigation of the subgrade such as over-excavation may be recommended. 12 ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL|T PROJECT NO. FC08493-115 REV 5 Slabs-on-Grade and Basement Floor Construction The use of slab-on-grade floors for unfinished basements should be limited to areas where soils within the depth likely to influence floor performance are consolidating to low - swelling. We believe most of the lots will be rated with low risk of poor slab performance. Structurally supported floor systems should be planned in all non -basement finished living areas and where higher swelling soils are encountered . Slab performance risk should be more thoroughly defined during the design level soils and foundation investigation. Below-Grade Construction Groundwater was encountered during this investigation and will limit below-grade-areas. A separation of 5 feet is recommended between ground water and the bottom of footings . Surface water can infiltrate and develop adjacent to foundations walls. To reduce the risk of hydrostatic pressure developing on foundation walls, foundation drains will be necessary around all below-grade areas. We suggest foundation drains be tied to the sewer underdrain system. They may also discharge to sumps where water can be removed by pumping. In our opinion, underdrain systems offer more comprehensive control of water from the foundation drain and the impact of swelling soils on foundations, slabs, and pavements. Foundation walls and grade beams should be designed to withstand lateral earth pressures. The design pressure should be established during design-level soils investigations. Surface Drainage The performance of foundations will be influenced by surface drainage. The ground surface around proposed residences should be shaped to provide runoff of surface wat er away from the structure and off of pavements. We generally recommend slopes of at least 12 inches in the first 10 feet where practical in the landscaping areas surrounding residences. There are practical limitations on achieving these slopes. Irrigation should be minimized to control wetting. Roof downspouts should discharge beyond the limits of backfill. Water should not be allowed to pond on or adjacent to pavements. Proper control of surface runoff is also important to limit the erosion of surface soils. Sheet flow should not be directed over unprotected slopes. Water should not be allowed to pond at the crest of slopes. Permanent slopes should be re - vegetated to reduce erosion. 13 ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL|T PROJECT NO. FC08493-115 REV 5 Water can follow poorly compacted fill behind curb and gutter an d in utility trenches. This water can soften fill and undermine the performance of the roadway s, flatwork, and foundations. We recommend compactive effort be used in placement of all fill. General Design Considerations Exterior sidewalks and pavements supported above the onsite clays are subject to post construction movement. Flat grades should be avoided to prevent possible ponding, particularly next to the building due to soil movement. Positive grades away from the structures should be used for sidewalks and flatwork around the perimeter of the buildings in order to reduce the possibility of lifting of flatwork, resulting in ponding next to the structures. Where movement of the flatwork is objectionable, procedures recommended for slab-on-grade floors should be considered. Joints next to buildings should be thoroughly sealed to prevent the i nfiltration of surface water. Where concrete pavement is used, joints should also be sealed to reduce the infiltration of water. Since some post construction movement of pavement and flatwork may occur, joints around the buildings should be periodically observed and resealed where necessary. Roof drains should be discharged well away from the structures, preferably by closed pipe systems. Where roof drains ar e allowed to discharge on concrete flatwork or pavement areas next to the structures, care shoul d be taken to ensure the area is as water tight as practical to eliminate the infiltration of this water next to the buildings. WATER SOLUBLE SULFATES Concrete that comes into contact with soils can be subject to sulfate attack. We measured water-soluble sulfate concentrations in four samples from this site. Concentrations were measured between 0.08 and 0.12 percent, with two samples having sulfate concentrations between 0.1 and 0.2 percent. Water-soluble sulfate concentrations between 0.1 and 0.2 percent indicate Class 1 exposure to sulfate attack, according to the American 14 ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL|T PROJECT NO. FC08493-115 REV 5 Concrete Institute (ACI). ACI indicates adequate sulfate resistance can be achieved by using Type II cement with a water-to-cementitious material ratio of 0.50 or less. ACI also indicates concrete in Class 1 exposure environments should have a minimum compressive strength of 4,000 psi. In our experience, superficial damage may occur to the exposed surfaces of highly permeable concrete, even though sulfate levels are relatively low. To control this risk and to resist freeze-thaw deterioration, the water-to-cementitious material ratio should not exceed 0.50 for concrete in contact with soils that are likely to stay moist due to surface drainage or high- water tables. Concrete should be air entrained. RECOMMENDED FUTURE INVESTIGATIONS Based on the results of this investigation and the proposed development, we recommend the following investigations be performed: 1. Review of final site grading plans by our firm; 2. Construction testing and observation for site development; 3. Subgrade investigation and pavement design after site grading and utility installation is complete; 4. Design-level soils and foundation investigations after grading; 5. Construction testing and observation for residential buil ding construction and paving. LIMITATIONS Our exploratory borings were located to obtain preliminary subsurface data indicative of conditions on this site. Although our borings were spaced to obtain a reasonably accurate picture of subsurface conditions, variations in the subsurface conditions not indicated in our borings are always possible. We believe this investigation was conducted i n a manner consistent with that level of skill and care ordinarily used by members of the profess ion currently practicing under similar conditions in the locality of this project. No warranty, express or implied, is made. 15 ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL|T PROJECT NO. FC08493-115 REV 5 This report was prepared from data developed during our field exploration, laboratory testing, engineering analysis, and experience with similar conditions. The recommendations contained in this report were based upon our understanding of the planned construction. If plans change or differ from the assumptions presented herein, we should be contacted to review our recommendations. If we can be of further service in discussing the contents of this report or in the analysis of the building and pavement from the geotechnical point of vi ew, please call. Very truly yours, CTL | THOMPSON, INC. John Byers R. B. “Chip” Leadbetter, PE Staff Geologist Senior Engineer MW-1 MW-2 MW-3 MW-4 MW-5 MW-6 MW-7 MW-8 MW-9 MW-10MW-11MW-12 MW-13 MW-14 MW-15 MW-16 MW-17 MW-18 Zi e g l e r R o a d Horsetooth Road HORSETOOTH RD. ZI E G L E R R D . WILLIAM NEAL PKWY. DRAKE RD. I- 2 5 SITE LEGEND: INDICATES APPROXIMATE LOCATION OF EXPLORATORY BORING INDICATES APPROXIMATE LOCATION OF PIEZOMETER INDICATES LOT INCLUDED IN THIS MW-1 MW-13 FIGURE 1 VICINITY MAP (FT. COLLINS, CO) NOT TO SCALE 600'300' APPROXIMATE SCALE: 1" = 600' 0' Locations of Exploratory Borings ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL I T PROJECT NO. FC08493-115 REV 5 4,810 4,820 4,830 4,840 4,850 4,860 4,870 4,880 4,890 4,810 4,820 4,830 4,840 4,850 4,860 4,870 4,880 4,890 19/12 4/12 4/12 50/10 WC=13.6DD=119SW=0.6 WC=15.2DD=109SW=-0.3SS=0.120 WC=22.6DD=104SW=-0.2 WC=4.2-200=8 WC=13.6DD=119SW=0.6 WC=15.2DD=109SW=-0.3SS=0.120 WC=22.6DD=104SW=-0.2 WC=4.2-200=8 MW-1 El. 4886.0 14/12 35/12 50/6 WC=18.0DD=113SW=0.2 WC=18.0DD=113SW=0.2 MW-2 El. 4875.8 9/12 30/12 50/6 WC=15.7LL=45 PI=25-200=51 WC=15.7LL=45 PI=25-200=51 MW-3 El. 4873.2 21/12 9/12 6/12 33/12 WC=11.3DD=120SW=0.4 WC=19.9DD=109SW=-0.2 WC=11.3DD=120SW=0.4 WC=19.9DD=109SW=-0.2 MW-4 El. 4885.2 20/12 6/12 19/12 50/12 WC=28.8DD=95SW=-0.2 WC=11.6-200=9 WC=28.8DD=95SW=-0.2 WC=11.6-200=9 MW-5 El. 4881.5 EL E V A T I O N - F E E T FIGURE 2 EL E V A T I O N - F E E T Summary Logs of Exploratory Borings ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL | T PROJECT NO. FC08493-115 REV 5 4,810 4,820 4,830 4,840 4,850 4,860 4,870 4,880 4,890 4,810 4,820 4,830 4,840 4,850 4,860 4,870 4,880 4,890 10/12 4/12 50/12 50/12 WC=18.5DD=108SW=0.0SS=0.090 WC=23.1DD=106-200=41 WC=18.5DD=108SW=0.0SS=0.090 WC=23.1DD=106-200=41 MW-6 El. 4873.8 31/12 11/12 8/12 24/12 50/9 WC=11.1DD=122SW=1.1 WC=22.8DD=103SW=-0.2 WC=23.9DD=102SW=-0.1 WC=7.3-200=8 WC=11.1DD=122SW=1.1 WC=22.8DD=103SW=-0.2 WC=23.9DD=102SW=-0.1 WC=7.3-200=8 MW-7 El. 4883.7 26/12 13/12 5/12 50/7 50/6 WC=9.1DD=115SW=0.7 WC=19.3DD=111SW=0.1 WC=9.1DD=115SW=0.7 WC=19.3DD=111SW=0.1 MW-8 El. 4880.5 6/12 8/12 44/12 WC=13.4DD=107SW=0.0 WC=13.4DD=107SW=0.0 MW-9 El. 4873.4 14/12 6/12 15/12 WC=14.6DD=118SW=0.5 WC=19.5DD=110SW=-0.1 WC=14.6DD=118SW=0.5 WC=19.5DD=110SW=-0.1 MW-10 El. 4870.6 EL E V A T I O N - F E E T FIGURE 3 EL E V A T I O N - F E E T Summary Logs of Exploratory Borings ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL | T PROJECT NO. FC08493-115 REV 5 4,820 4,830 4,840 4,850 4,860 4,870 4,880 4,890 4,900 4,910 4,820 4,830 4,840 4,850 4,860 4,870 4,880 4,890 4,900 4,910 20/12 8/12 32/12 WC=7.3DD=120SW=0.2SS=0.080 WC=20.9DD=106SW=-0.1 WC=7.3DD=120SW=0.2SS=0.080 WC=20.9DD=106SW=-0.1 MW-11 El. 4877.6 15/12 5/12 5/12 5/12 28/12 WC=18.0DD=115SW=0.4 WC=29.3DD=94SW=-0.2 WC=25.1DD=99SW=-0.1 WC=23.8DD=382SW=-0.1 WC=18.0DD=115SW=0.4 WC=29.3DD=94SW=-0.2 WC=25.1DD=99SW=-0.1 WC=23.8DD=382SW=-0.1 MW-12 El. 4880.7 39/12 50/6 WC=0.9-200=4 WC=6.5LL=42 PI=19-200=17 WC=0.9-200=4 WC=6.5LL=42 PI=19-200=17 MW-15 El. 4906.9 21/12 10/12 5/12 8/12 WC=9.4DD=125SW=2.0 WC=21.3DD=107SW=0.4 WC=21.8DD=105SW=-0.2 WC=9.4DD=125SW=2.0 WC=21.3DD=107SW=0.4 WC=21.8DD=105SW=-0.2 MW-17 El. 4877.5 6/12 5/12 35/12 WC=15.0DD=112SW=0.1 WC=23.9DD=101SW=-1.5SS=0.100 WC=15.0DD=112SW=0.1 WC=23.9DD=101SW=-1.5SS=0.100 MW-18 El. 4868.8 EL E V A T I O N - F E E T FIGURE 4 DRIVE SAMPLE. THE SYMBOL 20/12 INDICATES 20 BLOWS OF A 140-POUND HAMMER FALLING 30 INCHES WERE REQUIRED TO DRIVE A 2.5-INCH O.D. SAMPLER 12 INCHES. EL E V A T I O N - F E E T WATER LEVEL MEASURED SEVERAL DAYS AFTER DRILLING. CLAY, SANDY, MOIST TO WET, MEDIUM STIFF TO STIFF, BROWN (CL) 2. 3. FILL, CLAY, SAND, GRAVEL, MOIST, STIFF TO VERY STIFF, BROWN, DARK BROWN THE BORINGS WERE DRILLED ON JULY 30 AND 31, 2018 USING 4-INCH DIAMETER CONTINUOUS-FLIGHT AUGERS AND A TRUCK-MOUNTED DRILL RIG. 1. LEGEND: NOTES: SAND, CLAYEY, MOIST TO WET, LOOSE, BROWN (SC) SAND AND GRAVEL, CLEAN TO SLIGHTLY CLAYEY, MOIST TO WET, DENSE TO VERY DENSE, BROWN, TAN, GRAY (SP, GP, GW, SW-SC, SP-SC, GP-GC) CLAYSTONE, SANDY, WITH OCCASIONAL SANDSTONE, CLAYEY INTERBEDS, MOIST TO WET, HARD, DARK GRAY WATER LEVEL MEASURED AT TIME OF DRILLING. BORING ELEVATIONS WERE SURVEYED BY A REPRESENTATIVE OF OUR FIRM REFERENCING THE TEMPORARY BENCHMARK SHOWN ON FIGURE 1. THESE LOGS ARE SUBJECT TO THE EXPLANATIONS, LIMITATIONS AND CONCLUSIONS IN THIS REPORT. 4. Summary Logs of Exploratory Borings WC DD SW -200 LL PI UC SS - - - - - - - - INDICATES MOISTURE CONTENT (%). INDICATES DRY DENSITY (PCF). INDICATES SWELL WHEN WETTED UNDER OVERBURDEN PRESSURE (%). INDICATES PASSING NO. 200 SIEVE (%). INDICATES LIQUID LIMIT. INDICATES PLASTICITY INDEX. INDICATES UNCONFINED COMPRESSIVE STRENGTH (PSF). INDICATES SOLUBLE SULFATE CONTENT (%). ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL | T PROJECT NO. FC08493-115 REV 5 Xref .\Surfer Files\contour overlay.dwg MW-1 MW-2 MW-3 MW-4 MW-5 MW-6 MW-7 MW-8 MW-9 MW-10 MW-112MW-1 MW-13 MW-14 MW-15 MW-16 MW-17 MW-18 Zi e g l e r R o a d Horsetooth Road (17.5) (10.5) (11)(10) )(9 (10.5) (6.5) (7.5) (7)(11) (9.5) (9) (10) (11) (5.5) (3.5) (5.5) (12) HORSETOOTH RD. ZI E G L E R R D . WILLIAM NEAL PKWY. DRAKE RD. I- 2 5 SITE LEGEND: INDICATES ESTIMATED GROUNDWATER CONTOUR ELEVATION INDICATES APPROXIMATE LOCATION OF EXPLORATORY BORING OR PIEZOMETER INDICATES MEASURED DEPTH TO GROUNDWATER MW-1 (10.5) FIGURE 5 Groundwater Elevation Contours VICINITY MAP (FT. COLLINS, CO) NOT TO SCALE 600'300' APPROXIMATE SCALE: 1" = 600' 0' ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL I T PROJECT NO. FC08493-115 REV 5 FIGURE 6 Underdrain Detail Sewer ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL\T Project No. FC08493-115 REV 5 FIGURE 7 Underdrain Cutoff Wall Detail ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL\T Project No. FC08493-115 REV 5 FIGURE 8 Conceptual Underdrain Service Profile ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL\T Project No. FC08493-115 REV 5 APPENDIX A LABORATORY TEST RESULTS TABLE A-I: SUMMARY OF LABORATORY TEST RESULTS Sample of FILL, CLAY, SANDY (CL) DRY UNIT WEIGHT=119 PCF From MW - 1 AT 4 FEET MOISTURE CONTENT=13.6 % ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL | T PROJECT NO. FC08493-115 REV 5 APPLIED PRESSURE -KSF CO M P R E S S I O N % E X P A N S I O N Swell Consolidation Test Results FIGURE A-1 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 ANTONSTNDER CUNOSIANXPE ETTINUE TO WDRU GESSREP 0.1 1.0 10 100 Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT=104 PCF From MW - 1 AT 9 FEET MOISTURE CONTENT=20.8 % ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL | T PROJECT NO. FC08493-115 REV 5 APPLIED PRESSURE -KSF CO M P R E S S I O N % E X P A N S I O N Swell Consolidation Test Results FIGURE A-2 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 RDEUNSIONSCOMPRELANOITIDDA GNTIRESSURPTA ETWTODUEENSTONC 0.1 1.0 10 100 Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT=104 PCF From MW - 1 AT 14 FEET MOISTURE CONTENT=22.6 % ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL | T PROJECT NO. FC08493-115 REV 5 APPLIED PRESSURE -KSF CO M P R E S S I O N % E X P A N S I O N Swell Consolidation Test Results FIGURE A-3 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 RDEUNSIONSCOMPRELANOITIDDA GNTIRESSURPTA ETWTODUEENSTONC 0.1 1.0 10 100 Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT=113 PCF From MW - 2 AT 4 FEET MOISTURE CONTENT=18.0 % Sample of FILL, CLAY, SANDY (CL) DRY UNIT WEIGHT=120 PCF From MW - 4 AT 4 FEET MOISTURE CONTENT=11.3 % ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL | T PROJECT NO. FC08493-115 REV 5 APPLIED PRESSURE -KSF APPLIED PRESSURE -KSF CO M P R E S S I O N % E X P A N S I O N Swell Consolidation Test Results FIGURE A-4 CO M P R E S S I O N % E X P A N S I O N -4 -3 -2 -1 0 1 2 3 TNASTONER CSION UNDNAPXE GINTTO WRE DUESU ETSERP -4 -3 -2 -1 0 1 2 3 TANSTONER CDSION UNNAPEX INTETWTORE DUEEEEPRESSU G 0.1 1.0 10 100 0.1 1.0 10 100 Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT=109 PCF From MW - 4 AT 9 FEET MOISTURE CONTENT=19.9 % Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT=95 PCF From MW - 5 AT 9 FEET MOISTURE CONTENT=28.8 % ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL | T PROJECT NO. FC08493-115 REV 5 APPLIED PRESSURE -KSF APPLIED PRESSURE -KSF CO M P R E S S I O N % E X P A N S I O N Swell Consolidation Test Results FIGURE A-5 CO M P R E S S I O N % E X P A N S I O N -4 -3 -2 -1 0 1 2 3 ONSSIMPRENAL COOIITDDA EUDRECONSTAR SURESNT PEDNU TINGWETTO -4 -3 -2 -1 0 1 2 3 ONSSIMPREONAL COIITDDA EUDRERESNT PCONSTAUN SURED TINGTO WET 0.1 1.0 10 100 0.1 1.0 10 100 Sample of FILL, CLAY, SANDY (CL) DRY UNIT WEIGHT=108 PCF From MW - 6 AT 4 FEET MOISTURE CONTENT=18.5 % Sample of FILL, CLAY, SANDY (CL) DRY UNIT WEIGHT=122 PCF From MW - 7 AT 4 FEET MOISTURE CONTENT=11.1 % ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL | T PROJECT NO. FC08493-115 REV 5 APPLIED PRESSURE -KSF APPLIED PRESSURE -KSF CO M P R E S S I O N % E X P A N S I O N Swell Consolidation Test Results FIGURE A-6 CO M P R E S S I O N % E X P A N S I O N -4 -3 -2 -1 0 1 2 3 GNTIEEEWETODUE TEMENTMOVON -4 -3 -2 -1 0 1 2 3 TANSTONER CDSION UNNAPEX INTETWTORE DUEEEEPRESSU G 0.1 1.0 10 100 0.1 1.0 10 100 Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT=103 PCF From MW - 7 AT 9 FEET MOISTURE CONTENT=22.8 % ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL | T PROJECT NO. FC08493-115 REV 5 APPLIED PRESSURE -KSF CO M P R E S S I O N % E X P A N S I O N Swell Consolidation Test Results FIGURE A-7 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 RDEUNSIONSCOMPRELANOITIDDA GNTIRESSURPTA ETWTODUEENSTONC 0.1 1.0 10 100 Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT=102 PCF From MW - 7 AT 14 FEET MOISTURE CONTENT=23.9 % ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL | T PROJECT NO. FC08493-115 REV 5 APPLIED PRESSURE -KSF CO M P R E S S I O N % E X P A N S I O N Swell Consolidation Test Results FIGURE A-8 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 RDEUNSIONSCOMPRELANOITIDDA GNTIRESSURPTA ETWTODUEENSTONC 0.1 1.0 10 100 Sample of FILL, CLAY, SANDY (CL) DRY UNIT WEIGHT=115 PCF From MW - 8 AT 4 FEET MOISTURE CONTENT=9.1 % Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT=111 PCF From MW - 8 AT 9 FEET MOISTURE CONTENT=19.3 % ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL | T PROJECT NO. FC08493-115 REV 5 APPLIED PRESSURE -KSF APPLIED PRESSURE -KSF CO M P R E S S I O N % E X P A N S I O N Swell Consolidation Test Results FIGURE A-9 CO M P R E S S I O N % E X P A N S I O N -4 -3 -2 -1 0 1 2 3 TNASTONER CSION UNDNAPXE GINTTO WRE DUESU ETSERP -4 -3 -2 -1 0 1 2 3 TANSTONER CDSION UNNAPEX INTETWTORE DUEEEEPRESSU G 0.1 1.0 10 100 0.1 1.0 10 100 Sample of SAND, CLAYEY (SC) DRY UNIT WEIGHT=107 PCF From MW - 9 AT 4 FEET MOISTURE CONTENT=13.4 % Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT=118 PCF From MW - 10 AT 4 FEET MOISTURE CONTENT=14.6 % ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL | T PROJECT NO. FC08493-115 REV 5 APPLIED PRESSURE -KSF APPLIED PRESSURE -KSF CO M P R E S S I O N % E X P A N S I O N Swell Consolidation Test Results FIGURE A-10 CO M P R E S S I O N % E X P A N S I O N -4 -3 -2 -1 0 1 2 3 GNTIEEEWETODUE TEMENTMOVON -4 -3 -2 -1 0 1 2 3 TANSTONER CDSION UNNAPEX INTETWTORE DUEEEEPRESSU G 0.1 1.0 10 100 0.1 1.0 10 100 Sample of SAND, CLAYEY (SC) DRY UNIT WEIGHT=110 PCF From MW - 10 AT 9 FEET MOISTURE CONTENT=19.5 % Sample of FILL, CLAY, SANDY (CL) DRY UNIT WEIGHT=120 PCF From MW - 11 AT 4 FEET MOISTURE CONTENT=7.1 % ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL | T PROJECT NO. FC08493-115 REV 5 APPLIED PRESSURE -KSF APPLIED PRESSURE -KSF CO M P R E S S I O N % E X P A N S I O N Swell Consolidation Test Results FIGURE A-11 CO M P R E S S I O N % E X P A N S I O N -4 -3 -2 -1 0 1 2 3 ONSSIMPRENAL COOIITDDA EUDRECONSTAR SURESNT PEDNU TINGWETTO -4 -3 -2 -1 0 1 2 3 TANSTONER CDSION UNNAPEX INTETWTORE DUEEEEPRESSU G 0.1 1.0 10 100 0.1 1.0 10 100 Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT=106 PCF From MW - 11 AT 9 FEET MOISTURE CONTENT=20.9 % Sample of FILL, CLAY, SANDY (CL) DRY UNIT WEIGHT=115 PCF From MW - 12 AT 4 FEET MOISTURE CONTENT=18.0 % ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL | T PROJECT NO. FC08493-115 REV 5 APPLIED PRESSURE -KSF APPLIED PRESSURE -KSF CO M P R E S S I O N % E X P A N S I O N Swell Consolidation Test Results FIGURE A-12 CO M P R E S S I O N % E X P A N S I O N -4 -3 -2 -1 0 1 2 3 ONSSIMPRENAL COOIITDDA EUDRECONSTAR SURESNT PEDNU TINGWETTO -4 -3 -2 -1 0 1 2 3 TANSTONER CDSION UNNAPEX INTETWTORE DUEEEEPRESSU G 0.1 1.0 10 100 0.1 1.0 10 100 Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT=94 PCF From MW - 12 AT 9 FEET MOISTURE CONTENT=29.3 % ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL | T PROJECT NO. FC08493-115 REV 5 APPLIED PRESSURE -KSF CO M P R E S S I O N % E X P A N S I O N Swell Consolidation Test Results FIGURE A-13 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 RDEUNSIONSCOMPRELANOITIDDA GNTIRESSURPTA ETWTODUEENSTONC 0.1 1.0 10 100 Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT=99 PCF From MW - 12 AT 14 FEET MOISTURE CONTENT=25.1 % ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL | T PROJECT NO. FC08493-115 REV 5 APPLIED PRESSURE -KSF CO M P R E S S I O N % E X P A N S I O N Swell Consolidation Test Results FIGURE A-14 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 RDEUNSIONSCOMPRELANOITIDDA GNTIRESSURPTA ETWTODUEENSTONC 0.1 1.0 10 100 Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT=382 PCF From MW - 12 AT 19 FEET MOISTURE CONTENT=23.8 % Sample of FILL, CLAY, SANDY (CL) DRY UNIT WEIGHT=125 PCF From MW - 17 AT 4 FEET MOISTURE CONTENT=9.4 % ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL | T PROJECT NO. FC08493-115 REV 5 APPLIED PRESSURE -KSF APPLIED PRESSURE -KSF CO M P R E S S I O N % E X P A N S I O N Swell Consolidation Test Results FIGURE A-15 CO M P R E S S I O N % E X P A N S I O N -4 -3 -2 -1 0 1 2 3 ONSSIMPRENAL COOIITDDA EUDRECONSTAR SURESNT PEDNU TINGWETTO -4 -3 -2 -1 0 1 2 3 TANSTONER CDSION UNNAPEX INTETWTORE DUEEEEPRESSU G 0.1 1.0 10 100 0.1 1.0 10 100 Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT=107 PCF From MW - 17 AT 9 FEET MOISTURE CONTENT=21.3 % ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL | T PROJECT NO. FC08493-115 REV 5 APPLIED PRESSURE -KSF CO M P R E S S I O N % E X P A N S I O N Swell Consolidation Test Results FIGURE A-16 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 ANTONSTNDER CUNOSIANXPE ETTINUE TO WDRU GESSREP 0.1 1.0 10 100 Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT=105 PCF From MW - 17 AT 14 FEET MOISTURE CONTENT=21.8 % ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL | T PROJECT NO. FC08493-115 REV 5 APPLIED PRESSURE -KSF CO M P R E S S I O N % E X P A N S I O N Swell Consolidation Test Results FIGURE A-17 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 RDEUNSIONSCOMPRELANOITIDDA GNTIRESSURPTA ETWTODUEENSTONC 0.1 1.0 10 100 Sample of FILL, CLAY, SANDY (CL) DRY UNIT WEIGHT=112 PCF From MW - 18 AT 4 FEET MOISTURE CONTENT=15.0 % ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL | T PROJECT NO. FC08493-115 REV 5 APPLIED PRESSURE -KSF CO M P R E S S I O N % E X P A N S I O N Swell Consolidation Test Results FIGURE A-18 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 ANTONSTNDER CUNOSIANXPE ETTINUE TO WDRU GESSREP 0.1 1.0 10 100 Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT=101 PCF From MW - 18 AT 9 FEET MOISTURE CONTENT=23.9 % ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL | T PROJECT NO. FC08493-115 REV 5 APPLIED PRESSURE -KSF CO M P R E S S I O N % E X P A N S I O N Swell Consolidation Test Results FIGURE A-19 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 RDEUNSIONSCOMPRELANOITIDDA GNTIRESSURPTA ETWTODUEENSTONC 0.1 1.0 10 100 Sample of GRAVEL, SANDY, SLIGHTLY CLAYEY (GP-GC)GRAVEL 49 %SAND 43 % From MW - 1 AT 19 FEET SILT & CLAY 8 %LIQUID LIMIT % PLASTICITY INDEX % Sample of SAND, GRAVELLY, SLIGHTLY CLAYEY (SP-SC)GRAVEL 22 %SAND 69 % From MW - 5 AT 14 FEET SILT & CLAY 9 %LIQUID LIMIT % PLASTICITY INDEX % ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL | T PROJECT NO. FC08493-115 REV 5 FIGURE A-20 Gradation Test Results 0.002 15 MIN. .005 60 MIN. .009 19 MIN. .019 4 MIN. .037 1 MIN. .074 *200 .149 *100 .297 *50 0.42 *40 .590 *30 1.19 *16 2.0 *10 2.38 *8 4.76 *4 9.52 3/8" 19.1 3/4" 36.1 1½" 76.2 3" 127 5" 152 6" 200 8" .001 45 MIN. 0 10 20 30 40 50 60 70 80 90 100 CLAY (PLASTIC) TO SILT (NON-PLASTIC)SANDS FINE MEDIUM COARSE GRAVEL FINE COARSE COBBLES DIAMETER OF PARTICLE IN MILLIMETERS 25 HR.7 HR. HYDROMETER ANALYSIS SIEVE ANALYSIS TIME READINGS U.S. STANDARD SERIES CLEAR SQUARE OPENINGS PE R C E N T P A S S I N G 0 10 20 30 50 60 70 80 90 100 PE R C E N T R E T A I N E D 40 0.002 15 MIN. .005 60 MIN. .009 19 MIN. .019 4 MIN. .037 1 MIN. .074 *200 .149 *100 .297 *50 0.42 *40 .590 *30 1.19 *16 2.0 *10 2.38 *8 4.76 *4 9.52 3/8" 19.1 3/4" 36.1 1½" 76.2 3" 127 5" 152 6" 200 8" .001 45 MIN. 0 10 20 30 40 50 60 70 80 90 100 CLAY (PLASTIC) TO SILT (NON-PLASTIC)SANDS FINE MEDIUM COARSE GRAVEL FINE COARSE COBBLES DIAMETER OF PARTICLE IN MILLIMETERS 25 HR.7 HR. HYDROMETER ANALYSIS SIEVE ANALYSIS TIME READINGS U.S. STANDARD SERIES CLEAR SQUARE OPENINGS PE R C E N T P A S S I N G PERCENT RET IA NED 0 10 20 30 40 50 60 70 80 90 100 Sample of SAND, GRAVELLY, SLIGHTLY CLAYEY (SP-SC)GRAVEL 34 %SAND 58 % From MW - 7 AT 24 FEET SILT & CLAY 8 %LIQUID LIMIT % PLASTICITY INDEX % Sample of GRAVEL, SANDY (GW)GRAVEL 69 %SAND 27 % From MW - 15 AT 4 FEET SILT & CLAY 4 %LIQUID LIMIT % PLASTICITY INDEX % ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL | T PROJECT NO. FC08493-115 REV 5 FIGURE A-21 Gradation Test Results 0.002 15 MIN. .005 60 MIN. .009 19 MIN. .019 4 MIN. .037 1 MIN. .074 *200 .149 *100 .297 *50 0.42 *40 .590 *30 1.19 *16 2.0 *10 2.38 *8 4.76 *4 9.52 3/8" 19.1 3/4" 36.1 1½" 76.2 3" 127 5" 152 6" 200 8" .001 45 MIN. 0 10 20 30 40 50 60 70 80 90 100 CLAY (PLASTIC) TO SILT (NON-PLASTIC)SANDS FINE MEDIUM COARSE GRAVEL FINE COARSE COBBLES DIAMETER OF PARTICLE IN MILLIMETERS 25 HR.7 HR. HYDROMETER ANALYSIS SIEVE ANALYSIS TIME READINGS U.S. STANDARD SERIES CLEAR SQUARE OPENINGS PE R C E N T P A S S I N G 0 10 20 30 50 60 70 80 90 100 PE R C E N T R E T A I N E D 40 0.002 15 MIN. .005 60 MIN. .009 19 MIN. .019 4 MIN. .037 1 MIN. .074 *200 .149 *100 .297 *50 0.42 *40 .590 *30 1.19 *16 2.0 *10 2.38 *8 4.76 *4 9.52 3/8" 19.1 3/4" 36.1 1½" 76.2 3" 127 5" 152 6" 200 8" .001 45 MIN. 0 10 20 30 40 50 60 70 80 90 100 CLAY (PLASTIC) TO SILT (NON-PLASTIC)SANDS FINE MEDIUM COARSE GRAVEL FINE COARSE COBBLES DIAMETER OF PARTICLE IN MILLIMETERS 25 HR.7 HR. HYDROMETER ANALYSIS SIEVE ANALYSIS TIME READINGS U.S. STANDARD SERIES CLEAR SQUARE OPENINGS PE R C E N T P A S S I N G PERCENT RE I T A NED 0 10 20 30 40 50 60 70 80 90 100 PASSING WATER- MOISTURE DRY LIQUID PLASTICITY APPLIED SWELL NO. 200 SOLUBLE DEPTH CONTENT DENSITY LIMIT INDEX SWELL*PRESSURE PRESSURE SIEVE SULFATES BORING (FEET)(%)(PCF)(%)(PSF)(PSF)(%)(%)DESCRIPTION MW-1 4 13.6 119 0.6 500 FILL, CLAY, SANDY (CL) MW-1 9 15.2 109 -0.3 1,100 0.12 CLAY, SANDY (CL) MW-1 14 22.6 104 -0.2 1,800 CLAY, SANDY (CL) MW-1 19 4.2 8 GRAVEL, SANDY, SLIGHTLY CLAYEY (GP-GC) MW-2 4 18.0 113 0.2 500 CLAY, SANDY (CL) MW-3 4 15.7 45 25 51 FILL, CLAY, SANDY (CL) MW-4 4 11.3 120 0.4 500 FILL, CLAY, SANDY (CL) MW-4 9 19.9 109 -0.2 1,100 CLAY, SANDY (CL) MW-5 9 28.8 95 -0.2 1,100 CLAY, SANDY (CL) MW-5 14 11.6 9 SAND, GRAVELLY, SLIGHTLY CLAYEY (SP-SC) MW-6 4 18.5 108 0.0 500 0.09 FILL, CLAY, SANDY (CL) MW-6 9 23.1 106 41 SAND, CLAYEY (SC) MW-7 4 11.1 122 1.1 500 FILL, CLAY, SANDY (CL) MW-7 9 22.8 103 -0.2 1,100 CLAY, SANDY (CL) MW-7 14 23.9 102 -0.1 1,800 CLAY, SANDY (CL) MW-7 24 7.3 8 SAND, GRAVELLY, SLIGHTLY CLAYEY (SP-SC) MW-8 4 9.1 115 0.7 500 FILL, CLAY, SANDY (CL) MW-8 9 19.3 111 0.1 1,100 CLAY, SANDY (CL) MW-9 4 13.4 107 0.0 500 SAND, CLAYEY (SC) MW-10 4 14.6 118 0.5 500 CLAY, SANDY (CL) MW-10 9 19.5 110 -0.1 1,100 SAND, CLAYEY (SC) MW-11 4 7.3 120 0.2 500 0.08 FILL, CLAY, SANDY (CL) MW-11 9 20.9 106 -0.1 1,100 CLAY, SANDY (CL) MW-12 4 18.0 115 0.4 500 1,300 FILL, CLAY, SANDY (CL) MW-12 9 29.3 94 -0.2 1,100 CLAY, SANDY (CL) MW-12 14 25.1 99 -0.1 1,800 CLAY, SANDY (CL) MW-12 19 23.8 382 -0.1 2,400 CLAY, SANDY (CL) MW-15 4 0.9 4 GRAVEL, SANDY (GW) MW-15 24 6.5 42 19 17 SANDSTONE, CLAYEY MW-17 4 9.4 125 2.0 500 FILL, CLAY, SANDY (CL) MW-17 9 21.3 107 0.4 1,100 2,000 CLAY, SANDY (CL) MW-17 14 21.8 105 -0.2 1,800 CLAY, SANDY (CL) MW-18 4 15.0 112 0.1 500 1,000 FILL, CLAY, SANDY (CL) MW-18 9 23.9 101 -1.5 1,100 0.10 CLAY, SANDY (CL) SWELL TEST RESULTS* TABLE A-I SUMMARY OF LABORATORY TESTING ATTERBERG LIMITS Page 1 of 1 * NEGATIVE VALUE INDICATES COMPRESSION. ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL|T PROJECT NO. FC08493-115 REV 5 APPENDIX B GUIDELINE SITE GRADING SPECIFICATIONS ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL|T PROJECT NO. FC08493-115 REV 5 B-1 GUIDELINE SITE GRADING SPECIFICATIONS 1. DESCRIPTION This item shall consist of the excavation, transportation, place ment and compaction of materials from locations indicated on the plans, or staked by the Engineer, as necessary to achieve preliminary street and overlot elevations. These specifications shall also apply to compaction of excess cut materials that may be placed outside of the development boundaries. 2. GENERAL The Soils Engineer shall be the Owner's representative. The Soils Engineer shall approve fill materials, method of placement, moisture contents and percent compaction, and shall give written approval of the completed fill. 3. CLEARING JOB SITE The Contractor shall remove all vegetation and debris before excavation or fill placement is begun. The Contractor shall dispose of the cleared material to provide the Owner with a clean, neat appearing job site. Cleared material shall not be placed in areas to receive fill or where the material will support structures of any kind. 4. SCARIFYING AREA TO BE FILLED All topsoil and vegetable matter shall be removed from the ground surface upon which fill is to be placed. The surface shall then be plowed or scarified until the surface is free from ruts, hummocks or other uneven features, which would prevent uniform compaction. 5. COMPACTING AREA TO BE FILLED After the foundation for the fill has been cleared and scarified, it shall be disked or bladed until it is free from large clods, brought to the proper moisture content (0 to 3 percent above optimum moisture content for clays and within 2 percent of optimum moisture content for sands) and compacted to not less than 95 percent of maximum dry density as determined in accordance with ASTM D698. 6. FILL MATERIALS Fill soils shall be free from organics, debris, or other deleterious substances, and shall not contain rocks or lumps having a diameter greater than six (6) inches. Fill materials shall be obtained from cut areas shown on the plans or staked in the field by the Engineer. ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL|T PROJECT NO. FC08493-115 REV 5 B-2 On-site materials classifying as CL, CH, SC, SM, SW, SP, GP, GC, and GM are acceptable. Concrete, asphalt, organic matter and other deleterious materials or debris shall not be used as fill. 7. MOISTURE CONTENT AND DENSITY Fill material shall be moisture conditioned and compacted to the criteria in the table, below. Maximum density and optimum moisture content shall be determined from the appropriate Proctor compaction tests. Sufficient laboratory compaction tests shall be made to determine the optimum moisture content for the various soils encountered in borrow areas. FILL COMPACTION AND MOISTURE REQUIREMENTS Soil Type Depth from Final Grade (feet) Moisture Requirement (% from optimum) Density Requirement Clay 0 to 15 feet 0 to +3 95% of ASTM D 698 Sand -2 to +2 95% of ASTM D 698 Clay Greater than 15 feet -2 to +1 98% of ASTM D 698 Sand -2 to +1 95% of ASTM D 1557 The Contractor may be required to add moisture to the excavation materials in the borrow area if, in the opinion of the Soils Engineer, it is not possible to obtain uniform moisture content by adding water on the fill surface. The Contractor may be required to rake or disc the fill soils to provide uniform moisture content through the soils. The application of water to embankment materials shall be made with any type of watering equipment approved by the Soils Engineer, which will give the desired results. Water jets from the spreader shall not be directed at the embankment with such force that fill materials are washed out. Should too much water be added to any part of the fill, such that the material is too wet to permit the desired compaction from being obtained, rolling and all work on that section of the fill shall be delayed until the material has been allowed to dry to the required moisture content. The Contr actor will be permitted to rework wet material in an approved manner to hasten its drying. ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL|T PROJECT NO. FC08493-115 REV 5 B-3 8. COMPACTION OF FILL AREAS Selected fill material shall be placed and mixed in evenly spread layers. After each fill layer has been placed, it shall be uniformly compacted to not less than the specified percentage of maximum density. Fill shall be compacted to the criteria above. At the option of the Soils Engineer, so ils classifying as SW, GP, GC, or GM may be compacted to 95 percent of maximum density as determined in accordance with ASTM D 1557 or 70 percent relative density for cohesionless sand soils. Fill materials shall be placed such that the thickness of loose materials does not exceed 12 inches and the compacted lift thickness does not exceed 6 inches. Compaction as specified above, shall be obtained by the use of sheepsfoot rollers, multiple-wheel pneumatic-tired rollers, or other equipment approved by the Engineer for soils classifying as CL, CH, or SC. Granular fill shall be compacted using vibratory equipment or other equipment approved by the Soils Engineer. Compaction shall be accomplished while the fill material is at the specified moisture content. Compaction of each layer shall be continuous over the entire area. Compaction equipment shall make sufficient trips to ensure that the required density is obtained. 9. COMPACTION OF SLOPES Fill slopes shall be compacted by means of sheepsfoot rollers or other suitable equipment. Compaction operations shall be continued until slopes are stable, but not too dense for planting, and there is not appreciable amount of loose soils on the slopes. Compaction of slopes may be done progressively in increments of three to five feet (3' to 5') in height or after the fill is brought to its total height. Permanent fill slopes shall not exceed 3:1 (horizontal to vertical). 10. PLACEMENT OF FILL ON NATURAL SLOPES Where natural slopes are steeper than 20 percent in grade and the placement of fill is required, benches shall be cut at the rate of one bench for each 5 feet in height (minimum of two benches). Benches shall be at least 10 feet in width. Larger bench widths may be required by the Engineer. Fill shall be placed on completed benches as outlined within this specification. ANDERSON CONSULTING ENGINEERS, INC. STRAUSS LAKE DEVELOPMENT CTL|T PROJECT NO. FC08493-115 REV 5 B-4 11. DENSITY TESTS Field density tests shall be made by the Soils Engineer at locations and depths of his choosing. Where sheepsfoot rollers are used, the soil may be disturbed to a depth of several inches. Density tests shall be taken in compacted material below the disturbed surface. When density tests indicate that the density or moisture content of any layer of fill or portion thereof is not within specification, the particular layer or portion shall be reworked until the required density or moisture content has been achieved. 12. SEASONAL LIMITS No fill material shall be placed, spread, or rolled while it is frozen, thawing, or during unfavorable weather conditions. When work is interrupted by heavy precipitation, fill operations shall not be resumed until the Soils Engine er indicates that the moisture content and density of previously placed materials are as specified. 13. NOTICE REGARDING START OF GRADING The Contractor shall submit notification to the Soils Engineer and Owner advising them of the start of grading operations at least three (3) days in advance of the starting date. Notification shall also be submitted at least 3 days in advance of any resumption dates when grading operations have been stopped for any reason other than adverse weather conditions. 14. REPORTING OF FIELD DENSITY TESTS Density tests made by the Soils Engineer, as specified under "Density Tests" above, shall be submitted progressively to the Owner. Dry density, moisture content, and percentage compaction shall be reported for each test taken. 15. DECLARATION REGARDING COMPLETED FILL The Soils Engineer shall provide a written declaration stating that the site was filled with acceptable materials and was placed in general accordance with the specifications.