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HomeMy WebLinkAboutSEVEN GENERATIONS MULTIFAMILY - FDP230008 - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORT CTL|Thompson, Inc. Denver, Fort Collins, Colorado Springs, Glenwood Springs, Pueblo, Summit County – Colorado Cheyenne, Wyoming and Bozeman, Montana Proposed Multi-Family Residential Building 3221 Eastbrook Drive Fort Collins, Colorado Prepared for: Black Timber Builders 417 Jefferson Street Fort Collins, Colorado 80524 Attention: Russell Baker Project No. FC10564-120 September 20, 2022 SOIL AND FOUNDATION INVESTIGATION Table of Contents Table of Contents 2 Scope 1 Summary Of Conclusions 1 Site Description 2 Proposed Construction 2 Investigation 3 Subsurface Conditions 3 Existing Fill 3 Natural Soils 4 Bedrock 4 Groundwater 4 Geologic Hazards 4 Foundations 5 Footings with Minimum Dead Load 6 Floor Systems 7 Porches, Decks and Patios 8 Exterior Flatwork 8 Below-Grade Walls 9 Backfill Compaction 9 Subsurface Drains and Surface Drainage 10 Concrete 11 Excavations 12 Construction Observations 12 Geotechnical Risk 12 Limitations 13 FIGURE 1 – LOCATIONS OF EXPLORATORY BORINGS FIGURE 2 – SUMMARY LOGS OF EXPLORATORY BORINGS APPENDIX A – RESULTS OF LABORATORY TESTS Table A-I – Summary of Laboratory Testing APPENDIX B – DRAIN DETAILS APPENDIX C – SAMPLE SITE GRADING SPECIFICATIONS EXHIBIT A – SURFACE DRAINAGE, IRRIGATION AND MAINTENANCE BLACK TIMBER BUILDERS 3221 EASTBROOK DR FORT COLLINS CTLT PROJECT NO. FC10564-120 1 Scope This report presents the results of our Soils and Foundation Investigation for the proposed 75-unit multi-family residential building located at 3221 Eastbrook Drive in Fort Collins, Colorado. The purpose of our investigation was to evaluate the subsurface conditions to provide geotechnical design and construction recommendations for the proposed building. The scope was described in our Service Agreement (Proposal No. FC-22-0382) dated August 15, 2022. This report was prepared from data developed during field exploration, laboratory testing, engineering analysis, and experience with similar conditions. It includes our opinions and recommendations for design criteria and construction details for foundations and floor systems, slabs-on-grade, lateral earth loads, and drainage precautions. The report was prepared for the exclusive use of Black Timber Builders in design and construction of the proposed structure. Other types of construction may require revision of this report and the recommended design criteria. A brief summary of our conclusions and recommendations follows. Detailed design criteria are presented within the report. Summary Of Conclusions 1. Strata encountered the borings generally consisted of sandy clay and/or clayey sand overlying weathered to competent claystone bedrock to the depths explored. The upper approximately 3 feet of borings TH-2 and TH-4 was determined to be fill. Samples of the overburden soils were non-expansive to low swelling. The claystone bedrock was low to moderate swelling, but below the water table and not expected to contribute to surface heave. 2. Groundwater was measured at depths of 17 to 19 feet in three borings during drilling. When measured several days later, groundwater was encountered at depths of 16½ to 17½ feet in all the borings. Groundwater is not expected to affect proposed construction. Further descriptions of the subsurface conditions are presented on our boring logs and in our laboratory test results. 3. The existing fill encountered in two borings is of unknown age and origin and is characterized as a potential hazard. The fill presents risk of differential heave or settlement. Improvements should not be constructed on existing fill unless documentation is provided indicating proper moisture treatment and compaction. Existing fill should be removed from below footings and slabs and recompacted or replaced. Alternatively, footings may be extended through the fill material to bear on native soil. Fill is often difficult to discern in boring samples. The depth of fill removal should be determined at the open hole inspection. BLACK TIMBER BUILDERS 3221 EASTBROOK DR FORT COLLINS CTLT PROJECT NO. FC10564-120 2 4. The presence of expansive soils and bedrock, constitutes a geologic hazard. There is risk that slabs-on-grade and foundations will heave or settle and be damaged. We judge the risk is low. We believe the recommendations presented in this report will help to control risk of damage; they will not eliminate that risk. Slabs-on-grade and, in some instances, foundations may be damaged. 5. Footing foundations designed to maintain a minimum dead load placed on natural, undisturbed soil and/or properly compacted fill are considered appropriate for the building. Design and construction criteria for foundations are presented in the report. 6. Basements are not planned for the building. A structural floor will be constructed over the crawlspace. Driveways and other exterior flatwork will be slabs-on-grade and may heave or settle and crack. 7. Surface drainage should be designed, constructed, and maintained to provide rapid removal of surface runoff away from the proposed structure. Conservative irrigation practices should be followed to avoid excessive wetting. 8. The design and construction criteria for foundations and floor system alternatives in this report were compiled with the expectation that all other recommendations presented related to surface and subsurface drainage, landscaping irrigation, backfill compaction, etc. will be incorporated into the project and that owners will maintain the structures, use prudent irrigation practices, and maintain surface drainage. It is critical that all recommendations in this report are followed. Site Description The site is located at 3221 Eastbrook Drive in Fort Collins, Colorado (Figure 1). The Union Pacific Railroad runs parallel along the western property boundary. Commercial offices are located to the south and east. Residences are located to the north. A commercial office is present in the northeast side of the property. Paved parking areas surrounding the perimeter of the property. The site was relatively flat with groundcover consisting of natural grasses. A natural drainage area is located to the north and west of the site. Proposed Construction The proposed multi-family residential building is anticipated to be a wood-framed, three- story structure, currently planned for 75 dwelling units. We understand that the building will be constructed over a crawlspace. The structure may have partial brick or stone veneer on the exterior. We anticipate excavations of up to 3 feet will be required for crawlspace construction and frost protection. Final grading and landscaping will result in slightly greater depth of backfill. BLACK TIMBER BUILDERS 3221 EASTBROOK DR FORT COLLINS CTLT PROJECT NO. FC10564-120 3 Investigation The field investigation included drilling four exploratory borings within the building footprint. The borings were drilled to depths of approximately 20 feet and 30 feet using 4-inch diameter continuous-flight augers, and a truck-mounted drill. Drilling was observed by our field representative who logged the soils and bedrock. Summary logs of the borings, including results of field penetration resistance tests, are presented on Figure 2. Soil and bedrock samples obtained during drilling were returned to our laboratory and visually examined by our geotechnical engineer. Laboratory testing was assigned and included moisture content, dry density, swell-consolidation, particle-size analysis, Atterberg limits, and water-soluble sulfate tests. Swell-consolidation test samples were wetted at a confining pressure which approximated the weight of overlying soils (overburden pressures). Results of the laboratory tests are presented in Appendix A and summarized in Table A-I. Subsurface Conditions Strata encountered the borings generally consisted of 19 to 19½ feet of sandy clay and/or clayey sand overlying weathered to competent claystone bedrock to the maximum depths explored. The upper approximately 3 feet of borings TH-2 and TH-4 was determined to be fill. The pertinent engineering characteristics of the soil encountered are described in more detail in the following paragraphs. Further descriptions of the subsurface conditions are presented on our boring logs and in our laboratory test results. Existing Fill Materials determined to be fill were found in two of the borings extending to depths of 3 feet. The depth of fill material may be greater than what was encountered and may exist in areas not explored by our borings. The fill consisted predominantly of clayey sand or sandy clay. The fill was medium dense or stiff based on the results of field penetration resistance tests. One sample of the fill exhibited a swell of 3.1 percent. The fill is of unknown age and origin and presents risk of heave or settlement. The fill material is considered unsuitable for structural support unless documentation can be provided that indicates otherwise. BLACK TIMBER BUILDERS 3221 EASTBROOK DR FORT COLLINS CTLT PROJECT NO. FC10564-120 4 Natural Soils The clayey sand was loose to medium dense. Samples of the sand contained 22 to 39 percent silt and clay-size particles (passing the No. 200 sieve). The natural sand is considered non-expansive or low-swelling based on the results of laboratory testing and our experience. The sandy clay was medium stiff to very stiff. Three samples of the clay exhibited swells of 0.3 to 2.9 percent. One sample had 50 percent silt and clay-size particles. Bedrock Weathered and comparatively competent claystone bedrock was encountered in all the borings underlying the natural soils, at depths of 19 to 19½ feet. The competent bedrock was medium hard to hard. Four samples of the claystone exhibited swells of 0.6 to 2.6 percent. The claystone is below the groundwater and is not expected to contribute to surface level heave. Groundwater Groundwater was measured at depths of 17 to 19 feet in three borings during drilling. When measured several days later, groundwater was encountered at depths of 16½ to 17½ feet in all the borings. Groundwater levels are expected to fluctuate seasonally and may be affected by water levels in the nearby drainage area. Groundwater is not expected to affect below-grade construction at the site. Geologic Hazards Colorado is a challenging location to practice geotechnical engineering. The climate is relatively dry, and the near-surface soils are typically dry and relatively stiff. These soils and related sedimentary bedrock formations tend to react to changes in moisture conditions. Some of the soils and bedrock swell as they increase in moisture and are called expansive soils. Other soils can settle significantly upon wetting and are referred to as collapsing soils. Most of the land available for development east of the Front Range is underlain by expansive clay or claystone bedrock near the surface. The soils that exhibit collapse are more likely west of the continental divide; however, both types of soils occur all over the state. BLACK TIMBER BUILDERS 3221 EASTBROOK DR FORT COLLINS CTLT PROJECT NO. FC10564-120 5 Covering the ground with houses, streets, driveways, patios, etc., coupled with lawn irrigation and changing drainage patterns, leads to an increase in subsurface moisture conditions. As a result, some soil movement is inevitable. It is critical that all recommendations in this report are followed to increase the chances that the foundations and slabs-on-grade will perform satisfactorily. After construction, homeowners must assume responsibility for maintaining the structure and use appropriate practices regarding drainage and landscaping. Expansive soils and bedrock are present at this site. The presence of expansive soils and bedrock, collectively referred to as expansive or swelling soils, constitutes a geologic hazard. There is risk that ground heave or settlement will damage slabs-on-grade and foundations. The risks associated with swelling and compressible soils can be mitigated, but not eliminated by careful design, construction, and maintenance procedures. We believe the recommendations in this report will help control risk of foundation and/or slab damage; they will not eliminate that risk. The builder and homebuyers should understand that slabs-on-grade and, in some instances, foundations may be affected. Homeowner maintenance will be required to control risk. We recommend the builder provide a booklet to the homebuyers that describes swelling soils and includes recommendations for care and maintenance of homes constructed on expansive soils. Colorado Geological Survey Special Publication 431 was designed to provide this information. Foundations Our investigation indicates predominantly low-swelling soils were encountered at depths where they are likely to affect foundation performance. Footing foundations, designed to maintain minimum dead load, are considered appropriate for the proposed construction. Footings should not be constructed on existing fill. Undocumented fill should be removed from below footings and recompacted or replaced. Alternatively, footings may be extended through the fill material to bear on native soil. 1“A Guide to Swelling Soils for Colorado Homebuyers and Homeowners,” Second Edition Revised and Updated by David C. Noe, Colorado Geological Survey, Department of Natural Resources, Denver, Colorado, 2007. BLACK TIMBER BUILDERS 3221 EASTBROOK DR FORT COLLINS CTLT PROJECT NO. FC10564-120 6 Design criteria for footing foundations developed from analysis of field and laboratory data and our experience are presented below. The builder and structural engineer should also consider design and construction details established by the structural warrantor (if any) that may impose additional design and installation requirements. Footings with Minimum Dead Load 1. The footing foundation should bear on undisturbed natural soils and/or on properly compacted fill. All existing, uncontrolled fill should be removed from under footings and within a 3-foot width of footings and replaced with properly compacted fill. Where soils are loosened during excavation or in the footing forming process the soils should be removed or compacted to at least 95 percent of standard Proctor maximum dry density (ASTM D 698, AASHTO T 99) between optimum and 3 percent above optimum moisture content, prior to placing concrete. Excavation backfill placed below foundations should be compacted using the same specifications. 2. Footings should be designed for a net allowable soil pressure of 2,000 pounds per square foot (psf) and a minimum dead load pressure of 600 psf. The soil pressure can be increased 33 percent for transient loads such as wind or seismic loads. We recommend a minimum 3-foot separation between foundation elements and groundwater. 3. We anticipate footings designed using the soil pressure recommended above could experience 1-inch of movement. Differential movement of ½-inch should be considered in the design. 4. If interrupted footings are necessary to maintain the specified dead load, a 4-inch void should be provided below grade beams or foundation walls, between the pads. 5. Footings should have a minimum width of 12 inches. Foundations for isolated columns should have minimum dimensions of 16 inches by 16 inches. Larger sizes may be required depending upon the loads and structural system used. 6. Foundation walls should be well reinforced both top and bottom. We recommend reinforcement sufficient to span an unsupported distance of at least 10 feet or the distance between pads whichever is greater. Reinforcement should be designed by the structural engineer considering the effects of large openings and lateral loads on wall performance. 7. Exterior footings must be protected from frost action per local building codes. Normally, 30 inches of cover over footings is assumed in the area for frost protection. BLACK TIMBER BUILDERS 3221 EASTBROOK DR FORT COLLINS CTLT PROJECT NO. FC10564-120 7 8. The completed foundation excavations should be observed by a representative of our firm prior to placing the forms to verify subsurface conditions are as anticipated from our borings. Our representative should also observe the placement and test compaction of new fill placed for foundation subgrade (if merited). Floor Systems A structural floor system over a crawlspace is planned for the building. A structural floor is supported by the foundation system. There are design and construction issues associated with structural floors that must be considered, such as ventilation and lateral loads. Where structurally supported floors are installed, the required air space depends on the materials used to construct the floor and the expansion potential of the underlying soils. Building codes require a clear space of 18 inches above exposed earth if untreated wood floor components are used. Where other floor support materials are used, a minimum clear space of 8 inches should be maintained. This minimum clear space should be maintained between any point on the underside of the floor system (including beams and floor drain traps) and the surface of the exposed earth. Where structurally supported floors are used, utility connections, including water, gas, air duct and exhaust stack connections to floor supported appliances, should be capable of absorbing some deflection of the floor. Plumbing that passes through the floor should ideally be hung from the underside of the structural floor and not lain on the bottom of the excavation. This configuration may not be achievable for some parts of the installation. It is prudent to maintain the minimum clear space below all plumbing lines. If trenching below the lines is necessary, we recommend sloping these trenches so they discharge to the foundation drains. Control of humidity in crawlspaces is important for indoor air quality and performance of wood floor systems. We believe the best current practices to control humidity involve the use of a vapor retarder (10-mil minimum), placed on the exposed soils below accessible sub-floor areas. The vapor retarder should be sealed at joints and attached to concrete foundation elements. If desired, we can provide designs for ventilation systems that can be installed in association with a vapor retarder, to improve control of humidity in crawlspace areas. The Moisture Management Task Force of Metro Denver2 has compiled additional discussion and recommendations regarding best practices for the control of humidity in below-grade, under-floor spaces. 2 “Guidelines for Design and Construction of New Homes with Below-Grade Under-Floor Spaces,” Moisture Management Task Force, October 30, 2003. BLACK TIMBER BUILDERS 3221 EASTBROOK DR FORT COLLINS CTLT PROJECT NO. FC10564-120 8 Porches, Decks and Patios Porches or decks with overhanging roofs that are integral with the structure such that excessive foundation movement cannot be tolerated, should be constructed with the same foundation type as the building. Simple decks, that are not integral with the structure and can tolerate foundation movement, can be constructed with less substantial foundations. A short pier or footing bottomed at least 3 feet below grade can be used if movement is acceptable. Use of 8-foot to 10-foot piers can reduce potential movement. Footings or short piers should not be bottomed in wall backfill or undocumented fill due to risk of settlement. The inner edge of the deck may be constructed on haunches or steel angles bolted to the foundation walls and detailed such that movement of the deck foundation will not cause distress to the structure. We suggest use of adjustable bracket-type connections or other details between foundations and deck posts so the posts can be trimmed or adjusted if movement occurs. Porches, patio slabs and other exterior flatwork should be isolated from the structure. Porch slabs can be constructed to reduce the likelihood that settlement or heave will affect the slabs. One approach (for smaller porches located over backfill zones) is to place loose backfill under a structurally supported slab. This fill will more likely settle than swell, and can thus accommodate some heave of the underlying soils. A lower risk approach is to construct the porch slab over void-forming materials. Conditions should allow the void-forming materials to soften quickly after construction to reduce the risk of transmitting ground heave to the porch slab. Wax or plastic-coated void boxes should not be used unless provisions are made to allow water to penetrate into the boxes. Exterior Flatwork Sidewalks and amenity areas are often constructed as slabs-on-grade. We understand that brick or paver options are also being considered in areas. Performance of conventional slabs and flatwork on expansive soils is erratic. Various properties of the soils and environmental conditions influence magnitude of movement and other performance. Increases in the moisture content in these soils will cause heaving and may result in cracking of slabs-on-grade and flatwork. The risk of damaging movements can be reduced, but not eliminated, by placing the improvements on 12 inches of moisture treated and compacted soil. The existing onsite soils are suitable for re-use as fill material provided debris or deleterious organic materials are removed. BLACK TIMBER BUILDERS 3221 EASTBROOK DR FORT COLLINS CTLT PROJECT NO. FC10564-120 9 Areas to receive fill should be scarified, moisture conditioned and compacted to at least 95 percent of standard Proctor maximum dry density. Clay fill soils should be moisture conditioned between optimum and 3 percent above optimum moisture content. Fill placement and compaction operations should not be conducted during freezing temperatures. Backfill below slabs and flatwork should be moisture conditioned and compacted to reduce settlement or heave, as discussed in BACKFILL COMPACTION. Exterior slabs founded on the backfill may settle and crack if the backfill is not properly moisture treated and compacted. Where slabs-on-grade are used, we recommend adherence to the precautions for slab-on-grade construction that are included in Exhibit A. Below-Grade Walls Foundation walls and grade beams that extend below grade should be designed for lateral earth pressures where backfill is not present to about the same extent on both sides of the wall. Many factors affect the value of the design lateral earth pressure. These factors include, but are not limited to, the type, compaction, slope and drainage of the backfill, and the rigidity of the wall against rotation and deflection. For a very rigid wall where negligible or very little deflection will occur, an "at-rest" lateral earth pressure should be used in design. For walls that can deflect or rotate 0.5 to 1 percent of the wall height (depending upon the backfill types), lower "active" lateral earth pressures are appropriate. Our experience indicates foundation walls can deflect or rotate slightly under normal design loads and that this deflection results in satisfactory wall performance. Thus, the earth pressure on the walls will likely be between the "active" and "at-rest" conditions. If onsite soils are used as backfill and the backfill is not saturated, we recommend design of walls at this site using an equivalent fluid density of at least 55 pounds per cubic foot (pcf). This value assumes deflection; some minor cracking of walls may occur. If very little wall deflection is desired, higher design density may be appropriate. The structural engineer should also consider site-specific grade restrictions and the effects of large openings on the behavior of the walls. Backfill Compaction Settlement of foundation wall and utility trench backfill can cause damage to concrete flatwork and/or result in poor drainage conditions. Compaction of backfill can reduce settlement. Attempts to compact backfill near foundations to a high degree can damage foundation walls and BLACK TIMBER BUILDERS 3221 EASTBROOK DR FORT COLLINS CTLT PROJECT NO. FC10564-120 10 may increase lateral pressures on the foundation walls. The potential for cracking of a foundation wall can vary widely based on many factors including the degree of compaction achieved, the weight and type of compaction equipment utilized, the structural design of the wall, the strength of the concrete at the time of backfill compaction, and the presence of temporary or permanent bracing. Proper moisture conditioning of backfill is as important as compaction because settlement commonly occurs in response to wetting. The addition of water complicates the backfill process, especially during cold weather. Frozen soils are not considered suitable for use as backfill because excessive settlement can result when the frozen materials thaw. Precautions should be taken when backfilling against a foundation wall. Temporary bracing of comparatively long, straight sections of foundation walls should be used to limit damage to walls during the compaction process. Waiting at least seven days after the walls are placed to allow the concrete to gain strength can also reduce the risk of damage. Compaction of fill placed beneath and next to counterforts, and grade beams may be difficult to achieve without damaging these building elements. Proper moisture conditioning of the fill prior to placement in these areas will help reduce potential settlement. Ideally, drainage swales should not be located over the backfill zone (including excavation ramps), as this can increase the amount of water infiltration into the backfill and cause excessive settlement. Swales should be designed to be a minimum of at least 5 feet from the foundation to help reduce water infiltration. Irrigated vegetation, sump pump discharge pipes, sprinkler valve boxes, and roof downspout terminations should also be at least 5 feet from the foundation. Subsurface Drains and Surface Drainage Water from surface irrigation of lawns and landscaping frequently flows through relatively permeable backfill placed adjacent to a structure and collects on the surface of less permeable soils occurring at the bottom of foundation excavations. This process can cause wet or moist conditions in below grade areas after construction. To reduce the likelihood water pressure will develop outside foundation walls and the risk of accumulation of water in below grade areas, we recommend provision of an exterior foundation drain around the perimeter of the foundation excavation. In addition, crawlspaces should be well ventilated per building code. BLACK TIMBER BUILDERS 3221 EASTBROOK DR FORT COLLINS CTLT PROJECT NO. FC10564-120 11 The provision of a drain will not eliminate slab movement or prevent moist conditions in crawlspaces. The exterior drain should consist of a 4-inch diameter open joint or slotted pipe encased in free draining gravel. The drain should lead to a positive gravity outlet, such as a sub- drain located beneath the sewer, or to a sump where water can be removed by pumping. If the drain discharges to the ground surface, the outlet should be a permanent fixture that provides protection from blockage from vegetation or other sources. A typical foundation drain detail is presented in Appendix B. Our experience indicates moist conditions can develop in crawlspace areas resulting in isolated instances of damp soils, musty smells and, in rare cases, standing water. Crawlspace areas should be well ventilated, depending on the use of a vapor retarder on the exposed soils and the floor material selected. Perimeter drains for non-basement crawlspace areas should be installed as required by the 2021 IRC. Proper design, construction and maintenance of surface drainage are critical to the satisfactory performance of foundations, slabs-on-grade, and other improvements. Landscaping and irrigation practices will also affect performance. Exhibit A contains our recommendations for surface drainage, irrigation, and maintenance. Concrete Concrete that comes into contact with soils can be subject to sulfate attack. We measured water-soluble sulfate concentrations in two samples from this site. Concentrations were measured between 0.01 and 0.08 percent. For this level of sulfate concentration, ACI 332-20 Code Requirements for Residential Concrete indicates there are no special requirements for sulfate resistance (Exposure class R0). 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 materials 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 have a total air content of 6 percent ± 1.5 percent. We advocate all foundation walls and grade beams in contact with the soil (including the inside and outside faces of garage and crawlspace grade beams) be damp-proofed. BLACK TIMBER BUILDERS 3221 EASTBROOK DR FORT COLLINS CTLT PROJECT NO. FC10564-120 12 Excavations Excavations made at this site, including those for foundations and utilities, may be governed by local, state, or federal guidelines or regulations. Subcontractors should be familiar with these regulations and take whatever precautions they deem necessary to comply with the requirements and thereby protect the safety of their employees and that of the general public. Some of the soils are soft and will be displaced if wheeled equipment is used in the excavations. To minimize soil disturbance, we recommend wheeled traffic not be allowed in the excavations. Construction Observations We recommend that CTL | Thompson, Inc. provide construction observation services to allow us the opportunity to verify whether soil conditions are consistent with those found during this investigation. Other observations are recommended to review general conformance with design plans. If others perform these observations, they must accept responsibility to judge whether the recommendations in this report remain appropriate. Geotechnical Risk The concept of risk is an important aspect with any geotechnical evaluation primarily because the methods used to develop geotechnical recommendations do not comprise an exact science. We never have complete knowledge of subsurface conditions. Our analysis must be tempered with engineering judgment and experience. Therefore, the recommendations presented in any geotechnical evaluation should not be considered risk-free. Our recommendations represent our judgment of those measures that are necessary to increase the chances that the structures will perform satisfactorily. It is critical that all recommendations in this report are followed during construction. Homeowners must assume responsibility for maintaining the structures and use appropriate practices regarding drainage and landscaping. Improvements performed by homeowners after construction, such as construction of additions, retaining walls, decks, patios, landscaping, and exterior flatwork, should be completed in accordance with recommendations in this report. BLACK TIMBER BUILDERS 3221 EASTBROOK DR FORT COLLINS CTLT PROJECT NO. FC10564-120 13 Limitations This report has been prepared for the exclusive use of Black Timber Builders for the purpose of providing geotechnical design and construction criteria for the proposed project. The information, conclusions, and recommendations presented herein are based upon consideration of many factors including, but not limited to, the type of structures proposed, the geologic setting, and the subsurface conditions encountered. The conclusions and recommendations contained in the report are not valid for use by others. Standards of practice evolve in the area of geotechnical engineering. The recommendations provided are appropriate for about three years. If the proposed structure is not constructed within about three years, we should be contacted to determine if we should update this report. Four borings were drilled throughout the footprint of the building during this investigation to obtain a reasonably accurate picture of the subsurface conditions. Variations in the subsurface conditions not indicated by our borings are possible. A representative of our firm should observe foundation excavations to confirm the exposed materials are as anticipated from our borings. We believe this investigation was conducted with that level of skill and care ordinarily used by geotechnical engineers practicing in this area at this time. No warranty, express or implied, is made. If we can be of further service in discussing the contents of this report or in the analysis of the influence of subsurface conditions on design of the structures, please call. CTLTHOMPSON, INC. Trace Krausse, EI Spencer Schram, PE Geotechnical Project Engineer Geotechnical Project Manager TH-1 TH-2 TH-3 TH-4 Eastbrook DriveTIMBERLINEDRAKE RD. E. HORSETOOTH RD. SITE LEGEND: INDICATES APPROXIMATE LOCATION OF EXPLORATORY BORING TH-1 BLACK TIMBER BUILDERS 3221 EASTBROOK DR FORT COLLINS CTL I T PROJECT NO. FC10564-120 FIGURE 1 Locations of Exploratory Borings VICINITY MAP FORT COLLINS, COLORADO NOT TO SCALE 100'50' APPROXIMATE SCALE: 1" = 100' 0' 0 5 10 15 20 25 30 35 40 0 5 10 15 20 25 30 35 40 19/12 27/12 5/12 14/12 45/12 50/8 WC=0.0DD=115SW=2.9SS=0.080 WC=8.1-200=50 WC=12.7-200=39 WC=20.3DD=104SW=0.6 WC=18.0DD=111SW=1.5 WC=0.0DD=115SW=2.9SS=0.080 WC=8.1-200=50 WC=12.7-200=39 WC=20.3DD=104SW=0.6 WC=18.0DD=111SW=1.5 TH-1 15/12 12/12 26/12 40/12 WC=14.9LL=32 PI=16-200=45 WC=5.4-200=22 WC=14.9LL=32 PI=16-200=45 WC=5.4-200=22 TH-2 10/12 17/12 9/12 41/12 50/11 WC=9.5DD=98SW=1.5 WC=0.0DD=104SW=0.3SS=<0.01 WC=8.7-200=39 WC=19.3DD=106SW=0.6 WC=18.4DD=111SW=2.6 WC=9.5DD=98SW=1.5 WC=0.0DD=104SW=0.3SS=<0.01 WC=8.7-200=39 WC=19.3DD=106SW=0.6 WC=18.4DD=111SW=2.6 TH-3 11/12 18/12 22/12 49/12 WC=11.7DD=101SW=3.1 WC=10.1DD=120SW=0.5 WC=11.7DD=101SW=3.1 WC=10.1DD=120SW=0.5 TH-4 THESE LOGS ARE SUBJECT TO THE EXPLANATIONS, LIMITATIONS AND CONCLUSIONS IN THIS REPORT. WATER LEVEL MEASURED SEVERAL DAYS AFTER DRILLING. CLAY, SANDY, SILTY, MEDIUM STIFF TO VERY STIFF, SLIGHTLY MOIST, LIGHT BROWN (CL) DRIVE SAMPLE. THE SYMBOL 19/12 INDICATES 19 BLOWS OF A 140-POUND HAMMER FALLING 30 INCHES WERE REQUIRED TO DRIVE A 2.5-INCH O.D. SAMPLER 12 INCHES. FILL, SAND, CLAYEY AND/OR CLAY, SANDY, SLIGHTLY MOIST, MEDIUM DENSE, STIFF, BROWN 1. NOTES: 3. LEGEND: SAND, CLAYEY, WITH OCCASIONAL GRAVEL, LOOSE TO MEDIUM DENSE, BROWN (SC) WEATHERED CLAYSTONE, SILTY, FIRM, MOIST, BROWN, GRAY CLAYSTONE, SILTY, MEDIUM HARD TO HARD, SLIGHTLY MOIST TO MOIST, BROWN, GRAY, RUST DEPTH - FEETWATER LEVEL MEASURED AT TIME OF DRILLING. Summary Logs of Exploratory Borings THE BORINGS WERE DRILLED ON AUGUST 14, 2022 USING 4-INCH DIAMETER CONTINUOUS-FLIGHT AUGERS AND A TRUCK-MOUNTED DRILL RIG. FIGURE 2 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 (%). 2.DEPTH - FEETBLACK TIMBER BUILDERS 3221 EASTBROOK DRIVE FORT COLLINS CTL | T PROJECT NO. FC10564-120 APPENDIX A RESULTS OF LABORATORY TESTS TABLE A-I – SUMMARY OF LABORATORY TESTING Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT=115 PCF From TH - 1 AT 4 FEET MOISTURE CONTENT=9.9 % Sample of CLAYSTONE, WEATHERED DRY UNIT WEIGHT=104 PCF From TH - 1 AT 19 FEET MOISTURE CONTENT=20.3 % BLACK TIMBER BUILDERS 3321 EASTBROOK DR FORT COLLINS CTL | T PROJECT NO. FC10564-120 APPLIED PRESSURE -KSF APPLIED PRESSURE -KSFCOMPRESSION % EXPANSIONSwell Consolidation FIGURE A-1COMPRESSION % EXPANSION-3 -2 -1 0 1 2 3 4 EXPANSION UNDER CONSTANT PRESSURE DUE TO WETTING -4 -3 -2 -1 0 1 2 3 EXPANSION UNDER CONSTANT PRESSURE DUE TO WETTING 0.1 1.0 10 100 0.1 1.0 10 100 Sample of CLAYSTONE DRY UNIT WEIGHT=111 PCF From TH - 1 AT 24 FEET MOISTURE CONTENT=18.0 % Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT=98 PCF From TH - 3 AT 4 FEET MOISTURE CONTENT=9.5 % BLACK TIMBER BUILDERS 3321 EASTBROOK DR FORT COLLINS CTL | T PROJECT NO. FC10564-120 APPLIED PRESSURE -KSF APPLIED PRESSURE -KSFCOMPRESSION % EXPANSIONSwell Consolidation FIGURE A-2COMPRESSION % EXPANSION-4 -3 -2 -1 0 1 2 3 EXPANSION UNDER CONSTANT PRESSURE DUE TO WETTING -4 -3 -2 -1 0 1 2 3 EXPANSION UNDER CONSTANT PRESSURE DUE TO WETTING 0.1 1.0 10 100 0.1 1.0 10 100 Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT=104 PCF From TH - 3 AT 9 FEET MOISTURE CONTENT=15.5 % Sample of CLAYSTONE DRY UNIT WEIGHT=106 PCF From TH - 3 AT 19 FEET MOISTURE CONTENT=19.3 % BLACK TIMBER BUILDERS 3321 EASTBROOK DR FORT COLLINS CTL | T PROJECT NO. FC10564-120 APPLIED PRESSURE -KSF APPLIED PRESSURE -KSFCOMPRESSION % EXPANSIONSwell Consolidation FIGURE A-3COMPRESSION % EXPANSION-4 -3 -2 -1 0 1 2 3 EXPANSION UNDER CONSTANT PRESSURE DUE TO WETTING -4 -3 -2 -1 0 1 2 3 EXPANSION UNDER CONSTANT PRESSURE DUE TO WETTING 0.1 1.0 10 100 0.1 1.0 10 100 Sample of CLAYSTONE DRY UNIT WEIGHT=111 PCF From TH - 3 AT 24 FEET MOISTURE CONTENT=18.4 % Sample of FILL, SAND, CLAYEY (SC) DRY UNIT WEIGHT=101 PCF From TH - 4 AT 2 FEET MOISTURE CONTENT=11.7 % BLACK TIMBER BUILDERS 3321 EASTBROOK DR FORT COLLINS CTL | T PROJECT NO. FC10564-120 APPLIED PRESSURE -KSF APPLIED PRESSURE -KSFCOMPRESSION % EXPANSIONSwell Consolidation FIGURE A-4COMPRESSION % EXPANSION-4 -3 -2 -1 0 1 2 3 EXPANSION UNDER CONSTANT PRESSURE DUE TO WETTING -3 -2 -1 0 1 2 3 4 EXPANSION UNDER CONSTANT PRESSURE DUE TO WETTING 0.1 1.0 10 100 0.1 1.0 10 100 Sample of SAND, CLAYEY (SC) DRY UNIT WEIGHT=120 PCF From TH - 4 AT 9 FEET MOISTURE CONTENT=10.1 % BLACK TIMBER BUILDERS 3321 EASTBROOK DR FORT COLLINS CTL | T PROJECT NO. FC10564-120 APPLIED PRESSURE -KSFCOMPRESSION % EXPANSIONSwell Consolidation Test Results FIGURE A-5 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 EXPANSION UNDER CONSTANT PRESSURE DUE TO WETTING 0.1 1.0 10 100 Sample of SAND, CLAYEY (SC)GRAVEL 21 %SAND 57 % From TH - 2 AT 14 FEET SILT & CLAY 22 %LIQUID LIMIT % PLASTICITY INDEX % Sample of GRAVEL %SAND % From SILT & CLAY %LIQUID LIMIT % PLASTICITY INDEX % BLACK TIMBER BUILDERS 3321 EASTBROOK DR FORT COLLINS CTL | T PROJECT NO. FC10564-120 FIGURE A-6 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 PERCENT PASSING0 10 20 30 50 60 70 80 90 100 PERCENT RETAINED40 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 PERCENT PASSINGPERCENT RETAINED0 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 TH-1 4 9.9 115 2.9 500 5,900 0.08 CLAY, SANDY (CL) TH-1 9 8.1 50 CLAY, SANDY (CL) TH-1 14 12.7 39 SAND, CLAYEY (SC) TH-1 19 20.3 104 0.6 150 CLAYSTONE, WEATHERED TH-1 24 18.0 111 1.5 3,000 CLAYSTONE TH-2 2 14.9 32 16 45 FILL, SAND, CLAYEY (SC) TH-2 14 5.4 22 SAND, CLAYEY (SC) TH-3 4 9.5 98 1.5 500 CLAY, SANDY (CL) TH-3 9 15.5 104 0.3 1,100 <0.01 CLAY, SANDY (CL) TH-3 14 8.7 39 SAND, CLAYEY (SC) TH-3 19 19.3 106 0.6 2,400 CLAYSTONE TH-3 24 18.4 111 2.6 3,000 19,000 CLAYSTONE TH-4 2 11.7 101 3.1 200 FILL, SAND, CLAYEY (SC) TH-4 9 10.1 120 0.5 1,100 SAND, CLAYEY (SC) SWELL TEST RESULTS* TABLE A-I SUMMARY OF LABORATORY TESTING ATTERBERG LIMITS Page 1 of 1 BLACK TIMBER BUILDERS 3321 EASTBROOK DR FORT COLLINS CTL|T PROJECT NO. FC10564-120 APPENDIX B DRAIN DETAILS BLACK TIMBER BUILDERS 3321 EASTBROOK DR FORT COLLINS CTL|T PROJECT NO. FC10564-120 FIGURE B-1 APPENDIX C GUIDELINE SITE GRADING SPECIFICATIONS GUIDELINE SITE GRADING SPECIFICATIONS 1. DESCRIPTION This item shall consist of the excavation, transportation, placement and compaction of materials from locations indicated on the plans, or staked by the Engineer, as necessary to achieve preliminary street and overlot elevations. These specifications shall also apply to compaction of 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. Appendix C-1BLACK TIMBER BUILDERS 3321 EASTBROOK DR FORT COLLINS CTLT PROJECT NO. FC10564-120 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 Overlot Grade (feet) Moisture Requirement (% from optimum) Density Requirement Clay 0 to 20 feet +1 to +4 95% of ASTM D 698 Sand -2 to +2 95% of ASTM D 698 Clay Greater than 20 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 co ntent. The Contractor will be permitted to rework wet material in an approved manner to hasten its drying. Appendix C-2BLACK TIMBER BUILDERS 3321 EASTBROOK DR FORT COLLINS CTLT PROJECT NO. FC10564-120 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, soils 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. 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. Appendix C-3BLACK TIMBER BUILDERS 3321 EASTBROOK DR FORT COLLINS CTLT PROJECT NO. FC10564-120 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 Engineer 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 cond itions. 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. BLACK TIMBER BUILDERS 3321 EASTBROOK DR FORT COLLINS CTLT PROJECT NO. FC10564-120 Appendix C-4 BLACK TIMBER BUILDERS 3221 EASTBROOK DR FORT COLLINS CTLT PROJECT NO. FC10564-120 EXHIBIT A-1 EXHIBIT A SURFACE DRAINAGE, IRRIGATION AND MAINTENANCE Performance of foundations and concrete flatwork is influenced by the moisture conditions existing within the foundation soils. Surface drainage should be designed to provide rapid runoff of surface water away from the proposed structure. Proper surface drainage and irrigation practices can help control the amount of surface water that penetrates to foundation levels and contributes to settlement or heave of soils and bedrock that support foundations and slabs-on- grade. Positive drainage away from the foundation and avoidance of irrigation near the foundation also help to avoid excessive wetting of backfill soils, which can lead to increased backfill settlement and possibly to higher lateral earth pressures, due to increased weight and reduced strength of the backfill. CTL | Thompson, Inc. recommends the following precautions. The owner should maintain surface drainage and, if an irrigation system is installed, it should substantially conform to these recommendations. 1. Wetting or drying of the open foundation excavations should be avoided. 2. Excessive wetting of foundation soils before, during and after construction can cause heave or softening of foundation soils and result in foundation and slab movements. Proper surface drainage around the structure is critical to control wetting. 3. The ground surface surrounding the exterior of each building should be sloped to drain away from the building in all directions. We recommend a minimum constructed slope of at least 12 inches in the first 10 feet (10 percent) in landscaped areas around each residence, where practical. The recommended slope is for the soil surface slope, not surface of landscaping rock. 4. We do not view the recommendation to provide a 10 percent slope away from the foundation as an absolute. It is desirable to create this slope where practical because we know that backfill will likely settle to some degree. By starting with sufficient slope, positive drainage can be maintained for most settlement conditions. There are many situations around a residence where a 10 percent slope cannot be achieved practically, such as around patios, at inside foundation corners, and between a house and nearby sidewalk. In these areas, we believe it is desirable to establish as much slope as practical and to avoid irrigation. We believe it is acceptable to use a slope on the order of 5 percent perpendicular to the foundation in these limited areas. 5. Construction of retaining walls and decks adjacent to the residence should not alter the recommended slopes and surface drainage around the residence. The ground surface under decks should be compacted and slope away from the residence. 10- mil plastic sheeting and landscaping rock may be placed under decks to soil erosion and/or formation of depressions under the deck. The plastic sheeting should direct water away from the residence. Retaining walls should not flatten the surface drainage around the residence or impede surface runoff. BLACK TIMBER BUILDERS 3221 EASTBROOK DR FORT COLLINS CTLT PROJECT NO. FC10564-120 EXHIBIT A-2 6. Swales used to convey water across yards and between buildings should be sloped so that water moves quickly and does not pond for extended periods of time. We suggest minimum slopes of about 2 to 2.5 percent in grassed areas and about 2 percent where landscaping rock or other materials are present. If slopes less than about 2 percent are necessary, concrete-lined channels or plastic pipe should be used. Fence posts, trees, and retaining walls should not impede runoff in the swales. 7. Backfill around the foundation walls should be moistened and compacted. 8. Roof downspouts and drains should discharge well beyond the limits of all backfill. Splash blocks and/or extensions should be provided at all downspouts so water discharges onto the ground beyond the backfill. We generally recommend against burial of downspout discharge. Where it is necessary to bury downspout discharge, solid, rigid pipe should be used and it should slope to an open gravity outlet. Downspout extensions, splash blocks and buried outlets must be maintained by the homeowner. 9. The importance of proper irrigation and drainage practices and maintenance cannot be over-emphasized. Irrigation should be limited to the minimum amount sufficient to maintain vegetation; application of more water will increase likelihood of slab and foundation movements. Landscaping should be carefully designed and maintained to minimize irrigation. Plants placed close to foundations, particularly within 5 feet of the foundation, should be limited to those with low moisture requirements and utilize only sub-surface irrigation such as standard low volume drip emitters or in-line drip irrigation. Irrigated grass, irrigation mainlines, above- surface spray heads, rotors, and other above-surface irrigation spray devices should not be located or discharge above the ground surface within 5 feet of the foundation 10. Plastic sheeting should not be placed beneath landscaped areas adjacent to foundation walls or grade beams. Geotextile fabric will inhibit weed growth yet still allow natural evaporation to occur.