3301 LOMBARD AVE COMPASS HEALTH SUPPORTIVE HOUSING Geotech Report 2022-10-25

0 0 Compass Health August 31, 2017 JN 17399 Page 3 The compaction of test pit backfill was not in the scope of our services. Loose soil will therefore be found in the area of the test pits. if this presents a problem, the backfill will need to be removed and replaced with structural fill during construction. CONCLUSIONS AND RECOMMENDATIONS GENERAL THIS SECTION CONTAINS A SUMMARY OF OUR STUDY AND FINDINGS FOR THE PURPOSES OF A GENERAL OVERVIEW ONLY. MORE SPECIFIC RECOMMENDATIONS AND CONCLUSIONS ARE CONTAINED IN THE REMAINDER OF THIS REPORT. ANY PARTY RELYING ON THIS REPORT SHOULD READ THE ENTIRE DOCUMENT. The test pits and test boring conducted for this study encountered dense or very dense native soil within about 5 feet of the ground surface. Those soils will provide excellent support to the proposed structure. Conventional footing can be used as the foundations for the building provided they bear on dense native soil. Some rover -excavation may be required to expose dense soil near the lower, east edge of the site. The dense native soils are generally silty, and thus can become easily softened or disturbed if they ae wet at the time of foundation construction. If the foundation subgrade is wet, such as during wet weather, several inches of imported, angular, clean crushed material should be placed over it as protection. One important geotechnical issue for this project is the excavation for the proposed parking garage. Temporary excavations in the loose to medium -dense soil within 5 feet of the ground surface can have an inclination as steep as 1:1 (H:V) and excavations in the underlying dense to very dense soil can be made at an 0.75:1 inclination. Where excavations cannot be contained within the site, and where agreements to extend excavations into adjacent properties are not available, shoring will be necessary. The glacial till that underlies the site is very dense, has a substantial silt content, and is essentially impervious. For these reasons it is not feasible to utilize stormwater infiltration for this project. The erosion control measures needed during the site development will depend heavily on the weather conditions that are encountered. We anticipate that a silt fence will be needed around the downslope sides of any cleared areas. Existing pavements, ground cover, and landscaping should be left in place wherever possible to minimize the amount of exposed soil. Rocked staging areas and construction access roads should be provided to reduce the amount of soil or mud carried off the property by trucks and equipment. Wherever possible, the access roads should follow the alignment of planned pavements. Trucks should not be allowed to drive off of the rock -covered areas. Cut slopes and soil stockpiles should be covered with plastic during wet weather. Following clearing or rough grading, it may be necessary to mulch or hydroseed bare areas that will not be immediately covered with landscaping or an impervious surface. On most construction projects, it is necessary to periodically maintain or modify temporary erosion control measures to address specific site and weather conditions. The drainage and/or waterproofing recommendations presented in this report are intended only to prevent active seepage from flowing through concrete walls or slabs. Even in the absence of active seepage into and beneath structures, water vapor can migrate through walls, slabs, and floors from the surrounding soil, and can even be transmitted from slabs and foundation walls due to the concrete curing process. Water vapor also results from occupant uses, such as cooking and GEOTECH CONSULTANTS, INC.