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

9 0 Compass Health August 31, 2017 J N 17399 Page 2 based on the proposed construction, anticipated subsurface conditions and those encountered during exploration, and the scope of work outlined in our proposal. The test pits were excavated on August 24, 2017 with a small, rubber -tracked excavator. A geotechnical engineer from our staff observed the excavation process, logged the test pits, and obtained representative samples of the soil encountered. "Grab" samples of selected subsurface soil were collected from the excavator bucket. The Test Pit Logs are attached to this report as Plates 3 and 4. The test boring was drilled on August 9, 2017 using a track -mounted, hollow -stem auger drill. Samples were taken at approximate 5-foot intervals with a standard penetration sampler. This split - spoon sampler, which has a 2-inch outside diameter, is driven into the soil with a 140-pound hammer falling 30 inches. The number of blows required to advance the sampler a given distance is an indication of the soil density or consistency. A geotechnical engineer from our staff observed the drilling process, logged the test borings, and obtained representative samples of the soil encountered. The Test Boring Logs are attached as Plate 5. Soil Conditions The test boring was located in the upper, western part of the property. It encountered sand with gravel and silt that was initially loose to medium -dense, but then dense at a depth of 5 feet. That soil transitioned to silty sand with gravel that was very dense at 10 feet. That material is known geologically as glacial till; this soil continued to the explored depth of 30.4 feet. The four test pits were excavated in the lower, central portion of the site. Those explorations revealed unengineered fill that was about 1.5 to 4 feet thick. The fill in three of the test pits contained rubble that likelyoriginated from the house that previously occupied that area. In the fourth test pit the fill was underlain by 6 inches of topsoil. The fill and topsoil, where' present, were followed by silty sand with gravel that was loose to medium -dense and became dense glacial till at depths of 4.5 to 5.5 feet. Although our explorations did not encounter cobbles or boulders, they are often found in soils that have been deposited by glaciers or fast-moving water. Groundwater Conditions No groundwater seepage was observed in the pits or boring. However, it should be noted that groundwater levels vary seasonally with rainfall and other factors, and are generally highest during the normally wet winter and spring months. It is possible that groundwater could be found in more permeable soil layers and between the looser near -surface soil and the underlying glacial till during this time. The stratification lines on the logs represent the approximate boundaries between soil types at the exploration locations. The actual transition between soil types may be gradual, and subsurface conditions can vary between exploration locations. The logs provide specific subsurface information only at the locations tested. Where a transition in soil type occurred between samples in the boring, the depth of the transition was interpreted. The relative densities and moisture descriptions indicated on the test pit and boring logs are interpretive descriptions based on the conditions observed during excavation and drilling. GEOTECH CONSULTANTS, INC.