3003 W CASINO RD 1992 SITE DEV 2018-01-01 MF Import

�DRAFT stormwater detention ponds in Powder Mill Gulch west of the site, a biofilvation swale near the southeastern corner of the site and a stormwater detention pond near the northcastern corner of the site. SUBSURFACE CONDITIONS Subsurface conditions at the site were ezplored by ezcavating 16 test pies and driliing 6 borings. The explorations were generally located by pacing along compass bearings from existing survey control points, The locations of the explorations, shown 3n Figure 2, should be considered accurate to within approzimately 5 feet. The test pits, designated TP-I to TP-]6, were excavated to depths ranging from 6 to 17 feet using a uack-mounted hydraulic excavator. 'Ilie borings, designated H-1 to Bfi, were drilled to depths ranging from 12.5 to 38 feet using a wck-mounted, continuous flight,hollow-stem auger drill. Temporary access roads for the drill rig were conscrucced using the hydraulic ezcavator mentioned above. Descriptions of the field exploration and laboratory testing procedures and detailed logs of the explorations aze presented in the append'u. Based on our observations at the aite and our review of existing information, we interpret the subsurface conditions to generally consist of several feet of loose to medium dense weathered glacial till underlain by dense to very dense unweathered glacial till. The glacial till consists of silty fine to coazse sand with occazional gravel, cobbles and boulders ranging in size up to approzimately 20 inches in diamecer. We observed the weathered till extending to depths ranging from 2 w 6 feet and containing numerous roots to depths of 1.5 to 3 feet. In TP-11, a 6-inch- thick layer of dense sand and gravel with a vace of silt waz encountered at the contact between tLe weathered and unweathered till. We observed glacially consolidated outwash deposits in test pits 5 and 6. In TP-5, the outwach uaderlies a thiclrness of 6 feet of loose to dense weathered till and consists of dense silty gravel, fine w coazse sand with silt, and occasional cobbles. In TP-6, the outwath consists of a thickness of 4.5 feet of loose, weathered silty fine to coazse sand with occasional gravel and cobbles underlain by dense gravel and silty grnvel with sand and occazional cobbles, The silty gravel also contains pockeu or leaces of inedium to coarse sand. TP-I, B-1 and B-2 are located within the soil stockpile at the southern portion of the site. We observed fill soils to depths of 9 feet in TP-i, 28 feet in B-1, and 25 feet in B-2. The fill soila gener,.11y consist of madium stiif silt and loose to medium dense silty fine to coarse sand with occasional gravel, cobbles and organic matter. 'Rie fill is underlain by very dense glacial till consisting of silty fine to coarse aand with occasional gravel and cobbles. In B-1, very dense fine to medium sand with silt and occasional gravel was encountered near the top of the till betwecn depths of approzimately 31 and 36 feet. Generalized cross sections shou�ing the subsurface conditions along four selected grid lines across the site are show•n in Figures 3 and 4. . G e o E n p i n e e r � 3 File No.0110.154P.IO/p6129I