4841 GLENWOOD AVE 2018-01-02 MF Import

( May 5, 2008 Mr. Ron Riach/JRR Engincering, Inc. L&tA Job No. 8A043 Page 3 Soil Conditions We probed the surficial soils along the wall alignment by manually pushing a steel T-bar into the ground to get an indication of the density or wnsistency of the soils on which the proposed pmcast concretc block w�ll is to be founded. The probe bar could penetrate no more than I8 to 30 inches, indicating very dense, fresh till soils most likely lie at shallow depth below the ground surface along the wall alignment. Groundwatcr Conditions The very-dense fresh till deposit underlying the wall alignment at shallow dcpth is of extremcly low penneability, and would perch stormwater infiltrating into the more permeable surficial topsoil and weathered soils. 7'his near-surface perched groundwater would fluctuate seasonally, and the depth to and thc amount of perchcd groundwater would also depend on prccipitation, storm runoff, vegetation cover, site utilization, etc. It may dry up completely in the summer months, and accumulatc and rise in the wet winter months. RECOMMENDATIONS Gencral Thc preposed block wall is to be constructed with 2.5 feet x 2.5 fcet x 5 fcet Ultra IIlock precast coneretc bl�:ks. Thc block wall should havc gcogrid mesh reinforcement embedded in its backfill, except whcrc thc wall is no more thun 6 fect tall. A drain line should be provided along the base behind the wall to collect and drain away groundwater tlowing towards the wall. The wall should be founded on a minimum 6-inch layer of compacted 7/S-inch crushed rock base placed over fim� bearing soils. A vcrtical drainage blanket should be placed against the back of wall, which should bc hydraulically connected to the drain line. The remaining wall backfill should be compactcd stn!�tural fill consisting of cican granular soils. Onsite cican sandy soils LIU & ASSOCIATES, INC. 3/r-1