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Borings The borings will be drilled between 10 and 24 feet below existing ground surface (bgs) or to refusal, whichever is shallower. The purpose of the borings will be to: a Obtain subsurface information. to Obtain undisturbed and bulk samples of the various soil types for laboratory testing. The borings will be drilled using a truck -mounted rig equipped with hollow -stem augers for soils sampling. Soils will be continuously logged and classified by the. geologist/englneer in the field by visual examination in accordance with the Unified Sol[ Classification System. Both undisturbed ring samples and bulk samples of the subsurface materials will be obtained at five- foot Intervals, at changes in soil profiles,. or where unusual conditions are encountered. The relatively undisturbed ring eaniples will be obtained using a Modified California Sampler (2.4 -inch inside diameter and 3.0 -inch outside dlameter) lined with thin-walled sample rings. The sampler will be driven into the bottom of the boreholes with successive drops of a 140 -pound hammer falling 30 inches. The number of successive drops of the drlving weight ("blows") required for one foot of penetration will be shown on the boring summary sheet. in the "blow/foot" column. The soil will be retained in brass rings (2.4 inches in diameter and 1.0 inch in height). The central portion of the sample will be retained and carefully sealed In waterproof plastic containers for shipment to the laboratory. Bulk samples ofrepresentative soil types will be collected in plastic bags. Groundwater levels, if encountered in the borings, will be recorded. The borings will be backfilled with soils cuttings and tamped. As a result of the backfill may settle over time. If construction is delayed, we recommend the owner monitor the boring site and backfill any settlement or depression that might occur to prevent trip and fall injuries from occurring near the area of any potential settlement. Water Infiltration Tests Two, 5 -foot deep borings will be prepared for Infiltration testing. A 2 -Inch diameter perforated plastic pipe will be installed inside each boring. Pea gravel filter pack will be poured down the center of the auger while withdrawing the auger to surround the pipe casing and whole bottom with the gravel filter pack. Waterwill be added to the bore hole until Proposal to provide Landscape Architectural Design for 6th & Lacy Park - RFP No. 18.038 the water level is as near the ground surface as could be achieved and allowed to pre-soak. Presoaking the test hole shall maintain a water level above the percolation testing level and at least 12 inches above the bottom of the boring. If the water seeps completely away within 30 minutes..after filling the boring 2 consecutive times, and. the subsurface exploration has yielded permeable. soils beneath the proposed Invert of infiltration, presoaking can be considered complete and the testing can proceed. If the water does not completely drain within 30 minutes, presoak the hole for at least 4 hours before conducting the Infiltration test. After presoaking, water will be added .to 12 inches above the top of the infiltration depth. After 30 minutes, if no water remains In the hole, a test time Interval of 10 minutes will be. used. If water remains in the hole, a test time interval of 30 minutes will be Used. Once the interval has been determined, the test shall commence. Water will be added to the hole to a depth of at least 12 inches above the depth of Infiltration. The water depth will be measured after the interval time has lapsed. The hole will be.refilled to the same water level at each interval and the test will continue for a minirnum.of 8 intervals or until a stable rate of drop is obtained, whichever is first. A stabilized rate is defined as when the highest and lowest reading from three consecutive Intervals are within 10 percent of each other: The average drop rate over the last 3 readings consecutive readings is the pre -adjusted percolation rate. Attempts will be made to remove the pipes from the borings. If the attempts fail, the pipes will be abandoned in place and the wholebackfilled with soils cutting. Laboratory Testing Program The laboratory testing program will depend upon the type of soils encountered during our fleld exploration and the quality of samples obtained. Laboratory. tests will include, but may not be limited to, the following: a In place moisture and density tests M Collapse David Evans and Associates, Inc. I May 21, 2018 1 7 250-25