Otak, Inc 8/15/2016 - Laserfiche WebLink

Exhibit A Continued 3.3 Phase 1 Subsurface Investigation The Otak team will perform supplemental field explorations along the dike alignment. Six(6) boreholes will be drilled along the dike at 1,000-foot intervals. The boreholes will be drilled through the centerline of the dike using a track-mounted drill rig.Five (5) of these borings will use a mud- rotary drilling technique,and the remaining boring will be performed using hollow-stem auger operated by the rig used for the mud rotary drilling. Soil samples will be collected at 2.5-foot intervals to a depth below ground surface (bgs) of 15 feet,then at 5-foot intervals to the bottom of the boring. Borehole depths will be to 50 feet bgs in 5 of the locations and to 80 feet bgs in the remaining location. Samples will be obtained with Standard Penetration Tests (SPTs),and with an occasional Shelby tube for undisturbed samples.All boreholes will be backfilled with cement- bentonite grout. The boring locations will be identified and marked during drilling for field survey by the Otak team. In the hollow-stem auger hole,a falling-head permeability test will be performed in the embankment and foundation soils. The soil samples collected from the borings will be brought to Comforth's laboratory for geologic interpretation and testing.A geologist will review each sample and prepare a log for each boring. 3.4 Phase 1 Laboratory Testing The City will contract with an independent laboratory to complete the testing of samples obtained by Cornforth collected during the subsurface investigations. Cornforth will coordinate with the soils laboratory to perform basic geotechnical index tests on samples,including: • Water content tests for most samples (up to 80 tests) • Minimum 1 grain-size and 1 fines content(%passing#200 sieve) for each boring,plus other selected samples of interest(up to 6 tests) • 2 Atterberg Limits for each boring(12 tests) • 1 Organic Content of a sample selected from each boring(6 tests) Assumptions • The City will provide a boat for the site reconnaissance. • The City will obtain all permission and access to drill the borings. • The Otak team will call the Underground Utilities Location Center(UULC) and private utility locator to locate underground utilities prior to drilling the borings.The fee is assumed to be $1,000 for a private utility locator. • The City will coordinate and obtain drilling permits (including the shoreline exemption for exploratory drilling) and will notify the Otak team about permit conditions. • The City will contract with an independent soils laboratory to complete the geotechnical testing. DD5 Dike Repairs and Improvements Project 6 otak K:\project\32700\32758\Contract\Scope for Phase 1—DD5 dike repairs final 7-22.docx