PROJ00400 - Laserfiche WebLink

Home Browse Search

I I I I I I I I I I I I I I I I I I I 2.1.3 Subsurface Investigation Barnes Meadow Dam and Reservoir were investigated using six rotary bore holes, five test pits, and 1,300 linear feet of seismic refraction survey lines. The 1 ocati on of the ho1 es, pi ts, and 1 i nes are shown in pl an on Fi gures V. 1 and V.2. Interpreti ve geol ogi c secti ons are shown on Fi gure V. 2. Logs of the bore holes and test pits, and the seismic refraction interpretations are included in Appendix B. The bore holes were drilled by Drillings Engineers, Inc. using a six-inch di ameter holl ow stem auger util i zi ng a truck mounted CME-55 rotary drilL Boulders were core drilled with an NX diameter diamond bit using the wire line technique. Standard penetration tests (SPT) were performed and disturbed soil samples were obtained at regular intervals using a split spoon sampler. Relatively undisturbed soil samples were periodically retrieved using Shelby tubes. Test pi ts were excavated wi th a Cat 225 track mounted backhoe bel ongi ng to Bath Excavating Company. The machine was equipped with a three-foot wide bucket and had an effective reach of 16 feet. The sei smi c refracti on survey was performed by Earth Data Acqui siti on Group using a 12-channe1 sei smograph. Geophones were spaced at 25-foot interval s. Seismic signals were initiated by impacting a steel plate with a 16 ounce hammer. 2.1.3.1 Dam The embankment dam was i nvesti gated by three bore ho1 es, two test pi ts, and 1 ,300 1 i near feet of sei smi c refracti on survey. A bri ef descri pti on of the materials encountered during the exploration follows. Bore hole BM-l was drilled from the dam crest at Station 3+99, approximately 20 feet right of the outlet works conduit. In the upper 22 feet, the hollow- stem auger encountered light brown, moist, dense, silty sand with gravel, 1231 H -47-