ARCHIVED REPORTS XR0010711 - Laserfiche WebLink

Home Browse Search

Introduction We are inclosing three cross-sections as shown in the Darpetro Station Wells and Borings Cross Sections Lines sheet In the Cross Section BM-9 to BM-11 please note that a clay layer extends from BM-7 to near BM-8 and is located between 26 and 37 feet below the surface Below the clay layer the soil is silt and silty sand Water from the ARCO Station will flow onto our site below any layer which causes the water gradient at the ARCO Station to flow to the southeast There are also enclosed a New Well BM-14 and Soil Gas Bores plot and a well Design plot showing the positions of the bonngs and well and the design of well BM-14 WORK PROPOSAL We propose to drill and install 1 Monitoring well (BM-14) located on the west side of the gasoline station property This well will monitor the groundwater coming from the east and contaminating well BM-3 The drilling will be performed with a hollow stem auger by Frontier Drilling The well will be drilled to a depth of 50 feet below the surface (bgs) Soil sampled will be taken every 5 feet during the drilling and analyzed with our OVA meter Soil sampled from 40 feet and 50 feet will be sent to Sherwood Labs for testing as outlined in the Laboratory Testing section of this report If any sal samples test positive during the OVA testing they will also be sent for analyses The well will be completed by placing 0 02 slotted casing in the bottom 20 feet of the well and blank casing from 30 feet to the surface Number 3 clean sand will be placed opposite the slotted casing and 5 feet above it A transitional seal will be placed from 25 feet to 22 feet which will consist of hydrated bentonite From 22 feet to the surface the casing annulus will be filled with hydrated cement Above the well a traffic box will be placed and the well be we capped with a locating cap The well will be developed about 3 days after it is installed and a water sample will be taken AIR TEST WELLS We plan to drill 7 soil gas test borings around the tanks and the pumps closest to well BM-3, which is impacted with MtBE The only possible sources of MtBE at this station are the tanks or the pumps Each sal gas boring will be 23 feet deep, which will put the soil gas being tested in a sandy silt located at 19 to 24 feet below the surface The borings will be located within 5 feet of the tanks and the pumps The bonngs will be drilled by Fisch Environmental Services Each boring will produce a gas sample which will be tested at GeoAnalytical Laboratories of Modesto, CA These wells will be drilled with a Geoprobe unit which can obtain the gas samples LABORATORY TESTING The following tests will be performed on the sod samples by Sherwood Labs, of Hilmar, CA and GeoAnalytical Laboratories, of Modesto, CA The samples will be placed on ice in a cooler until -. they are delivered to the laboratory