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0 Work Plan for Septic Dralnfield Investigation March 7,2013 8700 Thornton Rd. Project No.1091 Stockton,California Page 3 Locating the Drainfield CES will locate the drainfield by inserting a downhole camera in the drainfield line that daylights in the former excavation. During backfilling of the former septic tank excavation, CES installed an 8-inch diameter riser pipe to access the drainfield line from the surface. The downhole camera will access the drainline from this riser and will be advance to map the surface projection of the drainfield. The camera will accurately measure distances and directions so that the surface projection of the drainline can be determined. The surface projection of the drainlines will be marked at the surface with white paint for future reference. Soil Sampling After the drain line locations are determined, soil borings will be advanced at 20 foot intervals along each drain line. The borings will be located within one foot of the projected drainline. One soil samples will be collected from each boring at a depth approximately one foot below the bottom of the drain line. The drainfield depth below the surface will be determined by measuring the depth of the effluent line access port below the surface grade. Samples will be collected by advancing a macrocore sampler attached to a Geoprobe sampling rig. The macrocore sampler consists of a 4-foot long sample barrel lined with disposable acrylic tub liners. After the macrocore sampler is retrieved from the boring, the liner is removed and the field geologist will log the soils using the USCS system. The geologist will also scan the core with a photo-ionization detector (PID) to determine the presence of volatile chemicals. The geologist will prepare a log for each boring that contains the boring identification number, soil descriptions, PID readings, depth of samples, the sample identification number, the total depth of the boring and the boring location. Soil Analyses Two soil samples were collected from the septic tank excavation on December 6 and 7, 2012. These samples detected chemical constituents typical of a hydrocarbon release. These constituents consisted of benzene, toluene, ethylbenzene, xylenes (BTEX), naphthalene, bis- phthalate, total petroleum hydrocarbons as gasoline (TPH-g), total petroleum hydrocarbons as diesel (TPH-d) and total petroleum hydrocarbons as motor oil (TPH-mo). Soil samples from the drainfield will be analyzed for these same constituents. These constituents and their respective laboratory analytical methods are as follows: Constituents Laboratory Method Total Petroleum Hydrocarbons as Gasoline (TPH-g) EPA method 8015 modified Total Petroleum Hydrocarbons as Diesel (TPH-d) EPA method 8015 modified Total Petroleum Hydrocarbons as Motor Oil (TPH-mo) EPA method 8015 modified BTEX, naphthalene and bis-phthalate EPA method 8260B