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foot depth, while dewatering was occurring from a pump installed into well RW 1 B, see Figure 4A A 20 foot reach excavator was then used to perform the necessary excavation as outlined in the approved workplan The size of the excavator was determined and the necessity to ramp into the excavation was dictated by the limited size of the lot and the over-head electrical utilities in proximity to the area to be excavated The area containing piezometers PZ2A and PZ213 was excavated to the 30 foot depth to act as a dewatering point 0 02 inch slotted 4 inch diameter Sch 40 PVC was placed into this portion of the excavation and then the pump that was installed into RW1B was placed into this temporary dewatering casing To prevent sidewall failure and to stabilize the PVC dewatering casing 1/4 clean rounded pea gravel was then placed into this portion of the excavation to the 14 foot depth Dewatering of the excavation then continued from this newly installed dewatering point The excavation was then extended to the north to remove the areas that contain wells RWIA and RW1B and piezometers PZIA and PZ1B This area was excavated to the 28 foot depth, once the wells mentioned above were exposed, they were removed using the excavator, palling the complete casing from the excavation The 28 foot depth excavation removed gasoline contaminated soils east past sample borings E and THI, see Figuare 4B and Table 2 - Soil Sample Results The remainder of the excavation was expanded to the east to the 20 foot depth The excavation removed an estimated 639 f� cubic yards of gasoline contaminated soil, reducing the mass of hydrocarbons left in the subsurface soils to a calculated 359 pounds for a mass reduction of 95%, see Table 3 SEWER DISCHARGE Prior to starting the excavation activities a sewer discharge permit was obtained from the City of Stockton The permit was necessary for the disposal of groundwater pumped during the one week pump tests on wells RWIA and RW1B and for the pumped groundwater that would be generated during the dewatering for the excavation The sewer discharge permit allowed the discharge of treated groundwater not to exceed 10 gallons per minute with a automatic shut down if the lower explosion limit (LEL) as Hexane exceed 10% 116,535 gallons of treated groundwater was pumped to the sewer, see Appendix C Of this 116,535 gallons 7913 gallons was produced during the pump test, 76166 gallons metered from the dewatering of the excavation, see Table 4, 29873 gallons of pumped from the excavation (non metered), 450 gallons was from previous groundwater monitoring rounds and fluids generated dunng the piezometer installations and developments and 2100 gallons from the purgeing of the storm drain system near the site to recovery spillage of a calculated 1951 gallons overfill of the Baker Tank It is calculated that the 106039 gallons of groundwater pumped from the excavation contained an average concentration of 8 05 mg/L as TPHgasoline This would indicate a mass removal of approximately 1 14 gallons or 7 2 pounds of gasoline from the groundwater EXCAVATED CONTAMINATED SOILS STORAGE Prior to starting excavating contaminated soils a excavated soil storage area was prepared Utilizing the fenced back lot of the site an 1850 square foot bermed and plastic 10 Update Status March 2003