WORK PLANS FILE 1 - Laserfiche WebLink

Home Browse Search

i U Ms. Vickie McCartney,REHS Page 2 San Joaquin County Environmental Health Department February 13, 2004 Previous Investigations Environmental work completed at the site to date includes the following: • August—September 1995: EMCON witnessed the installation of six vertical soil borings (B-1,13- 3,B-4,B-5,B-7, and B-8) and two 45-degree angle borings (B-2 and B-6). Three borings (B-1, B4, and B-5) were converted to monitoring wells (MW-1 through MW-3,respectively). Three borings (B-3,B-7, and B-8) were converted to dual-completion vapor extraction wells (VW-1 through VW-3,respectively). October 1996: EMCON witnessed the drilling of one vertical soil boring(B-9). B-9 was subsequently converted to monitoring well MW-4. • June—July 1999: Two 10,000-gallon and one 8,000-gallon double-walled fiberglass gasoline USTs, associated dispensers, and piping were removed.from the site. Two 20,000-gallon USTs were installed in the same cavity as the former USTs. The excavation areas were backfilled with pea gravel. Pinnacle Environmental Consultants conducted compliance soil sampling activities for the tank pull. Analysis of compliance soil samples indicated that total petroleum hydrocarbons as gasoline (TPHg), benzene, and methyl tertiary butyl ether (MtBE) contamination were present in the soil. Used • August 1999: The IT Group(IT)conducted a soil and groundwater assessment consisting of two PTY`S cone penetrometer test(CPT) borings (CPT-2 and CPT-3)on the eastern edge of the site and ko1!a one CPT boring north of the site(CPT-1). Benzene and MtBE were detected in groundwater push F014 samples from CPT-2. No petroleum hydrocarbon compounds were detected in the groundwater samples collected - I � p ec ed from CPT-1 or CPT 3. • September 2000: Delta Environmental Consultants (Delta)conducted a soil vapor extraction test at the site. Three separate 4-hour tests were conducted. Soil vapors were extracted from wells VW-lA,VW-2A, and VW-3A. The tests indicated that extraction of soil vapors from these wells at 9 to 10 cubic feet per minute(efm), with 50 to 100 inches of water column, resulted in a radius of influence between 34 and 45 feet. The initial hydrocarbon mass extraction rates were calculated to be between 1.10 and 3.88 pounds of TPHg per day. • August 2001: Delta installed three groundwater monitoring wells (MW-5, MW-6, and MW-7). MW-5 is east of the site on American Street. MW-6 and MW-7 are in Oak Park. KAWproccssV5 BP ARCM2186\2186 WP 04.doc