SITE INFORMATION AND CORRESPONDENCE

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SEP 17 '99 04:47PM ESCNC F-_-'10NT P.3/10 File No. NFS-4463-02 Doc. No. 9909-057 September 17, 1999 development, surface soil samples be collected and analyzed for pesticides and that the one onsite water supply well be properl% destroyed. Soil Engineering Study for the 14 Acre Commercial Development The geotechnical investigation was performed in March 1999. The drilling of 21 borings and three percolation tests was performed from March 29 and 30, 1999 by Spectrum Drilling. A geotechnical permit application was submitted for the borings and percolation tests using Spectrum Drilling. The percolation tests were performed at the proposed locations of storm water retention ponds. A separate permit was applied for the percolation tests, but returned by the county with the explanation that the percolation tests would be performed under the geotechnical permit. Four cone penetrometer tests (CPT) for liquefaction evaluation were performed by Gregg Drilling on April 29, 1999. Four test borings to complete the geotechnical field study were drilled by Exploration Geoservices on May 12, 1999. The soils encountered in the upper 5 feet during the drilling and CPT holes consisted of silty sand to sandy silt with a low expansion potential. From 5 to approximately 15 feet below ground surface (bgs), the soils consist of highly compressible silty clay to clay, based on consolidation testing. Below 15 feet soils consist of layers of clayey sand and clayey silt interbedded with thin layers of clean, fine-grained sand. Groundwater was encountered between 9 and I1 feet bgs. The three percolation tests were performed for the purpose of evaluating the three proposed storm water retention ponds. Two of the three tests were observed by a PHS/EHD representative. The percolation rates ranged from 4.5 to 10 inches per ten minutes (2.2 to 5 minutes per inch). The conclusions stated that the site is generally suitable for the proposed development. The site is not located within an Alquist-Priolo Special Study Zone, and there are no known faults that cross the site. However, a moderate to major seismic event on the San Andreas, Hayward, or Coast Range-Central Valley Faults could cause moderate to strong ground shaking at the site. The geotechnical report was issued on May 17, 1999. File Review and Pesticide and Petroleum Sarnoling Results The files were reviewed for three facilities in the vicinity of the subject site. The Chevron station (1960 West I ld, Street) on the south side of West I Vh Street contains fiberglass underground storage tanks (USTs) that were installed in 1991. The former Chevrolet auto dealer (1615 West 11 Street), located approximately 1,000 feet east of the subject site, received closure from PHS/EHD on February 19, 1999 for further environmental investigation. The Monterosso property. located in the southwest corner of Byron and Corral Hollow Roads. was investigated regarding the underground pipeline by Geomatrix Consultants (Geomatrix) in 1988 because of proposed residential development on the property. The results of the investigations indicated low amounts and concentrations of degraded crude oil or Bunker C between depths of 5 and 15 feet extending less than 50 feet onto the property. In addition, groundwater, at a depth of approximately 7 feet, was not affected by hydrocarbons. A health riskassessment, completed by Geomatrix, concluded that future site residents would not be exposed to unacceptable health risks related to the crude oil/Bunker C. The Department of Toxic Control Substances (DISC) and PHS/EHD agreed with the conclusions of the health risk assessment and issued a "No Further Action" letter on September 30. 1996. Currently, the Monterosso property is residential housing. Historical information, but apparently not public information, discovered at Chevron Pipeline, Co. indicated that petroleum hydrocarbons were released from the underground pipeline along Byron Road in 1935_ There was a sketch showing the resulting 8,750 square feet of alfalfa damage in the northern corner of the subject site. A voucher from Standard Oil Company was issued to Mr. Martin RUStan for 5350 "in full settlement of all claims and demands for any and all damages arising out of, or connected with, the pipe lines." During the May 12, 1999 liquefaction confirmation borings, one Earth Systems Consultants Northern California 2