SITE INFORMATION AND CORRESPONDENCE_FILE 1

Home Browse Search

d —I John and Margaret Marci Page 2 20 Mobile Lane December 31, 2008 Crescent City,California 95531-8409 To address the EHD reservations regarding the DPE test design due to the limited screen lengths of EW-1 and EW-101, and the very limited vadose zone addressed by the longer screened well (MW-5)under natural conditions, the EHD recommends the following: • If possible, monitor depth-to-water in the active extraction well; if depth-to-water is not significantly below the top of the screen interval,terminate the test. • Monitor air flow rate continuously as depth-to=water increases; one would anticipate an increase of air flow as the vadose zone expands and is addressed by a larger portion of the well screen interval. • Demonstrate that the soil intervals addressed by the fairly small screened intervals are representative of site conditions and that the findings of the test are applicable to the whole impacted soil plume. By email dated November 26, 2008, the EHD was notified by GTI that TP.Hd results were significantly different between the two environmental laboratories employed to analyze groundwater samples collected from MW-5 and MW-7 on October 28, 2008. Argon Laboratories reported TPHd at 580 micrograms per liter.(µg/L) for groundwater collected from MW-5, and 620 µg/L for groundwater collected from MW-7; Excelchem Environmental Laboratories reported TPHd at 2,210 gg/L for groundwater collected from MW-5, and 7,480 pg/L for groundwater collected from MW-7. The EHD approved by email on December 2, 2008, sending groundwater samples collected from MW-4, MW-5, and MW-7 to Argon Laboratories and two additional laboratories for comparison of the TPHd results during the first quarter sampling event of 2009. The EHD has reconsidered having three different laboratories analyze groundwater samples for TPHd. Instead, the EHD believes sending the groundwater samples collected from MW4, MW-5, and MW-7 to Argon Laboratories and one other laboratory (different from Excelchem Environmental Laboratories).should be sufficient for comparison of the TPHd groundwater results during the first quarter 2009 sampling event. Provide the EHD a response to these comments and a revised work plan, if appropriate, for DPE pilot testing by February 26, 2009. If you have any questions, please contact Vicki McCartney at (209)468-9852 or by email at vmccartn.ey, i?s'cehci..com. Sincerely, Victoria L. McCartney,REHS Nuel C. Henderson, Jr.,PG Senior Registered Environmental Health Specialist Engineering Geologist c: Mr. Reza Namdar Ghanbari, Geological Technics Inc., 1101 7`h .Street, Modesto, California 95354 Mr. James L.L. Barton, PG, California Regional Water Quality Control Board Central Valley Region, 11020 Sun Center Drive, Suite 200,Rancho Cordova, California 95670 I i