WORK PLANS_FILE 2 - Laserfiche WebLink

Home Browse Search

ENVIROiMENTAL HEALTHDEPARTMENT SAN JOAQUIN COUNTY a Donna K.Heran,R.E.H.S. Unit Supervisors Director 304 East Weber Avenue, Third Floor Carl Borgman,R.E.H.S. Al Olsen,R.E.H.S. Stockton, California 95202-2708 Mike Huggins,R.E.H.S.,R.D.I. Program Manager Douglas W.Wilson,R.E.H.S. Laurie A.Cotulla,R.E.H.S. - Telephone: (209) 468-3420 Margaret Lagorio,R.E.H.S. Fax: (209) 464-0138 Robert McClellon,R.E.H.S. Program Manager Mark Barcellos,R.E.H.S. JOE ALDRIDGE ULTRAMAR INC JUL 12 2005 685 WEST THIRD ST HANFORD CA 93230 RE: Former Beacon #12474 SITE CODE: 1173 3440 E. Main St. RO#: 00066 Stockton, CA., 95205 San Joaquin County Environmental Health Department (EHD) has reviewed Results of Additional Ground Water Assessment and Updated Site Conceptual Model, dated June 7, 2005 as submitted by Horizon Environmental on June 20, 2005 and has the following comments. The report summarizes the investigative requirements for determining the lateral and vertical extents of 1,2-DCA as noted in EHD correspondence dated June 2002. After several addendum submittals, EHD approved the February 26, 2003 work plan in January 2004 with approval of the December 22, 2003 addendum. The approved work plan was implemented in March 2004. The ground water assessment portion of the report covers the installation of five monitoring wells, MW-13 through MW-17. This report included an updated Site Conceptual Model (SCM) but EHD has not received the original SCM. Please advise EHD of the date of the original SCM and when it was submitted. The five monitoring wells were placed along the site boundaries and typically had five-foot screened intervals placed approximately 135 to 140 feet or 145 to 150 feet below ground surface (' bgs). Five ground water sampling events have been conducted on these wells since March 2004. The laboratory analytical results indicate that 1,2-DCA has only been detected in MW-14 on June 10, 2004 at 0.6 ug/I. Since that time, 1,2-DCA has not been detected in any of these five monitoring wells. One report conclusion, based on hydro-punch samples collected from boring B-9 at 95' and 108' bgs and at 95' bgs from boring B-10, is that TPH as gasoline and 1,2-DCA are not laterally delineated at these intermediate depth intervals in the southern portion of the site. However, 'non-detect' ground water analytical results from the deeper, recently installed MW-15 and MW-16 indicates that the vertical delineation of these dissolved constituents at the deeper depth along the southern site margin has been established.