ARCHIVED REPORTS_XR0007285 - Laserfiche WebLink

Home Browse Search

Vertical and Horizontal Delineation of Plume History Monitoring Wells MW#1,MW#2, and MW#3 were installed in September of 1999 to a depth of sixty feet Soil samples from the soil bores were extracted at five foot intervals from a depth often feet to sixty feet(see site map for location attached) All three soil bores produced samples above detection levels for BTEX and TPHg and TPHd (see Soil Sample Recap Attached) Monitoring Wells MW#4S and MW#4D were installed on the east side of Wilson Way in September of 2000 Also,monitoring wells MW#5D,MW#6S and MW#6D,MW97S and MW97D were installed north and south of the pump islands in September of 2000 (see attached Site Map) Monitoring wells MW#8S andMW#8D were installed in a single bore hole inside the existing building, west of the pump islands on October 3,2000 Monitoring wells MW99S and MW49D were constructed in a single soil bore on August 14, 2002 The installation of five CPT's was completed on March 19, 2003 Monitoring well MW#1D was installed on May 28, 2003 to a depth of 150' Monitoring well MW#10D was installed on October 23,2003 to a depth of 100' This monitoring well is located in the northwest corner of the main building THIRD QUARTER 2003 MONITORING WELL SAMPLE ANALYSIS REPORT Sampled 09/20/03 WATER ANALYSIS OF SAMPLES FROM MONITORING WELLS On September 20, 2003, Del-Tech Geotechnical Support Services extracted water samples from morntonng wells MW#1 D,MW94D,MW#5D,MW#6D,MW#7D,MW#SD,MW#9D&MW#9S,using standard industry practices under the supervision of Foothill Engineering The remaining monitoring we]is on the site were dry for this sample event A report of this work by Del-Tech Geotechnical Support Services is attached and is a part of this report The water samples were transported on ice by chain of custody to Sherwood Labs for analysis by Method SW802OF for BTEX,and TPHg Samples of each set of groundwater extractions were forwarded to Entech Analytical Labs of Santa Clara, California for analysis by EPA Methods 8260FA FINDINGS FROM GROUNDWATER SURFACE DETERMINATION The groundwater elevation on this site has lowered more than seven feet from the last sample event and is about one foot lower than in the third quarter of last year The slope of the groundwater gradient for this event is down slope to the southwest at S=0 001 The last monitoring event had a hydraulic gradient with the down slope was in the northeast direction FINDINGS FROM MONITORING WELL SAMPLE ANALYSIS FOR BTEX AND TPHg Samples from monitoring wells MW#1D, MW#4D, MW#6D, and MW#7D were analyzed at below detection limits for TPHg Monitoring wells MW#5D, MW#8D, and MW#9S are the only monitoring wells that analyzed higher than the last event for TPHg Maximum concentrations of TPHg were typically found in MW#1 and MW#2 which were dry for this event (See groundwater analysis recap attached) The highest concentrations of TPHg were recorded in MW#9S for this event 2