|
Brusea File No. 137-002
<br />Page 2
<br />December 27, 2018
<br />Murphy Parkway Property Soil Gas Monitoring
<br />BACKGROUND
<br />The approximate 48 -acre subject parcel is located about 500 feet easterly of Murphy Parkway and
<br />about 1,500 feet southerly of East Louise Avenue in a commercial and industrial area of Lathrop,
<br />San Joaquin County, California (See Plate 1, Vicinity Map). Development of the property
<br />currently underway, including the construction of a large light-industrial/warehouse building and
<br />associated pavements. The general layout of the development is shown on Plate 2, Site Map.
<br />The lead agency overseeing environmental conditions at the site is the San Joaquin County
<br />Environmental Health Department (SJCEHD). CalRecycle and the Central Valley Regional
<br />Water Quality Control Board (CVRWQCB) also have been involved with review of site
<br />conditions. These agencies have indicated that implementation of a soil gas monitoring program
<br />is required due to the presence of uncharacterized wastes that reportedly exist offsite to the west
<br />of the subject property (property formerly occupied by a cogeneration facility). As requested by
<br />the SJCEHD, our firm prepared a Soil Gas Monitoring Workplan dated August 10, 2017.1 Upon
<br />review, the SJCEHD requested minor modifications to the Workplan, and we prepared an
<br />Addendum to the Workplan dated November 7, 2017.2 The required soil gas monitoring program
<br />consists of monthly monitoring for a period of one year, and quarterly monitoring for a period of
<br />four years thereafter. The SJCEHD indicated approval of the monitoring program via email on
<br />November 8, 2017. The soil gas monitoring wells (identified as SGMW 1 and SGMW2) were
<br />installed on January 16, 2018; the locations of the wells are shown on Plates 2 and 3.3 Monthly
<br />soil gas monitoring commenced in January 2018. One of the soil gas monitoring wells
<br />(SGMW1) was accidentally damaged by construction equipment in July 2018; this well was
<br />replaced in August 2018.4
<br />SOIL GAS MONITORING/SAMPLING
<br />Soil gas monitoring/sampling was performed at the site on December 17, 2018. At that time,
<br />the soil gas monitoring wells were inspected to confirm they were sound and without damage.
<br />Prior to sample collection, each well was screened with a portable gas indicator (RKI Eagle)
<br />connected to the sampling ports on the wells. Screening measurements (including methane
<br />percentage, carbon dioxide concentration, oxygen percentage, and hydrogen sulfide
<br />concentration) were recorded and are presented on the attached Table I. As shown on Table I,
<br />methane was not detected in either of the soil gas monitoring wells via field screening.
<br />Following screening, laboratory -provided sampling containers (one -liter Summa canisters) were
<br />attached to the sampling ports on the wells and soil gas samples were collected from each well.
<br />1 Brusca Associates, Inc.; "Soil Gas Monitoring Workplan, Murphy Parkway Property, APN 198-120-009, 17100
<br />Murphy Parkway, Lathrop, California"; August 10, 2017.
<br />2 Brusca Associates, Inc.; "Addendum to Soil Gas Monitoring Workplan, Murphy Parkway Property, APN 198-120-
<br />009, 17100 Murphy Parkway, Lathrop, California"; November 7, 2017.
<br />s Brusca Associates, Inc.; "Soil Gas Monitoring Wells Installation, Murphy Parkway Property, APN 198-120-009,
<br />17100 Murphy Parkway, Lathrop, California"; February 12, 2018.
<br />4 Brusca Associates, Inc.; "Replacement of Soil Gas Monitoring Well SGMW1, Murphy Parkway Property, APN
<br />198-120-009, 17100 Murphy Parkway, Lathrop, California"; August 31, 2018.
<br />
|