|
Stantec
<br /> Site History and Previous Investigations
<br /> Stockton Charter Way Commingled Plume No. CP0057
<br /> November 15, 2011
<br /> property. TPHg and benzene were detected in soil samples collected during the installation
<br /> activities at concentrations up to 250 and 1.0 mg/kg, respectively.
<br /> In August 2000, SECOR International Incorporated (SECOR) contracted Precision Sampling of
<br /> Richmond, California (Precision) to advance three soil borings (SB-2 through SB-4). Cone
<br /> penetrometer testing (CPT) technology was used to advance SB-3 and SB-4. No soil samples
<br /> were collected from SB-3/CPT-01 or SB-4/CPT-02. TPHg was detected in soil samples
<br /> collected from SB-2 at concentrations up to 130 mg/kg. TPHg, benzene, and MTBE were
<br /> detected in groundwater samples collected from these borings at concentrations up to 42,000,
<br /> 10,000, and 46,000 pg/L, respectively. These activities are summarized in the SECOR Site
<br /> Assessment Report dated January 18, 2001.
<br /> In May 2001, SECOR contracted Gregg Drilling & Testing, Inc. (Gregg) to advance four soil
<br /> borings (SB-5 through SB-8) using CPT technology. A second borehole was advanced
<br /> adjacent to each soil boring, and groundwater samples were collected at discrete intervals
<br /> based upon the pore pressure observations. No soil samples were collected. TPHg,
<br /> CPT/membrane interface probe technology, and DP-1 and benzene, and MTBE were detected
<br /> in groundwater samples collected from these borings at concentrations up to 100,000, 6,900,
<br /> and 280 pg/L, respectively. These activities are summarized in the SECOR Site Assessment
<br /> Report and Work Plan for Further Assessment dated March 5, 2002.
<br /> In a March 4, 2004, Conceptual Site Model, SECOR stated that five supply wells were located
<br /> between Y, and '/2 mile of the site.
<br /> In July and August 2005, SECOR contracted Precision to advance 19 soil borings (CPT-1
<br /> through CPT-10; using DP-3 through DP-10; using direct push technology). No soil samples
<br /> were collected from CPT-1 through CPT-10. TPHg, total petroleum hydrocarbons as diesel
<br /> (TPHd), benzene, and MTBE were detected in soil samples collected during the direct push
<br /> activities at concentrations up to 1,700, 1,600, 3.4, and 0.68 mg/kg, respectively. TPHg, TPHd,
<br /> benzene, and MTBE were detected in groundwater samples collected from these borings at
<br /> concentrations up to 380,000, 210,000, 24,000, and 17,000 pg/L, respectively. These
<br /> activities are summarized in the Blasland, Bouck & Lee, Inc., an ARCADIS company of
<br /> Syracuse, New York Site Assessment Report dated December 18, 2006.
<br /> In January 2008, ARCADIS contracted Cascade Drilling Incorporated of Rancho Cordova,
<br /> California to install nine groundwater monitoring wells (four A zone: MW-4A through MW-7A,
<br /> one B zone: MW-76, and four C zone: MW-4C through MW-7C). TPHg, TPHd, benzene, and
<br /> MTBE were detected in groundwater samples collected from these borings at concentrations up
<br /> to 380,000, 160,000, 24,000, and 34,000 pg/L, respectively. These activities are summarized in
<br /> the ARCADIS Groundwater Assessment Report dated August 2008.
<br /> A groundwater monitoring and sampling program has been in place at this property since March
<br /> 1995.
<br /> Remediation Activities
<br /> In September 1996, Touchstone Developments Environmental Management (Touchstone)
<br /> supervised the removal of two 10,000-gallon gasoline USTs, one 6,000-gallon gasoline UST,
<br /> Stockton Charter Way Site History and Previous Investigations.doc 4
<br />
|