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California&9ional Water
<br /> Quality Con I Board
<br /> Central Valley Region `
<br /> Linda S.Adams Karl E. Longley,SCD,F.E.,Chair e
<br /> Secretary far '�<=:•'
<br /> f 68 E Street,Fresno,California 93706
<br /> Environmental (559)445-51 i6•Fax(559)445 5910 Arnold
<br /> Protection http;//}vww,water6oards. (559)/44 -591tralv /ley Sehwamnegger
<br /> Governor
<br /> 22 October 2008 C
<br /> M. Scott Mansholt OCT 2 4 2.008
<br /> Chevron Environmental Management Company
<br /> 6111 Bollinger Canyon Road D,1VIRON[O.E f HEALTH
<br /> Rm 3432 I�IEM,111T/CEWICE5
<br /> San Ramon, CA 94583
<br /> REVIEW - NO FURTHER ACTION REQUIRED REQUEST, MOUNTAIN HOUSE
<br /> DEVELOPMENT SITE #4, MOUNTAIN HOUSE, SAN JOAQUiN COUNTY
<br /> On behalf of Chevron Environmental Management Company (Chevron), Science Applications
<br /> Required Request (NFAR), Mountain House Development Site #4 (Site)
<br /> International Corporation (SAIL) submitted the 15 September 2008 report Na Fu her located
<br /> tion
<br /> . The Site is
<br /> along Byron Road approximately 2,000 feet northwest of the Mountain House Creek crossing
<br /> ted
<br /> and Mountain House Development Site #1, northwest of Tracy, in western San Joaquin
<br /> County. q
<br /> The Site lies within the Byron Road right-of-way (ROW) easement, primarily beneath the
<br /> Byron Road alignment. The ROW easement is approximately 125 feet wide and includes the
<br /> historical Old Valley Pipeline (OVP) that lies adjacent the southwest side of Byron Road. The
<br /> Union Pacific Railroad (UPRR) ROW, adjacent the northeast side of the highway, includes the
<br /> historical Tidewater Associated Oil Company (TAOC) pipelines, as well as the UPRR tracks.
<br /> Additionally, within the UPRR easement and next to the tracks are the Bay Area Products Line
<br /> (BAPL), operated by Chevron Pipeline Company, and the Kinder Morgan, LLC pipeline, both
<br /> of which transport refined petroleum products.
<br /> Central Valley Regional Water Quality Control Board (Central Valley Water Board) staff has
<br /> reviewed the NFAR. Additionally, 2001 to 2008 soil and groundwater investigation reports,
<br /> including an environmental risk evaluation prepared for Chevron by SAIL and other
<br /> environmental consulting firms, were also reviewed. in 2001, the initial Site investigation
<br /> identified petroleum hydrocarbon affected soil in two borings at depths between 8 and 16 feet
<br /> below ground surface (bgs). Analysis of soil samples collected at 13.5 and 15 feet bgs
<br /> detected total petroleum hydrocarbons as crude oil (TPHc), attributed to leaks from the
<br /> historical OVP pipeline, at concentrations of 13,000 milligrams per kilogram (mg/kg) and 3,600
<br /> mg/kg, respectively. Visually affected groundwater was noted but not sampled.
<br /> SAIC conducted an investigation in latter 2005, advancing seven borings to depths of 14 to
<br /> 44 feet bgs, and collected 28 soil samples and five groundwater samples for analysis. Soil
<br /> boring MH4-1, completed to 44 feet near the 2001 borings, reported TPHc in samples from 1,
<br /> 8.5, and 16 feet bgs at concentrations of 740, 1,600, and 19,000 mg/kg, respectively.
<br /> Benzene, toluene, ethylbenzene, and xylenes (BTEX) were non detect (ND). Low
<br /> concentrations of polynuclear aromatic hydrocarbons (PAHs) were ND and/or detected at
<br /> slightly over respective method detection limits (MDLs) except in the MI-14-1 soil samples.
<br /> California Environmental Protection Agency
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