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LSA ASSOCIATES, INC.
<br />SEPTEMBER 2016
<br />ROCKETSHIP REDWOOD CITY ELEMENTARY SCHOOL PROJECT
<br />INITIAL STUDY/ MITIGATED NEGATIVE DECLARATION
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<br />P:\RWC1401B Rocketship School\PRODUCTS\IS-MND\Public\Rocketship Public Review 09-29-16.docx (09/29/16) PUBLIC REVIEW DRAFT 53
<br />Based on the information reviewed, the shallow groundwater in the vicinity of the project site appears
<br />to be impacted with volatile organic compounds (VOCs) including tetrachloroethene (PCE),
<br />trichloroethene (TCE), and cis-1,2-dichloroethene (cis-1,2-DCE). Historically, PCE and TCE were
<br />commonly used as cleaning solvents at industrial facilities. As PCE naturally degrades in the
<br />environment, it can form TCE and TCE can degrade to form cis-1,2-DCE. The groundwater
<br />monitoring performed at 2201 Bay Road indicates that shallow groundwater’s piezometric surface59
<br />historically ranges from 6.5 to 9.1 feet below ground surface and the apparent groundwater flow
<br />direction is generally to the northwest toward the San Francisco Bay, away from the project site.60
<br />Based on the results of groundwater monitoring performed at 2201 Bay Road in 2010, the highest
<br />concentration of PCE in groundwater was reported to be 36 micrograms per liter (µg/L), the highest
<br />TCE was 3.7 µg/L, and the highest cis-1,2-DCE was 1.7 µg/L. The concentration of all three VOCs
<br />were higher along the downgradient (northwest) side of that property; however, PCE, TCE, and cis-
<br />1,2-DCE were also reported in a groundwater monitoring well upgradient from 2201 Bay Road,
<br />suggesting other possible sources contributing to the groundwater impact. Groundwater monitoring
<br />reports for the 2201 Bay Road site state that “regional chlorinated solvent plume may be contributing
<br />to the on-site concentrations.”61 Because the project site is located upgradient from the 2201 Bay Road
<br />site, contamination of soil at the project site from past land use at 2201 Bay Road is unlikely; however,
<br />if the VOC concentrations in groundwater reported at 2201 Bay Road are the result of an upgradient
<br />source, VOCs may also be present in the groundwater at the project site.
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<br />The Phase I ESA identified the following Recognized Environmental Condition (REC),62 as defined
<br />by ASTM E1527-05,71 on the project site due to former site uses: “There is a potential that hazardous
<br />material used by past Site occupants or nearby commercial businesses could have impacted the Site.
<br />Additionally, a reported regional groundwater solvent plume may extend beneath the site. Sampling
<br />of soil, soil vapor, and groundwater is recommended to better evaluate site conditions prior to future
<br />use as a school.” The investigation conducted by Cornerstone Earth Group in 2014 evaluated soil, soil
<br />vapor, and groundwater quality at the project site. The investigation consisted of the collection and
<br />analyses of soil, groundwater, and subsurface and sub-slab vapor samples (i.e., vapor samples from
<br />beneath existing building foundation slabs, where vapors may collect).
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<br />Six soil borings were made at the project site to depths of 15 feet below ground surface (bgs) and
<br />shallow soil samples were collected at each boring location. At four of the locations, deeper soil
<br />samples (6 to 8 feet bgs) were also collected. Soil samples were analyzed for total petroleum
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<br />59 Piezometric surface refers to an imaginary surface that defines the level to which water in a confined or semi-
<br />confined aquifer rises to when measured in wells. For instance, groundwater may be located within permeable soil zone
<br />under clay at 10 feet below ground surface (bgs) but within a well where it is not confined by the clay layer, rise to 5 feet
<br />bgs.
<br />60 Amec Geomatrix, Inc., 2011. Fourth Quarter 2010, Groundwater Monitoring Program Report, 2201 Bay Road,
<br />Redwood City, CA. January 28.
<br />61 Ibid.
<br />62 REC are defined in ASTM E1527-05 as “the presence or likely presence of any hazardous substances or petroleum
<br />products on a property under conditions that indicate an existing release, a past release, or a material threat of a release of
<br />any hazardous substances or petroleum products into structures on the property or into the ground, groundwater, or surface
<br />water of the property.” According to ASTM E1527-05, the term “REC” is not intended to include de minimis conditions that
<br />generally do not present a material risk of harm to public health or the environment and that generally would not be the
<br />subject of an enforcement action if brought to the attention of appropriate governmental authorities.
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<br />ATTY/RESO.0032/PC RESO APPROVING CEQA - 860 CHARTER ST. EXHIBIT A
<br />REV: 06-15-17 PR
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