monolithic memories


The former Monolithic Memories Superfund Site (the “Site”) comprised three buildings, at 1165 E. Arques Avenue, 1175 E. Arques Avenue, and 1160 Kern Avenue in Sunnyvale, California. Two buildings, referred to as Building 1 (1165 E. Arques) and Building 2 (1175 E. Arques), were used for semiconductor manufacturing from 1970 until 1987, when Advanced Micro Devices, Inc. (AMD) merged with Monolithic Memories, Inc. (MMI) and assumed responsibility for the Site. MMI began leasing the 1160 Kern property in 1974. The building on this property, Building 3, was used for office space, product handling and testing, and administration until it was closed in 2003. The 1165/1175 E. Arques property has been sold and redeveloped as a fitness center. The 1160 Kern Avenue property is currently occupied by a non-profit organization. In 1982, soil and groundwater at the Site were found to be impacted with volatile organic compounds (VOCs) attributed to leaks from underground chemical storage tanks, acid neutralization systems (ANSs), and chemical handling areas associated with Buildings 1 and 2. The tanks and ANSs were removed, along with impacted soil. Soil vapor and groundwater extraction systems were installed and operated to remove VOCs from soil and groundwater. The Site cleanup is being conducted under an order from the California Regional Water Quality Control Board (Regional Water Board). In 2005, AMD donated the 1165/1175 E. Arques property to a local charity, which then sold the property to TWC Storage, LLC (TWC). Buildings 1 and 2 and associated facilities, including the on-Site groundwater treatment system, were demolished to accommodate redevelopment. During demolition activities, TWC’s contractors damaged a transformer, spilling approximately 250 gallons of tetrachloroethylene (also known as Perc, or PCE) on the ground surface. TWC implemented soil and groundwater cleanup operations under oversight of the Regional Water Board. VOCs from off-Site industrial operations to the south have contributed to a regional groundwater plume extending beneath and downgradient (north) of the Site. Impacts related to former Site operations are generally localized and limited to shallow (A Zone) groundwater, whereas impacts from the regional plume extend into the deeper (B) Zone. The Site contamination is not impacting municipal drinking water supplies.

Hazardous Ranking Score

36 / 100

A score of 28.5 or higher qualifies a site for the Superfund National Priority List.

Regional Contact

Region 9
Phone: (415) 947-4251

Contact Region



Site Inspection
Preliminary Assessment
Final Listing On NPL

Contaminants & Health Effects

      Endocrine Disrupter
      Reproductive Toxin
      Persistent, bioaccumulative and toxic


        African American
        American Indian and Alaska Native
        Native Hawaiian


        People living
        within a 1 mile radius


        Average Income


        Occupied homes

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