SEMS-RM DOCID # 100010693
FIFTH FIVE-YEAR REVIEW REPORT FOR
NATIONAL SEMICONDUCTOR CORPORATION SUPERFUND SITE AND MONOLITHIC MEMORIES SUPERFUND SITE
SANTA CLARA COUNTY, CALIFORNIA
PREPARED BY
U.S. Army Corps of Engineers, Seattle District
FOR
U.S. Environmental Protection Agency, Region IX
and
Regional Water Quality Control Board
Date: Apprnv~ IW~ B Cj IZ-t.f ( I & Dana Ba ~ stant Division Director Superfund Site Cleanup Branch U.S. Environmental Protection Agency, Region 9
Digitally signed by
--A¾i;-----~uit 1 Stephen Hill 'C / ,J / ' -- - ,-~ Approved by: Date: 2018.09.21 Date: 08:27:29 -07'00' September 21, 2018 Stephen Hill, Chief of Toxic Cleanup Division, Regional Water Quality Control Board San Francisco Bay Region
Fifth Five-Year Review for NSC and MMI Superiund Sites 1 [This page is intentionally left blank.]
Executive Summary
This is the fifth Five-Year Review of both the Monolithic Memories Superfund Site and the National Semiconductor Corporation Superfund Site (collectively, the Sites). The Monolithic Memories Superfund Site (a.k.a. Monolithic Memories Site, Monolithic Memories, Inc. Site or Advanced Micro Devices 1165/1175 East Arques Avenue Site) is located in Sunnyvale, California. The National Semiconductor Corporation Superfund Site (a.k.a. National Semiconductor Site or Texas Instruments Site) is located in Santa Clara, California. The purpose of this Five-Year Review (FYR) is to review information from the investigation and remediation activities conducted over the previous five years (2013 to 2018) to determine if the remedy is and will continue to be protective of human health and the environment. Previous FYRs have been issued for each site individually; however, because the Sites are adjacent and the plumes emanating from the Sites have comingled, the two FYRs have been combined into one report. The Sites have been subdivided into three Subunits (see Figures 1 and 2):
• Subunit 1 - the former National Semiconductor Corporation campus; located between Kifer Road and East Arques Avenue at 2900 Semiconductor Drive, and includes the former United Technologies Corporation (UTC) facility at 1050 East Arques Avenue.
• Subunit 2 - the former Monolithic Memories, Inc. campus; including two properties at 1165/1175 East Arques Avenue (former Buildings 1 and 2, demolished in 2005) and 1160 Kern Avenue (Building 3).
• Subunit 3 - the comingled solvent plume downgradient of the former National Semiconductor Corporation campus, former United Technologies Corporation facility, and former Monolithic Memories, Inc. campus.
Semiconductor manufacturing activities previously conducted at the Sites has resulted in soil, soil vapor, and groundwater that is predominately contaminated with volatile organic compounds (VOCs), including chlorinated solvents and aromatics, as well as semi-VOCs. The following chemicals were identified, with approval of the California Regional Water Quality Control Board, San Francisco Bay Region (Regional Water Board), as indicator compounds to define the extent of groundwater contamination at the Sites: trichloroethene (TCE), 1,1,1-trichloroethane (1,1,1-TCA), cis-1,2- dichloroethene (cis-1,2-DCE), 1,1-dichloroethene, and trichlorotrifluoroethene (Freon 113). Other contaminants of concern, including benzene, xylenes, polynuclear aromatic hydrocarbons (PAHs), and phenols, have also been identified at the Sites to a varying extent.
A Record of Decision (ROD) was issued by the United States Environmental Protection Agency (USEPA) on September 11, 1991, to remediate the groundwater and soil contamination at the Sites. The selected final remedy included groundwater extraction, treatment of groundwater by air stripping or ozone oxidation, discharge of treated water under a National Pollution Discharge Elimination System (NPDES) permit, soil vapor extraction or excavation, and institutional controls or deed restrictions prohibiting the use of shallow groundwater and controlling activities that could endanger public health or the environment. All remedies described above have been implemented for the Sites.
Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites iii On January 31, 2002, Texas Instruments, Inc. assumed responsibility for groundwater monitoring throughout all Subunits.
Currently groundwater is extracted through two systems, the National Semiconductor Corporation On- Site Extraction System in the southern portion of Subunit 1 (a.k.a. Bisco air stripper system) and the Lakeside system in the northern part of Subunit 3. Another groundwater extraction and treatment system located in the northern portion of Subunit 1 (Arques system) has been offline since September 2016 due to aging infrastructure and decreased mass recovery. Regional Water Board approval of the continued shutdown was issued in January 2018.
A fourth groundwater extraction and treatment system was operating in Subunit 2 until 2005, at which time the Regional Water Board approved its shutdown based on the near attainment of cleanup goals for the extracted groundwater and plans for redevelopment. Months after the shutdown of the treatment system in Subunit 2, a perchloroethene (PCE) spill occurred at the former Monolithic Memories Site. TWC Storage was the property owner and responsible party at the time of the PCE spill. Regular monitoring of indoor air or soil vapor in this area is warranted due to the proximity of sensitive populations (i.e., a daycare for children) and elevated contaminant concentrations in groundwater. Select monitoring wells near the 2005 PCE spill area (MW-3, EX-1, and EX-2) have not been sampled since the last FYR, counter to direction by the Regional Water Board.
In addition to groundwater extraction and treatment, in-situ technologies, including chemical oxidation via persulfate injection and bioremediation, have been utilized to treat groundwater at suspected source areas at Subunit 1 (at and near the former National Semiconductor Corporation campus). Vapor intrusion assessments have been completed in several buildings throughout Subunits 1 and 2 and parts of Subunit 3. Mitigation measures to address vapor intrusion issues have been implemented where warranted.
Exposure assumptions are still valid, since the existing land use covenants restrict usage of groundwater for a drinking water source and prevent the use of the Sites for residential purposes on Subunits 1 and 2. Drinking water is supplied to residences and business in Subunit 3 from the City of Santa Clara. Therefore, there is no exposure to contaminated groundwater. The exposure assumptions used to develop the Human Health Risk Assessment (HHRA) were for potential future exposures if untreated groundwater were to be used for drinking water and if residential land uses were to occur on the Sites. A number of toxicity value revisions have occurred since the ROD. These changes do not affect the protectiveness of the cleanup levels selected in the ROD. There have been no changes in standardized risk assessment methodologies during this FYR period that could affect the protectiveness of the remedy.
Overall, the remedy is progressing as expected towards meeting Remedial Action Objectives (RAOs). Concentrations of contaminants of concern in groundwater have been significantly reduced and continue to decrease. Soil source areas have been remediated and no further releases are occurring.
The remedies at the Monolithic Memories and National Semiconductor Superfund Sites protect human health and the environment because exposure pathways that could result in unacceptable risks are iv Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites being controlled and institutional controls restrict land use and groundwater use as a drinking water source. Vapor intrusion assessments are ongoing in buildings over the plume. Where necessary, mitigation measures to address vapor intrusion issues are being implemented, however, the remedy does not require these measures. To be protective in the long-term, consideration should be given to modifying the remedy to: incorporate existing mitigation systems; require evaluation and mitigation of vapor intrusion, as appropriate; and implement long-term monitoring plans for mitigated buildings and buildings at risk for future unacceptable vapor intrusion.
At the Monolithic Memories Site, multiple indoor air sampling events were completed at a children’s daycare facility which showed no evidence of unacceptable vapor intrusion. The two most recent indoor air sampling events in June 2012 continued to indicate no unacceptable vapor intrusion risk to children or staff. However, TCE concentrations in soil vapor and groundwater monitoring wells near the daycare remain elevated and the daycare occupants are considered a sensitive population. To be protective in the long-term, and considering the sensitive population and out of caution, additional confirmatory sampling should be conducted at the daycare facility and a long-term indoor air monitoring program should be developed and implemented to continue to verify that indoor air VOC levels due to vapor intrusion remain protective. The frequency of future monitoring may be reduced based on an evaluation of the sampling results obtained.
Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites v Contents
1. Introduction ...... 1 1.1. Background...... 3 1.2. Physical Characteristics ...... 3 1.3. Hydrology ...... 7 1.3.1. Regional ...... 7 1.3.2. Local ...... 7 2. Remedial Actions Summary ...... 8 2.1. Basis for Taking Action ...... 8 2.2. Remedy Selection ...... 8 2.3. Remedy Implementation ...... 9 2.4. Operation and Maintenance (O&M) ...... 14 3. Progress Since the Last Five-Year Review ...... 14 3.1. Previous Five-Year Review Protectiveness Statement and Issues ...... 14 3.2. Work Completed at the Site During this Five-Year Review Period ...... 16 4. Five-Year Review Process ...... 18 4.1. Community Notification, Involvement and Site Interviews ...... 18 4.2. Data Review ...... 18 4.2.1. Soil ...... 18 4.2.2. Groundwater ...... 19 4.2.3. Vapor Intrusion ...... 23 4.3. Site Inspection ...... 25 5. Technical Assessment ...... 26 5.1. Question A: Is the remedy functioning as intended by the decision documents? .... 26 5.2. Question B: Are the exposure assumptions, Toxicity Data, Cleanup Levels, and Remedial Action Objectives (RAOs) Used at the Time of Remedy Selection Still Valid? .. 27 5.3. Question C: Has Any Other Information Come to Light That Could Call Into Question the Protectiveness of the Remedy? ...... 27 6. Issues/Recommendations ...... 28 7. Protectiveness Statement ...... 29 8. Next Review ...... 30 Appendix A: List of Documents Reviewed ...... 31 Appendix B: Site Chronology ...... 34
vi Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites Appendix C: Vapor Intrusion Data Review ...... 39 Appendix D: Groundwater Data Review ...... 56 1. Groundwater Gradient ...... 56 2. Hydraulic Control ...... 56 3. Groundwater Concentration Analysis ...... 56 A-aquifer ...... 57 Building C ...... 57 Building G...... 57 B1-aquifer ...... 58 B2-aquifer ...... 58 Appendix E: ARAR Assessment ...... 72 Appendix F. Toxicity Assessment ...... 74 Appendix G: Press Notice ...... 76 Appendix H: Interview Forms ...... 77 Appendix I: Site Inspection Checklist ...... 82 Appendix J: Photographs from Site Inspection Visit ...... 91
List of Figures
Figure 1. Location Map for the National Semiconductor Superfund Site and Monolithic Memories Superfund Site ...... 5 Figure 2. Detailed Map of the National Semiconductor Superfund Site and Monolithic Memories Superfund Site ...... 6 Figure 3. A-Aquifer TCE Concentration Contour, October 2017 ...... 21 Figure 4. B-1-Aquifer TCE Concentration Contour, October 2017 ...... 22
List of Tables
Table 1. Five-Year Review Summary Form ...... 2 Table 2. Cleanup Standards and ARARs from 1991 ROD ...... 9 Table 3. Summary of Planned and/or Implemented Institutional Controls (ICs) ...... 13 Table 4. Status of Recommendations from the 2013 & 2014 FYRs ...... 15 Table 5. Status of Buildings considered for Vapor Intrusion ...... 23 Table 6. Issues and Recommendations Identified in the Five-Year Review ...... 28
Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites vii Table 7. Protectiveness Statement ...... 29
List of Abbreviations
AMD Advanced Micro Devices, Inc. ARAR Applicable or Relevant and Appropriate Requirement bgs below ground surface CERCLA Comprehensive Environmental Response, Compensation, and Liability Act DCE dichloroethene ESL Environmental Screening Level (Regional Water Board) FYR Five-Year Review GWET groundwater extraction and treatment systems HVAC heating, ventilation, and air conditioning ICs institutional controls MCL maximum contaminant level MMI Monolithic Memories, Inc. NFA No Further Action NPDES National Pollutant Discharge Elimination System NPL National Priorities List NSC National Semiconductor Corporation OU operable unit O&M operation and maintenance PAH polycyclic aromatic hydrocarbon PCE perchloroethene or tetrachloroethene RAO remedial action objectives RAP Remedial Action Plan ROD Record of Decision RSL Regional Screening Level RWQCB California Regional Water Quality Control Board, San Francisco Bay Region (Regional Water Board) SMP Soil Management Plan SVE soil vapor extraction SVOC semi-volatile organic compounds TCE trichloroethene TI Texas Instruments, Inc. TWC TWC Storage LLC USACE United States Army Corps of Engineers USEPA United States Environmental Protection Agency VOC volatile organic compounds
viii Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites 1. Introduction
The purpose of this Five-Year Review (FYR) is to evaluate the implementation and performance of a remedy at and near the Monolithic Memories (MM) Superfund Site (Monolithic Memories Site) and the National Semiconductor Corporation (NSC) Superfund Site (National Semiconductor Site), together, the Sites. This evaluation is being conducted to determine if the remedy will continue to be protective of human health and the environment. The methods, findings, and conclusions of reviews are documented in FYR reports. In addition, FYR reports identify issues found during the review, if any, and document recommendations to address them.
The United States Environmental Protection Agency (USEPA) and California Regional Water Quality Control Board, San Francisco Bay Region (Regional Water Board) are preparing this FYR pursuant to the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) Section 121, 40 Code of Federal Regulation Section 300.430(f)(4)(ii) of the National Hazardous Substances Pollution Contingency Plan and USEPA policy.
This is the fifth FYR for the Sites. Previously, FYRs were prepared individually for each site; this is the first year where the Sites are combined into a single FYR report. The triggering action for this statutory review is the completion of the previous FYRs for the Sites. This FYR has been prepared due to the fact that hazardous substances, pollutants, or contaminants remain at the Sites above levels that allow for unlimited use and unrestricted exposure. Monolithic Memories, Inc. and NSC have transferred the cleanup responsibilities for the Monolithic Memories Site and National Semiconductor Site to Advanced Micro Devices, Inc. (AMD) and Texas Instruments, Inc. (TI), respectively.
The Sites consist of two Operable Units (OUs) – OU1 and OU2 (now referred to as the Stewart Drive OU). OU1 consists of three Subunits (Figure 1), all of which will be addressed in this FYR. OU1 addresses remediation of contaminated soil on the facility property and groundwater in the upper aquifer zone. This OU includes areas that have been thoroughly investigated such that a final remedy has been selected. A remedy has not been selected for OU2 (now referred to as the Stewart Drive OU) and therefore, it is not addressed in this FYR.
This FYR was led by Ron Goloubow, Engineering Geologist, Regional Water Board, and Melanie Morash, Remediation Project Manager, USEPA. Participants included U.S. Army Corps of Engineers (USACE) staff Kayla Patten (Environmental Engineer), Benino McKenna (Geologist), Leanna Woods Pan (Environmental Engineer), and Amy LeFebvre (Geologist). The review began on October 13, 2017.
Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites 1 Table 1. Five-Year Review Summary Form SITE IDENTIFICATION
Site Name: Monolithic Memories Superfund Site / National Semiconductor Corporation Superfund Site
USEPA ID: CAD049236201 / CAD041472986
City/County: Sunnyvale/Santa Clara Co. and Santa Region: 9 State: CA Clara/Santa Clara Co.
SITE STATUS
NPL Status: Final
Multiple OUs? Yes Has the site achieved construction completion? Yes
REVIEW STATUS
Lead agency: State of California Author name (Federal or State Project Manager): Ron Goloubow (State) and Melanie Morash (Federal) Author affiliation: USACE for California Regional Water Quality Control Board, San Francisco Bay Region and USEPA Review period: 10/13/2017 – 7/21/2018 Date of site inspection: 1/9/2018 Type of review: Statutory Review number: 5 Triggering action date: 9/30/2013
Due date: 9/30/2018
2 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites 1.1. Background
The Monolithic Memories and National Semiconductor Corporation Superfund Sites, together, the Sites, are former semiconductor manufacturing facilities located in Sunnyvale and Santa Clara, Santa Clara County, California. The properties have transferred ownership several times, and therefore the responsible parties have changed throughout the history of the Sites. Advanced Micro Devices, Inc. (AMD) assumed clean up responsibilities at the Monolithic Memories Site in 1987 after Monolithic Memories, Inc. merged into AMD and continued industrial operations at the site until 1989. Following a settlement agreement between NSC and AMD, NSC assumed responsibility for groundwater remediation of the entire comingled plume on January 31, 2002. TWC Storage LLC (TWC) purchased Building 1 on Monolithic Memories Site, located at 1165 East Arques Avenue, in April 2005. Texas Instruments, Inc. (TI) acquired the National Semiconductor Site through a merger with NSC in September 2011, assuming responsibility for clean-up at the National Semiconductor Site, as well as monitoring of all Subunits.
1.2. Physical Characteristics
Remediation of the Sites has been combined because releases of volatile organic compounds (VOCs) at the Sites contribute to the same groundwater contamination problem. The Sites are located in Sunnyvale and Santa Clara, Santa Clara County, California, which each have populations greater than 100,000. Land surrounding the Sites is primarily used for commercial and light industrial purposes, with some residential land use downgradient (north) of the source areas and within Subunit 3. The Sites are located within the confined area of the Santa Clara Valley groundwater basin. Groundwater from this basin currently provides approximately 62% of the municipal drinking water for Santa Clara Valley residents.
The Sites are approximately 345 acres in size and are subdivided into three Subunits (Figures 1 and 2):
• Subunit 1 – The National Semiconductor Site is located within Subunit 1, which includes the former National Semiconductor Corporation Campus between Kifer Road and East Arques Avenue in the southern portion of Subunit 1 (south of Central Expressway), as well as the former United Technologies Corporation (UTC) facility at 1050 East Arques Avenue, in the northwest corner of Subunit 1. Subunit 1 is approximately 150 acres in size;
• Subunit 2 – The Monolithic Memories Site is bounded within Subunit 2, and includes the former Monolithic Memories, Inc. properties at 1165/1175 East Arques Avenue (former Buildings 1 and 2) and the property at 1160 Kern Avenue (Building 3). Subunit 2 is approximately 7 acres in size; and
• Subunit 3 - the comingled solvent plume downgradient of the source zones (former NSC campus, former UTC facility, and former Monolithic Memories campus). Subunit 3 is approximately 190 acres in size.
Site investigations at the Sites began in 1982. Soil and groundwater samples were collected adjacent to underground solvent tanks, sumps, and associated piping. Chemical analyses of these samples at the National Semiconductor Site indicated that VOCs, including trichloroethene (TCE), perchloroethene or tetrachloroethene (PCE) and their degradation products, had impacted soil and groundwater in these
Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites 3 areas. Extensive investigations confirmed that VOCs have impacted soil at the Sites and the two uppermost aquifers to a depth of approximately 60 feet below grade. In addition, relatively low concentrations of perchlorate were detected in groundwater samples at the former UTC facility. NSC assumed the environmental liability for the former UTC facility in 1987. Contamination at the Monolithic Memories Site included VOCs and polynuclear aromatics (now called polycyclic aromatic hydrocarbons or PAHs), and the source of this contamination included releases from solvent tanks and acid waste neutralization systems. An additional PCE spill occurred at the Monolithic Memories Site on a property that had been purchased by TWC Storage LLC (TWC) in 2005. Current and former land use at the Sites and surrounding area is restricted to light industrial and commercial, with some residential areas in Subunit 3. Groundwater use is restricted in all Subunits and groundwater is not used for drinking water.
A chronology of key events and activities at the Sites are included in Appendix B.
4 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites .... s :: Ca rson :c tf1ty
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San Fran cisco .,. 0 ? -i. San Jos9, ....0 ? Site Location_J 0 C. ;,. w.' AL If RN! M...... A
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Legend
[=:J Operable Unit 1, Subunit 1, 2, 3 Figure 1 SITE LOCATION MAP ,,f.______.....______. • Map modified from Figure 1 in Soil and Groundwater Investigation Work Pl an. Prepared by Langan Treadwell Rollo. 11 February 2016 Figure 1. Location Map for the National Semiconductor Superfund Site and Monolithic Memories Superfund Site
Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites 5 ;-- ,_ ' :' \ / '1 ./ r :/ ,Iii, :!
i' II
OU 1 Subunit 3 : I : - l..:: , / (Monot,h11~·ai1e.f. orles site) /
j L _ _ L ~ ----······ 1---- v OU 1 Subunit 1 /
························
Legend
• '• Operable Unit 1 and Subunit Boundanes
D Texas Instruments Campus, ...... /! - Former Advanced Miero Deviees Campus
Figure 2. SITE PLAN Operable Unit 1 (OU1),
Subunits 1, 2 1 and 3
~or,-.-r.,no. Figure 2. Detailed Map of the National Semiconductor Superfund Site and Monolithic Memories Superfund Site 6 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites 1.3. Hydrology 1.3.1. Regional The Sites are located in the Santa Clara Valley which extends southeast of San Francisco Bay, bounded by the Diablo Range to the northeast and by the Santa Cruz and Gabilan Ranges to the southwest. The Santa Clara Valley is a fault-bounded structural basin filled with marine and alluvial sediments from the adjacent mountain ranges with alternating layers of coarse and fine deposits in a heterogeneous sequence of interbedded sands, gravels, silts, and clays. These deposits are up to 1,500 feet thick. At the base of the adjacent mountains, gently sloping alluvial fans of the basin tributaries laterally merge to form an alluvial apron extending into the interior of the basin. The Santa Clara Valley groundwater basin is divided into two broad areas: (1) the recharge zone or forebay, and (2) the confined zone. The Sites are in the confined zone. The forebay occurs along the elevated edges of the basin where the basin receives its principal recharge. The confined area is in the flatter interior portion of the basin and is stratified or divided into individual beds separated by significant aquitards. The confined zone is divided into the upper and lower aquifer zones. The division is formed by an extensive regional aquitard that occurs at depths ranging from about 100 feet, near the confined zone's southern boundary, to 150 to 250 feet in the center of the confined zone and beneath San Francisco Bay. Thickness of this regional aquitard varies from about 20 feet to over 100 feet. 1.3.2. Local Stratigraphy in the local area is characterized by interbedded gravel, sands, silts, and clays. These soils were deposited in complex patterns by fluvial alluvial systems draining the uplands on the east and west of the valley; sediments were deposited as the various streams flowed northward towards San Francisco Bay. The nomenclature applied to the water-bearing zones is representative of the hydrogeology within the Santa Clara groundwater basin. Several shallow water-bearing zones are separated from deeper zones by the thick, persistent regional aquitard. The shallow zones may be subdivided into a variety of zones depending upon depth, lithology, and lateral persistence. These zones are frequently labeled as the A and B aquifer zones (A and B aquifers). The deeper aquifer is commonly referred to as the C aquifer and the clay layer separating the upper and lower water-bearing aquifers is commonly referred to as the B-C aquitard. The shallowest water-bearing zone at the Sites has been identified as the A aquifer and it occurs between 5 and 25 feet below ground surface (bgs). The next deeper water-bearing zone has been identified as the B aquifer and has been subdivided into three water-bearing aquifers, B1 through B3, based on the depths at which major sand units are encountered. The B1 aquifer is encountered between 30 and 45 feet bgs; the B2 aquifer between 45 and 70 bgs; and the B3 aquifer between 70 and 90 feet bgs. The A aquifer and B aquifer is separated by the A/B aquitard. The groundwater gradient in all identified aquifer zones is in a north-northeast direction. Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites 7 2. Remedial Actions Summary 2.1. Basis for Taking Action The Sites overly the Santa Clara Valley groundwater basin. At the time the Record of Decision (ROD) was signed, groundwater from this basin provided up to approximately 50% of the municipal drinking water for over 1.4 million residents of Santa Clara Valley. The presence of VOCs in soils and groundwater at the Sites, including groundwater contaminated with known human carcinogens (vinyl chloride) and probable human carcinogens (1,1-DCA, PCE, and TCE) and the threat of migration to public water supplies provided the basis for taking action. 2.2. Remedy Selection USEPA selected a remedy for the Sites in a Record of Decision (ROD), signed in September 1991. The Remedial Action Objectives (RAOs) were to remove and permanently destroy the contaminants from both soils and groundwater or to significantly reduce the toxicity, mobility or volume of hazardous substances in both media. The RAO of the groundwater component of the remedy was to return groundwater to its beneficial uses within a reasonable timeframe. The RAO of the soil component of the remedy was to prevent direct exposure to soil contamination and to remove enough contamination to protect the groundwater. The selected final remedy in the 1991 ROD included the following elements: • Groundwater extraction to control further migration of site chemicals in the contaminated aquifers and reduce concentrations until cleanup standards have been achieved; • Treatment of extracted groundwater with air stripping or ozone oxidation under Bay Area Air Quality Management District (BAAQMD) permit or pursuant to USEPA Office of Solid Waste and Emergency Response (OSWER) Directive 9355.0-28; • Discharge of extracted and treated groundwater to storm sewers under National Pollutant Discharge Elimination System (NPDES) permits; • Soil Vapor Extraction (SVE) where vadose zone soils present a potential continuing source of contamination to groundwater or where shallow soils represent a health risk due to direct contact. SVE conducted under a BAAQMD permit; • Removal of shallow soils at the Monolithic Memories Site, contaminated with semi-volatile organic compounds (SVOCs), if SVE unsuccessful; and • Institutional Controls prohibiting the use of the A and B aquifer groundwater and for controlling activities that could endanger the public health or the environment. The ROD set groundwater cleanup standards at California proposed or adopted Maximum Contaminant Levels (MCLs), USEPA MCLs, California Action Levels, or levels based on a risk assessment (Table 2- 1). 8 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites Table 2. Cleanup Standards from 1991 ROD Site Cleanup Chemical Name Basis of Standard Standard (µg/L) Groundwater Benzene 1 California MCL Chlorobenzene 30 California MCL Site-specific health protective standards set considering Chloroform 5 calculated cancer risks and hazard indices. Site-specific health protective standards set considering Chloromethane 5 calculated cancer risks and hazard indices. Site-specific health protective standards set considering 4-Chloro-3-methylphenol 7 calculated cancer risks and hazard indices. 1,2-Dichlorobenzene 60 One-tenth the federal MCL 1,1-Dichloroethane 5 California MCL 1,1-Dichloroethylene 6 California MCL 2,4-Dimethylphenol 46 California Action Level Site-specific health protective standards set considering 2,4-Dinitrophenol 5 calculated cancer risks and hazard indices. Ethylbenzene 68 One-tenth California MCL Freon 113 1200 California MCL Site-specific health protective standards set considering 2-Methyl-4,6-dinitrophenol 1 calculated cancer risks and hazard indices. Pentachlorophenol 1 Federal MCL Phenol 5 California and Federal MCL Tetrachloroethene 5 California MCL Trichloroethene 5 California and Federal MCL Vinyl chloride 0.5 California MCL Xylene (total) 175 One-tenth California MCL Site Cleanup Chemical Name Standard Basis of Standard (mg/kg) Soil Site-specific health protective standards set considering Total VOCs 1 calculated cancer risks and hazard indices. Polynuclear Aromatic Site-specific health protective standards set considering 10 Hydrocarbons calculated cancer risks and hazard indices. 2.3. Remedy Implementation Soil Remediation – Subunit 1 SVE and treatment was initiated in 1992 and has been conducted at 14 former source areas within the former NSC campus in Subunit 1. By February 2005, SVE was concluded in all but one of these source Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites 9 areas upon receiving confirmation from the Regional Water Board that soil cleanup standards were met. The SVE system at the Building C Leak 5 Area was shut down in March 2005. Total VOC mass removed to date by the SVE system is 26,261 pounds. The last known remaining soil source area within the former NSC campus in Subunit 1 is near and under Building C1. Between December 21, 2009 and January 2, 2010, approximately 1,440 tons of VOC- impacted soil exceeding the cleanup criteria was removed from Subunit 1 and sent to a permitted landfill. Soil between 11 and 12 feet was treated through in-situ chemical oxidation via an infiltration gallery, where over 20,000 gallons of persulfate has been injected into the soil since 2013 to treat impacted soil and groundwater. Soil Remediation – Subunit 2 An SVE system was installed and operated north of Building 2 at the former Monolithic Memories facility in Subunit 2 in 1993 to treat vadose zone soil contamination. The SVE system operated until 1996 when it was demonstrated, to the satisfaction of the Regional Water Board, that soil cleanup standards had been achieved. The SVE system was removed in 2000 and the seven associated SVE wells were decommissioned in 2005. Following a PCE spill from a transformer damaged during demolition of Building 1 at the former Monolithic Memories facility in Subunit 2, TWC conducted soil excavation and cleanup activities during the summer of 2005. These activities included removing approximately 3,100 tons or 2,300 cubic yards of contaminated soil and the application of 2,430 pounds of hydrogen release compound prior to backfilling the excavation. A Remedial Action Plan (RAP) to address the PCE spill was approved by the Regional Water Board on April 25, 2007, separate from the ROD. The remediation goal was to restore the soil and groundwater quality at Monolithic Memories Site to its approximate historic conditions prior to the 2005 PCE release. A groundwater cleanup standard of 40 micrograms per liter (μg/L) was initially selected based on the historical average PCE concentration in groundwater at the Monolithic Memories Site prior to the PCE release. The soil cleanup standard was the Regional Water Board Environmental Screening Level (ESL), which was 240 micrograms per kilogram (μg/kg) at that time. In November 2007, the ESL, and consequently the soil cleanup standard, was changed to 700 μg/kg. Multi-Phase Extraction wells (i.e., soil vapor and groundwater extraction wells) were proposed in the RAP as the remedial technology to further remediate PCE-affected soil and groundwater beneath the Monolithic Memories Site and vicinity. Nine Multi-Phase Extraction wells were installed in September 2007 to remediate PCE soil and groundwater contamination related to the 2005 spill. The soil vapor and groundwater extraction and treatment system was shut down on November 10, 2008, with Regional Water Board approval, because PCE mass removal had reached an asymptotic condition. Concentrations in soil have decreased and no soil concentrations exceeding soil cleanup goals are known to remain at the Monolithic Memories Site. A No Further Action (NFA) Work Plan was approved by the Regional Water Board for the 2005 PCE release in April 2012, with the caveat of requiring additional groundwater monitoring. 1 TWC Storage purchased the 1165 and 1175 East Arques Avenue property in 2005 to develop a self-storage facility. 10 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites Groundwater – Subunits 1, 2, and 3 Groundwater extraction and treatment (GWET) has been conducted at Subunits 1 and 2 since 1984 with additional groundwater extraction capabilities implemented in 1986, 1988, 1990, and 1992. In 2001, an extraction well and large drain dewatering system (Lakeside drain) started operating in Subunit 3. In 2002, NSC assumed responsibility for groundwater monitoring and treatment systems of the entire commingled plume. NSC operated 36 extraction wells and the Lakeside dewatering system (Subunit 3) from 2001 to 2005. From 2008 to 2016, NSC operated two GWETs in Subunit 1 (the Arques system and the On-Site system), and one GWET in Subunit 3 (the Lakeside system). The Arques system was shut down in September 2016 due to a leak in the main conveyance line for untreated groundwater and has not been restarted due to declining concentrations downgradient and liabilities associated with the age of the system. Regional Water Board approval of the continued shutdown was issued in January 2018. Currently, only the On-Site and Lakeside groundwater extraction systems are operating. Effluent from the treatment systems is treated by air stripping and ozone technologies and then discharged under an NPDES permit to Calabasas Creek. NSC installed an ozone sparging system with SVE and treatment in September 2001 at Subunit 1 to address lingering high VOC concentrations in groundwater at a former source area near former Buildings 2, 3, and 4. As cleanup progressed in various zones, ozone injection was halted in March 2007 and in February 2008. OS/SVE was discontinued in the A zone at the end of January 2009 due to required OS/SVE system repairs. Alternative in-place remedial approaches are being evaluated. The GWET system at Subunit 2 was decommissioned in 2005 to accommodate property redevelopment. Currently there is no groundwater cleanup system operating at Subunit 2. In addition to the decommissioning of the GWET system at Subunit 2, extraction from several wells throughout the plume were suspended with approval of the Regional Water Board because they had low VOC mass removal, low pumping/extraction rates, or both. Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites 11 .. ,'. ·- ...... ,'. ·- ...... 16,._oo: ;.,.., ..,~ t• .., '. . .. '' ,,,• ...... J / I ,,, ., ...... ,..,,,' )t-t/d',ii._ •••••••• / kv ...,,,., ' ' ' .. -··········· / . 0./' I!! Du<1neAY• ,' 1 ' 1 .. .. .: '. SDOU ,' . . .'' ' / ,,.: OakmudPlic'f .. . , .. . , OU 1 .. / ~,#' Subunit 3 .. . ~ . , ,• I . ,. . ······ ...... ~ .' r.- Ste..wartOr . . . ,' 0 . . TltanWJy . .. . .i I 1 KernA..., ••••-- • . ,.., 'OU 1 1 .. .. •'ff S~bunit 2 : .. .. ,, ...... 1; :., 1· .. ·: .' 1 . 1 1'.I I I . . I I I I . ,' _.,E~!Jtu_es.. 4,ye .. • ..! .... I : ! 2 • 3 • : ;-~~-1 I ...... ; - .. _, -- .. - - - - - • - - -·- --- .. - I,, - .. -- ..... ------: . .' . . OU 1 . . .. Subunit 1 ...... : ...... Centr•I Expy . i (>r,\,:,\t.1,f'i . parking ...... D E .. .. 19 9 39 .. j ::" . . B . . 0 . . I W C A l G I I ~ I I I j 1' •• • • ...... • ...... ,Ktfer,Aw. - .. I ... - ...... ,. ,. ,. .. ,. Kifer Ave SonoraCI JOO 600 Legend 1.200 t • Monkoring Well ,.~ Figure. Operable Unk Boundary Road Edge Select Building Bulling SOOU • Sew11rd Drive Operable Unit Locations at NSC and Notes: 001 - Operable Unil: 1 1. Al locations lobe considered accurate MMI Sites 2. TCE cc:ncentratlons dis played a~ In ugll. 3. Map displayed In Califoml11 State P111ne Cooninete System, Zone Ill, North American Datum of 1983 (NAD83). US survey Feet. Map modified from Figure 8 in the 2016 Annual Groundwater Monitoring Report prepared for Texas Instruments, prepared by Langan *Former buildings on the Monolithic Memories/AMD property. Former Building 3 is currently referred to as 1160 Kern Ave. Former Buildings 1 and 2 have been demolished. Figure 3. Select Building Locations at the Sites 12 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites Table 3. Summary of Planned and/or Implemented Institutional Controls (ICs) ICs Called Title of IC ICs for in the Impacted IC Instrument Media Needed Decision Parcel(s) Objective Implemented and Documents Date NSC Site: Restrict installation 205-38-008 of groundwater Covenant and 205-38-022 wells, groundwater Environmental Groundwater Yes Yes 205-38-021 use, and on-site Restriction on 205-39-022 activities (land use) Property, 205-39-018 that could endanger September 2014 205-39-025 public health Restrict installation MMI Site: of groundwater Covenant and 205-24-013 wells, groundwater Environmental Groundwater Yes Yes (former use, and on-site Restriction on TWC activities (land use) Property, March Property) that could endanger 2013 public health NSC Site: Restrict soil 205-38-008 excavation and on- Covenant and 205-38-022 site activities (land Environmental Soil Yes Yes 205-38-021 use) in the former Restriction on 205-39-022 source areas that Property, 205-39-018 could endanger September 2014 205-39-025 public health Restrict soil MMI Site: excavation and on- Covenant and 205-24-013 site activities (land Environmental Soil Yes Yes (former use) in the former Restriction on TWC source areas that Property, March Property) could endanger 2013 public health Require assessment, mitigation, and long- term monitoring, as Indoor Air Yes No All appropriate, of vapor N/A intrusion pathway that could endanger public health Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites 13 2.4. Operation and Maintenance (O&M) Annual groundwater monitoring for all Subunits is conducted by Langan Treadwell Rollo on behalf of TI and reports are submitted annually to the Regional Water Board. In addition, treated groundwater discharge is monitored by TI and quarterly NPDES compliance reports are submitted to the Regional Water Board. In December 2014, a new groundwater treatment system (with Bisco Air Stripper) was installed in Subunit 1 and activated near Building E, replacing the previous GWET system. Four new extraction wells and an upgraded groundwater conveyance piping system were installed to facilitate the new system in March 2016. Portions of the groundwater conveyance piping were upgraded from polyvinyl chloride (PVC) to double-walled high-density polyethylene (HDPE); the upgrade also included the addition of controls and alarms to alert TI of leaks in real-time. In April 2017, a system leak occurred and the system was shut down from May to September while TI investigated and made repairs to the system. The system resumed operation in October 2017. Currently, system operation is being refined to optimize the flow rate. The Arques groundwater extraction system immediately south of Subunit 2 was shut down in September 2016 and there are no plans to restart the aged extraction system. Regional Water Board approval of the continued shutdown of the Arques groundwater extraction system was issued in January 2018. The Lakeside groundwater capture system is operating as expected in the north area of Subunit 3. 3. Progress Since the Last Five-Year Review 3.1. Previous Five-Year Review Protectiveness Statement and Issues The protectiveness statement from the 2013 FYR for the National Semiconductor Site stated the following: A protectiveness determination of the remedy at the NSC Superfund Site cannot be made until a vapor intrusion assessment is completed at all buildings overlying the contamination. Recent indoor air sampling at on-property buildings south of the Central Expressway have indicated that there is vapor intrusion; however, the exposure levels are below screening health levels while the heating, ventilation, and air conditioning (HVAC) systems are operating. All other exposure pathways that could result in unacceptable risks are being controlled, and institutional controls are preventing exposure to, or the ingestion of contaminated groundwater. To be protective in the long term, new restrictive covenants need to be recorded, the site management plans needs to be revised to include operation and maintenance (O&M) requirements for the HVAC systems, and the Site Cleanup Requirements (SCR) and Record of Decision (ROD) will need to be mended to select a new remedy. Once the source area and downgradient vapor intrusion assessment is completed a protectiveness determination will be made. The Five-Year Review addendum, which will include the protectiveness determination, will be completed by December 31, 2014. 14 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites The protectiveness statement from the 2014 FYR for the MMI Site stated the following: The remedy at the MMI Site is currently protective of human health and the environment. Exposure pathways that could result in unacceptable risks are being controlled. Institutional Controls restrict the use of groundwater as a drinking water source. In order to be protective in the long-term, the preferential pathway investigation, mitigation and indoor air monitoring at 1160 Kern Avenue (Building 3) should be continued and an evaluation of the need for restarting the pump and treat system or a determination of an alternate remedy needs to be completed. The 2013 NSC FYR (including Subunit 1) and 2014 MMI FYR (including Subunit 2) included five issues and recommendations. Each recommendation and the current status is discussed below in Table 3-1. Table 4. Status of Recommendations from the 2013 & 2014 FYRs SubUnit Issue Recommendations Current Current Completion # Status Implementation Date (if Status Description applicable) Subunit 1 Sampling results Amend ROD and Considered Vapor intrusion indicate that vapor revise the Site But Not assessments ongoing. intrusion is occurring Management Plan to Implemented O&M Plans developed when HVAC include O&M and implemented for systems are turned requirements for the buildings that required off in select HVAC systems. vapor intrusion buildings south of Meanwhile, continue mitigation. the Central sampling indoor air Expressway. and require operation of buildings HVAC systems. Subunit 1 Existing deed A new restrictive Completed Deed restrictions have 9/25/2014 restriction is not covenant should be been updated. consistent with State recorded for the TI law because it was property that is recorded prior to the consistent with passage of California current California Civil Code section law. 1471. Subunit 1 Further vapor Conduct indoor air Ongoing Vapor intrusion intrusion assessment sampling at off- assessments have been is required off- property buildings completed at off- property. downgradient of the property buildings source area. where access was granted. Property owner for buildings SU3-5 and SU1-6 through SU1-10 denied access. Building owner conducted sampling in buildings SU1-7 through SU1-10. No Further Action with ICs are proposed for all buildings except for building SU1-1 and buildings where access Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites 15 SubUnit Issue Recommendations Current Current Completion # Status Implementation Date (if Status Description applicable) has not yet been granted. ICs will be developed for buildings at risk for vapor intrusion where access for sampling has not yet been granted. Subunit 2 Air monitoring at Continue preferential Completed Mitigation measures 8/23/2017 Building 3 (1160 pathway were implemented to Kern Ave) shows investigation, address a finding of exceedances of up to mitigation and indoor unacceptable vapor 3.5 μg/m3 of air monitoring at intrusion. Post- commercial/ 1160 Kern Ave to mitigation indoor air industrial Regional ensure compliance samples did not contain Screening Level with RSLs. TCE or PCE at (RSL) of 3.0 μg/m3. concentrations greater than the applicable commercial ESLs or RSLs. USEPA and Regional Water Board approved the Vapor Mitigation Completion Report in August 2017. Subunit 1, The pump and treat An evaluation of the Under There are currently no Subunit 2 system selected in need for restarting the Discussion plans to restart or the ROD was shut pump and treat modify the pump and down in 2005. system or a treat system. determination of an alternate remedy needs to be done. This should also be documented in a decision document. 3.2. Work Completed at the Site During this Five-Year Review Period To make current with California law, deed restrictions for a portion of the former Monolithic Memories property (1165 E Arques Ave.) were updated in March 2013 and deed restrictions were updated for the NSC campus in September 2014. The updated restrictions stipulate land use as industrial or commercial. No excavation greater than 10 feet bgs can be conducted without approval from the Regional Water Board. Furthermore, all development on the NSC campus must be in accordance with the Soil Management Plan (SMP), which was completed in November 2014. The SMP details the management of soil below 2 feet and within 50 feet of a former source area, requires soil testing for waste determination, orders monitoring wells and remediation systems be protected, and outlines notification and approval requirements. Additionally, the updated restrictions stipulate that groundwater cannot be used for human consumption, and access must be granted to Regional Water Board and persons acting on behalf of the Regional Water Board to inspect, monitor, and perform remediation. 16 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites The last known remaining soil source area within the former NSC campus is near and under Building C. Over 1,400 tons of soil exceeding VOC cleanup criteria were removed to a depth of 11 feet in 2010. Soil between 11 and 12 feet was treated through in-situ chemical oxidation via an infiltration gallery, where over 20,000 gallons of persulfate was injected into the soil since 2013 to treat impacted soil and groundwater. In-situ bioremediation is ongoing at former Building G within the former NSC campus. There is an extensive remedial history for this location including OS/SVE, in-situ chemical oxidation, and bioremediation. Most recently, bioremediation injections occurred in 2011 and 2016. Results indicate that active remediation is occurring and VOCs have been significantly reduced. In 2013, the NSC On-Site groundwater extraction system for the southern portion of Subunit 1 was upgraded as a smaller, more efficient, treatment system consisting of a single air stripper unit (Bisco Shallow Tray® Low Profile Air Stripper Model 3651) to minimize the potential for future untreated groundwater releases. The new groundwater treatment system was designed to be compatible with increased or decreased flow as groundwater extraction needs change. The new treatment system became functional in December 2014. A new double-walled piping system was installed predominately aboveground and includes leak detection and improved system monitoring controls. Two A-zone extraction wells and three B1-zone extraction wells were installed, increasing the total number of system wells to nine. Following treatment, the effluent groundwater is then re-used on campus by TI or discharged to the storm drain under a NPDES permit. The groundwater flow model was updated in September 2014 based on the current groundwater extraction system pumping locations and flow rates. Vapor intrusion assessments have been completed for several buildings in Subunits 1 and 2 and parts of Subunit 3. All eleven occupied buildings on the former NSC campus in Subunit 1 were assessed between 2013 and 2016. The Regional Water Board has issued NFA letters for nine of those buildings. Buildings 39 and C have implemented voluntary vapor mitigation systems. Throughout the remainder of Subunit 1, ten buildings were considered for vapor intrusion. Mitigation measures were implemented at one of those buildings (SU1-1), which requires additional post-mitigation indoor air sampling. Access was not available to five of the buildings in Subunit 1; at these five buildings, vapor intrusion was evaluated by the property owner. USEPA reviewed the results on-site and concluded the remedy was protective at those buildings at that time. Two buildings in Subunit 2 were evaluated and determined not to pose a risk to human health. The third building in Subunit 2 – the 1160 Kern Avenue building – was evaluated during the previous FYR period and found to be affected by unacceptable vapor intrusion, which was subsequently addressed through mitigation. Ten buildings were evaluated in Subunit 3 during this review period and no further evaluation was recommended for each building. Additional information regarding vapor intrusion work is in Section 4.2.3 and Appendix C. Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites 17 4. Five-Year Review Process 4.1. Community Notification, Involvement and Site Interviews A public notice regarding this FYR was made available by newspaper posting in the Santa Clara Weekly on May 2, 2018, stating that there was currently a FYR underway and inviting the public to submit any comments to the Regional Water Board or USEPA. The results of this review and the associated report will be made available at the Sites’ information repositories, located electronically on the Regional Water Board’s GeoTracker website and USEPA’s websites, as well as in hard copy at USEPA’s Superfund Records Center at 75 Hawthorne Street, Room 3110, San Francisco, California (Appendix G). Interviews were conducted with Hector Vargas and Elma Fung from TI and Josh Graber and Elizabeth Kimbrel from Langan Treadwell & Rollo (consultant for TI). Overall, interviewees indicated that the project was moving in the right direction. Soil source areas have been remediated and no further releases are occurring. Groundwater concentrations have been significantly reduced both on-property and off- property and continue to decrease. The current on-property GWETS (aka Bisco) is functioning and remains protective, and has been upgraded and optimized within the last five years. The Arques groundwater extraction system was approved for shutdown in 2018 due to decreased mass recovery and aging infrastructure. The Lakeside groundwater extraction and treatment system continues to operate in the downgradient portion of the plume. On-property areas at the National Semiconductor Site with elevated groundwater concentrations are undergoing in-situ remediation, which has successfully and significantly reduced concentrations. The on- and off-property vapor intrusion assessments have addressed this pathway, which supports a short-term protectiveness determination. However, it is uncertain if vapor intrusion is occurring or has the potential to occur at the six buildings where access was not granted. Access efforts may be intensified for these buildings, and if unsuccessful, will be addressed via a future set of ICs for the vapor intrusion pathway. The GWET system at the Monolithic Memories Site was shut down in 2005; there are currently no plans to restart the system or prepare a decision document for an alternate remedy at the Monolithic Memories Site. The responsible party for the 2005 PCE spill (TWC Storage) has not conducted any activities at the Monolithic Memories Site in the past five years. Groundwater monitoring near a children’s daycare, as required by the Regional Water Board, has not been continued. An Interview Record is provided in Appendix H. 4.2. Data Review 4.2.1. Soil A data review completed during the previous FYR looked at soil vapor monitoring data from 2001 to 2012. The data indicated that 13 out of 14 former source areas at the NSC Site achieved soil cleanup standards for VOCs and SVOCs in unsaturated soil. The source area at Building C (Leak L5) is the last remaining soil source area within the former NSC campus containing soil exceeding VOC and SVOC cleanup standards. At Building C, all soil exceeding cleanup level that could feasibly be removed was excavated and disposed offsite. The remaining source area was limited to a discrete depth just above the groundwater table (11 to 12.5 feet depth). Following excavation, multiple rounds of in-situ chemical 18 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites oxidation were conducted via an infiltration gallery at the source area to treat soil. No additional soil sampling has been performed since the remedial excavation in 2009 and 2010. As part of a real estate transaction, a limited soil investigation was conducted at the National Semiconductors Site beneath Buildings 9 and 19 in October 2013. Demolition of Buildings 9 and 19 was planned as part of the property transfer. The soil in this former source area was previously remediated by SVE and determined to be successful by the Regional Water Board. Eighteen soil samples were collected from nine borings (five from Building 9 and four from Building 19) and analyzed for VOCs and metals. Building 9 samples were also analyzed for SVOCs and cyanide. PCE (ranging from below laboratory reporting limits to 0.022 mg/kg) and TCE (ranging from below laboratory reporting limits to 0.041 mg/kg) in soil samples were below the commercial land use ESL (0.7 mg/kg and 0.46 mg/kg, respectively). Arsenic was detected above the commercial land use ESL in all samples at concentrations ranging from 1.7 to 3.8 mg/kg, which is thought to be related to background concentrations naturally present in native soils, rather than releases from the site. Cyanide was detected above the commercial land use ESL in eight out of ten samples analyzed. Given that the current use of the former Building 9 and 19 properties is a parking lot, there are no risk to human health. However, it was determined that the presence of cyanide may require additional evaluation if future development was proposed. Soil cleanup standards related to historic contamination were achieved at the Monolithic Memories Site in 1996. Subsequent excavation and sampling occurred in 2006 due to redevelopment of the former Monolithic Memories, Inc. property and demolition of Buildings 1 and 2. Soils affected by the 2005 PCE spill were investigated in 2008 and found to be successfully remediated to concentrations below the corresponding ESL (the soil RAO approved by the Regional Water Board). No additional on-property soil work has been completed at the Monolithic Memories Site during the review period. 4.2.2. Groundwater USACE reviewed groundwater monitoring data collected from 2011 to 2017 to evaluate progress in remediation of the comingled groundwater contaminant plume. Comparison of TCE plume maps from 2013 and 2017 show minimal change in the extent of the plume over the review period. TCE concentrations exceed the cleanup goal in most of the wells in the A-aquifer with the highest concentrations at 580 micrograms per liter (µg/L) at well 36A, followed by 450 µg/L at well 58A and 430 µg/L at well 46A (Figure 3). Concentrations of TCE in the B1- and B2 -Aquifers are lower than the A- Aquifer with the highest concentration of 220 µg/L at well 72B1 in the B1-Aquifer, and 71 µg/L at well 39B2 in the B2-Aquifer. For the majority of the wells in the A, B-1, and B-2 Aquifers, the concentrations of TCE and cis-1,2-DCE are steady or declining slightly. The largest VOC concentrations in the A-Aquifer are near Building C, Building G, and by the Central Expressway (Figure 3). Elevated TCE concentrations (above 500 µg/L) are in the immediate vicinity of the National Semiconductor On-Site Extraction Well 46A, located in the middle of Subunit 1 between a parking area and the Central Expressway. The source of the VOCs detected in samples collected from extraction well 46A are due to releases at the former NSC campus, which are pulled towards the extraction well. Elevated TCE concentrations are also present at well 36A, located in the southern portion of Subunit 1 between Buildings C and A. Persulfate injection events took place at Building C in November 2011, March 2012, July 2012, and June 2013. Concentrations of TCE and cis-1,2-DCE in most Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites 19 of the monitoring wells around Building C have been near or below the cleanup goal since 2014. One well at Building C, 154A, still exceeds the cleanup goals for TCE with 39 µg/L and for cis-1,2-DCE with 170 µg/L. An enhanced bio-remediation injection event took place outside of Building G in May 2016. The concentration of TCE in well 150A (near Building G) decreased from more than 3,000 µg/L in 2015 to 58 µg/L in 2016. Concentrations of cis-1,2-DCE in well 150A have been greater than 2,000 µg/L and recently increased to 17,000 µg/L in 2017. Well 150A also exceeds the cleanup goals for Freon 113, 1,2- DCB, ethylbenzene, and vinyl chloride. A groundwater modeling study was conducted to evaluate the efficiency of the groundwater remediation systems. The results of the study influenced upgrades in the NSC On-Site GWET system in the southern portion of Subunit 1, with the intent of expanding the capture of groundwater from the upgradient source areas. The results of the modeling study also determined that while the shutdown of the Arques Avenue System in the northern portion of Subunit 1 would no longer provide capture of contaminants north of the Central Expressway, any fugitive contaminants would continue to be captured by the downgradient Lakeside extraction system to the north in Subunit 3. Current groundwater extraction operations continue to remove contaminants from the groundwater per the selected remedy and continue towards meeting the RAO of restoring the groundwater to beneficial use. Analysis of the groundwater concentration trends for the B1 and B2-Aaquifers were completed via Mann- Kendall statistical method and demonstrate stable and/or reducing trends for TCE and cis-1,2-DCE. Analysis of the groundwater concentration trends in the A Aquifer were also conducted via Mann-Kendall statistical method but did not yield any discernable trends. The fluctuation of concentration trends is potentially due to the shutdown for upgrades to the National Semiconductor On-Site GWET system, shutdown of the Arques GWET system or a lack of consistent sampling data for key sets of wells. 20 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites ...' ... --6 ---- IiJ Leg end -30D 6D0 1,200 I TEXAS INSTRUMENTS a Extr.iction Wei ~~iiiiiiii~~~~ ~ Santa Clara, California SDO U - Stew.ardOri'i'e ~~ble un· • Monitoring Wei I .______, o Off-S" e Wei 001 - Ope.-ableU, , 1 A -AQUIFER TC E CONCENTRATION CONTOUR ~ ld~h~n~::~C:~tour Note-s: OCTOBER 2017 -- • Operable Unit Boundary 1. All locations to be considered accurate 2.. TCE concentrations displayed are in micrograms per Date 2/28120 18 Proj ec:1750620760 Figure 6 - Road Edge '"" (ug/L~ Build ing 3. Map displ ayed in California Stal e Plane Coon::linatE System , Zone 111 , North American Olt1A11 of 1983 (NAD83). US Survey feet . L ANG AN Figure 3. A-Aquifer TCE Concentration Contour, October 2017 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites 21 D DI A gLH 7 IID7J - DUI - LANliAN Figure 4. B-1-Aquifer TCE Concentration Contour, October 2017 22 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites 4.2.3. Vapor Intrusion Multiple vapor intrusion assessments have been completed during this review period. In total, 34 buildings have been evaluated for vapor intrusion. The findings generally show that the vapor intrusion pathway is complete at the Sites, with certain, but not all, buildings showing evidence of unacceptable vapor intrusion and requiring implementation of appropriate mitigation measures. Table 5. Status of Buildings considered for Vapor Intrusion Bldg Location Indoor Air Exceedances Status On-Property Buildings 9 NSC None due to vapor intrusion (VI) Demolished. Currently a parking lot 19 NSC None Demolished. Currently a parking lot TCE and PCE in restroom samples. Unoccupied. Operate SSDS in Voluntary sub-slab depressurization accordance with Operations & system (SSDS) installed and Maintenance (O&M) plan. Evaluate 39 NSC operational. No Volatile Organic what Institutional Controls (ICs) may Compounds (VOCs) detected above be necessary to ensure long-term risk-based screening levels following implementation of O&M plan. SSDS activation. No further VI evaluation A NSC None recommended No further VI evaluation B NSC None recommended PCE in most samples. Voluntary SSDS Operate SSDS in accordance with installed and operational. PCE O&M plan. Evaluate what ICs may C NSC detected below risk-based screening be necessary to ensure long-term levels following SSDS activation. implementation of O&M plan. TCE in tunnel samples. Access to No further active VI evaluation tunnel restricted and mitigation recommended. Evaluate what ICs E NSC measures implemented. Post-mitigation may be necessary to ensure long- sampling showed no exceedances of term protectiveness. risk-based screening levels. No further VI evaluation F NSC None recommended No further VI evaluation G NSC None due to VI recommended No further VI evaluation M NSC None recommended No further VI evaluation W NSC None recommended TCE exceedances. Mitigation measures No further active VI evaluation 1160 implemented. Post-mitigation sampling recommended. Evaluate what ICs Kern MM showed no exceedances of risk-based may be necessary to ensure long- Ave screening levels. term protectiveness. Multiple rounds of indoor air sampling conducted in this daycare from 2005 to 1155 Prepare and implement long-term 2012 showing no evidence of East monitoring plan. Evaluate what ICs MM unacceptable VI. Most recent rounds of Arques may be necessary to ensure long- sampling in 2012 continued to show no Ave term protectiveness. exceedances of risk-based screening levels. Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites 23 Bldg Location Indoor Air Exceedances Status 1165 Additional performance testing PCE and TCE in VMS riser pipes, East (indoor air sampling) required. MM expected and indicates mitigation Arques Evaluate what ICs may be necessary system is functioning. Ave to ensure long-term protectiveness. Off-Property Buildings Unoccupied. Additional indoor air TCE in restrooms. Mitigation sampling recommended following measures, including conduit sealing, construction (summer 2018). SU1-1 Subunit 1 implemented. Post-mitigation sampling Evaluate what ICs may be necessary showed no exceedances of risk-based to ensure long-term implementation screening levels. of O&M plan. Sampling completed, no exceedances No further VI evaluation SU1-2 Subunit 1 due to VI recommended Sampling completed, no exceedances No further VI evaluation SU1-3 Subunit 1 due to VI recommended No further VI evaluation SU1-4 Subunit 1 Sampling completed, no exceedances recommended No further VI evaluation SU1-5 Subunit 1 Sampling completed, no exceedances recommended SU1-6 Subunit 1 Access for sampling not granted. Evaluate what ICs may be necessary. On-site review conducted, however results not formally provided. SU1-7 Subunit 1 Building Survey completed by Owner Evaluate what ICs may be necessary to ensure long-term protectiveness. On-site review conducted, however results not formally provided. SU1-8 Subunit 1 Building Survey completed by Owner Evaluate what ICs may be necessary to ensure long-term protectiveness. On-site review conducted, however results not formally provided. SU1-9 Subunit 1 Building Survey completed by Owner Evaluate what ICs may be necessary to ensure long-term protectiveness. On-site review conducted, however SU1- results not formally provided. Subunit 1 Building Survey completed by Owner 10 Evaluate what ICs may be necessary to ensure long-term protectiveness. PCE in unoccupied vault at low levels No further active VI evaluation with HVAC off. No exceedances of recommended. Evaluate what ICs SU3-1 Subunit 3 risk-based screening levels in occupied may be necessary to ensure long- areas while HVAC-on. term protectiveness. TCE in restrooms at low levels with No further active VI evaluation HVAC off. No exceedances of risk- recommended. Evaluate what ICs SU3-2 Subunit 3 based screening levels in occupied may be necessary to ensure long- areas while HVAC on. term protectiveness. No further VI evaluation SU3-3 Subunit 3 Sampling completed, no exceedances recommended TCE and 1,1-TCA in computer rooms No further VI evaluation SU3-4 Subunit 3 and imaging area, likely due to indoor recommended source. SU3-5 Subunit 3 Access for sampling not granted. Evaluate what ICs may be necessary. Sampling completed, no exceedances No further VI evaluation SU3-6 Subunit 3 due to VI recommended 24 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites Bldg Location Indoor Air Exceedances Status No further VI evaluation SU3-7 Subunit 3 Sampling completed, no exceedances recommended PCE in buildings 1245, 1247, and 1257. Methylene chloride also in No further VI evaluation SU3-8 Subunit 3 buildings 1247 and 1257. Likely due to recommended indoor air source. Investigations and mitigation measures continue to be implemented at Buildings C, 39, and SU-1. Further details regarding vapor intrusion work, including site maps, is available in Appendix C. Multiple indoor air sampling events have been completed at 1155 East Arques Ave., a children’s daycare facility located approximately 30 feet west of the 2005 PCE spill, showing no evidence of unacceptable vapor intrusion. The two most recent indoor air sampling events at this building were performed with the HVAC system on and off in June 2012. Both HVAC-on and -off indoor air samples did not contain concentrations of PCE, TCE, cis-1,2-DCE, 1,1,1-TCA, or vinyl chloride at or above laboratory reporting limits or their respective residential land use ESLs. These results are consistent with those obtained during the previous five years and show no evidence of unacceptable health risks. However, considering this sensitive population and out of caution, additional confirmatory sampling should be conducted at the daycare facility and a long-term indoor air monitoring program should be developed and implemented to continue to verify that indoor air VOC levels due to vapor intrusion remain protective. The frequency of future monitoring may be reduced based on an evaluation of the sampling results obtained. In addition, TWC Storage was directed by the Regional Water Board to continue monitoring three wells (EXT-1, EXT-2, and MW-3) close to the daycare facility, but monitoring of these wells did not occur during this review period. 4.3. Site Inspection Site inspections were conducted on 1/9/2018. In attendance were Ron Goloubow, Regional Water Board; Benino McKenna of USACE; and Hector Vargas, Elma Fung, Jonathon Weisberg, and Jim Greene of TI; and Joshua Graber of Langan Treadwell Rollo. The purpose of the inspection was to assess the protectiveness of the remedy. An overview of the Sites and remedial history was provided prior to a tour of the former NSC campus. Since the previous FYR was completed in 2013, deed restrictions on the former NSC property were updated to comply with current California law; an SMP was also prepared for the former NSC property. The last known soil source area at the National Semiconductor Site (former laboratory at Building C) has been remediated and a request from TI for a no further action letter from the Regional Water Board regarding the soil issues at this location is pending. During the information exchange, Jonathan Weisberg (attorney for TI) indicated that preparing a combined FYR for the Sites could be problematic and requested to be updated on the progress of the FYR report. Discussion also included the sale of a portion of the former NSC campus (Buildings G, 19, 39, and 9) in 2014 to Bay View Development. Buildings 9 and 19 have since been demolished. The Regional Water Board approved shutting down the pump and treat system at Subunit 2 (Arques Ave extraction system) in 2008, as it was over 30 years old, leaked untreated groundwater to the ground surface, and was Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites 25 not efficiently removing contaminants of concern from the groundwater. Since this time, the area around Subunit 2 has been redeveloped and it would be very difficult to modify or construct a new extraction system. A Site Inspection Checklist is provided in Appendix I. Photographs taken during the Site Inspection are provided in Appendix J. 5. Technical Assessment 5.1. Question A: Is the remedy functioning as intended by the decision documents? The remedy is performing as intended. The ROD calls for air stripping of extracted groundwater, use of an SVE system for soils, and the discharge of extracted groundwater to storm sewers under an NPDES permit. Currently there are two operating GWET systems, located in the southern portion of Subunit 1 and in the northern portion of Subunit 3. A second GWET in the northern portion of Subunit 1 has been shut down with approval of the Regional Water Board. Overall, the groundwater portion of the remedy is functioning as intended. Groundwater extraction and treatment at Subunit 1 continues and groundwater elevation and quality data shows that the extraction and treatment systems are controlling further migration of impacted groundwater within the affected aquifers. Concentrations of contaminants of concern in groundwater within subunit 2 have decreased to concentrations below levels detected prior to the release of PCE that occurred in 2005. Concentrations in downgradient monitoring wells have remained below laboratory reporting limits or below the ROD cleanup level. Thus, based on the groundwater quality data, the commingled plume has not expanded in size and has not migrated vertically. Contamination remains confined to the shallow groundwater-bearing zones. Soil cleanup standards for VOCs and SVOCs in unsaturated soil have been achieved in most areas of the Sites. The SVE system at Subunit 1 was shut down in 2005 after cleanup goals were achieved. Additional soil cleanup after shutdown of the SVE at Subunit 1 has been completed by localized excavation and soil vapor mitigation within selected buildings. A Covenant and Environmental Restriction for the property at 1165 East Arques Ave (former Building 1 and 2005 PCE spill area) was recorded on March 19, 2013. A new Covenant and Environmental Restriction for all parcels on the TI property was recorded on September 25, 2014. These covenants prohibit the use of the properties for residential uses or as a school for children less than 21 years of age, and limits use to only commercial or industrial. The most recent covenants are consistent with current State law (CCC Section 1471), which established the framework for environmental covenants in California. Residences and businesses receive their drinking water from the City of Santa Clara, which currently receives its water from Hetch Hetchy reservoir, not local groundwater. There are no active water supply wells within subunits 1, 2, or 3. Therefore, there is no exposure to contaminated groundwater. 26 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites 5.2. Question B: Are the exposure assumptions, Toxicity Data, Cleanup Levels, and Remedial Action Objectives (RAOs) Used at the Time of Remedy Selection Still Valid? Yes, exposure assumptions are still valid, since the current restrictive covenant prevents the extraction of groundwater at the Sites for drinking water and therefore there is no exposure to contaminated groundwater. Groundwater cleanup standards for TCE, PCE, and cis-1,2-DCE (primary chemicals which routinely exceed cleanup standards in the commingled plume) have not changed since the ROD was issued. The exposure assumptions used to develop the Human Health Risk Assessment (HHRA) were for potential future exposure if untreated groundwater were to be used for drinking water and if residential uses were to occur on the Sites. A number of toxicity value revisions have occurred since the ROD. These changes do not affect the protectiveness of the cleanup levels selected in the ROD. There have been no changes in standardized risk assessment methodologies during this FYR period that could affect the protectiveness of the remedy. The existing covenant restricts usage of groundwater for a drinking water source and prevents the use of the Sites by residential dwellings. Vapor intrusion has been assessed at several buildings at and near the Sites. Vapor mitigation measures were implemented at four buildings. Access was not granted to six buildings and documentation regarding building owner sampling activities at five of those buildings has not been formally made available. Multiple rounds of indoor air investigations leading up to 2012 at an operating daycare facility showed no evidence of unacceptable vapor intrusion risk. The most recent rounds of indoor air sampling at this building in 2012 included testing under worst-case conditions – in the absence of ventilation – and continued to show no evidence of vapor intrusion. However, indoor air quality was not assessed at the daycare facility during this FYR period. Furthermore, TCE concentrations in soil vapor and groundwater monitoring wells near the daycare remain elevated and have not been monitored, as required by the Regional Water Board. Overall, the project is moving in the right direction and the remedy is progressing as expected towards meeting RAOs. Groundwater concentrations have been significantly reduced and continue to decrease or remain stable, based on Mann Kendall data analysis and contaminant plume map evaluations. Soil source areas have been remediated and no further releases are occurring. 5.3. Question C: Has Any Other Information Come to Light That Could Call Into Question the Protectiveness of the Remedy? No, there is no new information that has become available that could call into question the effectiveness of the remedy. Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites 27 6. Issues/Recommendations Table 6. Issues and Recommendations Identified in the Five-Year Review Issues and Recommendations Identified in the Five-Year Review: OU(s): Monolithic Issue Category: Other Memories Site and National Issue: Although mitigation measures to address vapor intrusion have been implemented Semiconductor Site where needed in buildings overlying the plume, the remedy does not require these measures. (OU1, Subunits 1, 2 and 3) Recommendation: Consider modifying the remedy to: incorporate existing mitigation systems; require evaluation and mitigation of vapor intrusion, as appropriate; and implement long-term monitoring plans for mitigated buildings and buildings at risk for future unacceptable vapor intrusion. Affect Current Affect Future Party Responsible Oversight Party Milestone Date Protectiveness Protectiveness No Yes State State 9/30/2021 OU(s): Monolithic Issue Category: Monitoring Memories Site Multiple indoor air sampling events were completed at a children’s daycare facility (OU1, Subunit 2) Issue: within the Monolithic Memories Site, showing no evidence of unacceptable vapor intrusion. The two most recent indoor air sampling events in June 2012 continued to indicate no unacceptable vapor intrusion risk to children or staff. However, TCE concentrations in soil vapor and groundwater monitoring wells near the daycare remain elevated and the daycare occupants are considered a sensitive population. Recommendation: Considering the sensitive population and out of caution, conduct additional confirmatory sampling at the daycare facility and develop and implement a long-term indoor air monitoring program to continue to verify that indoor air VOC levels due to vapor intrusion remain protective. The frequency of future monitoring may be reduced based on an evaluation of the sampling results obtained. Affect Current Affect Future Party Responsible Oversight Party Milestone Date Protectiveness Protectiveness No Yes State State 9/30/2019 28 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites In addition, the following recommendations do not affect current and/or future protectiveness; however, they were identified during this FYR as a suggested improvement: • Cleanup for the 2005 PCE Spill is regulated under the authority of the State of California and therefore the spill is not subject to CERCLA authority or evaluated in this FYR. However, the accidental spill occurred approximately 30 feet west of an operating daycare facility, located in Subunit 3. In June 2013, the Regional Water Board partially approved a well deconstruction workplan submitted by TWC Storage, with the caveat that monitoring at wells MW-3, EX-1, and EX-2 should continue to follow natural attenuation of residual VOCs in soil and groundwater. Counter to direction by the Regional Water Quality Control Board, TWC Storage has not monitored the groundwater wells that are closest to the daycare facility (EX-1, EX-2, and MW-3) during the last five years. Additional monitoring is appropriate to demonstrate that RAOs are achieved and that rebound does not occur. • Deed restrictions have been updated at the former NSC property. A small parcel (APN 205-38- 020) is not owned by TI, but this parcel is surrounded by the National Semiconductor Site. The parcel is currently owned by Air Products and the last date of transfer is recorded to be October 17, 1983. There are reportedly no workers at the parcel and the property is used to fill tanker trucks with liquid nitrogen. The Regional Water Board is not interested in pursuing a land use restriction, but usage restriction of this parcel may be warranted in the future. 7. Protectiveness Statement Table 7. Protectiveness Statement Protectiveness Statement – Monolithic Memories and National Semiconductor Superfund Sites Operable Unit: 1 Protectiveness Determination: Subunits: 1, 2 and 3 Short-term Protective Protectiveness Statement: The remedies at the Monolithic Memories and National Semiconductor Superfund Sites protect human health and the environment because exposure pathways that could result in unacceptable risks are being controlled and institutional controls restrict land use and groundwater use as a drinking water source. Vapor intrusion assessments are ongoing in buildings over the plume. Where necessary, mitigation measures to address vapor intrusion issues are being implemented, however, the remedy does not require these measures. To be protective in the long-term, consideration should be given to modifying the remedy to: incorporate existing mitigation systems; require evaluation and mitigation of vapor intrusion, as appropriate; and implement long-term monitoring plans for mitigated buildings and buildings at risk for future unacceptable vapor intrusion. Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites 29 Protectiveness Statement – Monolithic Memories Superfund Site Site Operable Unit: 1 Protectiveness Determination: Subunit: 2 Short-term Protective Protectiveness Statement: At the Monolithic Memories Site, multiple indoor air sampling events were completed at a children’s daycare facility which showed no evidence of unacceptable vapor intrusion. The two most recent indoor air sampling events in June 2012 continued to indicate no unacceptable vapor intrusion risk to children or staff. However, TCE concentrations in soil vapor and groundwater monitoring wells near the daycare remain elevated and the daycare occupants are considered a sensitive population. To be protective in the long-term, and considering the sensitive population and out of caution, additional confirmatory sampling should be conducted at the daycare facility and a long-term indoor air monitoring program should be developed and implemented to continue to verify that indoor air VOC levels due to vapor intrusion remain protective. The frequency of future monitoring may be reduced based on an evaluation of the sampling results obtained. 8. Next Review The next FYR report for the Sites is required within five years from the completion date of this review. 30 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites Appendix A: List of Documents Reviewed Regulatory activities documents and environmental data and site reports pertaining to the AMD Arques (Monolithic Memories) Site (SL720801215) stored in the State of California State Water Resource Control Board Geotracker database: http://geotracker.waterboards.ca.gov/profile_report.asp?global_id=SL7208012155 Regulatory activities documents and environmental data and site reports pertaining to the TWC Storage Site (SL0608512762) stored in the State of California State Water Resource Control Board Geotracker database: http://geotracker.waterboards.ca.gov/profile_report.asp?global_id=SL0608512762 Regulatory activities documents and environmental data and site reports pertaining to the Texas Instruments, Santa Clara Site (SL720841216) stored in the State of California State Water Resource Control Board Geotracker database: http://geotracker.waterboards.ca.gov/profile_report.asp?global_id=SL720841216 Haley and Aldrich, 2014a. Vapor Intrusion Evaluation Report 1160 KERN AVENUE SUNNYVALE, CALIFORNIA. Prepared by Haley & Aldrich, Inc. Prepared for Advanced Micro Devices, Inc. 28 February 2014. Haley and Aldrich, 2014b. Addendum to Vapor Intrusion Evaluation Report 1160 Kern Avenue Sunnyvale, California. Prepared by Haley & Aldrich, Inc. Prepared for Advanced Micro Devices, Inc. 31 March 2014. Haley and Aldrich, 2015. VAPOR MITIGATION COMPLETION REPORT 1160 KERN AVENUE SUNNYVALE, CALIFORNIA. Prepared by Haley & Aldrich, Inc. Prepared for Advanced Micro Devices, Inc. 22 May 2015. Haley and Aldrich, 2016. Addendum to Vapor Mitigation Completion Report 1160 Kern Avenue Sunnyvale, California. Prepared by Haley & Aldrich, Inc. Prepared for Advanced Micro Devices, Inc. 4 February 2016. Langan, 2013a. Limited Soil Investigation Work Plan Buildings 9 and 19, Texas Instrument Corporation. Prepared by Langan Treadwell Rollo. 11 October 2013. Langan, 2013b. Limited Soil Investigation Technical Memorandum Buildings 9 and 19, Texas Instrument Corporation. Prepared by Langan Treadwell Rollo. 16 December 2013. Langan, 2014a. 2013 Annual Groundwater Monitoring Report, Texas Instruments Incorporated. Prepared by Langan Treadwell Rollo. 24 April 2014. Langan, 2014b. Work Plan for Off-Property Vapor Intrusion Assessment National Semiconductor and Monolithic Memories Superfund Sites, Operable Unit 1, Subunits 1 and 3, Santa Clara and Sunnyvale, California. Prepared by Langan Treadwell Rollo. 28 August 2014. Fifth Five-Year Review for NSC and MMI Superfund Sites 31 Langan, 2014c. POST-CONSTRUCTION VMS MONITORING PLAN 1165 East Arques Avenue Sunnyvale, California. Prepared by Langan Treadwell Rollo. Prepared for Exstra Arques L.L.C. 26 September 2014. Langan, 2014d. Soil Management Plan APNs: 205-38-021, 205-38-0008, 205-38-022, 205-39-025, 205- 39-022, and 205-39-018. Prepared by Langan Treadwell Rollo. 23 October 2014. Langan, 2014e. ON-PROPERTY VAPOR INTRUSION ASSESSMENT REPORT FOR EASTERN PARCELS (BUILDINGS 9, 19, 39, AND G). Prepared by Langan Treadwell Rollo. 10 November 2014. Langan, 2014f. Completion Report for Vapor Mitigation System 1165 East Arques Avenue. Prepared by Langan Treadwell Rollo. Prepared for Exstra Arques L.L.C.. 8 December 2014. Langan, 2015a. ON-PROPERTY VAPOR INTRUSION ASSESSMENT REPORT FOR WESTERN PARCELS (BUILDINGS A, B, C, E, F, M, AND W). Prepared by Langan Treadwell Rollo. 29 January 2015. Langan, 2015b. 2014 Annual Groundwater Monitoring Report, Texas Instruments Incorporated. Prepared by Langan Treadwell Rollo. 7 April 2015. Langan, 2015c. Memorandum to RWQCB and USEPA. Results of Indoor Air Testing at Building SU3-7, February 2015. Prepared by Langan Treadwell Rollo. 17 April 2015. Langan, 2015d. Memorandum to RWQCB and USEPA. Results of Indoor Air Testing at Buildings SU3- 1, February and March 2015. Prepared by Langan Treadwell Rollo. 24 April 2015. Langan, 2015e. Memorandum to RWQCB and USEPA. Results of Indoor Air Testing at Buildings SU1-2 and SU1-3, February 2015. Prepared by Langan Treadwell Rollo. 30 April 2015. Langan, 2015f. Memorandum to RWQCB and USEPA. Results of Indoor Air Testing at Buildings SU3- 4, March 2015. Prepared by Langan Treadwell Rollo. 4 May 2015. Langan, 2015g. Memorandum to RWQCB and USEPA. Results of Indoor Air Testing at Buildings SU3- 6, March 2015. Prepared by Langan Treadwell Rollo. 4 May 2015. Langan, 2015h. Memorandum to RWQCB and USEPA. Results of Indoor Air Testing at Building SU3-8, March 2015. Prepared by Langan Treadwell Rollo. 26 May 2015. Langan, 2015i. Memorandum to RWQCB and USEPA. Results of Chemical Inventory at Building SU3- 4, June 2015. Prepared by Langan Treadwell Rollo. 15 June 2015. Langan, 2015j. Memorandum to RWQCB and USEPA. Results of Indoor Air Testing at Building SU3-1, September 2015. Prepared by Langan Treadwell Rollo. 4 December 2015. Langan, 2016a. Groundwater Extraction System Modification Report, Texas Instruments Incorporated. Prepared by Langan Treadwell Rollo. 8 February 2016. Langan, 2016b. Memorandum to RWQCB and USEPA. Results of Indoor Air Testing at Buildings SU3- 2, March 2016. Prepared by Langan Treadwell Rollo. 20 May 2016. 32 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites Langan, 2016c. 2015 Annual Groundwater Monitoring Report, Texas Instruments Incorporated. Prepared by Langan Treadwell Rollo. 27 June 2016. Langan, 2016d. Memorandum to RWQCB and USEPA. Results of Indoor Air Testing at Building SU1-1, August 2016. Prepared by Langan Treadwell Rollo. 24 October 2016. Langan, 2016e. Memorandum to RWQCB and USEPA. Results of Indoor Air Testing at Building SU1-4, August 2016. Prepared by Langan Treadwell Rollo. 3 November 2016. Langan, 2016f. Memorandum to RWQCB and USEPA. Results of Indoor Air Testing at Building SU1-5, August 2016. Prepared by Langan Treadwell Rollo. 3 November 2016. Langan, 2017a. Memorandum to RWQCB and USEPA. Summary of Vapor Mitigation Activities and Air Sampling Results, Building SU1-1, December 2016. Prepared by Langan Treadwell Rollo. 13 January 2017. Langan, 2017b. 2016 Annual Groundwater Monitoring Report, Texas Instruments Incorporated. Prepared by Langan Engineering and Environmental Services, Inc. 27 April 2017. Langan, 2017c. Request for Modification of Groundwater Extraction and Treatment System Shutdown of Arques Avenue Wells, National Semiconductor Superfund Site, Subunit 1, Operable Unit 1, August 2017. Langan, 2017d. Bioremediation Injection Report. Prepared by Langan Engineering and Environmental Services. 25 August 2017. USEPA, 1991. EPA Superfund Record of Decision. NATIONAL SEMICONDUCTOR CORP. and MONOLITHIC MEMORIES EPA ID: CAD041472986 and CAD049236201 OU(s) 01 & 01 SUNNYVALE, CA. 11 September 1991. USEPA, 1999. First Five-Year Review Report for Monolithic Memories Superfund Site (Subunit 2) Santa Clara County, California. 29 September 1999. USEPA, 2013. Fourth Five-Year Review for National Semiconductor Corporation 2900 Semiconductor Drive Santa Clara, Santa Clara County, California. 30 September 2013. USEPA, 2014. Fourth Five-Year Review Report for Monolithic Memories Superfund Site (Subunit 2) Santa Clara County, California. 24 September 2014. Fifth Five-Year Review for NSC and MMI Superfund Sites 33 Appendix B: Site Chronology Event Date National Semiconductor Corporation (NSC) begins manufacturing semiconductors at the National 1967 Semiconductor Site Monolithic Memories, Inc. (MMI) begins semiconductor manufacturing operations at the 1165 East Arques Avenue (Building 1), 1175 East Arques Avenue (Building 2), and 1160 Kern Avenue 1970 (Building 3) complex Initial investigations and removal of leaking Underground Storage Tanks and associated piping at MMI; soil and groundwater contamination discovered at both National Semiconductor and 1982 Monolithic Memories Sites (together, the Sites) Removal of 22 underground solvent storage tanks and acid waste sumps and associated piping and 1982 -1991 excavation of 400 cubic yards of contaminated soils at the National Semiconductor Site Groundwater extraction and treatment begins at the National Semiconductor Site. National Pollutant 1984 Discharge Elimination System (NPDES) permit issued for discharge of treated effluent. MMI begins groundwater extraction from A-zone aquifer at the Monolithic Memories Site 1986 California Regional Water Quality Control Board, San Francisco Bay Region (Regional Water Board) issues Waste Discharge Requirements Order WDR 86-64 requiring delineation of volatile August 1986 organic chemical (VOC) plume Advanced Micro Devices, Inc (AMD) acquires MMI and assumes site cleanup responsibility 1987 NSC accepts responsibility for groundwater contamination from adjacent United Technologies 1987 Corporation (UTC) facility Sites added to National Priorities List (NPL) July 1987 AMD begins groundwater extraction begins from the B-zone aquifer at the Monolithic Memories Site 1988 Regional Water Board adopts Site Cleanup Requirements April 1989 AMD ceases its industrial operations at the Monolithic Memories Site 1989 Baseline Public Health Evaluation (BPHE) completed for the National Semiconductor Site July 1990 AMD completes BPHE for the Monolithic Memories Site April 1991 Regional Water Board and the United States Environmental Protection Agency (USEPA) approve September 1991 Final Remedial Investigation/Feasibility Study (RI/FS) workplans for the Sites Regional Water Board adopts Orders No. 91-137, 91-139, and 91-140, the Final Site Cleanup September 1991 Requirements for Subunits 1, 2, and 3 of Operable Unit 1 (OU1). USEPA issues Record of Decision (ROD) for the Sites September 1991 AMD installs two A-zone extraction wells (E42A and E43A) and performs soil investigation at the 1992 Monolithic Memories Site AMD installs and operates soil vapor extraction (SVE) system at the Monolithic Memories Site 1993 NSC submits first State-required Five-Year Review (5YR) Report to Regional Water Board September 1996 AMD ceases SVE operations at the Monolithic Memories Site upon achieving soil cleanup standards 1997 NSC submits Preliminary Close-out Report October 1997 Regional Water Board submits first USEPA-required 5YR Report for the National Semiconductor September 1998 Site to USEPA, Region 9 The first USEPA 5YR Report for the Monolithic Memories Site is signed September 1999 Low levels of perchlorate detected at former UTC facility 2000 Ozone sparging/soil vapor extraction system installed at a former source area at the National 2001 Semiconductor Site 34 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites Event Date NSC submits second State-required 5YR Report to Regional Water Board August 2001 NSC takes over operations of the OU1 groundwater extraction, treatment and monitoring program January 2002 Regional Water Board submits second USEPA-required 5YR Report for the National Semiconductor September 2003 Site to USEPA, Region 9 Focused Risk Assessment Report, Potential Vapor Intrusion July 2004 The second USEPA 5YR Report for the Monolithic Memories Site is signed September 2004 February and March SVE systems shut down at the National Semiconductor Site 2005 AMD records an environmental restriction covenant for the 1165 East Arques Avenue property April 2005 (Building 1). TWC Storage LLC (TWC) purchases the property. TWC damages an electrical transformer in the northwest corner of Building 1 during building demolition activities and 250 gallons of tetrachloroethene (PCE) leak into Monolithic Memories Site July 2005 soils and shallow groundwater TWC removes approximately 2,000 cubic yards (3,100 tons) of PCE-impacted soil within two excavation areas in the northwest corner of the property. TWC places hydrogen release compound in October 2005 the bottom of each excavation prior to backfilling to accelerate the bioremediation (breakdown) of residual PCE in soil and shallow groundwater. TWC conducts soil and groundwater sampling in area of PCE spill November 2005 NSC conducts soil vapor and indoor air sampling at the daycare center located at 1155 East Arques September and Avenue October 2005 TWC conducts its second round of biannual indoor air sampling at the 1155 East Arques Avenue December 2005 daycare center TWC installs seven SVE wells in the northwest corner of Building 1 and conducts SVE feasibility February 2006 test TWC conducts first of two in-situ chemical oxidation (ISCO) injection events using RegenOx™ February 2006 AMD removes below-surface grade wastewater conveyance lines and overburden from the 1160 March 2006 Kern Avenue property (Building 3) TWC conducts second of two ISCO injection events using RegenOx™ March 2006 TWC installs four soil-gas probes on the 1155 East Arques Avenue property for yearly concurrent March 2006 indoor air and soil-gas monitoring AMD conducts soil excavation activities at the Monolithic Memories Site in Areas 1 and 2 (historical), Area 3 (discovered in March 2005), Area 4 (discovered in July 2005), and 1160 Kern November 2006 Avenue (Building 3) Areas 1 and 2 (identified in March 2006) NSC submits third State-required 5YR Report to Regional Water Board November 2006 Pilot Study entitled, Work Plan for Vegetable Oil Injection to Accelerate Remediation of Chlorinated November 2006 Volatile Organic Compounds at Building E conducted at the National Semiconductor Site Field Sampling Report in Support of Remedial Alternatives Evaluation, Building C: Tank T13/Leak November 2006 L5 Areas at the National Semiconductor Site Fifth Five-Year Review for NSC and MMI Superfund Sites 35 Event Date AMD conducts two soil sampling programs to establish the extent of Area 2 at the Monolithic November and Memories Site December 2006 Vegetable oil injections conducted at Building C at the National Semiconductor Site January 2007 TWC installs groundwater extraction and treatment (GWET) system and begins groundwater extraction from well MM17A to capture and treat contaminated groundwater related to the 2005 PCE July 2007 spill. TWC installs four groundwater monitoring wells and nine multi-phase extraction wells in the area of September 2007 the 2005 PCE spill. Remedial Action Plan (RAP) for Building C: Tank T13 and Leak 5 Areas at the National November 2007 Semiconductor Site TWC installs a Multi-Phase Extraction (MPE) system and combines it with the GWET system. The January 2008 combined treatment systems begin operation. Work Plan for ISCO pilot study at Building C: Leak 5 Area at the National Semiconductor Site February 2008 ISCO pilot study implemented at Building C: Leak 5 Area at the National Semiconductor Site March and July 2008 TWC records a new environmental restriction covenant for the 1165 East Arques Avenue (former July 2008 Building 1) property. Regional Water Board submits third USEPA-required 5YR Report for the National Semiconductor August 2008 Site to USEPA, Region 9 AMD completes soil excavation and backfill of contaminated soil in Area 2 at the Monolithic September 2008 Memories Site Combined MPE/GWET system ceases operation. November 2008 OS/SVE was discontinued at the National Semiconductor Site Building G in the E zone due to January 2009 required repairs. TWC injects 10,000 gallons of 3DMe™ hydrogen release compound to remediate PCE-impacted soil June 2009 and shallow groundwater in the PCE spill area. The third USEPA 5YR Report for the Monolithic Memories Site is signed. September 2009 Leak L5 Area Work Plan for the National Semiconductor Site is submitted to the Regional Water December 2009 Board and subsequently approved Leak L5 Area remediation conducted. Excavation and disposal of 1,440 tons of soil and injection December 2009 and pipe at the National Semiconductor Site January 2010 Well installation report submitted for Building G hydrogen peroxide injection at the National January 2010 Semiconductor Site February and March Building C former SVE wells abandoned at the National Semiconductor Site 2010 No Further Action (NFA) granted for former source area Tank T13 at National Semiconductor Site June 2010 Bioremediation pilot study began at Building 9 at the National Semiconductor Site July 2010 Seventeen SVE wells were abandoned at the National Semiconductor Site, inside and outside of Building C. Three new monitoring wells were added to the existing monitoring well network in the November 2010 area adjacent to Building C (153A-TR, 154A, and 155A). 36 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites Event Date TWC injects approximately 7,000 gallons of 3DMe™ hydrogen release compound to remediate December 2010 PCE-impacted groundwater in the PCE spill area. Bioremediation pilot study begins at Building G at National Semiconductor Site June 2011 AMD submits workplan to Regional Water Board and USEPA for evaluation of potential vapor July 2011 intrusion at 1160 Kern Avenue (Building 3) of the Monolithic Memories Site Based on ventilation-off air sampling results, the Regional Water Board requests that AMD undertake mitigation measures to address vapor intrusion detected in floor drains in the women’s August 2011 restroom at 1160 Kern Avenue (Building 3) and perform post-mitigation confirmation sampling. Texas Instruments (TI) acquires the National Semiconductor Site through a merger with NSC, September 2011 assuming responsibility for operation and monitoring of Operable Unit 1 (OU1) Pilot study persulfate injection event conducted at Building C at the National Semiconductor Site November 2011 AMD conducts vapor intrusion mitigation measures in the 1160 Kern Avenue restrooms and December 2011 conducts a confirmatory ventilation-off indoor air sampling event. TWC submits a NFA Workplan for the 2005 PCE release. January 2012 TWC submits an Addendum to the NFA Workplan for the 2005 release which includes a March 2012 groundwater monitoring schedule. First full persulfate injection event at Building C at the National Semiconductor Site completed March 2012 Regional Water Board approves NFA Workplan and Addendum for the 2005 PCE release, requiring April 2012 some continued groundwater monitoring at three wells. AMD conducts additional indoor air sampling at 1160 Kern Avenue (Building 3) July 2012 Second persulfate injection event at Building C at the National Semiconductor Site completed July 2012 December 2012 and Vapor intrusion assessments conducted at on-property buildings at the National Semiconductor Site January 2013 TWC submits groundwater monitoring report documenting completion of the NFA Workplan and March 2013 Addendum for the PCE release. TWC records an amended environmental restriction covenant for the 1165 East Arques Avenue March 2013 (former Building 1) property. TWC submits Well Destruction Request and Workplan for 1165/1175 East Arques Avenue (former April 2013 Buildings 1 and 2) AMD conducts preferential pathway investigation at 1160 Kern Avenue (Building 3) to evaluate May 2013 additional measures to reduce vapor intrusion in the women’s restroom. Regional Water Board issues partial approval for Well Destruction Request and Workplan stipulating that wells MW-3, EX-1, and EX-2 should continue to monitor natural attenuation of residual VOCs June 2013 in soil and groundwater. Third persulfate injection event at Building C at the National Semiconductor Site completed June 2013 AMD conducts ventilation-on air monitoring at 1160 Kern Avenue (Building 3) prior to the start of September 2013 vapor intrusion mitigation efforts (building ventilation enhancements and other mitigation activities). AMD conducts vapor intrusion mitigation measures (floor sealing activities, ventilation January 2014 improvements) at 1160 Kern Avenue (Building 3). Fifth Five-Year Review for NSC and MMI Superfund Sites 37 Event Date AMD conducts ventilation-on indoor air sampling at 1160 Kern Avenue (Building 3) to determine February 2014 effectiveness of mitigation measures. AMD submits Vapor Mitigation Completion Report to Regional Water Board and USEPA. February 2014 AMD submits Addendum to Vapor Intrusion Evaluation Report to Regional Water Board and March 2014 USEPA Regional Water Board and USEPA issue 4th 5YR for the Monolithic Memories Site September 2014 On-Property Vapor Intrusion Assessment Report for Eastern Parcels (Buildings 9, 19, 39, and G) for November 2014 the National Semiconductor Site is submitted On-Property Vapor Intrusion Assessment Report for Western Parcels (Buildings A, B, C, E, F, M, November 2014 and W) for the National Semiconductor Site is submitted Building G OS/SVE system abandonment completed at the National Semiconductor Site in accordance with Santa Clara Valley Water District guidelines. Seventy nested wells were abandoned December 2014 by pressure grouting. A new groundwater treatment system (Bisco System) was installed and activated near Building E at the National Semiconductor Site. Treated groundwater is either re-used on-site or discharged to the December 2014 storm water system under NPDES permit. AMD seals the floor drains in the warehouse restrooms of 1160 Kern Avenue with high-strength mortar. Retro-Coat™ was then applied. To comply with building codes and to prevent future vapor March 2015 intrusion, some bathroom fixtures (e.g., showers) were removed and drains plugged. AMD conducts post-mitigation confirmation indoor air sampling at 1160 Kern Avenue. April 2015 AMD submits Vapor Mitigation Completion Report to Regional Water Board and USEPA for the May 2015 1160 Kern Avenue vapor intrusion mitigation efforts. Design of new groundwater conveyance piping system at the National Semiconductor Site is May 2015 completed. AMD conducts cold-weather, post-mitigation confirmation indoor air sampling at 1160 Kern December 2015 Avenue. Groundwater Extraction System Modification Report for the National Semiconductor Site is January 2016 submitted AMD submits Addendum to Vapor Mitigation Completion Report to Regional Water Board and February 2016 USEPA for additional confirmatory sampling conducted at the 1160 Kern Avenue building. Four new groundwater extraction wells (45R-B1, A-1, B1-1, B1-2) are installed at the National Semiconductor Site for use in the new extraction system. Construction of new groundwater March 2016 conveyance system is underway. Enhanced In-Situ Bioremediation (EISB) injection event at Building G at the National May 2016 Semiconductor Site is completed The Arques Avenue extraction system at the National Semiconductor Site is temporarily shut down September and to repair the groundwater conveyance line. October 2016 Request submitted to Regional Water Board to shut down extraction wells along East Arques Avenue August 2017 at the National Semiconductor Site Regional Water Board issues letter approving the Addendum to Vapor Mitigation Completion Report for the 1160 Kern Avenue building at the Monolithic Memories Site and stating that additional August 2017 indoor air sampling at the site is not required. 38 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites Appendix C: Vapor Intrusion Data Review Monolithic Memories Site A vapor intrusion assessment was first conducted at the 1160 Kern Avenue Building at the Monolithic Memories Site (Figure C-1) during the summer of 2011. Perchloroethene (PCE) and trichloroethene (TCE) were detected in indoor air samples collected in the women’s restroom at concentrations above the United States Environmental Protection Agency (USEPA) Regional Screening Levels (RSLs) for commercial use. Mitigation measures were implemented at both adjoining women’s and men’s restrooms to address the exceedances. Subsequent indoor air sampling was conducted, which led to the implementation of additional mitigation measures, including floor sealing activities and ventilation system enhancements. To confirm the effectiveness of the mitigation measures, indoor air samples were collected in April 2015 and December 2015. Indoor air samples were collected at the same locations and under the same conditions as during the previous two sampling events (September 27, 2013 and February 10, 2014) where TCE concentrations were previously observed at concentrations above RSLs. Indoor air samples collected in April 2015 showed PCE, TCE, 1,1,1-trichloroethane (1,1,1-TCA), and Freon 113 in all four indoor air sampling locations and chlorobenzene at two indoor air sample locations at concentrations below the respective RSLs for commercial use (see Table C-1). Confirmation indoor sampling was completed in December 2015 with the heating, ventilation, and air conditioning (HVAC) system off. Similarly, results of sampling during the cold weather month contained PCE, TCE, and Freon 113 in all four indoor air sampling locations; 1,1,1-TCA was detected at two indoor air sample locations; and chlorobenzene was not detected at indoor air locations. The concentrations of all compounds detected during the December 2015 sampling event were also below their respective commercial air RSLs. In February 2016, an “Addendum to Vapor Mitigation Completion Report” was submitted to USEPA and the California Water Quality Control Board, San Francisco Bay Region (Regional Water Board). Both agencies approved the findings in this report, acknowledging that the results of the April and December 2015 indoor air sampling events confirmed the effectiveness of the vapor intrusion mitigation measures implemented in the building, and approving no further action to address the vapor intrusion pathway at the 1160 Kern Avenue building. Table C-1. Analytical Results for Indoor and Outdoor Air Samples (1160 Kern Avenue) Sample Location Date Chlorobenzene PCE 1,1,1-TCA TCE Freon 113 Ambient 4/9/2015 0.2 0.069 J 0.027 J <0.11 0.53 Women's Restroom 4/9/2015 0.076 J 1.0 0.073 J 1.6 0.60 Women's Restroom 4/9/2015 0.070 J 1.0 0.069 J 1.7 0.63 Volunteer Room 4/9/2015 0.068 J 0.43 0.059 J 0.4 0.55 Warehouse/Storage Area 4/9/2015 <0.092 0.33 0.041 J 0.25 0.55 Men's Restroom 4/9/2015 <0.092 0.47 0.062 J 0.53 0.54 Ambient 12/21/2015 <0.092 0.12 J <0.11 0.059 J 0.50 Women's Restroom 12/21/2015 <0.092 1.3 0.035 J 1.5 0.59 Fifth Five-Year Review for NSC and MMI Superfund Sites 39 Sample Location Date Chlorobenzene PCE 1,1,1-TCA TCE Freon 113 Women's Restroom 12/21/2015 <0.092 1.4 0.034 J 1.5 0.58 Volunteer Room 12/21/2015 <0.092 0.99 <0.11 0.56 0.56 Warehouse/Storage Area 12/21/2015 <0.092 1.1 <0.11 0.52 0.53 Men's Restroom 12/21/2015 <0.092 1.1 0.030 J 0.85 0.54 USEPA Region 9 RSL for Commercial Air a 220 2.1 b 4,400 b 3.0c 130,000 Results reported in micrograms per cubic meter (µg/m3) a. USEPA, 2016, Regional Screening Levels, http://www.epa.gov/risk/risk-based-screening-table-generic-tables. b. DTSC-modified screening level (DTSC, 2015, HERO HHRA Note 3.2, October). c. USEPA updated the RSL for TCE in November 2011; the RSL for TCE used in prior reports for this site is 6.1 μg/m3 J represents estimated values < represents values below laboratory reporting limits. As part of a redevelopment project for the property at 1165 East Arques Avenue on the Monolithic Memories Site, a vapor mitigation system (VMS) was installed during construction of a new fitness center between May and September 2014. The VMS consisted of a continuous vapor barrier membrane, a passive vapor collection and venting system, and exterior perimeter vents. VMS performance monitoring and post-construction indoor air testing was conducted in October 2014. Only PCE (ranging 0.22 to 0.26 micrograms per cubic meter or µg/m3) and Freon 113 (ranging 0.53 to 0.56 µg/m3) were detected in indoor air samples, at concentrations below their respective screening levels for commercial use. The low levels of volatile organic compounds (VOCs) detected in indoor air appeared to be attributed to ambient outdoor air conditions. Both PCE (ranging from 5.0 to 28 µg/m3) and TCE (ranging from 5.6 to 47 µg/m3) were detected in the riser pipe of the VMS. Elevated VOC concentrations were expected from these samples, indicating that the VMS is collecting and venting vapors from beneath the building and directing the vapors to the ambient outdoor air at the roof of the building. Additional VMS performance testing at the riser pipes was performed in January 2015 and April 2015, the results of which are presented as an Addendum to the Completion Report for Vapor Mitigation System (Attachment E). Since VOCs were found to be present below applicable screening criteria, it was determined that the VMS system provided adequate protection against vapor intrusion and no additional air testing was recommended. National Semiconductor Site (On-Property) A vapor intrusion assessment was conducted in December 2012 and January 2013 at seven buildings (buildings C, E, F, G, 9, 19, and 39) located on the former NSC campus (Figure C-2), which overlay groundwater concentrations exceeding 100 micrograms per liter (µg/L) of TCE. Indoor air samples were collected with HVAC systems operating normally and turned off, as well as sub-slab soil vapor samples. During this event, indoor air samples from Buildings 9, 39, C, and E contained VOCs above the commercial/industrial State Environmental Screening Levels (ESLs) or RSLs. Sub-slab samples were compared to an adjusted ESL for industrial air, using an assumed 0.01 attenuation factor. In December 2013, USEPA and the Regional Water Board transmitted a letter to Texas Instruments, Inc. (TI), the Responsible Party (RP) for the National Semiconductor Site, requiring vapor intrusion assessments to be completed for all eleven buildings (A, B, C, E, F, G, M, W, 9, 19, and 39) located on the former NSC campus. The assessment was conducted in March and April 2014 and included Buildings 40 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites A, B, C, G, M, W, and 39. Samples collected from Buildings C, 39, and G contained VOCs at concentrations above the commercial/industrial ESLs or RSLs for indoor air. At Building 9, 1,2-dichloroethane (1,2-DCA) was detected at a concentration of 0.66 µg/m3 in one HVAC-off indoor air sample. No other compounds detected in samples collected from Building 9 exceeded ESLs or RSLs. It was determined that the 1,2-DCA exceedance was likely related to an indoor source, since the compound was not detected in any sub-slab samples collected from Building 9. While concentrations of TCE and PCE exceeded the adjusted screening level at sub-slab sample locations (Table C-2), these VOCs were not detected in indoor air. Therefore, it was determined that VOCs in the subsurface were not causing an unacceptable risk to indoor air quality. No further sampling or mitigation was recommended for Building 9, which is currently unoccupied and planned for demolition. Table C-2. Building 9 Air Sample Exceedances in µg/m3 Sample Location HVAC Date 1,2-DCA PCE TCE 1900 1- Sub Slab c - 12/14/2012 - - 1800 dup c 2- Sub Slab - 12/14/2012 - 380 2500 Classroom No 12/30/2012 0.66 - - Regional Water Board ESL for Commercial Air 0.58 2.1 3.0 USEPA Region 9 RSL for Commercial Air 0.47 47 3.0 ESL adjusted for Sub Slab Commercial Air c - 210 300 c - Indoor air screening levels have been adjusted for sub-slab using an assumed attenuation factor of 0.01 (EPA 530-R-10- 002. March 16) At Building 39, three indoor air sample locations, one pathway location, and three sub-slab locations were sampled and analyzed. In an HVAC-off January 2013 sampling event, air samples collected in the men’s restroom pathway sample contained VOCs at levels above the commercial/industrial ESLs and RSLs (chloroform at 3.5 µg/m3; TCE at 27 µg/m3 and above; and PCE at 6.2 µg/m3). Concentrations of other analyzed compounds in that HVAC-off sampling event throughout Building 39 were below the commercial/industrial ESLs and RSLs. Following a preferential pathway assessment, mitigation measures were implemented by sealing the bathroom conduits (i.e., pipes, drains, and cracks in tiles). Follow-up sampling was conducted in the restrooms of Building 39 in April 2013 with the HVAC-off. TCE was detected in samples collected from the men and women’s restrooms at concentrations above the ESL and RSL (16 µg/m3 and 13 µg/m3 respectively). In the men’s restroom, PCE (3.2 µg/m3) was detected at a concentration above the ESL and chloroform (1.6 µg/m3) was detected above the RSL. A second round of testing was completed in March 2014. With the HVAC system off, the following ESL/RSL exceedances were detected in the men’s and women’s restrooms: TCE (ranging up to 40 µg/m3), PCE (ranging up to 9.1 µg/m3), and chloroform (ranging up to 2.9 µg/m3). Additionally, with the HVAC system operating, the following ESL/RSL exceedances were detected in the men’s and women’s restrooms: PCE (ranging up to 2.8 µg/m3) and TCE (ranging up to 17 µg/m3). Since the screening level exceedances were all located in the Building 39 restrooms and based on a reasonable estimate of the typical occupancy time, a one-hour exposure scenario was used to calculate a modified ESL and RSL for TCE of 24 µg/m3. Considering this modified screening level and in light of Fifth Five-Year Review for NSC and MMI Superfund Sites 41 HVAC-on indoor air sampling results meeting this screening level, unacceptable exposures to TCE to building occupants were likely very low. Air purifying filters and a sub-slab depressurization system (SSDS) were installed in Building 39 in June and October 2014 to address vapor intrusion Post-mitigation indoor air sampling completed in December 2014 confirmed that mitigation measures were effective in that all COCs were either not detected or well below both the Regional Water Board’s ESL and the USEPA Region 9’s RSL. Table C-3. Building 39 Air Sample Exceedances in µg/m3 Sample Location HVAC Date Chloroform PCE TCE 1 Sub Slab - 12/13/2012 1000/1000 2 Sub Slab - 12/13/2012 510 Men's Restroom No 1/6/2013 3.5 6.2 27 Men's Restroom No 4/28/2013 1.6 3.2 16 Women's Restroom No 4/28/2013 - - 13 Men's Restroom Yes 3/7/2014 - 2.8 17 Women's Restroom Yes 3/7/2014 - - 5.6 Men's Restroom No 3/9/2014 1.8 9.1 40 Women's Restroom No 3/9/2014 2.9 2.6 11 Regional Water Board ESL for Commercial Air 2.3 2.1 3.0 USEPA Region 9 RSL for Commercial Air 0.53 47 3.0 ESL adjusted for Sub Slab Commercial Air - - 300 At Building C, samples were collected and analyzed from seven indoor air locations, two pathway locations, and four sub-slab locations. In January 2013 with the HVAC turned off, PCE was detected at six of nine indoor air or pathway locations inside Building C at concentrations ranging from 2.7 to 18 µg/m3, all of which exceeded the ESL. A preferential pathway evaluation was completed and mitigation measures were implemented by sealing interior groundwater monitoring wells, slab penetrations, and an elevator pit. A second round of indoor air sampling was completed in March 2014 with the HVAC turned off. Sampling results from this event showed PCE detections at three of nine sample locations at concentrations ranging from 4.0 to 8.8 µg/m3, all of which exceeded the ESL. With the HVAC system operating, there were no COC indoor air exceedances of the ESL or RSL at any time. Therefore, it was determined that there is no unacceptable risk to building occupants from vapor intrusion while the HVAC system is operating. Installation of an SSDS was scheduled to begin in early 2015 to further reduce the potential for PCE vapor intrusion. Table C-4. Building C Air Sample Exceedances in µg/m3 Sample Location HVAC Date PCE Sub Slab - 12/15/2012 5200 Lab 2 area No 1/20/2013 2.7 Office Area (central portion) No 1/20/2013 12 IA6-C-2013-01-20 No 1/20/2013 18 42 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites Sample Location HVAC Date PCE DUP4-2013-01-20 No 1/20/2013 16 IA7-C-2013-01-20 No 1/20/2013 5.0 Office Area (SW portion) No 1/20/2013 9.8 In front of stairs (2nd Floor) No 1/20/2013 17 Office Area (central portion) No 3/23/2014 4.7 IA6-C-2014-03-23 No 3/23/2014 8.1 DUP6-C-2014-03-23 No 3/23/2014 8.8 Office Area (SW portion) No 3/23/2014 4.0 Regional Water Board ESL for Commercial Air 2.1 USEPA Region 9 RSL for Commercial Air 47 ESL adjusted for Sub Slab Commercial Air 210 At Building E, samples were collected and analyzed from six indoor air locations, four pathway locations, and four sub-slab locations. In January 2013 with the HVAC on and off, TCE was detected in a pathway sample at concentrations of 16 and 18 µg/m3, respectively, exceeding the ESL and RSL for that compound. This pathway exceedance was located in a restricted subterranean tunnel beneath Building E. The tunnel is accessed infrequently and for short durations, and thus unacceptable exposures to occupants were likely very low. A notice was posted at the entrance, directing personnel to contact Environmental Health and Safety (EHS) for access. Additionally, 1,4-dichlorobenzene (1,4-DCB) was detected at a concentration of 1.8 µg/m3 in a pathway sample collected in front of an elevator, exceeding the ESL and RSL for that compound. This detection was likely related to an indoor source, since 1,4-DCB was not detected in any of the sub-slab samples collected from Building E. While TCE was detected in sub-slab soil vapor at a concentration of 800 µg/m3 as well as in the tunnel, no other samples showed evidence of unacceptable levels of TCE. To mitigate vapor intrusion in the tunnel, preferential pathway sealing activities were conducted by TI in early 2015. Follow-up testing was performed in August 2016, following the sealing event. Although TCE levels in the tunnel were reduced, elevated levels of TCE were still detected, with the highest levels oddly detected with the tunnel ventilation exhaust fan operating. Based on these results, a pressure assessment was performed within the tunnel using a manometer. The results assessment indicated a significant negative pressure environment existed in the tunnel, resulting from operating the exhaust fan without sufficient air intake into the tunnel. In January 2017, TI modified the HVAC operation in the tunnel by adding a supply fan, in an effort to reduce the negative pressure environment in the tunnel. Following the HVAC modification, another round of testing was completed in the tunnel in March 2017. Table C-5. Building E Air Sample Exceedances in µg/m3 Sample Location HVAC Date TCE 1,4- DCB c Sub Slab - 12/15/2012 800 - Inside Basement tunnel Yes 1/18/2013 16 - Fifth Five-Year Review for NSC and MMI Superfund Sites 43 Sample Location HVAC Date TCE 1,4- DCB Inside Basement tunnel Yes 8/5/2016 12.7 - Inside Basement tunnel Yes 3/22/2017 0.136 - In front of the SW Elevator No 1/20/2013 - 1.8 Inside Basement tunnel No 1/20/2013 18 - Inside Basement tunnel No 8/8/2016 3.16 - Inside Basement tunnel No 3/24/2017 1.09 - Regional Water Board ESL for Commercial Air 3.0 1.1 USEPA Region 9 RSL for Commercial Air 3.0 1.1 ESL adjusted for Sub Slab Commercial Air a 300 - At Building G, samples were collected and analyzed from five indoor air locations, three pathway locations, and three sub-slab locations while the HVAC system was turned off. In December 2012, concentrations of TCE and PCE exceeded their adjusted screening levels at one sub-slab sample location. However, no compounds were detected above applicable screening criteria in the indoor air or pathway samples during this event. During the March 2014 sampling event with the HVAC system off, chloroform was detected at a concentration of 1.2 µg/m3, which exceeded its ESL. Chloroform was not detected in the sub-slab samples collected from Building G and is likely associated with an indoor source or from off- gassing from municipal water. No additional assessment or mitigation was recommended for Building G. Table C-6. Building G Air Sample Exceedances in µg/m3 Sample Location HVAC Date Chloroform PCE TCE c Sub Slab - 12/14/2012 250 660 Office Area (NE portion) No 3/16/2014 1.2 Regional Water Board ESL for Commercial Air 2.3 2.1 3.0 USEPA Region 9 RSL for Commercial Air 0.53 47 3.0 ESL adjusted for Sub Slab Commercial Air - 210 300 44 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites . .. .. OU 1 ... . >-::----;..• -✓• ... l_111A/Bl 27 044AJ ] o.s •I ... 5 . D . Unoccupied ...... Legend . Monitoring Wei! .. 011A • . 4.11 ~ • Extraction Well :, . 2013 TCE Concentration Contour {ug/L) . 'Cl . C A-Aquifer . 0 . u Operable Unit Boundary .. E . Q) . ---=--1 5 (/) X On Property Building Sampled (Eastern Parcels) . OB~ . On Property Building Sampled (Western Parcels) . 2.1 "' 250 500 ••••••········•••••·••••••••••••·········•·••Ki~rRoad• ···········•••••••••········••••••••••••••••••········••••••••• Figure X. Buildings Assessed for Vapor Intrusion Notes: (On Property NSC Site) 1. Contour interval as shown. 2. Concentration contours displayed in micrograms per liter (µg/L). 3. Map displayed in California State Plane Coordinate System , Zone Ill, North American Datum of 1983 (NAD63), US Survey Feet. *Map modified from Figure3 in the ON-PROPERTY VAPOR INTRUSION ASSESSMENT REPORT FOR EASTERN PARCELS (BUILDINGS 9. 19, 39, ANO G). Prepared for Texas Instruments Incorporated. Prepared by Langan Treadwell Rollo. 10 November 2014 Figure C-2. On-Property National Semiconductor Site Buildings Assessed for Vapor Intrusion Fifth Five-Year Review for NSC and MMI Superfund Sites 45 National Semiconductor Site and Monolithic Memories Site (Off-Property) The off-property vapor intrusion assessment area associated with the Sites includes buildings north of the former NSC campus and Monolithic Memories Site, bounded by Central Expressway in Subunit 1 (SU1 off-property), and buildings in Subunit 3 (SU3) downgradient of the former NSC campus and former AMD campus at 1165/1175 East Arques Avenue. An iterative approach was utilized to first assess vapor intrusion in buildings overlying groundwater with TCE concentrations of 100 µg/L or greater, which was followed by screening of buildings overlying 5 µg/L (the TCE MCL) to 100 µg/L of TCE in groundwater. Based on the 2013 TCE isoconcentration contours, 18 buildings were identified as overlying groundwater with concentrations of TCE of at least 100 µg/L in the off-property area of SU1 and SU3. One of the 18 buildings (1145/1155 East Arques Avenue, located in SU3) was impacted by a PCE spill in 2005 caused by TWC. As a result of the spill, the Regional Water Board required multiple rounds of indoor air sampling at this property from 2005 to 2012, which showed no evidence of unacceptable vapor intrusion. Of the remaining 17 buildings overlying groundwater TCE concentrations of at least 100 µg/L, 10 buildings were located in the off-property portion of SU1 and seven were located within SU3. Three buildings were added to the assessment (collectively, SU3-8) as they comprise a residential apartment community and overly groundwater with concentrations of TCE above 5 µg/L. Indoor, pathway, and ambient outdoor air samples were collected and analyzed from the buildings identified as SU1-1, SU1-2, SU1-3, SU1-4, SU1-5, SU3-1, SU3-2, SU3-3, SU3-4, SU3-6, SU3-7, and SU3-8 to assess the vapor intrusion pathway (Figure C-3). Buildings SU3-5, and SU1-6 through SU1-10 were not sampled because the property owner did not grant access for assessment and sampling. Additionally, the owner of buildings SU1-7 through SU1-10 completed their own indoor air assessment. These results were shared with USEPA during a site visit to verify adequacy of assessment approach and comparability to the approach taken by the Agencies at the Sites, but the data is not publicly available and could not be reviewed for this analysis. Indoor air samples collected from seven of the off-property buildings (SU1-1, SU1-2, SU1-3, SU3-1, SU3-2, SU3-4, and SU3-6) contained concentrations of chloroform, ethylbenzene, 1,2-dichloroethane (1,2-DCA), 1,1,1-trichloroethane (1,1,1-TCA), PCE, or TCE above the Regional Water Board commercial/industrial ESL or USEPA’s commercial/industrial RSL. Indoor air samples collected from the off-property residential building community (SU3-8) contained concentrations of chloroform, ethylbenzene, 1,2-DCA, methylene chloride, and PCE above the Regional Water Board residential ESL or USEPA’s residential RSL. More detail about these building results and the mitigation measures implement is provided below. Building SU1-1 is currently vacant and was last occupied by a semiconductor research and design company. It is believed that manufacturing was not performed on the premises. Groundwater in the vicinity of this building is expected to be present at approximately 11 feet below ground surface (bgs) with TCE concentrations in the likely range of 400 to 500 µg/L. Six indoor air samples, seven pathway samples (plus one duplicate) and one ambient outdoor air sample were collected from building SU1-1 for a total of 15 air samples while the HVAC system was off. Of the indoor air and pathway samples collected, four locations contained concentrations of chloroform (ranging from 2.96 to 26.1 µg/m3) and TCE (ranging from 3.08 to 19 µg/m3) exceeding their ESL and RSL. In general, the elevated 46 concentrations of TCE were detected in the restrooms, suggesting vapor intrusion from underlying groundwater-TCE via plumbing penetrations and enhanced by poorer ventilation. Based on the results of the August 2016 sampling event, vapor intrusion mitigation and sealing activities, operation of the HVAC units, and an additional round of sampling was proposed at Building SU1-1. The additional round of HVAC-on and -off indoor air sampling was conducted in December 2016, which showed no VOCs in any indoor air or pathway samples above the Regional Water Board’s commercial/industrial land use ESLs and USEPA’s commercial air RSLs. Based on these results, it was determined that the mitigation activities were effective and no unacceptable risks to building occupants are posed with the HVAC system on or off. With the building layout and HVAC operational areas unchanged, another round of indoor air and pathway sampling with the HVAC systems operating is planned at this building in summer 2018, following some planned tenant improvements and to account for seasonal variations. If the building layout changes significantly due to the tenant improvements, then a building survey will be performed prior to sampling activities and an updated sampling plan will be proposed. Table C-7. Building SU1-1 Air Sample Exceedances in µg/m3 Sample Location HVAC Date Chloroform TCE Lobby area (east) No 8/29/2016 - 3.08 Lobby area (east) Yes 12/19/2016 - 0.27 Lobby area (east) No 12/21/2016 - 0.896 Women's restroom (north) No 8/29/2016 26.1 8.21 Women's restroom (north) Yes 12/19/2016 0.246 0.208 Women's restroom (north) No 12/21/2016 0.287 Women's restroom (east) No 8/29/2016 13.1 19 Women's restroom (east) Yes 12/19/2016 0.23 0.198 Women's restroom (east) No 12/21/2016 0.287 1.19 Men's Restroom (southwest) No 8/29/2016 2.96 3.81 Men's Restroom (southwest) No 8/29/2016 3 4 Men's Restroom (southwest) Yes 12/19/2016 0.24 0.292 Men's Restroom (southwest) No 12/21/2016 0.257 1.06 Ambient Air N/A 8/29/2016 0.137 < 0.0537 Regional Water Board ESL for Commercial Air 2.3 3 USEPA Region 9 RSL for Commercial Air 0.53 3 Buildings SU1-2 and SU1-3 each have multiple suites (12 suites in each building) occupied by various tenants. Each suite generally consists of a front office space and a rear warehouse/storage space with roll-up truck doors. Each suite has its own individual HVAC unit containing its own heating and cooling devices for the front office areas, which each suite independently controls. The warehouse/storage areas located in the rear of the suites do not have active ventilation, though some warehouses contain natural gas unit heaters suspended from the ceiling. Groundwater in the vicinity of these buildings is expected to be present at approximately 11 feet bgs with TCE concentrations likely Fifth Five-Year Review for NSC and MMI Superfund Sites 47 ranging from 100 to 200 μg/L. Indoor air samples were collected from building areas that are normally occupied throughout the day during working hours. Pathway sample were collected from areas not normally occupied for a continuous 8-hour period. One ambient outdoor air and one field duplicate sample were collected on the same day as the indoor air and pathway samples were collected. Both buildings had RSL and ESL exceedances of ethylbenzene, 1,2-DCA and chloroform with the HVAC system operating and turned off, which are likely attributable to materials within the individual suites or off-gassing from the municipal water supply. Given that these compounds are not typically detected in groundwater samples from nearby monitoring wells, the fact that these chemicals are commonly used in commercial settings, and that ethylbenzene was also detected in ambient outdoor air, it is not likely that these chemicals are associated with vapor intrusion from underlying groundwater. Table C-8. Building SU1-2 and SU1-3 Air Sample Exceedances in µg/m3 Sample Location HVAC Date Ethylbenzene 1,2-DCA Chloroform Business #1 (SU1-2) Yes 2/17/2015 - - 1.2 Business #2 (SU1-2) No 2/22/2015 8.1 0.57 - Business #1 (SU1-2) No 2/22/2015 - - 0.57 Business #3 (SU1-3) Yes 2/17/2015 7.4 0.74 - Business #3 (SU1-3) dup Yes 2/17/2015 10 0.87 - Business #4 (SU1-3) Yes 2/17/2015 - - 5.1 Regional Water Board ESL for Commercial Air 4.9 0.6 2.3 USEPA Region 9 RSL for Commercial Air 4.9 0.47 0.53 Building SU1-4 is a three-story office building constructed over a podium-style garage. Groundwater in the vicinity of the site likely ranges from 8 to 10 feet below ground surface and contains concentrations of trichloroethene (TCE) ranging from 100 to 200 micrograms per liter (µg/L). One indoor air samples, four pathway samples and one ambient outdoor air were collected while the HVAC system was operating. No VOCs, including TCE and PCE, were detected above the Water Board’s Commercial/Industrial Land Use ESL, the USEPA’s Industrial Air RSL, or the USEPA’s RAL in any of the samples collected. Table C-9. Building SU1-4 Air Sample Results in µg/m3 Sample Location HVAC Date TCE PCE Lobby area near the elevator on the first Yes 6/8/2016 < 0.0537 < 0.0678 floor above the garage Adjacent to the garage sump Yes 6/8/2016 1.63 0.131 Inside the garage electrical room Yes 6/8/2016 0.304 < 0.136 Elevator shaft Yes 6/8/2016 0.152 0.106 Outside the entrance to building N/A 6/8/2016 < 0.0537 < 0.0678 Regional Water Board ESL for Commercial Air 3 2.1 USEPA Region 9 RSL for Commercial Air 3 47 48 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites Building SU1-5 is a three-story office building constructed over a podium-style garage. The building is approximately 77,000 square feet in size. Groundwater in the vicinity of the site ranges from 8 to 10 feet below ground surface and contains concentrations of trichloroethene (TCE) likely ranging from 100 to 200 micrograms per liter (µg/L). One indoor air and three pathway samples were collected with the HVAC system operating. The indoor air sampling was collected in an area normally occupied over the course of a typical business day. Pathway samples were collected in areas that are either not accessed by workers or are not normally occupied for a full work day, adjacent to the garage sump and inside the garage electrical room. A grab pathway sample was collected from near the bottom of the elevator shaft. One outdoor sample was collected. No VOCs, including TCE and PCE, were detected above the Water Board’s Commercial/Industrial Land Use ESL, the USEPA’s Industrial Air RSL, or the USEPA’s RAL in any of the samples collected. Table C-10. Building SU1-5 Air Sample Results in µg/m3 Sample Location HVAC Date TCE Lobby area near the elevator on the first Yes 6/8/2016 < 0.0537 floor above the garage Adjacent to the garage sump Yes 6/8/2016 0.174 Inside the garage electrical room Yes 6/8/2016 < 0.107 Elevator shaft Yes 6/8/2016 < 0.215 Outside the entrance to building N/A 6/8/2016 < 0.0537 Regional Water Board ESL for Commercial Air a 3 USEPA Region 9 RSL for Commercial Air b 3 Building SU3-1 is occupied by a business with offices, a janitor’s closet, restrooms, and a vault. Based on sampling data obtained during the 2014 groundwater monitoring event, groundwater in the vicinity of the building is expected to be present at approximately 9 to 11 feet bgs with TCE concentrations ranging from 100 to 200 µg/L. Indoor air samples were collected from building areas that are normally occupied throughout the day during working hours. Pathway sample were collected from areas not normally occupied for a continuous 8-hour period. One ambient outdoor air and one field duplicate sample were collected on the same day as the indoor air and pathway samples were collected. During the February and March 2015 sampling events, chloroform exceeded the commercial ESL and RSL in the janitor’s storage room at concentrations of 0.55 µg/m3 and 0.91 µg/m3 with the HVAC system turned off and on, respectively. Additionally, PCE exceeded the commercial ESL and RSL in the operations/vault area at a concentration of 2.7 µg/m3 with the HVAC system turned off. It was determined that the chloroform detections were likely attributable to off-gassing from the municipal water supply at the janitorial sink. PCE has generally been either below laboratory reporting limits or less than 5 μg/L at nearby monitoring wells since 2004, which suggests that the elevated PCE concentration was likely associated with an indoor air source, rather than from vapor intrusion from underlying groundwater. An additional round of indoor sampling was completed in September 2015 to evaluate seasonal variability and to assess concentrations of PCE. With the HVAC system off, chloroform exceeded the commercial ESL and RSL in the janitor’s storage room at a concentration of 1.8 µg/m3. Chloroform Fifth Five-Year Review for NSC and MMI Superfund Sites 49 also exceeded the commercial ESL and RSL in the ambient outdoor air sampling location near the southwest emergency exit at a concentration of 0.63 µg/m3. PCE was not detected above the laboratory’s reporting limit of 0.17 µg/m3 in any of the indoor air or pathway samples collected in September 2015 with the HVAC systems off. It was determined that vapor intrusion does not pose a significant risk to building occupants and further evaluation of the vapor intrusion pathway was not recommended. Table C-11. Building SU3-1 Air Sample Exceedances in µg/m3 Sample Location HVAC Date Chloroform PCE Janitor's Storage Room Yes 2/27/2015 0.55 - Operations and Vault No 3/1/2015 - 2.7 Janitor's Storage Room No 3/1/2015 0.91 - Janitor's Storage Room No 9/27/2015 1.8 - Ambient Outdoor Air (SW Emergency - 9/27/2015 0.63 - Exit) Regional Water Board ESL for Commercial Air a 2.3 2.1 USEPA Region 9 RSL for Commercial Air 0.53 47 a- Regional Water Quality Control Board (Regional Water Board) Environmental Screening Level (ESL) indoor air from Table E-3, December 2013. Building SU3-2 is occupied by a business with offices, restrooms, and image processing rooms. Groundwater in the vicinity of the building is expected to be present at approximately 11 feet bgs with TCE concentrations ranging from 100 to 200 μg/L. Indoor air samples were collected from building areas that are normally occupied throughout the day during working hours. Pathway samples were collected from areas not normally occupied for a continuous 8-hour period. One ambient outdoor air and one field duplicate sample were collected on the same day as the indoor air and pathway samples were collected. With the HVAC system operating, chloroform was detected above the commercial ESL and RSL in women’s restroom on the south side of the building (at a level of 1.39 µg/m3) and the processing room on the east side of the building (at a level of 0.561 µg/m3). With the HVAC system turned off, chloroform was again detected above the commercial ESL and RSL in the same women’s restroom at a concentration of 14.5 µg/m3. This restroom also showed TCE levels above the commercial ESL and RSL (at a level of 4.37 µg/m3). It was determined that the chloroform detections were likely attributable to off-gassing from the municipal water supply. It was determined the HVAC-off TCE levels just above the commercial ESL/RSL do not pose a significant risk to building occupants because: 1) the HVAC off condition is not the normal operating condition for the building and 2) pathway samples are collected in areas that are not normally occupied for 8 hours per day, 50 weeks a year, which are the exposure assumptions on which the screening levels are based. 50 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites Table C-12. Building SU3-2 Air Sample Exceedances in µg/m3 Sample Location HVAC Date Chloroform TCE Women's Restroom (South) Yes 3/6/2016 1.39 - Processing Room (East) Yes 3/13/2016 0.561 - Women's Restroom (South) No 3/13/2016 14.5 4.37 Regional Water Board ESL for Commercial Air 2.3 3 USEPA Region 9 RSL for Commercial Air 0.53 3 Building SU3-3 is a commercial building. Indoor air samples were collected from building areas that are normally occupied throughout the day during working hours. Pathway samples were collected from areas not normally occupied for a continuous 8-hour period. One ambient outdoor air was collected on the same day as the indoor air and pathway samples were collected. TCE was not detected above the USEPA’s RSL or above Regional Board’s RSL in any of the samples collected. Table C-13. Building SU3-3 Air Sample Exceedances in µg/m3 Sample Location HVAC Date TCE Indoor Air No 2015 <0. 1 Pathway sample No 3/13/2016 <0. 1 Ambient Air No 3/13/2016 <0. 1 Regional Water Board ESL for Commercial Air a 3 USEPA Region 9 RSL for Commercial Air 3 Building SU3-4 is occupied by a business specializing in printing and data transferring services. The southeastern portion of the building is used by an imaging company. Based on information obtained during a recent groundwater monitoring event, groundwater in the vicinity of the building is expected to be present between 8 and 10 feet bgs with TCE concentrations ranging from 100 to 200 μg/L. Indoor air samples were collected from building areas that are normally occupied throughout the day during working hours. Pathway samples were collected from areas not normally occupied for a continuous 8-hour period. One ambient outdoor air and one field duplicate sample were collected on the same day as the indoor air and pathway samples were collected. During the March 2015 sampling event with the HVAC system operating, chloroform was detected above the commercial RSL in six sampling locations, ranging in concentration from 0.56 to 2.01 µg/m3. With the HVAC system turned off, chloroform was again detected above the commercial RSL in two sampling locations: the men’s restroom (at a level of 2.01 µg/m3) and the western utility trench near the printers (at levels of 0.888 and 0.609 µg/m3). It was determined that the chloroform detections were likely attributable to off-gassing from the municipal water supply. Additionally, TCE was detected above the commercial ESL and RSL in the computer room (at levels of 4.89 and 6.17 µg/m3) and the imaging area (at a level of 5.07 µg/m3) with the HVAC system turned off. TCE air sampling data was reviewed relative to other compounds detected in indoor and pathway air to evaluate concentration ratios and trends. Detected groundwater concentrations in nearby Fifth Five-Year Review for NSC and MMI Superfund Sites 51 monitoring wells were also compared to compounds detected in indoor air and pathway samples to further understand the potential source of TCE. 1,1,1-TCA was detected in all indoor air and pathway samples collected but was not detected in groundwater samples collected in 2013 or 2014. It was determined that detected concentrations of TCE and 1,1,1-TCA have a linear relationship, specifically with HVAC off. Considering the above information (i.e., multiple lines of evidence), and given the chemicals used by these businesses, the presence of TCE and 1,1,1-TCA in indoor air samples is likely associated with an indoor source. To evaluate and identify potential indoor source(s) for TCE and 1,1,1-TCA, a review of cleaning materials, printing inks and chemicals used at the building was completed in June 2015. 1,1,1-TCA was identified as the primary component in two film cleaning products in use at the facility (i.e. Kodak film cleaner and Stanco film cleaner/conditioner). TCE is a known impurity of technical grade 1,1,1- TCA at concentrations of up to 7.6%, which is present and in use at the facility. Based on these findings, it was determined that the elevated 1,1,1-TCA and TCE concentrations detected with HVAC units off were most likely related to the use of the film cleaners at the facility and not vapor intrusion from underlying groundwater. Based on these findings, additional vapor intrusion evaluation at the building was not recommended. Table C-14. Building SU3-4 Air Sample Exceedances in µg/m3 1,1,1- Sample Location HVAC Date Chloroform TCE TCAa Computer Room No 3/1/2015 126 4.89 Computer Room (dup) No 3/1/2015 148 6.17 Men's Restroom No 3/1/2015 0.582 Imaging area (floor drain) No 3/1/2015 130 5.07 Western utility trench (near printers) No 3/1/2015 0.888 Western utility trench (near printers) (dup) No 3/1/2015 0.609 Behind entry reception desk Yes 3/6/2015 0.553 Conference Room Yes 3/6/2015 0.543 Lunch Room Yes 3/6/2015 1.48 Men's Restroom Yes 3/6/2015 2.01 Imaging area (floor drain) Yes 3/6/2015 0.56 Cleanout from sink (near printers) Yes 3/6/2015 0.579 Regional Water Board ESL for Commercial Air 21,900 2.3 3 USEPA Region 9 RSL for Commercial Air 22,000 0.53 3 a- 1,1,1-TCA did not exceed its commercial ESL/RSL during this sampling event. Detections of 1,1,1-TCA are noted for comparison to TCE detections Building SU3-6 is occupied by a business specializing in computer assembly with offices, restrooms, and a warehouse. Based on the results for groundwater samples collected in 2014, groundwater in the vicinity of the building is expected to be present at approximately 9 to 10 feet bgs with TCE concentrations ranging from 50 to 100 μg/L. Indoor air samples were collected from building areas that are normally occupied throughout the day during working hours. Pathway samples were collected from areas not normally occupied for a continuous 10-hour period. One ambient outdoor air and one 52 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites field duplicate sample were collected on the same day as the indoor air and pathway samples were collected. During the March 2015 sampling event with the HVAC system operating, chloroform was detected above the commercial ESL and RSL in the women’s restroom at a concentration of 2.3 µg/m3 and above the commercial ESL in the janitor’s closet at a concentration of 0.643 µg/m3. The chloroform detections were likely attributable to off-gassing from the municipal water supply. It was determined that vapor intrusion does not pose a significant risk to building occupants and additional evaluation of the vapor intrusion pathway was not recommended. Table C-15. Building SU3-6 Air Sample Exceedances in µg/m3 Sample Location HVAC Date Chloroform Janitor Closet (west) Yes 3/6/2015 0.643 Women's restroom Yes 3/6/2015 2.3 Regional Water Board ESL for Commercial Air 2.3 USEPA Region 9 RSL for Commercial Air 0.53 Buildings SU3-7 are zoned in a commercial/industrial area of Sunnyvale, California and consist of storage units and offices (Figure 1). The storage units are located in one- to four-story, slab on-grade buildings, some climate-controlled and some without heating, ventilation, and air conditioning (HVAC) systems installed. There are no offices or other continuously occupied spaces within the storage buildings. Based on information provided by the owner, customers typically access the storage units for approximately 15 to 20 minutes per visit. The occupied office buildings are shown on Figure 2, and include the reception and administrative office to the storage facility and a small office park, consisting of three suites. The storage reception and administrative building is an approximately 970 square foot, single story, slab-on-grade building that extends off the northern side of a storage building. Indoor air samples were collected in February 2015 from the reception area, as well as pathway samples in the building and one ambient air sample. TCE was not detected above Water Board ESLs or USEPA RSLs in any of the samples collected. TCE results in indoor air samples ranged from less than the detection limit of 0.13 µg/m3 to 0.39 µg/ m3. TCE results in pathway samples were 0.32 and 2.4 µg/ m3. Building SU3-8 does not overlie shallow groundwater concentrations of TCE greater than 100 µg/L, but since it is a residential apartment community within OU1 (Subunit 3 or SU3), a survey was completed to assess the layout and construction of the buildings and it was added to the assessment. Groundwater in the vicinity of the building is expected to be present at approximately 12 feet bgs with TCE concentrations ranging from 5 to 15 µg/L. Potential pathways associated with the elevators in the three residential buildings were evaluated, as these are the only buildings with elevators that open into enclosed, common spaces. HVAC units were operating normally during sampling in the elevator lobbies. According to the property owner, HVAC units in the common areas of these three buildings are set to a constant temperature and operate every day in the same manner and therefore were not adjusted during sampling. Three pathway sample locations were tested in each building, one from the elevator lobby on the ground floor, one from the elevator lobby on the 1st floor, and one from the parking garage on the ground floor. Fifth Five-Year Review for NSC and MMI Superfund Sites 53 Of the VOCs detected, 1,2-DCA, chloroform, ethylbenzene, methylene chloride, and PCE were the only compounds detected above the Regional Water Board’s residential ESLs and USEPA’s residential RSLs. These compounds are commonly associated with background VOC concentrations in residential settings, as they are commonly found in a variety of products used in residential settings. Furthermore, 1,2-DCA, ethylbenzene, methylene chloride, and PCE were not detected in groundwater samples collected in December 2014 from the dewatering system present beneath the building or in the nearest groundwater monitoring wells, which suggests that the presence of these chemicals is not associated with vapor intrusion from underlying groundwater. Considering the multiple lines of evidence evaluated, it was determined that the 1,2-DCA, chloroform, ethylbenzene, methylene chloride, and PCE concentrations detected were likely associated with an indoor or outdoor ambient air sources and not vapor intrusion. It was concluded that vapor intrusion is not significantly impacting air quality at these buildings and no additional evaluation was recommended. Table C-16. Building SU3-8 Air Sample Exceedances in µg/m3 1,2- Ethyl Methylene Sample Location Building Date Chloroform PCE DCA benzene Chloride Elevator Lobby (Ground) #1 3/27/2015 - 0.34 - - - Elevator Lobby (Ground) dup #1 3/27/2015 - 0.33 - - - Parking Garage (Ground) #1 3/27/2015 0.15 0.48 - - 0.57 Elevator Lobby (1st Floor) #1 3/27/2015 - 0.31 - - - Elevator Lobby (Ground) #2 3/27/2015 - 0.14 - - 0.53 Parking Garage (Ground) #2 3/27/2015 - 0.15 3.4 - - Elevator Lobby (1st Floor) #2 3/27/2015 0.85 0.77 1.8 1500 24 Elevator Lobby (Ground) #3 3/27/2015 0.14 8.7 1 41 0.98 Parking Garage (Ground) #3 3/27/2015 - 0.44 - - - Elevator Lobby (1st Floor) #3 3/27/2015 0.21 1.8 - - - Outdoor Air 3/27/2015 - 1.9 2.3 - - Regional Water Board ESL for Residential Air a 0.12 0.46 0.97 5.18 0.41 USEPA Region 9 RSL for Residential Air 0.11 0.12 1.1 100 11 54 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites Figure C-3. Off-Property Buildings assessed for Vapor Intrusion Fifth Five-Year Review for NSC and MMI Superfund Sites 55 Appendix D: Groundwater Data Review 1. Groundwater Gradient Groundwater flow in the A, B1, B2, and B3 aquifers is towards the north to northeast direction. Between October 2013 and October 2016, gradients in the A aquifer range from 4.8E-3 to 5.1E-3 feet/feet; in the B1 aquifer, 1.9E-3 to 5.3E-3 feet/feet; and in the B2 and B3 aquifers, 4.8E-3 to 5.2E-3 feet/feet (Figures D-4, D-5, and D6). 2. Hydraulic Control In 2016, a groundwater investigation program and groundwater modeling were performed to evaluate proposed modifications to the groundwater extraction system. The investigation included soil borings to log lithology and collect groundwater and soil samples for laboratory analysis, step-drawdown tests at existing extraction wells, and groundwater flow modeling to evaluate pumping scenarios. Results of the groundwater modeling for the proposed modifications to the groundwater extraction system are shown in Figure D-7 and Figure D-8. Based on the plume capture analysis, Langan Treadwell Rollo recommended installation of one new A-aquifer well (EW A-1), converting two A-aquifer monitoring wells into extraction wells (21A and 46A), installing three new B1-aquifer extraction wells (EW 45R- B1, EW B1-1 and EW B1-2), maintaining existing A-aquifer extraction wells 45A-B1 and 48A, and maintaining existing B1-Aquifer extraction well 12B1 to obtain optimal capture of the on-site groundwater plume. The proposed changes to the groundwater extraction system were implemented in October 2016. The Arques Avenue groundwater extraction system has been shut down since September 2016, after the release of approximately 3,000 gallons of untreated groundwater to the ground surface following a rupture in the polyvinyl chloride (PVC) conveyance piping. An access agreement could not be arranged to make repairs to the pipeline. Groundwater quality data near the Arques Avenue groundwater extraction system indicate that lower concentrations of contaminants have been observed in groundwater extracted by the Arques wells. The largest decrease of contaminants in groundwater occurred at well 103A where trichloroethene (TCE) decreased from 530 µg/L to 84 µg/L between 2003 and 2016. The smallest decrease was observed at well 71A, where concentrations of TCE decreased from 370 µg/L to 200 µg/L in the same time frame. A request for permanent shutdown of the Arques Avenue groundwater extraction system was requested in 2017 and granted in early 2018. The areas that are no longer captured by the Arques Avenue extraction system are within the capture zone of the Lakeside extraction system. 3. Groundwater Concentration Analysis Groundwater samples are collected annually from monitoring wells and analyzed for volatile organic compounds (VOCs). The 2017 groundwater sampling included 60 A-aquifer wells, 13 A/B1-aquifer wells, 25 B1-aquifer wells, and three B2-aquifer wells. Results of prior groundwater data collected between 2011 and 2017 are discussed in the following sections. 56 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites A-aquifer TCE concentrations contour maps for the A-aquifer from 2013 and 2016 are shown in Figur9 through D-13. Comparison of the 100 µg/L contour for TCE between the maps shows little change in the extent of the TCE plume for the review period. TCE concentrations exceeded the cleanup goal in 47 of the 60 A-aquifer wells sampled in 2017. The highest concentration of TCE measured in the A-aquifer in 2017 was 580 µg/L at well 36A followed by 450 µg/L at well 58A and 430 µg/L at extraction well 46A. TCE concentrations exceeded the cleanup goal in 11 of the 13 A/B1-aquifer wells sampled in 2017. The highest concentration of TCE measured in the A/B1-aquifer wells was 210 µg/L in well 71A/B1. Cis-1,2-dichloroethene (Cis-1,2-DCE) concentrations exceeded the cleanup goal in 45 of the 60 A-aquifer wells sampled in 2017. The highest concentration of cis-1,2-DCE was 17,000 µg/L in well 150A followed by 680 µg/L in well 153A. After the groundwater extraction system was modified in 2016, TCE concentrations decreased slightly in wells 36A, 31A, and 21A and cis-1,2-DCE concentrations in well 21A increased. The Arques Avenue extraction system has been shut down since September 2016. Concentrations of TCE and cis-1,2-DCE have been relatively consistent in these wells between 2011 and 2017. Groundwater concentrations for the A aquifer for the five-year period were analyzed for trends using the Mann-Kendall method, however data from the selected wells showed no discernable trends. Data anomalies for groundwater characterization include recent upgrades/changes to groundwater extraction and treatment (GWET) systems, discontinued operation of the Arques system and inconsistent sampling of well sets in OU-1. Building C Persulfate injection events took place at Building C in November 2011, March 2012, July 2012, and June 2013. TCE concentrations in well 154A increased to 760 µg/L in October 2013, following the third injection event. The concentration has since dropped and was 39 µg/L in 2017. TCE concentrations in the remainder of the monitoring wells by Building C are below the cleanup goal. Concentrations of cis-1,2-DCE have varied between 36 and 310 µg/L in well 154A since 2012. The concentrations in the remaining wells have been near or below the cleanup goal for cis-1,2-DCE since 2014. Well 154A also exceeds the cleanup goals for 1,1-dichloroethane (1,1-DCA), 1,2- dichlorobenzene (1,2-DCB), 1,4-dichlorobenzene (1,4-DCB), and perchloroethene (PCE). Building G The concentration of TCE in well 150A dropped from more than 3,000 µg/L in 2015 to 58 µg/L in 2016. This decline followed an enhanced bio-remediation injection event that took place in May 2016 outside of Building G. Concentrations of cis-1,2-DCE in well 150A have been greater than 2,000 µg/L and recently increased to 17,000 in 2017. Well 150A also exceeds the cleanup goal for Freon 113, 1,2- DCB, ethylbenzene, and vinyl chloride. Fifth Five-Year Review for NSC and MMI Superfund Sites 57 B1-aquifer TCE concentrations for the B1-aquifer from 2013 and 2017 are shown in Figure D-11 and Figure D-12 respectively. Groundwater concentrations for the B1 aquifer for the five-year period were characterized using data from sampling events. Trends for key wells were generated using the Mann- Kendall method. For the wells that were selected, concentrations showed stable to decreasing trends for PCE and cis-1,2-DCE. TCE concentrations exceeded the cleanup goal in 20 of the 25 B1-aquifer wells sampled in 2017. The highest concentration of TCE measured in the B1-aquifer wells was 220 µg/L in well 72B1. Twenty wells exceeded the cleanup goal for cis-1,2-DCE in 2017. The highest concentration of cis-1,2-DCE was 290 µg/L in 21B1. Five wells had concentrations above the cleanup goal for vinyl chloride in 2017. The highest concentration of vinyl chloride was 5.4 µg/L in well 72B1. All of the B1-aquifer wells were below the cleanup goals for the remaining contaminants of concern. Concentrations of TCE in the B1-aquifer are steady or declining slightly with the exception of wells 72B1, 100B1, 57B1, and MM17B1. TCE concentrations in well 72B1 have varied between 180 and 290 µg/L since 2011. TCE concentrations in well 100B1 increased in 2013 but have been consistent from 2014 through 2017. Concentrations of TCE in wells 14B1 and MM17B1 increased in 2016, then returned to lower levels in 2017. Concentrations of cis-1,2-DCE have been decreasing or steady in most wells. The most dramatic change was in well 57B1, decreasing from 450 µg/L in 2014 to 98 µg/L in 2017. B2-aquifer TCE concentrations in the B2-aquifer from 2013 and 2017 are shown in Figure D-13 and Figure D-14 respectively. Groundwater concentrations in the B2 aquifer for the five-year period were characterized using data from sampling events. Trends for key wells were generated using the Mann-Kendall method. For the wells that were selected, concentrations showed stable to decreasing trends for PCE and cis-1,2-DCE. TCE concentrations exceeded the cleanup goal in two of the three wells sampled in 2017. The highest concentration of TCE measured in the B2-aquifer was 71 µg/L in well 39B2. One well exceeded the cleanup goal for cis-1,2-DCE in 2017: well 71B2 with 12 µg/L. Well 39B2 exceeded the cleanup goal for PCE at a level of 6.7 µg/L. All three wells were below the cleanup goals for the remainder of the contaminants of concern. The TCE plot shows some concentration fluctuations in well MM33B2 while concentrations in the other three wells were relatively steady. Figure D-14 shows a temporary increase of cis-1,2-DCE in well ME19B2 in 2015. The concentration dropped back down to below the cleanup goal in 2017. The TCE concentration in well 71B2 has been consistently just above the cleanup goal between 2011 and 2017. The overall footprint of the TCE and cis-1,2-DCE plume appears stable across OU-1. Recent remedial work at Building C and Building G have resulted in VOC concentration reductions near both buildings. 58 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites • Mooilollnfl- ---Edge ·- ------A-AQUIFER GROUNDWATER L_j - - • OIi-Siii>- ELEVATION CONTOURS I.-~- 2,1. Al-lob&...-..i-___ .... _,.~ OCTOBER 2018 ...... =.,~- -3., ~~djSpl8yed8Atil'lfe1t~ meen ..MII. 4, NIia Nol,,.,.,,_ 5.Map-.. ~------OU1 -Opo,mellm1 (NAD831.USSUM!yl'"81. LAN&AN -·---- -·-··---« Figure D-4: October 2016 A Aquifer Groundwater Elevation Contours. Extraction wells 21A, 46A, 48A, 72A, EWA-1, 103A, 45A/B1, 71A/B1, 98A/B1, 102A/B1, 104A/B1, and 106A/B1, active. Fifth Five-Year Review for NSC and MMI Superfund Sites 59 ••• ~Uflitlk!Undlfy •-•. -.- ---Edge u- - Bi-AQUIFER 8ROUNDWATER . ELEVATION CONTOURS -- OCTOBER 2016 ---- 2.t ..... GfOlnJwuferefevatians~wvinfMltabutte-.. .. ""------Pl'ojlct 750620748 , - -. ----___ ...... __z...111, ___.,,11113 ------3.--.,~----.us-Feot LAN&AN Figure D-5: October 2016 B1 Aquifer Groundwater Elevation Contours. Extraction wells 15B1, 72B1, 100B1, 126B1, EW-45B1-R, EW-B1-1, and EW-B1-2 active. 60 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites ---~u.it~ -l: Figure D-6: October 2016 B2 and B3 Aquifer Groundwater Elevation Contours. Fifth Five-Year Review for NSC and MMI Superfund Sites 61 .. lf20. t 9A/Bl. 07-481. ! f'""' NlO,f; Bl--.r-lf07 ! lft~ --::::::i TEXAS INSTRUMENTS INCORPORATED Santa aara, Galifomia Legend • Morvloff,gW.. - E, tma•dA-AquNrC..p<,.. PROPOSED ON.CAMPUS 1. Downg,-n1•><1ra Figure D-7: Capture Zone Analysis Results for Revised Groundwater Extraction System: A-Aquifer. 102.l/B.l .. LFZO. '!194/81. 07-481. fr'"" HlO/;e1-jU'Ol ,: l fl9~ TEXAS INSTRUMENTS INCORPORATED Santa aara, Galifomia Legend • MonitctingW.. -Estwnait 62 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites ' "" .. - -- Figure D-9: A-Aquifer TCE Concentration Contour, October 2013 Fifth Five-Year Review for NSC and MMI Superfund Sites 63 ~ l ~ul Legend Notes: TEXAS INSTRUMENTS Extraction We ll Santa Clara. California • 1. All locations to be considered acrurare • Monitoring Well 2. TCE ooncer,aations displayed are in u9'L 3. Map dis played in California State Pla ne Coorcfnate A-AQUIFER TCE o Off-Site wen System , Zone 111 , NOl'th American Oatwn of 1Q83 CONCENTRATION CONTOUR i TCE Concentration Contour (NA083), US Survey Feet. ! "'- (dashed where infe rred) OCTOBER 2014 ~ • -- Operable Unit Boundary O.3.e- 3/2412015 Proje ct 7506207 17 Fig-u re 6 l ! Building 600 1.200 1 LANGAN THEAUWELL HULLU Feet i Figure D-10: A-Aquifer TCE Concentration Contour, October 2014 64 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites 1 J J , _•-••--...::::------••••KW.A-•• ~·---- Legend 300 600 1,200 TEXAS INSTRU MENTS Extraction Wei Oper.1ble Unit Boundary f eet i f------s_,_n_1._ c_1a_,._._c_,_1if_o_m_i•______. Monitoring Wei Road Edge o Off-Site Wel Building A -AQUIFER TCE TCE Conc,e,n tration Contour .-...... (dashed wbere infen-ed) CONCENTRATION CONTOUR OCTOBER 2015 SDOU - Steward Orive Ope,rable Unit Note.-s : OU1 • Opaatte Unit 1 1. Al locations to be considered .3CO.J rate Dace 6115/20 16 Proje c; 7 50620734 Figure 6 2. TOE concentratioos ctisplayed are in ug/L. 3. Ma p displayed in Cafifomia State P lane Coonfnate System. Zone Ill. North Am!,rican Datum of 19S3 LAN6AN THEAUWELL HULLO (NADB3), US Stney f eet. Figure D-11: A-Aquifer TCE Concentration Contour, October 2015 Fifth Five-Year Review for NSC and MMI Superfund Sites 65 :~ - _...... a -- : L egend 300 600 1.200 I TEXAS INSTRUMENTS ci Extract:on Wei ~~iiiiiiiiF~.. ~, ~~~ i ,______Sa_ n1a_ c_1a_ra_, c_a1_;1o_mi_a ----1 : • Monitoring Wei SOO U - Steward Ori tJ e ()perable U =I: ~ Sample'S colected on 2 1 N O'i' ember 20 1tl in accordance • w:th the Building G bio-cemediation wori:plan O U 1 - Ope,able Unit 1 A -AQUIFER TCE l o Off-S" e Wei CONCENTRATION CONTOUR OCTOBER 2016 j "-.., TCE Concentration Contour Notes.: - • - OPE:rable Unit Boundary 1. Al locations to be ccnsidered .JCCUrate Date 2/2 1/20 17 Project 75062074,8 Figure 6 i - Road Edge 2. TCE ooncentrati ons displayed are in ug,1- Buil Figure D-12: A-Aquifer TCE Concentration Contour, October 2016 66 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites Leg end -30D 6D0 1,200 TEXAS INSTRUME NTS a Extr.iction Wei ,.. , ~I .______Santa Clara, California __. • Monitoring Wei SDO U - Steward Ori'i'e Operable un· o Off-S" e Wei OU 1 - Opet'able U nit 1 A -AQUIFER TC E CONCENTRATION CONTOUR ~ ld~h~n~::~C:~tour Note-s: OCTOBER 2017 -- • Operable Unit Boundary 1. All locations to be considered accurate 2.. TCE concentrations displayed are in micrograms per Date 2/28120 18 Proj ec:1750620760 Figure 6 - Road Edge '"" (ug/L~ Building 3. Map displ ayed in California Stal e Plane Coon::linatE System , Zone 111 , North American Olt1A11 of 1983 (NAD83). US Survey feet . LANGAN Figure D-13: A-Aquifer TCE Concentration Contour, October 2017 Fifth Five-Year Review for NSC and MMI Superfund Sites 67 GSI MANN-KENDALL TOOLKIT for Constituent Trend Analysis Evaluation Date: 11 -J u l -18 Job ID:I Faci lity Name:1-, M..,.,,M,,.l/c-NccSccCc--=Oc-Ucc1--,-Bc-c-1 """'A- u..,.if,...e-r ------, Constituent: TCE Conducted By: USAC E Concentration Units: ,-~µ;:9-;:_1L-;:_-=--=--=--=--=----_-_,~------~ ~----r-:_-:_-:_-:,~-;:,,~-:_-:_-:_-:_~-:_-:_-:_-:_~~~-:_-:_-:_-:_-=:~-~=--~-...,...,,=-,--~-~=-,--~-----,-= ,-,--~--=,-,--~ 72B1 14B1 15B 1 77B1 126B 1 21B 1 1 12-Oct-11 21 0 59 130 75 130 83 2 10-Oct-12 240 68 110 140 67 130 75 3 16-Oct-13 180 72 110 2.20 59 120 65 4 13--Nov-1 4 240 70 110 150 56 140 64 5 13-Oct-15 290 73 120 170 57 130 62 6 13-Oct-16 21 0 140 120 140 53 130 62 7 11-Oct-17 220 57 99 140 45 120 56 8 9 10 11 12 13 14 15 16 17 18 19 20 Coefficient of Variation: Mann-Kendall Statistic (SJ: f-~~~~-r.--'lffl~~-+-"!'l!el4r-,f.,-""!!i~~-• -""l'.!'.!l~~-li!-"""'l~Mil:~--~"""'l'l!!!!ieltr---l Confidence Factor: Concentration Trend: 1000 - 72B1 - 14B1 :J' ~ c, .-. - - 15B1 .:; 100 ...... _ - -100B1 -,, _ - - C: - -·· - 77B1 .Q - = iii - 1268 1 - 215 1 -=C: 10 CIIu C: 0 0 1 11/10 04112 08113 1V14 05M6 09117 02119 Sampling Date Notes: 1. At least four independent sampling events per wetl are required for calculating the trend. Methodology is valid for4 to 40samples. 2. Confidence in Trend = Confidence (in percent) that constituent concentration is increasing (S>O) or decreasing (S DISCLAIMER: The GS/ Mann-Kendall Toolkit is available "as is". Coosiderab/e care has been exerdsed in prepating this software product. however, no pany, induding without limitation GS/ Environmental Inc., makes any representarion or watranly regarding the accuracy, correctness, or complereness of the infotmation contained herein, and no such pafty shall be liable for any direct, indirect, consequential, inddental or other damages resulting from the use of this product or the information contained herein. Information in this publicarion is subject to change withour notice. GS/ Environmental Inc., disdaims any responsibiJiry or obligation to update the infotmarion contained herein. GSI Environmental Joc., www.g~-neLcom Figure D-11: Mann-Kendall Statistical Analysis for TCE in B1 Aquifer. 68 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites GSI MANN-KENDALL TOOLKIT for Constituent Trend Analysis Evaluation Date:1------1 11-Jul-18 Job ID:I Faci lity Name: MMI/NSC OU1-B1 A u ifer Constituent: rc_is..,-_1~,2_-D_ C_E_-,------~ Conducted By: ~U_S_A_C_E______~ Concentration Units: ~µ~g_/L____ ~ 72B1 14B1 15B1 100B1 77B1 126B1 21B1 CIS-1 ,2-DCE CONCENTRATION (µg/L) 220 26 92 120 150 170 370 280 32 86 100 130 170 290 3 16-Oct-13 180 34 95 150 150 160 320 4 13-Nov-14 220 27 71 110 110 150 220 5 13-Oct-15 240 33 97 1J0 82 140 200 6 13-Oct-16 200 66 95 110 82 130 360 7 11-Oct-17 190 13 62 120 75 110 290 8 9 10 11 12 13 14 15 16 17 18 19 20 Coefficient of Variation: Mann-Kendall Statistic (S): 1--.iil!l!li'--ii--~l!illi--+--IIM'""'-"'!t"-""""ifl!lil.-~--'ifli!!!----li~-,lijj!fl!!'----i~--iiljlp""'"--I Confidence Factor: Concentration Trend: - 7281 :J' - 1481 "c, - 1s51 ::::i. 100 - 1•081 C: - 778 1 .Q ni - 12681 .b - 2rn1 C: 10 CII tJ C: u0 1 11/10 0411 2 08/13 12114 05/1 6 09117 02119 Sampling Date Notes: 1. At least four independent sampling events per well are requi red for calculating the trend. Methodology is valid tor 4 to 40 samples. 2. Confidence in Trend = Confidence (in percent) that constituent concentration is increasing (S>O) or decreasing (S DISCLAIMER: The GS/ Mann-Kendall Toolkit is available "as is". Considerable care has been exercised in preparing inis software product; however, no paJty, including without limitation GS/ Environmental Inc., makes any representarion or warranty regarding the accuracy, co,recmess, or complereness of the infonnarion contained herein, and no such party shall be liable for any direct, indirect, consequential, incidental or Olher damages resulting from ine use of tllis product or ine informa tion contained herein. Information in /his publicarion is subject lo change without notice. GS/ Environmental Inc., disclaims any responsibility or obligation to update the infonnarion contained herein. GS/ Enviroomenta/ Inc., www.gsi-nel.com Figure D-12: Mann-Kendall Statistical Analysis for cis-1,2-DCE in B1 Aquifer Fifth Five-Year Review for NSC and MMI Superfund Sites 69 GSI MANN-KENDALL TOOLKIT for Constituent Trend Analysis Job ID:I Constituent: TCE Concentration Units::µ:::9:::_1L-::_-::_-::_-::_-::_-::_-_-_-~~------~ 39B2 TCE CONCENTRATION (µg/L) 72 2.9 2.4 3.7 2 10-Oct-12 71 9.3 1.9 18 3 15-Oct-13 78 10 1.4 4.1 4 11-Nov-14 44 9.3 1.7 87 5 13-Oct-15 80 21 100 6 13-Oct-16 67 3.9 11 7 10-Oct-17 71 6.8 2 8 9 10 11 12 13 14 15 16 17 18 19 20 Coeffici ent of Variation: Mann-Kendall Statistic (S): Confidence Factor: Concentration Trend: - 39B2 ::::i - 71B2 c, - ME19B2 - MM33B2 -==C: .Q 10 iii b C: CII CJ C: 0 0 11110 04112 08/13 12114 0511 6 09117 02119 Sampling Date Notes: 1. At least four independent sampling events per well are required for calculating the trend. Methodology is valid tor 4 to 40 samples. 2. Confidence in Trend = Confidence (in percent) that constituent concentration is increasing (S>O) or decreasing (S<0): >95% = Increasing or Decreasing; ~ 90% = Probably Increasing or Probably Decreasing; < 90% and S>0 = No Trend; < 90%, S,c0, and COV ~ 1 = No Trend; < 90% and COV < 1 = stable. 3. Methodology based on "MAROS: A Decision Support System for Optimizing Monitori ng Plans•, J.J. Aziz, M. Ling , H.S. Rifai, C.J. Newell, and J.R. Gonzales, Ground Water , 41(3):355-367, 2003. DISCLAIMER: The GS/ Mann-Kendall Too/lift is available "as is". C-Onsiderable care has been exercised in preparing tllis software product; however, no party, including without limftation GS/ Environmental Inc., makes any representation or warranty regarding the accuracy, co!Tectness, or completeness of the intonnation contained herein, anrJ no such party shalt be liable for any dire ct, indirect, consequential, incidental or other damages resulting from tile use of this product or the information contained /Jeiein. Information in this publication is subject to change witllout notice. GS/ Environmental Inc., disclaims any responsibility or obligation to update the intonnation containerJ herein. GS/ Enviroomen/,1 Inc., www.gsi-nel.com Figure D-13: Mann-Kendall Statistical Analysis for TCE in B2 Aquifer. 70 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites GSI MANN-KENDALL TOOLKIT for Constituent Trend Analysis Evaluation Date: 11 -Jul-18 1------1 Job ID:I Fac ility Name: M MI/NSC OU1-B2 A uifer Constituent: 1-c~i~s-,_1~,2~-~D~C~E~----.------~ Conducted By:~U_S_A_C_ E______~ Concen tration Units: ~µ~g~/L____ ~ 39B2 71B2 M E19B2 MM33B2 CIS-1 ,2-DCE CONCENTRATION (µg/L) 1.5 5.3 0.92 0.71 2 10-Oct-12 1.5 14 0.9 5.4 3 15-Oct-13 2 15 0.9 1 4 11-Nov-1 4 0.8 10 0.9 36 5 13-Oct-15 1.4 19 110 39 6 13-Oct-16 1.2 3.5 3.3 7 10-Oct-17 1.2 12 1.4 8 9 10 11 12 13 14 15 16 17 18 19 20 Coeffi cient of Variation: Mann-Kendall Statistic (S): t---""'Rlf"'"- !!-- ':!!ll!e!l!!ll:'"- ~ - -•-- -+- -ll!!i-- ~ ~-----;f,------!!------1 Confidence Factor: Concentration Trend : - 39B2 :::::i - 71B2 c, 100 - ME19B2 :::L - MM33B2 C: .2 10 'la J:, C: a, u C: 0 0 0.1 11110 04112 08113 12114 05116 09117 02119 Sampling Date Notes: 1. At least four independent sampli ng events per well are required for calculating the trend . Methodology is valid for4 to 40samples. 2. Confidence in Trend = Confidence (in percent) that constituent concentration is increasir,;i (S>O) or decreasir,;i (S DISCLAIMER: The GS/ Mann-Kendall Toolkft is available "as is". Considerable care has been exercised in preparlng rilis software product; however, no pafl'f, including without limiration GS/ Environmental Inc., makes any representaUon or wananry regarding the accuracy, CDffectness, DI completeness of the infDmlation contained herein, and no such pafl'f shall be liable tor any direc/, indirect, consequential, incidental or olher damages resulting from rile use of this product or rile information contained herein. Information in this publicaUon is subjeet to change witllout norice. GS/ Environmental Inc., disclaims any responsibllily or obligation to update the infof111aUOn contained herein. GS/ Enwonmenlal Inc., KWW.gsi-ne/.com Figure D-14: Mann-Kendall Statistical Analysis for cis-1,2-DCE in B2 Aquifer. Fifth Five-Year Review for NSC and MMI Superfund Sites 71 Appendix E: Applicable or Relevant and Appropriate Requirement Assessment Section 121(d)(1)(A) of CERCLA requires that remedial actions at CERCLA sites attain (or justify the waiver of) any federal or state environmental standards, requirements, criteria, or limitations that are determined to be legally applicable or relevant and appropriate requirements (ARARs). Federal ARARs may include requirements promulgated under any federal environmental laws. State ARARs may only include promulgated, enforceable environmental or facility-siting laws of general application that are more stringent or broader in scope than federal requirements and that are identified by the state in a timely manner. ARARs are identified on a site-specific basis from information about the chemicals at the site, the remedial actions contemplated, the physical characteristics of the site, and other appropriate factors. ARARs include only substantive, not administrative, requirements and pertain only to onsite activities. There are three general categories of ARARs: chemical-specific, location-specific, and action-specific. Chemical-specific ARARs identified in the selected remedy within the ROD for the groundwater at this Site and considered for this FYR for continued groundwater treatment, are shown in Table A.1. Contaminants with cleanup goals that exceed their current Maximum Contaminant Level (MCL) are highlighted in light green below. Table A.1. Summary of Groundwater ARAR Changes Contaminants of 1991 ROD State MCL Federal MCL Is the cleanup goal Concern cleanup (µg/L) (µg/L) above the current standards (µg/L) MCL? Benzene 1 1 5 No Chlorobenzene 30 70 100 No 1 Chloroform 5 NA 803 No 1 Chloromethane 5 NA NA No 4-chloro-3-methlyphenol1 7 NA NA No 1,2-dichlorobenzene 60 600 600 No 1,1-dichloroethane 5 5 NA No 1,1-dichloroethylene 6 6 7 No 2,4-dimethylphenol 46 NA NA No 2,4-dinitrophenol1 5 NA NA No Ethylbenzene 68 300 700 No Freon 1132 1,200 1,200 NA No 2-methyl-4,6-dinitrophenol1 1 NA NA No Pentachlorophenol 1 1 1 No Phenol 5 NA NA No Tetrachloroethylene 5 5 5 No Trichloroethylene 5 5 5 No Vinyl chloride 0.5 0.5 2 No Xylenes (total) 175 1,750 10,000 No 72 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites 1 – Cleanup standards for these compounds are risk-based. Appendix F discusses protectiveness related to changes in toxicity values. 2 – Freon 113 is also known as 1,1,2-trichloro-1,2,2-trifluoroethane. 3 – The federal MCL listed here is for total trihalomethanes (TTHMs) of which chloroform is included. State and federal MCLs have changed since the 1991 ROD. However, the 1991 ROD cleanup standards are equal to or more stringent than the current MCLs. Therefore, these changes do not affect protectiveness. Federal and State laws and regulations other than the chemical-specific ARARs that have been promulgated or changed over the past five years are described in A-2. The table does not include those ARARs identified from the 1991 ROD that are no longer pertinent. For example, ARARs related SVE systems that are no longer operating. The following ARARs have not changed since the last Five-Year Review; and therefore, do not affect protectiveness: • California’s Resolution 68-16 • National Pollutant Discharge Elimination System • Bay Area Air Quality Management District Regulation 8, Rule 47 • Resource Conservation Recovery Act Land Disposal Restrictions Fifth Five-Year Review for NSC and MMI Superfund Sites 73 Appendix F. Toxicity Assessment Revisions to toxicity assessments for site-related contaminants may call into question the protectiveness of cleanup levels established in the Record of Decision (ROD) for a Superfund site. Thus, it is appropriate during a site's Five-Year Review (FYR) to re-evaluate protectiveness for contaminants where risk-based cleanup levels were chosen in the ROD. Cleanup levels at Superfund sites are typically set to either Applicable or Relevant and Appropriate Requirements (ARARs), such as drinking water Maximum Contaminant Goals (MCLs). When an ARAR is not available for a contaminant, the National Oil and Hazardous Substances Pollution Contingency Plan directs USEPA to set a cleanup level that is "protective of human health and the environment", usually based on the risk assessment for the site. While ARARs are "frozen" at the time of the ROD, risk-based cleanup levels should be re-evaluated considering any revisions to underlying toxicity assessments, to ensure continued protectiveness. If a Superfund site remedy is intended to meet a site-specific, risk-based cleanup level, the FYR guidance requires USEPA to assess whether toxicity or other contaminant characteristics used to determine the original cleanup level have changed and whether it remains protective in light of the change(s). Table F-1. Contaminants of Concern and Basis for Selecting Cleanup Level Cleanup Contaminant of Concern Level Basis for Cleanup Level (µg/L) Benzene 1 State MCL Chlorobenzene 30 State MCL Chloroform 5 Site-Specific Health Protective Standards set considering calculated cancer risks and Hazard Indices. Chloromethane 5 Site-Specific Health Protective Standards set considering calculated cancer risks and Hazard Indices. 4-Chloro-3-methylphenol 7 Site-Specific Health Protective Standards set considering calculated cancer risks and Hazard Indices. 1,2-Dichlorobenzene 60 One-tenth the federal MCL 1,1-Dichloroethane 5 State MCL 1,1-Dichloroethylene 6 State MCL 2,4-Dimethylphenol 46 State Action Level 2,4-Dinitrophenol 5 Site-Specific Health Protective Standards set considering calculated cancer risks and Hazard Indices Ethylbenzene 68 One-tenth California MCL Freon 113 1200 State MCL 2-Methyl-4,6-dinitrophenol 1 Site-Specific Health Protective Standards set considering calculated cancer risks and Hazard Indices Pentachlorophenol 1 Federal MCL Phenol 5 State or Federal MCL Tetrachloroethylene 5 State MCL Trichloroethylene 5 State or Federal MCL 74 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites Cleanup Contaminant of Concern Level Basis for Cleanup Level (µg/L) Vinyl Chloride 0.5 Federal MCL Xylene (total) 175 One-tenth California MCL Benzene 1 State MCL Chlorobenzene 30 State MCL The clean-up levels for the following chemicals of concern were based on the toxicity values when the 1991 ROD was signed: Chloroform, Chloromethane, 4-Chloro-3-methylphenol, 2,4-Dinitrophenol and 2-Methyl-4,6-dinitrophenol. To assess if there are any changes to the toxicity values for these chemicals of concern, USEPA relied on USEPA’s Integrated Risk Information System (IRIS). IRIS has a program to update toxicity values used by the Agency in risk assessment when newer scientific information becomes available. To evaluate the protectiveness of the clean-up levels for this FYR, those levels were compared to USEPA’s current Regional Screening Levels (RSLs) [May 2018]. The RSLs for cancer are chemical- specific concentrations for individual contaminants that correspond to an excess cancer risk level of 1x10-6 (or a Hazard Quotient [HQ] of 1 for non-carcinogens), and they have been developed for a variety of exposures scenarios (e.g., residential, commercial/industrial). RSLs are not de facto cleanup standards for a Superfund site, but they do provide a good indication of whether actions may be needed to address potential human health exposures. The USEPA risk range is between 1x10-6 and 1x10-4. RSL values that fall within this range are determined to be acceptable from a risk stand point. The non-cancer RSLs correspond to a hazard index of 1. Table F-2 below presents this comparison. Table F-2. Comparison of Tap Water RSL to ROD Cleanup Standards Protective Is the 2018 Tap 2018 Tap Water Cancer Risk Cleanup Cleanup Water RSL RSL for non- Contaminant of Concern Range Standard Standard for cancer cancer hazard (µg/L) (µg/L) Still risk (µg/L) (µg/L) Protective? Chloroform 0.22 0.22-22 - 5 Yes Chloromethane 190 5 Yes 4-Chloro-3-methylphenol - - 1450 7 Yes 2,4-Dinitrophenol - - 39 5 Yes 2-Methyl-4,6-dinitrophenol - - 1.51 1 Yes There have been changes to RSLs for the chemicals of concern at the National Semiconductor and Monolithic Memories Sites, however, the cleanup standards are either below their respective non- cancer hazard concentration or within USEPA’s protective risk range. Therefore, the changes to toxicity do not affect protectiveness. Fifth Five-Year Review for NSC and MMI Superfund Sites 75 Appendix G: Press Notice Santa Clara WEEKLY Phone 40S-243-2000 Fax 408-243-1408 May 2, 2018 - May 8, 2018 www.SantaClaraWeekly.com SCUSDNEWS 7 school and a 1600-student Opportunity To Remain For The Time Being school wo uld lose no time and By Atoosa Savarnejad confidence, resilience and that if we don·t do it ri ght bring in funds to develop a the hi gh school wo uld open --0o11 ·1 take away oppor personal growth with the goal as we transition is we won ·1 comprehensive 1,600-student when promised. If a bond is tunity! .. of helping students return to be able to go back,'" Board high school. not presented in November That was the resounding traditio na l c lasses and pro fember N~lani Pearl llunt T hree o pt io ns were pre or docs not pass, the financial cry of half a dozen attendees grams.·· However, the district said . '·So I want to make sure sented at the Apri l 26 board impact wo uld be the cost of at th e Santa C lara Unified administratio n felt that this that we don ·1 pigeo nhole our meeting: To design a compre th e designs. But no time o r School District"s boa rd mcct res ult ed in too much isolation selves,·· hensive hi gh school, to hold momentum would be lost. ing o nApril 26. The board was from their peers. off o n th e design until >lo Board embers said they consideri ng an agenda item on Instead, the district has District CouJd Receive $8.S ve mbcr when a general bond wanted to see a comprehen changes to the support struc added wellness coordinators Million in Land Deal wo uld possibly go for a vote sive hi gh school, not a smaller ture for 2018-201 9 school and wellness centers, coun The unwinding of Califor o r to proceed o n designing a 400-person school. No action year, which included eliminat seling interns and academi c nia ·s redevelopment agencies 400-student hi gh school. was taken sin ce Ibi s was a ing th e existing O pportunity counselors at all school sites. will bring SCUSD ano the r Hold ing off on design unli l plan ning item o n the agend a. classroom at Peterson Midd le It expects this will fulfill the cash infusion this year \\~th the November delay in the high The Board req uested that it School. same functio ns as O ppo r sa le o f redevelopment agency school"s o pening for a year come back as an action item .. The dec ision t o shut tunity. It has a lso added a property in the north San JosC later than promised. However, in a subsequent school board down Opportunity was done ommunity Day school that part o f the di strict. designing both a -«X>-st udent meeting. without proper and thorough it expects to sen'e the same The pro pe rty is near the investi gati on,·· one attendee gro up of students currently Dirid on trai n station in San asked. ""There has been no in Opportuni1y. Community Jose-at one time intended data or evidence th at it is not Day arc schools for students for a sports stadium- where workin g or been successful. who have been expell ed o r Google, lnc. is planning to dc Conv ersely, th ere has been who have had problems in at ,•elopa newcampus. SCU D's no indication to suggest that tendance or be ha"ior. C hief Bus in ess Official Mark these proposed changes will Board Member Mark A ll gire said that Google is 390 N_ Winchester Blvd, Santa Cl ara work. Once O ppo rtunity is Richardson said he sym1x1 - involved in this process. The (Close to Santana Row) gone, there is no turning back. thized with the wish to keep ••fai r market price·· for the sale 1-408.241-7750 How is that possibly worth the O pportunity for at least o ne of t he entire land is estimated ri sk?" more year to assess whether to bring in $69 million. The O pportunity Ed ucati o n the o ther s uppo rt systems district ·s share would be $8.5 schools provide s uppo rtive would be an adequate replace million. Mini Studios environments with s pecial ment for Oppo rtunity, but he When Cali fornia legisla ized curriculum, instructi on, was also hesitant about allow ture dissolved the state ·s rede Now Available! guidance and counseling to ing th e program to continue. "elopment agencies in 2012, it students who are habitually •·1 do understand the fe ar: provided that < 76 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites Appendix H: Interview Forms Five-Year Review Interview Record National Semiconductor Co. & EPA ID Site: CAD049236201 Monolithic Memories Inc. No: I Interview Type: Teleconference Call Date: March 22, 2018 Time: 1:00 pm Interviewers Name Title Organization Kayla Patten Environmental Engineer USACE Seattle Leanna Woods Pan Environmental Engineer USACE Seattle Ron Goloubow Engineering Geologist San Francisco Bay Regional Water Quality Control Board Interviewees Name Organization Title Telephone Email Senior Project Josh Graber Langan 510.874.7086 [email protected] Manager Hector Vargas TI Project Manager 214.479.3773 [email protected] Elma Fung TI On-Site Associate 214.479.3773 [email protected] Elizabeth Langan Associate 510.874.7000 [email protected] Kimbrel Summary of Conversation NOTE: Langan & TI provided written responses to many questions prior to the interview. These responses are included below along with the topics discussed in the interview. Josh Graber is with Langan has been working on the project since 2004 as the primary consultant. Hector Vargas works for Texas Instruments in Dallas as the remediation manager for the site. Elma Fung works for TI in Santa Clara and has been with the site since 2003. Elizabeth Kimbrel is with Langan as an environmental consultant. 1) What is your overall impression of the project? Overall, the project is moving in the right direction. Soil source areas have been remediated and no further releases are occurring. Groundwater concentrations have been significantly reduced both on-site and off-site and continue to decrease. The groundwater extraction and treatment system (the remedy, GWET) is functioning and remains protective. The on-site remedy has been upgraded and optimized within the last five years, which will increase hydraulic control and mass recovery on-site and reduce O&M costs moving forward. The Arques groundwater extraction system was approved for shutdown in 2018 due to decreased mass recovery and aging infrastructure. The Lakeside groundwater extraction and treatment system continues to operate in the downgradient portion of the plume. Areas with elevated groundwater concentrations are undergoing in situ remediation, which has successfully and significantly reduced concentrations. The results of on-site and off-site vapor intrusion assessments have been positive with no significant risk to building occupants identified, which supports a protectiveness determination. 2) Is the remedy functioning as expected? How well is the remedy performing? Yes, the remedy is functioning as expected. On-site and downgradient concentrations continue to decrease. Significant upgrades were made to the extraction well network and overall groundwater conveyance infrastructure in 2016. Specifically, recent on-site GWET system modifications included installing five new extraction wells, re-starting former extraction wells, and replacing aging conveyance piping. To evaluate proposed GWET system modifications, the existing groundwater flow model was updated to simulate contemplated changes in the GWET system, a groundwater investigation was performed and Fifth Five-Year Review for NSC and MMI Superfund Sites 77 groundwater concentrations were evaluated to provide recommendations for improving hydraulic control and increasing VOC mass recovery. In addition to the articulated remedy, TI has supplemented the remedial strategy by proactively implementing in situ remedial approaches in areas of elevated groundwater concentration to accelerate a reduction in plume concentrations and extent. We plan to continue to focus resources on areas of elevated concentrations using in-situ approaches to accelerate achievement of remedial goals both on-site and in the downgradient plume, and will monitor results. The August 30, 2017 memo from TI, requested to have the Arques extraction system shut down. There are monitoring wells upgradient from Arques Ave and down gradient from the onsite extraction wells that still have high concentrations of TCE (58A, 57A, 72A, 72B1, 71A/B1). Water Board's approval memo required a proposal for modification to the self-monitoring program which will be submitted to Water Board by tomorrow. 3) What does the monitoring data show? Are there any trends that show contaminant levels are decreasing? Concentration trends are decreasing across the plume, with the most significant reduction occurring in the A-zone. Modeling and historical data suggests groundwater concentrations will continue to decrease over time and that reduction may be accelerated by additional in situ remedial approaches. For the Arques groundwater extraction system, the monitoring program is currently being updated. The update will include the same wells, but some will be monitored more twice a year instead of the current once a year. TI is doing this to better assess trends. The three wells TWC is responsible (EX-1, EX-2, and MW-3) for have not been monitored in the last five years. Ron is planning to follow up with TWC and MMI directly regarding these wells. TI is not responsible for monitoring these wells, but they do have wells nearby that might reasonably characterize that area. Well MM17A is nearby and has good historic data from before TWC’s spill. A spike was seen when the spill occurred. This well is sampled annually. All the MM- and ME- wells are owned by AMD. 4) Is there a continuous O&M presence? If so, please describe staff and activities. If there is not a continuous on-site presence, describe staff and frequency of site inspections and activities. Yes, we have a continuous O&M presence for both the on-site and Lakeside groundwater extraction and treatment units. A new on-site treatment unit (i.e. air stripper) was designed and installed in 2014 and a new on-site groundwater conveyance piping system was designed and constructed in 2016. Generally, TI staff (consisting of three technicians), and contract support, CalCon, and Glacier Labs provide continuous O&M services related to the GWET. The O&M services performed by TI staff include daily monitoring and weekly inspections, air stripper cleaning, maintenance of pumps and groundwater conveyance lines, and meter reading. CalCon performs monthly and quarterly preventative maintenance activities which includes inspecting and cleaning air stripping trays, pump inspections and maintenance, and compressor maintenance. Glacier Labs provides anti-scalant as part of the groundwater treatment process. Additionally, granular activated carbon is periodically replaced, as needed. For Building 39 and Building C there is an O&M Plan for operation of the SSDS. This was given to the new owner of Building 39 when sold. There is no requirement to run the HVAC system at the building because the post construction data showed no exceedances. However, the HVAC system is usually running and is rarely turned off. 5) Have there been any significant changes in the O&M requirements, maintenance schedules, or sampling routines in the last five years? If so, do they affect protectiveness of the remedy? Please describe changes and impacts. O&M requirements, maintenance schedules and sampling routines have been generally consistent over the last five years. Some additional O&M has taken place related to groundwater conveyance line leaks, which should no longer be an issue since the on-site conveyance system has been replaced with upgraded to double-walled piping and the Arques extraction system has been shut down, as approved by the Water Board. 6) What are the annual operating costs for your organization's involvement with the site? 78 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites Annual operating costs over the last five years have been $1,526,000 on average. 7) Have there been unexpected O&M difficulties or costs at the site in the last five years? If so, please give details. Several groundwater conveyance line leaks have occurred in the last five years. The leaks were generally caused by tree root intrusion and the age of the single-walled piping. Based on the occurrence of the leaks, TI designed and constructed a new groundwater conveyance piping system on-site. In the off-site portion of the system along Arques Ave, leaks were also caused by third party activity. With the approved termination of the Arques System, that issue will no longer occur. 8) Have there been opportunities to optimize O&M or sampling efforts? Please describe changes and resultant or desired cost savings or improved efficiency. Yes, the on-site groundwater extraction system was optimized based on groundwater sampling and modeling. Specifically, recent GWET system modifications included installing new extraction wells, re-starting former extraction wells, and replacing aging conveyance piping. To evaluate proposed GWET system modifications, the existing groundwater flow model was updated to simulate changes in the GWET system, a groundwater investigation was performed and groundwater concentrations were evaluated to provide recommendations for improving hydraulic control and increasing VOC mass recovery. Additionally, based on decreasing mass recovery, the off-site extraction system along Arques Avenue was approved for shutdown in 2018. While the cost to implement the GWET system changes were high, we expect O&M costs to decrease. Preliminary results indicate that mass recovery has increased on-site. 9) Are you aware of any changes in Federal/State/County/Local laws and regulations that may impact the protectiveness of the remedy? Sate implementation of new Federal vapor intrusion guidance prompted on-site and off-site vapor intrusion assessments. From 2012 to 2017, TI collected indoor air samples from 11 occupied on-campus buildings. From 2014 to 2016, TI collected indoor air samples from 11 accessible off-campus buildings. The results of the vapor intrusion assessments were positive, indicating that the remedy is protective. Additionally, new National Pollutant Discharge Elimination System (NPDES) requirements issued by the State of California will require additional treatment of effluent groundwater. This regulation will have significant cost implications but should not affect the protectiveness of remedy. 10) Do you have any comments, suggestions, or recommendations regarding the project? TI’s strategy is to focus resources on areas of elevated groundwater contaminant concentration and utilize in-situ approaches, while continuing to operate the groundwater extraction and treatment system. In addition, as instructed by the Water Board, TI will evaluate off-site contaminant concentrations on an increased schedule to evaluate the recent shut down of Arques wells and will continue to report our findings to the Water Board and USEPA. Changes to VOC concentrations will be evaluated and additional actions will be recommended, if necessary. We also believe that TI’s approach to the overall plume management (i.e., enhanced on-site groundwater extraction, combined with focused in-situ remediation), will continue to be successful at reducing groundwater concentrations and move the site more expeditiously towards achieving its cleanup goals. Lastly, TI recommends the Five-Year Reporting associated with the Monolithic Memories site remains separate, as they have been historically. TI has agreements with AMD which can be complicated, and writing one report doesn’t fit in well with these agreements. TI is particularly concerned about clearly designating who is responsible for which portions. For example, TI doesn’t want it to sound like they are responsible for the work related to the TWC spill. Additional Site-Specific Questions 11) What is the status of the No Further Action Request for the Leak L5 area? TI is currently formally requesting NFA status for this area. Groundwater is still being reviewed in the area, but would like to close out the soil portion. A removal action did cleanup all the soil in that area. Sampling after excavation showed no exceedances which were detailed in the Remedial Completion Report in 2011. Some chemical oxidation treatment was also done. Currently, groundwater wells are being installed in that area. Fifth Five-Year Review for NSC and MMI Superfund Sites 79 12) Does Bay View Development currently own the properties of Buildings G, 19, 39, and 9? Has this impacted work at Building G? Yes, the properties have recently been sold. We have not encountered or expect any difficulties associated with the remediation or access. We are currently preparing for another round of performance monitoring and well installation to expand the treatment area at Building G. 13) Was additional sampling conducted after installation of the sub-slab depressurization system (SSDS) in Building 39 (installation in October 2014, last sampling data March 2014)? If so, when? Yes, follow up sampling after installation was completed. Josh will provide this data. Building 39 was sold right as TI was beginning to do VI work. During initial sampling, elevated concentrations were found in the bathroom but nowhere else in the building. TI installed an SSDS under the bathroom. Post construction sampling did not show any exceedances. Building C has subsequently transferred ownership, and it has been unoccupied since then. 14) Has the SSDS been installed in Building C? If so, when? Any follow up sampling? Yes, follow up sampling after installation was completed. Josh will provide this data. Building C is still owned and operated by TI. The only exceedances seen were when the HVAC system was off. Although it wasn’t required, TI decided to install a SSDS. After installation, sampling was completed with the HVAC system on and off. All results were below ESLs (California Environmental Screening Levels). 15) Has additional sampling been conducted in SU1-1 with the HVAC system operating? Is construction complete? Confirmation sampling was planned during summer 2017 to account for seasonal variations… Has the building layout changed significantly due to construction? If yes, are additional sampling activities planned? Yes, things have changed at SU1-1. When the original VI work was being completed at other sites the owner of SU1-2 didn’t allow TI access and declined sampling. Since then the tenant has moved out. While the building was unoccupied the owner allowed TI access to do sampling. When sampling was completed, the HVAC system had been off for about 3 months. The recent tenant, still responsible for utilities, would not allow the HVAC system to be turned on. VI data collected at this time showed exceedances in some bathrooms. Since the building was unoccupied, TI was able to open up walls and seal around pipes and floor drains. After these renovations were completed, sample was conducted with the HVAC system on and off. There were no exceedances. The building has since been leased to a new tenant. This tenant is completing improvements such as moving office spaces and changing wall layout. The bathrooms are still located in the same place. TI will complete new VI sampling once these improvements are completed. 16) Any additional sampling planed for SU3-1 (low PCE exceedance in 2015), a retail banking branch? What is the status of this building? Requesting NFA? TI did request an NFA during the most recent technical memorandum. USEPA has stopped providing NFAs. This was discussed with the Regional Water Board. 17) Any additional sampling planed for SU3-2 (low TCE exceedance in 2016), an image and document processing company? What is the status of this building? Requesting NFA? Same as above with SU3-1. 18) Any response from SU3-5 building owner? What is the status? The owner is still denying access for monitoring. EPA has sent the owner a formal letter acknowledging that TI has offered sampling and that they have formally declined. If the owner changes their mind they can request sampling by TI, but this hasn’t happened yet. 19) Any plans to document building owner sampling conducted in SU1-7 through SU1-10? Any plans for SU1-6? SU1-7 through SU1-10 were previously sampled by the owner and results were presented to USEPA; due to security/privacy reasons, the tenant did not want others to complete the sampling. USEPA had planned to follow up with a formal review of the data to indicate if the sampling was sufficient but this hasn’t been completed. These buildings were recently sold to a new owner but the tenant remains the same. The new owner is interest in having VI sampling done and will follow up with the tenant. 80 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites 20) Any thoughts as to why methylene chloride was present at SU3-8 at such high levels (1500 µg/m3)? Was NFA granted? These buildings are constructed on podiums with the parking area underneath the building that is open to the outside air. Because of this the vapor intrusion pathways into the building is broken. This is why VI sampling was atypical and only done in the elevated podium areas, elevator shafts, and elevator lobbies. Some of the indoor air samples taken were near a pool and spa area. Some of the detected chemicals are products of the municipal water system, so this could be the source. It was also later discovered that painting was occurring at the same time as some sampling which could also be a source. Methylene chloride is not often found in groundwater. Some of the detected chemicals in the air are not associated with chemicals detected in the plume below that area. 21) Why do you think there were so many chloroform exceedances in so many of the buildings? Same as #20. 22) Has performance testing of the vapor mitigation system (VMS) been completed following construction of the new fitness center on the former 1165 East Arques Ave property? Attachment E of the Completion Report for Vapor Mitigation System was supposed of present testing results 3 and 6 months after installation, but Attachment E is not available on Geotracker Josh will check Geotracker for this document. There is a separate Geotracker website for the City Sports Club. Langan didn’t sample the indoor air here, only the risers which is common for new construction. There were riser samples taken at 3 and 6 months after construction Hector Vargas clarified that this is not a TI building. Langan happened to also get consulting work for this building outside of its work for TI. Fifth Five-Year Review for NSC and MMI Superfund Sites 81 Appendix I: Site Inspection Checklist I. SITE INFORMATION Site name: Monolithic Memories / NSC Date of inspection: 1/9/2018 Location: Sunnyvale, CA EPA ID: CAD049236201 Agency, office, or company leading the five-year Weather/temperature: Cool, Rainy review: USEPA / USACE Remedy Includes: (Check all that apply) • Landfill cover/containment • Monitored natural attenuation • Access controls • Groundwater containment ~ Institutional controls • Vertical barrier walls ~ Groundwater pump and treatment • Surface water collection and treatment ~ Other: Vapor Mitigation Attachments: • Inspection team roster attached • Site map attached II. INTERVIEWS (Check all that apply) 1. O&M site manager Josh Graber _Senior Project Manager, Langan Treadwell & Rollo_ _9 January 2018_ Name Title Date Interviewed ~ at site • at office • by phone Phone no. ______Problems, suggestions; ~ Report attached ______ ______ 82 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites 3. Local regulatory authorities and response agencies (i.e., State and Tribal offices, emergency response office, police department, office of public health or environmental health, zoning office, recorder of deeds, or other city and county offices, etc.) Fill in all that apply. Agency: California RWQCB Contact: Ron Goloubow _Project Manager_ _9 January 2018_ _510.622.2442_ Name Title Date Phone no. Problems; suggestions; • Report attached ______ 4. Other interviews (optional) • Report attached. Hector Vargas, Texas Instruments Inc. III. ON-SITE DOCUMENTS & RECORDS VERIFIED (Check all that apply) 1. O&M Documents ~ O&M manual ~ Readily available ~ Up to date • N/A ~ As-built drawings ~ Readily available ~ Up to date • N/A ~ Maintenance logs ~ Readily available ~ Up to date • N/A Remarks on National Semiconductor Campus 2. Site-Specific Health and Safety Plan ~ Readily available ~ Up to date • N/A ~ Contingency plan/emergency response plan ~ Readily available ~ Up to date • N/A Remarks______ ______3. O&M and OSHA Training Records ~ Readily available ~ Up to date • N/A Remarks______ ______ Fifth Five-Year Review for NSC and MMI Superfund Sites 83 4. Permits and Service Agreements • Air discharge permit • Readily available • Up to date • N/A • Effluent discharge • Readily available • Up to date • N/A • Waste disposal, POTW • Readily available • Up to date • N/A • Other permits______• Readily available • Up to date • N/A Remarks Two NPDES locations, Campus and Lakeside Building C has Air stripper and Vapor Mitigation System are permitted with BAAQMD 5. Gas Generation Records • Readily available • Up to date ~ N/A Remarks______ ______6. Settlement Monument Records • Readily available • Up to date ~ N/A Remarks______ ______7. Groundwater Monitoring Records ~ Readily available ~ Up to date • N/A Remarks Geotracker 8. Leachate Extraction Records • Readily available • Up to date ~ N/A Remarks______ ______ 9. Discharge Compliance Records ~ Air ~ Readily available • Up to date • N/A ~ Water (effluent) ~ Readily available • Up to date • N/A Remarks Geotracker 10. Daily Access/Security Logs ~ Readily available ~ Up to date • N/A Remarks______ ______ 84 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites IV. O&M COSTS 1. O&M Organization • State in-house • Contractor for State • in-house • Contractor • Federal Facility in-house • Contractor for Federal Facility • Other______ 2. O&M Cost Records • Readily available • Up to date • Funding mechanism/agreement in place Original O&M cost estimate______• Breakdown attached Total annual cost by year for review period if available From______To______• Breakdown attached Date Date Total cost From______To______• Breakdown attached Date Date Total cost From______To______• Breakdown attached Date Date Total cost From______To______• Breakdown attached Date Date Total cost From______To______• Breakdown attached Date Date Total cost 3. Unanticipated or Unusually High O&M Costs During Review Period Describe costs and reasons: - 2014 Upgrade to Air stripper - 2016 Conveyance pipeline Fifth Five-Year Review for NSC and MMI Superfund Sites 85 V. ACCESS AND INSTITUTIONAL CONTROLS ~ Applicable • N/A A. Fencing 1. Fencing damaged • Location shown on site map ~ Gates secured • N/A Remarks______ ______ B. Other Access Restrictions 1. Signs and other security measures • Location shown on site map • N/A Remarks______ ______ C. Institutional Controls (ICs) 1. Implementation and enforcement Site conditions imply ICs not properly implemented • Yes • No • N/A Site conditions imply ICs not being fully enforced • Yes • No • N/A Type of monitoring (e.g., self-reporting, drive by) ______ Frequency ______ Responsible party/agency ______ Contact ______ Name Title Date Phone no. Reporting is up-to-date • Yes • No • N/A Reports are verified by the lead agency • Yes • No • N/A Specific requirements in deed or decision documents have been met • Yes • No • N/A Violations have been reported • Yes • No • N/A Other problems or suggestions: • Report attached ______ ______ ______ ______ 86 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites 2. Adequacy • ICs are adequate • ICs are inadequate • N/A Remarks: D. General 1. Vandalism/trespassing • Location shown on site map 181 No vandalism evident Remarks: 2. Land use changes on site • N/A Remarks: 3. Land use changes off site • N/A Remarks: VI. GENERAL SITE CONDITIONS A. Roads • Applicable • N/A 1. Roads damaged • Location shown on site map • Roads adequate • N/A Remarks: B. Other Site Conditions Remarks: Fifth Five-Year Review for NSC and MMI Superfund Sites 87 VII. LANDFILL COVERS • Applicable ~ N/A VIII. VERTICAL BARRIER WALLS • Applicable ~ N/A IX. GROUNDWATER/SURFACE WATER REMEDIES ~ Applicable • N/A A. Groundwater Extraction Wells, Pumps, and Pipelines ~ Applicable • N/A 1. Pumps, Wellhead Plumbing, and Electrical ~ Good condition • All required wells properly operating G Needs Maintenance G N/A Remarks______ ______ ______ 2. Extraction System Pipelines, Valves, Valve Boxes, and Other Appurtenances ~ Good condition • Needs Maintenance Remarks______ ______ 3. Spare Parts and Equipment ~ Readily available • Good condition • Requires upgrade • Needs to be provided Remarks -Minor______ ______B. Surface Water Collection Structures, Pumps, and Pipelines • Applicable ~ N/A 1. Collection Structures, Pumps, and Electrical • Good condition • Needs Maintenance Remarks______ ______ 2. Surface Water Collection System Pipelines, Valves, Valve Boxes, and Other Appurtenances • Good condition • Needs Maintenance Remarks______ ______ 3. Spare Parts and Equipment • Readily available • Good condition • Requires upgrade • Needs to be provided Remarks______ ______ 88 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites C. Treatment System ~ Applicable • N/A 1. Treatment Train (Check components that apply) • Metals removal • Oil/water separation ~ Bioremediation ~ Air stripping • Carbon adsorbers • Filters______• Additive (e.g., chelation agent, flocculent)______• Others______• Good condition • Needs Maintenance • Sampling ports properly marked and functional • Sampling/maintenance log displayed and up to date • Equipment properly identified • Quantity of groundwater treated annually______• Quantity of surface water treated annually______Remarks______ ______ 2. Electrical Enclosures and Panels (properly rated and functional) • N/A • Good condition • Needs Maintenance Remarks______ ______ 3. Tanks, Vaults, Storage Vessels • N/A • Good condition • Proper secondary containment • Needs Maintenance Remarks______ ______ 4. Discharge Structure and Appurtenances • N/A • Good condition • Needs Maintenance Remarks______ ______ Fifth Five-Year Review for NSC and MMI Superfund Sites 89 5. Treatment Building(s) • N/A • Good condition (esp. roof and doorways) • Needs repair • Chemicals and equipment properly stored Remarks______ ______ 6. Monitoring Wells (pump and treatment remedy) • Properly secured/locked • Functioning • Routinely sampled • Good condition • All required wells located • Needs Maintenance • N/A Remarks______ ______ D. Monitoring Data 1. Monitoring Data ~ Is routinely submitted on time ~ Is of acceptable quality 2. Monitoring data suggests: ~ Groundwater plume is effectively contained ~ Contaminant concentrations are declining D. Monitored Natural Attenuation 1. Monitoring Wells (natural attenuation remedy) • Properly secured/locked • Functioning • Routinely sampled • Good condition • All required wells located • Needs Maintenance ~ N/A Remarks______ ______ 90 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites Appendix J: Photographs from Site Inspection Visit Fifth Five-Year Review for NSC and MMI Superfund Sites 91 ~-· Former location of National Semiconductor Site Buildings 9 and 19 Abandoned wells at National Semiconductor Site Buildings 9 and 19 92 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites National Semiconductor Site Building C interior National Semiconductor Site Building C interior; soil vapor mitigation system piping Fifth Five-Year Review for NSC and MMI Superfund Sites 93 Monitoring well inside National Semiconductor Site National Semiconductor Site Building C monitoring well Building C identification in ceiling 94 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites On-property former National Semiconductor campus air stripper Fifth Five-Year Review for NSC and MMI Superfund Sites 95 On-property former National Semiconductor campus groundwater treatment system -1 On-property former National Semiconductor campus groundwater treatment system -2 96 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites On-property former National Semiconductor campus On-property former National Semiconductor campus groundwater treatment system- 3 conveyance piping Fifth Five-Year Review for NSC and MMI Superfund Sites 97 On-property former National Semiconductor campus extraction well open On-property former National Semiconductor campus extraction well closed 98 Fifth Five-Year Review for National Semiconductor and Monolithic Memories Superfund Sites