2013_04 Final DQU_2012 Monitoring Rpt.pdf

FINAL

2012 MONITORING REPORT

D-Q UNIVERSITY, YOLO COUNTY, CALIFORNIA

Prepared fo r

U .S. Army Corps o f Eng ineers

1325 J S t reet

Sacramento, CA 95814

Apr i l 2013

FUDS Project No.: J09CA1180

D-Q UNIVERSITY, YOLO COUNTY, CALIFORNIA

SIGNATURE PAGE

Signatures of pr inc ipal personnel responsible for development and execut ion of th is report .

Approved by:

Date: April 29, 2013

Dhananjay Rawal, REM. # 11266 ECS/ECSBC JV Quality Control Systems Manager

Date: April 29, 2013

Guy Graening, P.E. # M29796 ECS/ECSBC JV Project Manager

D-Q UNIVERSITY, YOLO COUNTY, CALIFORNIA

DISTRIBUTION LIST

ADDRESS NUMBER OF COPIES

Mr. Tim Crummett ............................................................................... 1 electronic (PDF and Native) and 5 hard copies

U.S. ARMY CORPS OF ENGINEERS

1325 J Street Sacramento, CA 95814-2922

Mr. Mark Clardy .......................................................................................................... 1 electronic PDF and 1 hard copy

CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD

11020 Sun Center Drive, Suite #200 Rancho Cordova, CA 95670

Mr. Dhananjay Rawal ............................................................................. 1 electronic (PDF and Native) and 2 hard copy

ECSBC JV

1571 Parkway Loop, Suite B Tustin, CA 92780

Mr. Guy Graening, Project Manager Mr. Greg Menna, Field Team Leader File .................................................................................................................................................. (1 electronic PDF) 1

BROWN AND CALDWELL

10540 White Rock Road, Suite 180 Rancho Cordova, CA 95670

Table of Contents D-Q University 2012 Monitoring Report i

TABLE OF CONTENTS

1. INTRODUCTION ..................................................................................................................................................... 1-1

1.1 FUDS Status and Background ...................................................................................................................... 1-1

1.2 Report Organization ...................................................................................................................................... 1-2

2. SITE BACKGROUND ............................................................................................................................................. 2-1

2.1 Site Description and Operational History ...................................................................................................... 2-1

2.2 Summary of Previous Investigations ............................................................................................................. 2-1

3. MONITORING ACTIVITIES AND RESULTS .......................................................................................................... 3-1

3.1 Field Activities ............................................................................................................................................... 3-1

3.2 Analytical Program ........................................................................................................................................ 3-1

3.3 Data Review ................................................................................................................................................. 3-6

3.3.1 Analysis ............................................................................................................................................ 3-6

3.3.2 Conclusions ...................................................................................................................................... 3-7

3.4 Results .......................................................................................................................................................... 3-7

3.4.1 Groundwater Elevations .................................................................................................................... 3-7

3.4.2 Analytical .......................................................................................................................................... 3-8

3.5 Investigative Derived Waste ....................................................................................................................... 3-14

4. RECOMMENDED GROUNDWATER MONITORING NETWORK .......................................................................... 4-1

5. REFERENCES ....................................................................................................................................................... 5-1

FIGURES ................................................................................................................................................................ FIG-1

APPENDIX A ................................................................................................................................................................ A Groundwater Purge and Sampling Field Data Sheets ............................................................................................. A

APPENDIX B ................................................................................................................................................................ B Certified Analytical Laboratory Reports ................................................................................................................... B

APPENDIX C ................................................................................................................................................................ C Waste Manifest ........................................................................................................................................................ C ii

LIST OF TABLES

1 Well Construction Summary 2 Historical Groundwater Elevations 3 Quality Control Sample Requirements 4 Analytical Completeness 5 Historical Groundwater Flow Direction and Gradients 6 Historical TCE Concentrations in Monitoring Wells 7 Proposed Groundwater Monitoring Network 8 Groundwater Monitoring Analytical Program

LIST OF FIGURES

1 Site Location 2 Groundwater Monitoring Elevation Contours, November 19-20, 2012 3 TCE Isoconcentration Contours, November 19-20, 2012 4 TCE and Breakdown Products, November 19-20, 2012 5 Recommended Monitoring Network

APPENDICES

A. Groundwater Purge and Sampling Field Data Sheets B. Certified Analytical Laboratory Reports C. Waste Manifest iii

LIST OF ACRONYMS

AOC area of concern AST above ground storage tank BC Brown and Caldwell bgs below ground surface CERCLA Comprehensive Environmental Response, Compensation, and Liability Act COC chemical of concern DCE dichloroethene DERP-FUDS Defense Environmental Restoration Program - Formerly Used Defense Site DO dissolved oxygen DoD Department of Defense EC electrical conductivity ECS Enviro-Compliance Solutions, Inc.

ECSBC JV Enviro-Compliance Solutions, Inc. Brown and Caldwell Joint Venture FS feasibility study FUDS Formerly Used Defense Site IDW investigative derived waste LCS laboratory control sample LTM long-term monitoring MCL maximum contaminant level MS/MSD matrix spike/matrix spike duplicate MSL mean sea level ORP oxidation reduction potential PRP potentially responsible party PVC poly vinyl chloride QA quality assurance QAPP Quality Assurance Project Plan QC quality control RI remedial investigation SARA Superfund Amendments and Reauthorization Act Site D-Q University TCE trichloroethylene TPH-DRO total petroleum hydrocarbons - diesel range organics µg/L micrograms per liter USEPA U.S. Environmental Protection Agency USACE U.S. Army Corps of Engineers UST underground storage tank VOCs volatile organic compounds

1-1

D - Q U N I V E R S I T Y 2 0 1 2 M O N I T O R I N G R E P O R T

1 . I N T R O D U C T I O N

This report describes monitoring in 2012 for impacted groundwater at the D-Q University Formerly Used Defense Site (FUDS) located in Yolo County, California (Site). This groundwater monitoring report was completed by Enviro Compliance Solutions Inc. (ECS) and Brown and Caldwell (BC) for the U.S. Army Corps of Engineers (USACE), Sacramento District under ECSBC Joint Venture, Contract # W1912BV-10- D-2012. D-Q University is located in Yolo County on the north side of County Road 31 (Covell Road) and approximately 9 miles west of Davis, California. The town of Davis is located approximately 14 miles west of Sacramento, California. The location of D-Q University is provided on Figure 1.

1.1 FUDS Status and Background

The land on which D-Q University currently lies was owned and occupied by the U.S. Army from 1952 to 1969 and was most commonly called the former West Coast Relay and Radio Transmitting Station. All real properties formerly owned by, leased by, possessed by, or otherwise under the jurisdiction of the Secretary of Defense or elements of the U.S. military are managed within the FUDS program. Policy and guidance for the FUDS program is provided in USACE Engineering Regulation 200-3-1 (USACE, 2004). The Remedial Investigation (RI) identified areas of concern (AOCs) where past Department of Defense (DoD) activities at the former station may have impacted the environment. FUDS program funding can only be used to assess and remediate DoD liability at an eligible property, which is defined as real property. Under the FUDS program, land that was previously utilized by DoD and that has no “beneficial use” history will be characterized and, if necessary, remediated to an appropriate standard.

Under the FUDS program, one of the parameters to be considered during the initiation of a project is whether the property (or specific item/site) has been beneficially used by any owner, operator, or other party that may be considered a potentially responsible party (PRP). If USACE determines the contamination was caused solely by DoD, it will be mitigated by USACE through the FUDS program. If an investigation is initiated (by any party) and DoD is determined to be only partially responsible, USACE will investigate to the extent necessary to determine DoD liability.

Consideration must also be given to the ability to identify DoD-generated contaminants from contaminants introduced by other PRPs, on or off the FUDS property. If identification of separate contaminant streams cannot be achieved, or if separate remediation of DoD-generated contaminants cannot be realized, the project may be ineligible for remediation under the FUDS program. If commingled contamination exists, a PRP project must be initiated and the Department of Justice will negotiate a contribution settlement with the current landowner/responsible party based on a liability analysis.

Further, the Defense Environmental Restoration Program – FUDS (DERP-FUDS) policy does not allow the USACE to provide cost recovery to property owners nor does it allow USACE to recover costs from property owners for remedial work. However, the property owner may initiate an investigation and/or clean-up action and subsequently seek cost reimbursement from the Department of Justice by filing a tort claim.

1: Introduction D-Q University 2012 Monitoring Report

1-2

The former West Coast Relay and Radio Transmitting Station is a FUDS site as defined by the DERP. The DERP-FUDS statute [10 USC 2701 (a) (2)] requires that projects addressing hazardous substances, pollutants, and contaminants be conducted consistent with the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA) and the Superfund Amendments and Reauthorization Act of 1986 (SARA). The FUDS identification number for D-Q University is J09CA1180.

1.2 Report Organization

Background information including Site location, description, and history is presented in Section 2. This section also discusses previous Site investigations. A description of field activities, analytical program, and data quality review is provided in Section 3. The results of groundwater elevation measurement and groundwater sample analysis are also discussed in Section 3. Section 4 presents USACE’s proposed groundwater monitoring network and Section 5 provides references used in this report.

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2 . S I T E B A C K G R O U N D

This section provides details about the Site including both historical and current Site uses. Other information summarized below includes property ownership and previous environmental investigations.

2.1 Site Description and Operational History

In 1952, 651.55 acres of agricultural land were acquired by the U.S. Army for the Sacramento Valley Radio Transmitter Station (Station) to support the Signal Corps Radio Station (call letters: WVY) (Hoover et al., 1990; Dynamac, 1992). The 651.55 acres is referred to as the Site in this report. The Site includes the surrounding agricultural fields and the former Station or the current D-Q University campus.

Improvements to the Site during U.S. Army occupation included the construction of a transmitter building (Building #100), a power generation building (Building #101), a relay building (Building #102), barracks (Building #103), storage buildings, two incinerators, utilities, six underground storage tanks (USTs), four above ground storage tanks (ASTs) inside Building #100, twenty-two transformers, two waste oxidation lagoons, two cooling water injection (disposal) wells, and one cooling water supply well (Dynamac, 1992).

At the time of the acquisition by D-Q University, the Station contained all of the original buildings, most of the generating and pumping machinery, two waste oxidation lagoons, two cooling water injection wells, six USTs, six ASTs, two incinerators, and 13 of the transformers. The other nine transformers were removed prior to the property transfer. All USTs, one AST not in use within Building #101, an incinerator, and 10 of the 13 transformers have been removed by USACE from the Station. The other incinerator and three of the four ASTs inside Building #101 had been removed prior to USACE involvement (USACE, 1997). The facilities, three remaining transformers, and two other ASTs are still being used by D-Q University.

There are no structures within a 1-mile radius other than those associated with the Campus or farming activities. Surrounding the Campus are agricultural lands that are currently leased to farmers that plant and harvest alfalfa (Figure 2).

2.2 Summary of Previous Investigations

As part of the FUDS process, an RI, inclusive of a Data Gap RI (Brown and Caldwell, 2010), was conducted by Brown and Caldwell for the USACE Sacramento District that defined potential source areas, nature and extent of contamination, subsurface characteristics, transport mechanisms, contaminant fate, and a conceptual site model (Brown and Caldwell, 2008). The Data Gap RI eliminated from further consideration those AOCs that pose little or no threat to public health or the environment, determined if there is any potential need for RA, set priorities for site inspections, and gathered existing data to facilitate later evaluation of the release pursuant to the Hazard Ranking System conducted by the U.S. Environmental Protection Agency (USEPA). The RI identified that the primary chemicals of concern (COCs) are volatile organic compounds (VOCs), primarily trichloroethylene (TCE) in groundwater and total petroleum hydrocarbon diesel range organics (TPH-DRO) in soil and groundwater.

The stratigraphy is comprised of fine-grained units of silt and clay with a predominant shallow unit of coarse-grained sand and gravel. Small discrete sand lenses were found at depths greater than 40 feet bgs but are

2: Site Background D-Q University 2012 Monitoring Report

2-2 discontinuous. The shallow sand/gravel unit is relatively continuous and generally encountered between 25 feet bgs and 40 feet bgs underlying the Site, thinning significantly toward the south and County Road 31.

Based on the data collected to date, there appears to be three hydrostratigraphic zones. They are outlined below in order of appearance from ground surface to the maximum depth logged (165 feet bgs):

Low permeable silts and clays (0 to ~25 feet bgs1), Permeable relatively continuous sand/gravel unit (generally at 25 feet bgs to 40 feet bgs), and

Low permeable silts and clays and discontinuous sand/gravel units (generally 40 feet bgs to 165 feet bgs).

The horizontal and vertical extent of TCE-impacted groundwater is defined and is primarily found within the shallow sand/gravel unit. TCE degradation is minimal based on data collected to date which indicate minor concentrations of TCE degradation (or breakdown) products in site groundwater samples. The extent of TPH-DRO in shallow groundwater has been defined laterally near the northeast corner of Building #102, the former location of four fuel oil USTs. TPH-DRO concentrations have been detected in stratigraphically lower discontinuous discrete sand lenses. The TPH-DRO plume is contained within the larger TCE plume.

The Feasibility Study (FS) was conducted at the Site in conjunction with the RI. As part of the FS, a pilot test was conducted to evaluate if enhanced biodegradation combined with groundwater recirculation could remediate the TCE source area. Post monitoring indicated that conditions conducive to biodegradation had been established in groundwater and TCE concentrations in the source area were reduced from 390 micrograms per liter (µg/L) to 15 µg/L. The FS identified candidate technologies for remediating contaminants in Site groundwater and evaluated their likely effectiveness, implementability, and cost. The Final FS Report (ECSBCJV, 2012) identified five alternatives; Alternative 1- No Action, Alternative 2 – Monitored Natural Attenuation, Alternative 3 – Enhanced Biodegradation and Groundwater Recirculation, Alternative 4 – Permeable Reactive Barriers, Alternative 5- In Situ Chemical Oxidation Direct Groundwater Injection.

In August 2012, eight shallow groundwater monitoring wells were installed to supplement the existing network by adding wells cross gradient and downgradient of the former TCE source area. The total number of wells now at the Site include sixteen groundwater monitoring wells and eight treatment wells. Table 1 summarizes the well construction details for the 24 wells on Site. It is USACE’s objective to establish a network that will monitor the natural attenuation of the TCE plume. Before agreeing on which wells to retain or eliminate, USACE agreed to sample all of the wells in 2012 and provide their recommendations for a monitoring network in 2013. The wells were sampled on November 19-20, 2012. This report summarizes the field activities, analytical program, data review, and results from this sampling event. USACE has also provided a recommendation for the monitoring network in Section 4 of this report.

1 As deep as 33 feet bgs in GMW-15, approximately 130 feet north of County Road 31.

2: Site Background D-Q University 2012 Monitoring Report

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Table 1. Well Construction Summary

Well ID Date

Installed

Top of Casing Elevation (feet MSL)

Ground Surface

Elevation (feet MSL)

Total Depth (feet)

Casing Diameter &

Type

Screen Interval

(feet bgs)

Screen Interval

(feet

MSL)

Slot Size

(inches)

GWM-1 1/4/01 102.78* 103.12 27 4 inch PVC 12 to 27 90 to 75 0.010

GWM-2 1/4/01 101.64* 102.18 27 4 inch PVC 12 to 27 89 to 74 0.010

GWM-3 1/5/01 101.98* 102.42 27 4 inch PVC 12 to 27 89 to 74 0.010

GWM-4 4/20/01 101.88* 102.31 26 4 inch PVC 11 to 26 90 to 75 0.010

GWM-5 2/20/01 102.41* 102.85 28 4 inch PVC 13 to 28 89 to 74 0.010

GWM-6 2/20/01 103.13* 103.42 28 4 inch PVC 13 to 28 90 to 75 0.010

DQ-GMW-7 8/10/09 101.67* 102.37 40 2 inch PVC 25 to 40 76 to 61 0.020

DQ-GMW-7A 8/11/09 101.97* 102.64 40 2 inch PVC 35 to 40 66 to 61 0.020

DQ-GMW-8 8/6/2012 102.69** 103.19 45 4 inch PVC 26.5 to 41.5 76 to 91 0.020

DQ-GMW-9 8/14/2012 101.23** 101.70 45 4 inch PVC 26.5 to 41.5 74 to 89 0.020

DQ-GMW-10 8/16/2012 101.90** 102.47 44 4 inch PVC 28 to 43 73 to 88 0.010

DQ-GMW-11 8/9/2012 104.29** 101.37 40 4 inch PVC 27 to 42 77 to 92 0.020

DQ-GMW-12 8/15/2012 104.36** 101.61 45 4 inch PVC 30 to 45 74 to 89 0.020

DQ-GMW-13 8/8/2012 102.17** 99.04 40 4 inch PVC 21.5 to 36.5 80 to 95 0.020

DQ-GMW-14 8/7/2012 102.02** 99.04 45 4 inch PVC 25 to 40 77 to 92 0.020

DQ-GMW-15 8/13/2012 101.77** 98.82 40 4 inch PVC 25 to 40 76 to 91 0.020

DQ-GIW-1 10/21/09 *** 103.43 38 4 inch PVC 18 to 38 85 to 65 0.030

DQ-GIW-2 10/21/09 *** 102.51 28 4 inch PVC 18 to 28 84 to 74 0.030

DQ-GIW-3 10/22/09 *** 102.57 28 4 inch PVC 18 to 28 85 to 75 0.030

DQ-GIW-4 10/20/09 *** 102.28 28 4 inch PVC 18 to 28 84 to 74 0.030

DQ-GIW-5/GEW-5 8/12/09 *** 102.70 38 6 inch PVC1 23 to 38 80 to 65 0.030

DQ-GEW-1 10/20/09 *** 102.57 40 4 inch PVC 25 to 40 77 to 62 0.030

DQ-GEW-2 10/22/09 *** 102.60 40 4 inch PVC 15 to 40 87 to 62 0.030

DQ-GEW-3 8/12/09 *** 102.84 35 4 inch PVC 15 to 35 87 to 67 0.030

*Surveyed 11/5/09.

** Surveyed 10/26/12.

Horizontal datum is State Plane Coordinate System, Zone 2, NAD83. Vertical datum is N. American Vertical Datum 1988.

***Top of well casing was reconfigured for the 2012 monitoring event. Top of well casing has not been resurveyed.

1 DQ-GIW-5/GEW-5 constructed with Schedule 40 PVC blank casing and stainless steel wire wrap screen.

MSL = mean sea level bgs = below ground surface PVC = poly vinyl chloride.

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3 . M O N I T O R I N G A C T I V I T I E S A N D R E S U L T S

Groundwater monitoring activities were conducted in accordance with requirements of the draft Long Term Monitoring (LTM) Work Plan (ECSBCJV, 2012). Current and historical water level data, analytical results, waste management, and the planned future groundwater sampling activities are discussed in this section.

3.1 Field Activities

On November 19, 2012, depths to water were measured in the 24 groundwater monitoring wells with an electric water level meter capable of measuring to the nearest 0.01 foot (Table 2).

The treatment system wells (DQ-GIW-1 thru DQ-GIW-5 and DQ-GEW-1 thru DQ-GEW-3) are hard plumbed directly to the pilot treatment system, which prevents sampling these wells. In order to sample these wells with bladder pumps, the wellheads were reconfigured by cutting and removing the aboveground piping attached to the wellhead. Additionally, electrical wiring, injection well pipes, and extraction well pumps were removed since there are no plans to re-start the system. A new well cap was fitted onto the well casing to allow for repeatable access. This reconfiguration of the wellheads removed the surveyed measuring point for depth to water measurements. Since the point was removed, the elevation used for this point is no longer valid. Therefore, groundwater elevations can not be calculated until the wellheads are resurveyed. The new measuring points were not surveyed for this sampling event.

Groundwater samples were collected from the 24 monitoring wells on November 19 and 20, 2012, following procedures outlined in the LTM Work Plan (ECSBCJV, 2012). Wells were purged at a rate of 300 milliliters per minute and sampled using bladder pumps with disposable Teflon® bladders and polyethylene tubing used between wells following procedures outlined in the USEPA Guidance for low-flow sampling (USEPA, 2010). Wells with lower concentrations were sampled first followed by wells that historically exhibited higher concentrations. A record of the rate and the amount of water purged is provided on Groundwater Purge and Sampling Field Data Sheet for each well attached as Appendix A.

Prior to beginning the monitoring event and after collection of each sample, all non-disposable purging and sampling equipment (e.g., bladder pump, meter probes, flow-through cell) was decontaminated using phosphate-free detergent and de-ionized water per the LTM Work Plan.

During purging, field parameters consisting of acidity (pH), electric conductivity (EC), water temperature, dissolved oxygen (DO), turbidity, oxidation reduction potential (ORP) were monitored using a YSI 556 water quality meter with flow-through cell. Readings were recorded during purging on the Groundwater Purge and Sampling Field Data Sheet for each well provided in Appendix A.

3.2 Analytical Program

Groundwater samples were analyzed by EMAX Laboratories, Inc. (EMAX) for select VOCs by EPA Method 8260B. The select VOCs analyzed are: TCE and its breakdown products (cis-1,2-dichloroethene [DCE], trans-1,2-DCE, and vinyl chloride). Quality Control (QC) samples included field duplicates and trip blanks per the LTM Work Plan. Sufficient sample volume was also collected for laboratory prepared matrix spike/matrix spike duplicate (MS/MSD) analyses. Certified analytical reports and chain-of-custody documentation are provided in Appendix B.

3: Monitoring Activities and Results D-Q University 2012 Monitoring Report

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Table 2. Historical Groundwater Elevations

Well ID Date Top of Casing

(feet) Depth to Groundwater

(feet bgs) Groundwater

Elevation (feet)

GMW-1 Jan 2001 98.39 12.11 86.28

GMW-1 4/11/02 98.39 9.28 89.10

GMW-1 8/8/02 98.39 8.73 89.66

GMW-1 1/7/03 98.39 7.90 90.49

GMW-1 3/24/03 98.39 6.89 91.50

GMW-1 9/10/03 98.39 10.16 88.23

GMW-1 12/15/03 98.39 12.25 86.14

GMW-1 4/8/04 98.39 7.59 90.80

GMW-1 5/30/06 98.39 4.40 93.99

GMW-1 6/21/07 98.39 7.20 98.39

GMW-1 6/9/08 98.39 8.35 90.04

GMW-1 11/9/09 102.78 22.50 80.28 ft MSL

GMW-1 12/10/09 102.78 22.88 79.90 ft MSL

GMW-1 7/23/10 102.78 14.16 88.62 ft MSL

GMW-1 2/11/11 102.78 15.23 87.55 ft MSL

GMW-1 11/19/12 102.78 14.56 88.22 ft MSL

GMW-2 Jan 2001 97.26 11.07 86.19

GMW-2 4/11/02 97.26 8.21 89.05

GMW-2 8/8/02 97.26 7.75 89.51

GMW-2 1/7/03 97.26 6.86 90.40

GMW-2 3/24/03 97.26 5.82 91.44

GMW-2 9/10/03 97.26 9.34 87.92

GMW-2 12/15/03 97.26 11.35 85.91

GMW-2 4/8/04 97.26 6.46 90.80

GMW-2 5/30/06 97.26 3.21 94.05

GMW-2 6/21/07 97.26 5.95 97.26

GMW-2 6/9/08 97.26 7.23 90.03

GMW-2 11/9/09 101.64 21.91 79.73 ft MSL

GMW-2 12/10/09 101.64 22.22 79.42 ft MSL

GMW-2 7/23/10 101.64 13.09 88.55 ft MSL

GMW-2 2/11/11 101.64 14.38 88.40 ft MSL

GMW-2 11/19/12 101.64 13.79 87.85 ft MSL

GMW-3 Jan 2001 97.61 11.24 86.37

GMW-3 4/11/02 97.61 8.36 89.25

GMW-3 8/8/02 97.61 7.79 89.82

GMW-3 3/25/03 97.61 9.06 88.55

GMW-3 9/10/03 97.61 9.39 88.22

GMW-3 12/16/03 97.61 11.44 86.17

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Well ID Date Top of Casing

(feet) Depth to Groundwater

(feet bgs) Groundwater

Elevation (feet)

GMW-3 4/8/04 97.61 6.60 91.01

GMW-3 5/30/06 97.61 3.45 94.16

GMW-3 6/21/07 97.61 6.20 97.61

GMW-3 6/9/08 97.61 7.39 90.22

GMW-3 11/9/09 101.98 22.2 79.78 ft MSL

GMW-3 12/10/09 101.98 22.34 79.64 ft MSL

GMW-3 7/23/10 101.98 13.35 88.63 ft MSL

GMW-3 2/11/11 101.98 14.49 88.29 ft MSL

GMW-3 11/20/12 101.98 13.75 88.23 ft MSL

GMW-4 4/11/02 97.67 8.39 89.28

GMW-4 8/8/02 97.67 7.86 89.81

GMW-4 3/25/03 97.67 6.97 90.70

GMW-4 9/10/03 97.67 8.92 88.75

GMW-4 12/16/03 97.67 12.00 85.67

GMW-4 4/8/04 97.67 6.66 91.01

GMW-4 5/30/06 97.67 3.55 94.12

GMW-4 6/21/07 97.67 6.41 97.67

GMW-4 6/9/08 97.67 7.58 90.09

GMW-4 11/9/09 101.88 21.81 80.07 ft MSL

GMW-4 12/10/09 101.88 22.04 79.84 ft MSL

GMW-4 7/23/10 101.88 13.20 88.68 ft MSL

GMW-4 2/11/11 101.88 14.24 88.54 ft MSL

GMW-4 11/19/12 101.88 13.49 88.39 ft MSL

GMW-5 4/11/02 98.39 8.97 89.42

GMW-5 8/8/02 98.39 8.28 90.11

GMW-5 1/13/03 98.39 6.74 91.65

GMW-5 3/25/03 98.39 6.56 91.83

GMW-5 9/10/03 98.39 9.95 88.44

GMW-5 12/16/03 98.39 11.90 86.49

GMW-5 4/5/04 98.39 7.16 91.23

GMW-5 5/30/06 98.39 3.85 94.54

GMW-5 6/21/07 98.39 6.70 98.39

GMW-5 6/9/08 98.39 7.90 90.49

GMW-5 11/9/09 102.41 22.55 79.86 ft MSL

GMW-5 12/10/09 102.41 22.98 79.43 ft MSL

GMW-5 7/23/10 102.41 13.18 89.23 ft MSL

GMW-5 2/11/11 102.41 14.97 87.81 ft MSL

GMW-5 11/20/12 102.41 14.22 88.19 ft MSL

3-4

Well ID Date Top of Casing

(feet) Depth to Groundwater

(feet bgs) Groundwater

Elevation (feet)

GMW-6 4/11/02 98.80 9.45 89.35

GMW-6 8/8/02 98.80 8.87 89.93

GMW-6 1/13/03 98.80 7.35 91.45

GMW-6 3/24/03 98.80 7.10 91.70

GMW-6 9/10/03 98.80 10.42 88.38

GMW-6 12/15/03 98.80 12.40 86.40

GMW-6 4/8/04 98.80 7.75 91.05

GMW-6 5/30/06 98.80 4.60 94.20

GMW-6 6/21/07 98.80 7.30 98.80

GMW-6 6/9/08 98.80 8.51 90.29

GMW-6 11/9/09 103.13 23.07 80.06 ft MSL

GMW-6 12/10/09 103.13 23.30 79.83 ft MSL

GMW-6 7/23/10 103.13 14.38 88.75 ft MSL

GMW-6 2/11/11 103.13 15.48 87.30 ft MSL

GMW-6 11/19/12 103.13 14.86 88.27 ft MSL

GMW-7 11/9/09 101.67 22.20 79.47 ft MSL

GMW-7 12/10/09 101.67 21.80 79.87 ft MSL

GMW-7 7/23/10 101.67 12.98 88.69 ft MSL

GMW-7 2/11/11 101.67 14.06 88.72 ft MSL

GMW-7 11/19/12 101.67 13.62 88.05 ft MSL

GMW-7A 11/9/09 101.97 21.92 80.05 ft MSL

GMW-7A 12/10/09 101.97 22.21 79.76 ft MSL

GMW-7A 7/23/10 101.97 13.29 88.68 ft MSL

GMW-7A 2/11/11 101.97 14.21 88.57 ft MSL

GMW-7A 11/20/12 101.97 14.02 87.95 ft MSL

GMW-8 11/19/12 102.69 15.85 86.84 ft MSL

GMW-9 11/19/12 101.23 14.09 87.14 ft MSL

GMW-10 11/19/12 101.90 14.79 87.11 ft MSL

GMW-11 11/20/12 104.29 16.78 87.51 ft MSL

GMW-12 11/20/12 104.36 17.73 86.63 ft MSL

GMW-13 11/20/12 102.17 17.01 85.16 ft MSL

GMW-14 11/20/12 102.02 17.22 84.79 ft MSL

GMW-15 11/20/12 101.77 17.18 84.59 ft MSL

DQ-GIW-1 11/9/09 103.84 23.83 80.01 ft MSL

DQ-GIW-1 12/10/09 103.84 23.84 80.00 ft MSL

DQ-GIW-1 7/23/10 103.84 15.07 88.77 ft MSL

DQ-GIW-1 2/11/11 103.84 15.25 87.53 ft MSL

3-5

Well ID Date Top of Casing

(feet) Depth to Groundwater

(feet bgs) Groundwater

Elevation (feet)

DQ-GIW-1 11/19/12 * 14.62 --

DQ-GIW-2 11/9/09 102.94 22.93 80.01 ft MSL

DQ-GIW-2 12/10/09 102.94 22.15 80.79 ft MSL

DQ-GIW-2 7/23/10 102.94 14.25 88.69 ft MSL

DQ-GIW-2 2/11/11 102.94 6.56 96.22 ft MSL

DQ-GIW-2 11/19/12 * 13.61 --

DQ-GIW-3 11/9/09 103.00 22.93 80.07 ft MSL

DQ-GIW-3 12/10/09 103.00 21.53 81.47 ft MSL

DQ-GIW-3 7/23/10 103.00 14.29 88.71 ft MSL

DQ-GIW-3 2/11/11 103.00 15.03 87.75 ft MSL

DQ-GIW-3 11/19/12 * 13.41 --

DQ-GIW-4 11/9/09 102.73 22.72 80.01 ft MSL

DQ-GIW-4 12/10/09 102.73 22.22 80.51 ft MSL

DQ-GIW-4 7/23/10 102.73 13.95 88.78 ft MSL

DQ-GIW-4 2/11/11 102.73 14.82 87.96 ft MSL

DQ-GIW-4 11/19/12 *** 13.58 --

DQ-GIW-5/GEW-5 11/9/09 103.01 23.39 79.62 ft MSL

DQ-GIW-5/GEW-5 12/10/09 103.01 22.85 80.16 ft MSL

DQ-GIW-5/GEW-5 7/23/10 103.01 13.45 89.56 ft MSL

DQ-GIW-5/GEW-5 2/11/11 103.01 15.00 87.78 ft MSL

DQ-GIW-5/GEW-5 11/20/12 * 14.27 --

DQ-GEW-1 11/9/09 102.20 22.15 80.05 ft MSL

DQ-GEW-1 12/10/09 102.20 21.96 80.24 ft MSL

DQ-GEW-1 7/23/10 102.20 13.42 88.78 ft MSL

DQ-GEW-1 2/11/11 102.20 14.50 88.28 ft MSL

DQ-GEW-1 11/19/12 * 13.90 --

DQ-GEW-2 11/9/09 102.11 22.10 80.01 ft MSL

DQ-GEW-2 12/10/09 102.11 22.38 79.73 ft MSL

DQ-GEW-2 7/23/10 -- Well could not be accessed for this event

DQ-GEW-2 2/11/11 102.11 14.88 87 ft MSL

DQ-GEW-2 11/20/12 * 13.85 --

DQ-GEW-3 11/9/09 102.52 22.57 79.95 ft MSL

DQ-GEW-3 12/10/09 102.52 22.83 79.69 ft MSL

DQ-GEW-3 7/23/10 -- Well could not be accessed for this event

DQ-GEW-3 2/11/11 102.52 15.33 87.45 ft MSL

DQ-GEW-3 11/20/12 * 14.20 --

*Top of well casing was reconfigured for the 2012 monitoring event. Top of well casing has not been resurveyed.

3-6

3.3 Data Review

This section summarizes the data quality assessment of analytical results reported for groundwater samples collected during the monitoring event. Validation and/or verification of the laboratory analytical data were performed per the criteria specified in the Workplan and the Quality Assurance Project Plan (QAPP) for the RI Workplan (USACE, 2005). Table 3 lists the types of QC samples and analytical acceptance limits that were used to assess both field and laboratory performance.

Table 3. Quality Control Sample Requirements

QC Sample Type Minimum Collection Frequency Acceptance Limits

Field Duplicates 1 per 10 investigative samples / matrix / method Relative Percent Difference (RPD) ≤ 35 %

Trip Blanks 1 per cooler with investigative samples to be analyzed for VOCs

No detected analytes

Temperature Blanks 1 per cooler 4º C ± 2º C

Equipment Rinsate Blanks 1 per day / sampling team for samples collected using reusable equipment

No detected analytes

Matrix Spikes 1 set of MS/MSD samples per 20 investigative samples / matrix / method

Statistically derived laboratory limits

The project laboratory had a quality assurance (QA) program that monitored data quality with internal QC checks. These laboratory QC checks included blank samples, laboratory control samples (LCSs), duplicate analyses, and MS/MSDs.

3.3.1 Analysis

Groundwater samples were shipped to EMAX Laboratories in Torrance, California for analysis of select volatile organic compounds: TCE, cis-1,2-DCE, trans-1,2-DCE, and vinyl chloride. EMAX is certified under the California Environmental Laboratory Accreditation Program (ELAP# 2672) and under the National Environmental Laboratory Accreditation Program (NELAP #02116CA). Samples were received at the required temperature and were analyzed within the required holding time.

A total of 24 normal samples and three field duplicates were collected (12.5 percent frequency):

D-Q-GMW-40 associated with primary sample D-Q-GMW-4; D-Q-GMW-100 associated with primary sample D-Q-GMW-10; and D-Q-GIW-10 associated with primary sample D-Q-GIW-1. The relative percent difference of analytical results between normal and field duplicates was well within the required precision.

Two trip blanks were collected (one per cooler on each sampling day): D-Q-TB-111912 for samples collected on November 19, 2012; and D-Q-TB-112012 for samples collected on November 20, 2012. None of the target analytes were detected in the two trip blanks. Four equipment blanks were collected (at least one per day that reusable equipment was used): D-Q-EB111912 and D-Q-EB111912-01 for equipment used on November 19, 2012; and D-Q-EB112012 and D-Q-EB112012-01 for equipment used on November 20, 2012. None of the target analytes were detected in the four equipment blanks.

Data were received in both hard copy and electronic formats. In general, the data collected in support of this monitoring event meet the data quality objectives and are considered usable for decision making. There were no data quality issues identified in the data quality assessment, and none of the results were rejected. A total of 14 results were qualified with a J-flag due to trace level detections between the laboratory method detection limit and practical quantitation limit. Two results (TCE in D-Q-GMW-3 and D-Q-GMW-5) were

3-7 initially estimated with an E-flag for exceeding the calibration range; however, the laboratory diluted and re-analyzed the samples to bring the results within the calibration range. Table 4 provides a summary of the results that were qualified by method.

Table 4. Analytical Completeness

Number of results Completeness

M et ho d

Pa ra m et e r

Sa m pl es

A na ly ze d

(N +F

D

A na ly te s pe r sa m pl e

To ta l

R ej ec te d

Es tim at ed d ue to

Q C d ef ic ie nc ie s

Es tim at ed d ue to

>M D

L bu t <

PQ

L

Pe rc en t u sa bl e

Pe rc en t qu an tit at iv e*

SW8260B Volatiles by GC/MS 24+3 4 108 0 0 14 100% 100%

* Note: Estimations due solely to results <PQL do not affect the calculated completeness Calculations do not include any required field or laboratory QC samples, except field duplicates.

N = normal environmental samples FD = field duplicate samples

3.3.2 Conclusions

In general, the results are of acceptable quality and are usable for their intended purpose. None of the results were rejected. No results required qualification due to QC deficiencies; however, 14 results were qualified for trace level detections.

3.4 Results

A discussion of groundwater elevation and analytical results are provided below.

3.4.1 Groundwater Elevations

As mentioned in Section 3.1, eight wellheads were reconfigured for this sampling event and these wellheads were not resurveyed for this report. Calculations of groundwater elevations were performed for the remaining wells by subtracting the depth to water measurement from the surveyed elevation of the notch in the top of the well casing. Table 2 provides groundwater elevation data collected during the current event, as well as historical groundwater elevation data since 2002.

On November 19, 2012 groundwater was found at a depth ranging from 13.41 feet below ground surface (ft bgs) in GIW-3 to 14.86 ft bgs in GMW-6. Direction of groundwater flow is towards the south-southwest for the northern portion of the plume (Figure 2) under an average hydraulic gradient of 0.003 ft/ft. Direction of groundwater flow turns south to southeast in the middle to southern section of the plume (Figure 2) under an average hydraulic gradient of 0.001 ft/ft. These results are consistent with previous monitoring data (Table 5).

3-8

Table 5. Historical Groundwater Flow Directions and Gradient

Date Generalized Flow Direction Approximate Gradient (feet/feet)

Jan 2001 Southeast 0.0009

4/11/02 East to southeast 0.0008 to 0.001

8/8/02 Northeast to east to southeast 0.001 to 0.003

3/24/03 Northeast to southeast 0.001 to 0.003

9/10/03 Northeast to southeast 0.001 to 0.004

12/15/03 Northeast to southeast 0.0009 to 0.008

4/8/04 East to southeast 0.001

5/30/06 East to southeast 0.001

6/21/07 East to northeast 0.003

6/9/2008 East to northeast 0.005

11/9/09 South to southeast 0.009

2/11/11 Variable due to operation of pilot test system Not calculated because of the variable gradient induced during pumping

11/20/12 Northern portion: south-southwest

Middle and southern portion: south to southeast Northern portion: 0.003

Middle and southern portion: 0.001

3.4.2 Analytical

Historical and current TCE concentrations are shown in Table 6. TCE concentration ranged from less than the detection limit of 0.20 µg/L in wells DQ-GIW-1, DQ-GIW-4, and DQ-GMW-11 to 310 µg/L in well DQ-GMW-5. For comparison purposes, the analytical data from this event was compared against USEPA Drinking Water Standards and Health Advisories for the Primary Maximum Contaminant Level (MCL).

Seven of 24 monitoring wells had TCE concentrations that exceeded the MCL of 5 µg/L.

3-9

Table 6. Historical TCE Concentrations in Monitoring Wells

Monitoring Well Sample Date TCE Concentration

(µg/L)

DQ-GMW-1 4/11/02 40

DQ-GMW-1 8/8/02 65

DQ-GMW-1 1/7/03 85

DQ-GMW-1 3/24/03 75

DQ-GMW-1 9/10/03 85

DQ-GMW-1 12/15/03 56

DQ-GMW-1 4/8/04 65

DQ-GMW-1 5/30/06 44

DQ-GMW-1 6/1/07 34

DQ-GMW-1 6/1/08 32

DQ-GMW-1 8/26/10 12

DQ-GMW-1 2/10/11 7.1

DQ-GMW-1 11/19/12 2.2

DQ-GMW-2 4/11/02 7.4

DQ-GMW-2 8/8/02 22

DQ-GMW-2 1/7/03 0.90

DQ-GMW-2 3/24/03 1.2

DQ-GMW-2 9/10/03 22

DQ-GMW-2 12/15/03 0.5

DQ-GMW-2 4/8/04 4.7

DQ-GMW-2 5/30/06 1.2

DQ-GMW-2 6/1/07 35

DQ-GMW-2 6/1/08 6.2

DQ-GMW-2 8/26/10 0.60

DQ-GMW-2 2/10/11 1.2

DQ-GMW-2 11/19/12 0.29J

DQ-GMW-3 4/11/02 600

DQ-GMW-3 8/8/02 670

DQ-GMW-3 3/25/03 230

DQ-GMW-3 9/10/03 460

DQ-GMW-3 12/16/03 440

DQ-GMW-3 4/8/04 290

DQ-GMW-3 5/30/06 570

DQ-GMW-3 6/1/07 590

DQ-GMW-3 6/1/08 580

DQ-GMW-3 11/9/09 140

DQ-GMW-3 11/19/09 130

3-10

Monitoring Well Sample Date TCE Concentration

(µg/L)

DQ-GMW-3 12/1/09 110

DQ-GMW-3 12/10/09 96

DQ-GMW-3 8/26/10 65

DQ-GMW-3 9/23/10 83

DQ-GMW-3 10/21/10 75

DQ-GMW-3 11/18/10 94

DQ-GMW-3 1/3/11 71

DQ-GMW-3 2/10/11 98

DQ-GMW-3 11/20/12 160

DQ-GMW-4 4/11/02 96

DQ-GMW-4 8/8/02 340

DQ-GMW-4 3/25/03 3.8

DQ-GMW-4 9/11/03 1.7

DQ-GMW-4 12/16/03 6.7

DQ-GMW-4 4/8/04 300

DQ-GMW-4 5/30/06 0.41J

DQ-GMW-4 6/1/07 73

DQ-GMW-4 6/1/08 0.64

DQ-GMW-4 8/26/10 160

DQ-GMW-4 2/10/11 64

DQ-GMW-4 11/19/12 14

DQ-GMW-5 4/11/02 150

DQ-GMW-5 8/8/02 480

DQ-GMW-5 1/13/03 150

DQ-GMW-5 3/25/03 110

DQ-GMW-5 9/11/03 730

DQ-GMW-5 12/16/03 210

DQ-GMW-5 4/8/04 630

DQ-GMW-5 5/30/06 190

DQ-GMW-5 6/1/07 450

DQ-GMW-5 6/1/08 390

DQ-GMW-5 11/9/09 480

DQ-GMW-5 11/19/09 470

DQ-GMW-5 12/1/09 490

DQ-GMW-5 12/10/09 500

DQ-GMW-5 8/26/10 300

DQ-GMW-5 9/23/10 280

DQ-GMW-5 10/21/10 210

3-11

Monitoring Well Sample Date TCE Concentration

(µg/L)

DQ-GMW-5 11/18/10 150

DQ-GMW-5 1/3/11 91

DQ-GMW-5 2/10/11 180

DQ-GMW-5 11/20/12 310

DQ-GMW-6 4/11/02 7.6

DQ-GMW-6 8/8/02 0.90

DQ-GMW-6 1/13/03 1.5

DQ-GMW-6 3/24/03 4.3

DQ-GMW-6 9/11/03 1.2

DQ-GMW-6 12/16/03 3.0

DQ-GMW-6 4/8/04 3.4

DQ-GMW-6 5/30/06 1.5

DQ-GMW-6 6/1/07 0.98

DQ-GMW-6 6/1/08 0.55

DQ-GMW-6 11/10/09 <0.50

DQ-GMW-6 11/19/09 <0.50

DQ-GMW-6 12/1/09 <0.50

DQ-GMW-6 12/10/09 0.60

DQ-GMW-6 8/26/10 0.59

DQ-GMW-6 9/23/10 0.58

DQ-GMW-6 10/21/10 0.37J

DQ-GMW-6 11/18/10 0.51

DQ-GMW-6 1/3/11 0.58

DQ-GMW-6 2/10/11 0.43J

DQ-GMW-6 11/19/12 0.65

DQ-GMW-7 11/9/09 86

DQ-GMW-7 11/19/09 19

DQ-GMW-7 12/1/09 0.91

DQ-GMW-7 12/10/09 0.51

DQ-GMW-7 8/26/10 160

DQ-GMW-7 9/23/10 0.24J

DQ-GMW-7 10/21/10 0.25J

DQ-GMW-7 11/18/10 1.0

DQ-GMW-7 1/12/11 <0.20

DQ-GMW-7 2/9/11 <0.20

DQ-GMW-7 11/19/12 69

DQ-GMW-7A 11/9/09 5.3

DQ-GMW-7A 11/19/09 48

3-12

Monitoring Well Sample Date TCE Concentration

(µg/L)

DQ-GMW-7A 12/1/09 38

DQ-GMW-7A 12/10/09 17

DQ-GMW-7A 8/26/10 6.1

DQ-GMW-7A 9/23/10 1.3

DQ-GMW-7A 10/21/10 1.9

DQ-GMW-7A 11/18/10 7.2

DQ-GMW-7A 1/3/11 4.6

DQ-GMW-7A 2/9/11 4.1

DQ-GMW-7A 11/20/12 2.3

DQ-GMW-8 8/20/12 1.2

DQ-GMW-8 11/19/12 1.6

DQ-GMW-9 8/20/12 5.4

DQ-GMW-9 11/19/12 12

DQ-GMW-10 8/20/12 0.70

DQ-GMW-10 11/19/12 0.67

DQ-GMW-11 8/17/12 0.20J

DQ-GMW-11 11/20/12 <0.20

DQ-GMW-12 8/20/12 0.80

DQ-GMW-12 11/20/12 0.62

DQ-GMW-13 8/17/12 8.0

DQ-GMW-13 11/20/12 9.0

DQ-GMW-14 8/17/12 1.3

DQ-GMW-14 11/20/12 3.4

DQ-GMW-15 8/17/12 0.50

DQ-GMW-15 11/20/12 0.81

DQ-GIW-1 11/19/12 <0.20

DQ-GIW-2 11/19/12 0.62

DQ-GIW-3 11/19/12 0.32J

DQ-GIW-4 11/19/12 <0.20

DQ-GEW-1 11/10/09 1.8

DQ-GEW-1 11/19/09 58

DQ-GEW-1 10/21/10 16

DQ-GEW-1 11/18/10 17

DQ-GEW-1 1/11/11 16

DQ-GEW-1 2/9/11 21

DQ-GEW-1 11/19/12 <0.20

DQ-GEW-2 11/10/09 86

DQ-GEW-2 11/19/09 72

3-13

Monitoring Well Sample Date TCE Concentration

(µg/L)

DQ-GEW-2 12/1/09 69

DQ-GEW-2 12/9/09 83

DQ-GEW-2 8/25/10 140

DQ-GEW-2 9/22/10 30

DQ-GEW-2 10/21/10 78

DQ-GEW-2 11/17/10 100

DQ-GEW-2 1/2/11 58

DQ-GEW-2 2/9/11 80

DQ-GEW-2 11/20/12 8.0

DQ-GEW-3 11/10/09 56

DQ-GEW-3 11/19/09 46

DQ-GEW-3 12/1/09 29

DQ-GEW-3 12/9/09 19

DQ-GEW-3 8/25/10 7.5

DQ-GEW-3 9/22/10 6.9

DQ-GEW-3 10/21/10 4.9

DQ-GEW-3 11/17/10 3.0

DQ-GEW-3 1/2/11 4.0

DQ-GEW-3 2/9/11 6.4

DQ-GEW-3 11/20/12 0.76

DQ-GIW/GEW-5 12/1/09 39

DQ-GIW/GEW-5 12/9/09 32

DQ-GIW/GEW-5 8/25/10 75

DQ-GIW/GEW-5 9/22/10 11

DQ-GIW/GEW-5 10/21/10 11

DQ-GIW/GEW-5 11/17/10 6.5

DQ-GIW/GEW-5 1/2/11 11

DQ-GIW/GEW-5 2/9/11 15

DQ-GIW/GEW-5 11/20/12 0.47J

Figure 3 presents current TCE concentrations at each well and TCE isoconcentration contours. The TCE plume begins northwest of the former source area just east of Building 100, extends approximately 2,700 feet to the southeast, and terminates near County Road 31 (Covell Road). If we consider the 5 µg/L contour (equal to the MCL for TCE), the plume is split between a higher concentration area (i.e., up to 310 µg/L at DQ-GMW-5) that extends from Building 100 to 102, and a lower concentration area (i.e., up to 9 µg/L at GMW-13) near the southeastern portion of the agricultural field. The highest TCE concentrations in groundwater on Site are no longer located in the former source area due primarily to successful TCE mass removal and degradation during the 2009/2010 pilot test. The highest TCE concentrations are currently

3-14 located just downgradient of the former source area at DQ-GMW-3 (160 µg/L) and DQ-GMW-5 (310 µg/L).

Figure 4 shows a graphical distribution of TCE and breakdown products (i.e., cis- and trans-1,2-DCE and vinyl chloride). Near each well, a pie chart is displayed with up to four slices that represent analytical results for TCE in blue, cis-1,2-DCE in maroon, trans-1,2-DCE in lime green, and vinyl chloride in violet. The size of each pie slice reflects the concentration of individual chemicals relative to the sum of all four chemical concentrations (if detected). For example, the pie chart at GEW-3 displays a blue pie slice that is about one-third the whole pie and a maroon pie slice that is two-thirds the pie. Concentrations of TCE at 0.76 µg/L and cis-1,2-DCE at 1.5 µg/L are posted next to the pie chart. This graphic indicates that only TCE and cis- 1,2-DCE were detected, and that the TCE detection of 0.76 µg/L was approximately 33 percent the sum of both detected chemical concentrations (2.26 µg/L).

Looking at the pie charts across the Site, it is evident that at many monitoring locations only TCE is detected (i.e., primarily whole blue pie charts) and there is little evidence that TCE is being degraded into its breakdown products. Lack of TCE degradation at the Site is mainly attributed to oxidative groundwater conditions that are not conducive to anaerobic biodegradation (primarily via reductive dechlorination).

However in the former source area, there are several monitoring locations where breakdown products are present (i.e., pie charts with maroon, lime green, and violet pie slices). For example, at pilot test well GIW-4 vinyl chloride was detected at 8.7 µg/L with no parent product TCE detected (i.e., primarily violet pie chart).

This indicates that the pilot test was successful in creating anaerobic groundwater conditions amended with nutrients that encouraged the biodegradation of the TCE. Note that it is typical for vinyl chloride to be biodegraded aerobically as the groundwater re-establishes its former oxidative conditions. Immediately downgradient of the former source area where the pilot test was implemented, the pie charts are primarily blue indicating that TCE is present with little to no breakdown products present.

3.5 Investigative Derived Waste

The investigative derived waste (IDW) consisted of liquid that was properly classified, labeled, managed, and disposed in accordance with the draft LTM Work Plan (ECSBCJV, 2012).

The liquid IDW was generated during the following activities:

Decontamination of non-disposable sampling equipment, and

Purged groundwater.

The liquid IDW, approximately 50 gallons, accumulated during this sampling event was stored onsite in one 55-gallon, steel Department of Transportation approved drum and secured with a ring lid, and its contents properly labeled. The IDW was profiled as non-hazardous waste based on the results from of the monitoring event. The profile was forwarded to USACE for approval and signature (Appendix C). The drum was removed from the site on December 6, 2012 using a non-hazardous manifest (Appendix C) and transported to a disposal facility in Rio Vista for processing through carbon.

4-1

4 . R E C O M M E N D E D G R O U N D W A T E R M O N I T O R I N G N E T W O R K

USACE recommends that the groundwater monitoring network consist of wells that are distributed throughout the TCE plume: upgradient; within the former TCE source area; within the more diffuse portion of the plume; crossgradient near the edges of the plume; and downgradient or near the toe of the plume.

Table 7 identifies the wells proposed for the monitoring network, wells proposed for abandonment, and the rationale behind the selection. Figure 5 displays the recommended monitoring network.

Table 7. Proposed Groundwater Monitoring Network

Well ID Well Type Location Relative to TCE Plume

Proposal Rationale

DQ-GMW-1 Monitoring In Plume Retain Defines plume boundary to northeast near agricultural fields

DQ-GMW-2 Monitoring In Plume Abandon Area adequately monitored by DQ-GMW-9

DQ-GMW-3 Monitoring In Plume Retain Immediately downgradient of former source area; Within the 50 µg/L concentration contour

DQ-GMW-4 Monitoring In Plume Retain Defines plume boundary to northeast near agricultural fields

DQ-GMW-5 Monitoring In Plume Retain Immediately downgradient of former source area; Within the 50 µg/L concentration contour; currently the maximum TCE concentration

DQ-GMW-6 Monitoring Upgradient Retain Indication of upgradient groundwater conditions

DQ-GMW-7 Monitoring Former source area

Retain Monitors former source area; within the 50 µg/L concentration contour

DQ-GMW-7A Monitoring Former source area

Abandon Area adequately monitored by DQ-GMW-7

DQ-GMW-8 Monitoring Crossgradient Retain Defines plume boundary to west near Buildings 102 and

DQ-GMW-9 Monitoring In Plume Retain Within the 5 µg/L concentration contour

DQ-GMW-10 Monitoring In Plume Retain Defines split of higher and lower concentration areas

4: Recommended Groundwater Monitoring Network D-Q University 2012 Monitoring Report

4-2

Table 7. Proposed Groundwater Monitoring Network

Well ID Well Type Location Relative to TCE Plume

Proposal Rationale

DQ-GMW-11 Monitoring Crossgradient Retain Defines plume boundary to east near sewage ponds

DQ-GMW-12 Monitoring In Plume Retain Defines split of higher and lower concentration areas

DQ-GMW-13 Monitoring In plume / crossgradient

Retain Defines plume boundary to southeast near agricultural fields

DQ-GMW-14 Monitoring In plume / Crossgradient

Retain Defines toe of plume boundary near County Road 31 (Covell Road)

DQ-GMW-15 Monitoring Downgradient Retain Indication of downgradient groundwater conditions

DQ-GIW-1 Injection/ monitoring

Former source area

Abandon Area adequately monitored by DQ-GIW-2

DQ-GIW-2 Injection/ monitoring

Former source area

Retain Monitors former source area

DQ-GIW-3 Injection/ monitoring

Former source area

Abandon Area adequately monitored by DQ-GIW-2

DQ-GIW-4 Injection/ monitoring

Former source area

Abandon Area adequately monitored by DQ-GIW-2

DQ-GIW-5/

GEW-5

Injection/ monitoring

Former source area

Abandon Area adequately monitored by DQ-GMW-7

DQ-GEW-1 Extraction/ monitoring

Former source area

Abandon Area adequately monitored by DQ-GIW-2

DQ-GEW-2 Extraction/ monitoring

Former source area

Abandon Area adequately monitored by DQ-GMW-7

DQ-GEW-3 Extraction/ monitoring

Former source area

Retain Immediately downgradient of former source area

4: Recommended Groundwater Monitoring Network D-Q University 2012 Monitoring Report

4-3

Table 8. Groundwater Monitoring Analytical Program

Method Parameter Contaminant Purpose

SW8260B Volatiles by GCMS TCE Source contaminant

Cis-1,2-DCE

Products of degradation Trans-1,2-DCE

Vinyl chloride

5-1

5 . R E F E R E N C E S

Brown and Caldwell. 2008. Remedial Investigation Report. May.

Brown and Caldwell. 2010. Draft Final Data Gap and Treatability Study. September.

California Regional Water Quality Control Board, Central Valley Region. 2008. Waste Discharge Requirements General Order for In-Situ Groundwater Remediation at Sites with Volatile Organic Compounds, Nitrogen Compounds, Perchlorate, Pesticides, Semi-Volatile Compounds, Hexavalent Chromium, and/or Petroleum Hydrocarbons. Order No. R5-2008.0149.

Dynamac Corporation. 1992. Draft Inventory Project Report, D-Q University, Yolo County, CA, prepared for U.S.

Army Corps of Engineers, Sacramento District. June.

ECSBCJV. 2012. Final Feasibility Study Results Report. D-Q University, Yolo County, California. June 12.

Hoover, Mildred B., H. E. Rensch, and E. G. Rensch. 1990. Historic Spots in California. 4th Ed. Stanford University Press, Stanford.

U.S. Army Corps of Engineers (USACE). 1997. Site Investigation Report, Diesel UST/Irrigation Ditch, D-Q University. November.

USACE. 2004. Formerly Used Defense Sites Program Policy,…