SDMS DOCID# 1123580 · Phoenix-Goodyear Airport-North Superfund Site Goodyear, Arizona Prepared...

SDMS DOCID# 1123580

Staff ~n~inee; r\ I i

Harry T3rentoK RG C/ P r o j e v g e r

epartrnent Manager

Final Work Plan Implementation of Additional Subunit A Plume Control Measures in the Northeast Area Phoenix-Goodyear Airport-North Superfund Site Goodyear, Arizona

Prepared for:

Crane Co.

Prepared by:

ARCADIS U.S., Inc. 8222 South 4~~ Street Suite 140 Phoenix Arizona 85044 Tel602 438 0883 Fax 602 438 01 02

Our Ref.:

AZ003987.0001.00004

Date:

May 4,2007

This document is intended only for the use of the individual or entify for which it was prepared and may contain information that is privileged, confidential, and exempt from disclosure under applicable law. Any dissemination, distribution, or copying of this document is strict/y pmhibited.

1.0 INTRODUCTION

2.0 BACKGROUND

Table of Contents

3.0 DESIGN CRITERIA

3.1 EA-05 Location

3.1.1 Maricopa County Flood Control District Retention Basins

3.1.2 West Valley Medical Campus

3.1.3 Target Center

3.2 EA-06 Location

3.3 Groundwater Extraction Rates

3.4 Groundwater Discharge OptionsIPlans

3.4.1 Injection

3.4.2 RID Canal Discharge

3.4.3 Irrigation

3.4.4 Sanitary Sewer Discharge

3.4.5 Storm Sewer Discharge

4.0 Technical Approach

4.1 Extraction Wells

4.1 .I Well Development

4.2 Treatment Technology Evaluation

4.2.1 Low-Profile Air Stripping With Vapor Phase Granular Activated Carbon

4.2.2 Low-Profile Air Stripping With No Further Treatment

4.2.3 Liquid Phase Carbon Treatment

4.3 Technology Selection

5.0 EA-05 DESIGN

5.1 Process Description

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Table of Contents

Design Components

5.2.1 Liquid Phase GAC System

5.2.3 System Tie-ins and Piping

5.2.4 Sequestering Agent Tank and Pump

5.2.5 Process Instrumentation and Controls

5.2.6 Submersible Pump

5.2.7 Irrigation Tank

5.2.8 Utilities

5.2.9 Treatment Structure

LGAC System Monitoring

EA-05 Operation and Maintenance

EA-05 O&M Activities

LGAC Change Out

Backwash

Waste Disposal

EA-05 Discharge

6.0 EA-06 DESIGN


6.2 Design Components


6.2.2 Pretreatment System





6.2.7 Utilities


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Table of Contents

6.3 LGAC System Monitoring

6.4 EA-06 Operation and Maintenance

6.5 EA-06 O&M Activities

6.6 LGAC Change out

6.7 Backwash

6.8 Waste Disposal

6.9 EA-06 Discharge

7.0 ACCESS, PERMllTlNG AND APPROVALS

7.1 Preliminary Agreements

7.2 Easements

8.0 IMPLEMENTATION SCHEDULE

9.0 REFERENCES

Tables

1 Estimated EA-05 Air Emissions

2 IA-10 and I I Injection Well Design

Figures

1 Site Location Map and Subunit A TCE Contour

Appendices

A UnidynamicslPhoenix 100% Groundwater Extraction and Treatment System EA-05

B UnidynamicslPhoenix 100% Groundwater Extraction and Treatment System EA-05

C Proposed Northeast Extraction Well (EA-05 and EA-06) Capture Analysis Memo

D Proposed Northeast Extraction Well (EA-05 and EA-06) Capture Analysis Memo Addendum

E Aqua-Clear MSDS

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EA-05 Vendor Supplied lnforrnation

LGAC Vendor Supplied Carbon lnformation

Vendor Supplied Flow Meter lnformation

Vendor Supplied Valve lnformation

Vendor Supplied Sequestering Agent lnformation

Vendor Supplied Pressure Guage lnformation

Vendor Supplied Submersible Pump Curve lnformation

EA-06 Vendor Supplied Information

Work Plan Implementation Schedule

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Table of Contents

I .O INTRODUCTION

ARCADIS U.S., Inc. (ARCADIS) on behalf of Crane Co. has prepared this Final Work Plan lmplementation of Additional Subunit A Plume Control Measures in the Northeast Area at the Phoenix-Goodyear Airport-North Superfund Site (PGA-North) in Goodyear, Arizona (Figure 1). The plume control measures were originally proposed during the July 2006 Focused Hydro Meeting between Crane Co. and the United States Environmental Protection Agency (USEPA) to control and manage the northeast portion of the Subunit A Trichloroethylene (TCE) plume. At that time Crane Co. presented a Plume Control Matrix that addressed the expanding TCE plume in the northeast. The matrix included potential extraction well locations, groundwater pumping rates, and extracted groundwater treatment options in the northeast area of the Subunit A TCE plume. As requested by the USEPA during the October 4, 2006 Focused Hydro Meeting, this Work Plan will provide the objectives, rationale, and design criteria for two groundwater extraction wells and treatment systems to be located in the northeast area of the current Subunit A TCE and perchlorate plume. This Work Plan also incorporates comments from the USEPA and Arizona Department of Environmental Quality (ADEQ) dated January 23, 2007, March 26, 2007, discussions that were conducted during the Technical Meeting on February 7, 2007, and Focused Hydro Meetings on March 7,2007 and April 19,2007.

Crane Co. acknowledges that additional groundwater extraction may become necessary in other parts of the Subunit A plume. However, additional data needs to be collected and evaluated in these areas prior to proposing additional extraction wells in other areas. Therefore, additional pumping enhancements will be covered in separate Work Plans.

Following completion of the groundwater extraction and treatment systems, Crane Co. will submit a Work Plan completion report that will contain detailed summaries of the drilling and well installation activities, field testing results and as-built treatment system construction drawings.

2.0 BACKGROUND

The overall project objectives of this Work Plan are to control and manage the northeast area of the Subunit A TCE plume with two new treatment systems with the help of the existing treatment system at extraction Well 33A. The proposed Work Plan will also help protect the following domestic supply and irrigation wells:

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I) SunCor Well 38

SunCor Well 3B is currently pumping groundwater to satisfy the irrigation needs for Palm Valley Golf Course. The well operates sporadically throughout the year based on the water needs of the golf course. On average, this well pumps approximately 500 acre-feet per year (ac-Wyr). However, during the summer months when the water needs are greatest, the well operates at a pumping rate of 2,200 gallons per minute every two days for 24 hours at a time. Hydrophysical testing activities conducted in June 2005 suggest that during pumping, approximately 40 to 50 percent of the flow is contributed from Subunit A with the remaining flow contributed from Subunit C. The results of hydrophysical testing conducted in September 2005 indicated that when SunCor Well 38 is operational, the radius of hydraulic influence extends to Subunit A monitor well MW-18 located approximately 1,400 feet to the west (ARCADIS, 2006) Observed TCE concentrations at monitor well MW-18 consistently exceed the site-specific performance standard for TCE (5 pg/L). Accordingly, plume control measures are crucial in this area to prevent TCE capture by SunCor Well 3B. To date, TCE has not been detected above the reporting limit at SunCor Well 3B; however, detections of perchlorate, toluene, methyl ethyl ketone, chloroform, and acetone have been observed.

2) Domestic Water Supply and Irrigation Wells in the Northeast Area

Based on records provided by Algonquin Water, the City of Avondale (COA), and the City of Litchfield Park increased water demands from development in the northeast area has resulted in increased pumping from domestic water supply wells in the area (Figure 1). Litchfield Park Lake well LPW-894 is used to supply water to a residential lake that is used for recreational purposes. From 2000 through 2005 the average annual withdrawal from this well has been approximately 180 ac-Wyr. The well construction details for this well are incomplete, but according to the Arizona Department of Water Resources (ADWR) records the well casing extends to approximately 555 feet below ground surface (bgs). Additionally, groundwater conductivity measured in December 2006 during groundwater sample collection at this well strongly correlates with the conductivity measured from wells completed in the MAU, which indicates that well LPW-894 primarily draws water from the MAU. Groundwater withdrawals by Algonquin's domestic supply wells in this area (4AL, 5AL, 9AL, TW-1, TW-2, TW-4, TW-5, and TW-6) have increased by approximately 84 percent from 5,432 ac-ft in 2001 to 9,975 ac-ft in 2006.

Final Work Plan Implementation of Additional Subunit A Plume Control Measures in the Northeast Area Phoenix-Goodyear Airport- North Superfund Site, Goodyear, Arizona

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Algonquin has also proposed to operate former SunCor well 34-C at 2,000 gpm. Similarly, COA groundwater withdrawal rates from domestic supply wells in this area (COA-06,-07,-10,-11,-12,-18,-19,-16, and -16B) have increased by approximately 73 percent from 7,182 ac-ft in 2001 to 12,414 ac-ft in 2006. Overall, these changes reflect an increase in excess of 77 percent in groundwater demand from Algonquin and COA supply wells located in the northeast area over the 2001 to 2006 time period.

To address the increased pumping demand and the consequent effects on the Subunit A TCE plume, in March 2006 Crane Co. initiated installation of the groundwater investigation Priority 1 monitor wells to better define the northeastern extent of the TCE plume in Subunit A. As a part of this investigation, monitor wells EPA MW-16A, EPA MW-18A, and EPA MW-20A were installed in the northeast region of the Subunit A plume (Figure I) . Results from initial groundwater samples collected from these wells revealed TCE concentrations above the site-specific performance standards. Figure 1 presents an isoconcentration map of the current Subunit A TCE plume based on March 2007 groundwater sampling results.

3.0 DESIGN CRITERIA

Two locations have been selected as the most viable sites (Appendix A and B, Drawing 2) for the two proposed groundwater extraction wells EA-05 and EA-06. These locations were selected based on the current boundary of the Subunit A TCE plume, observed groundwater flow directions, and a groundwater capture analysis that indicated the extraction rates necessary to effectively prevent further TCE migration towards the existing water supply and irrigation wells mention in Section 2. As presented in the April 13, 2007 Technical Memorandum, which discussed the capture analysis for the proposed extraction Wells EA-05 and EA-06 (ARCADIS, 2007b), the proposed flow rates and locations were determined using the PGA-North Groundwater Flow Model (ARCADIS, 2005a) under current steady-state flow conditions (i.e., current local pumping conditions). A copy of this memo is included in Appendix C.

The design of each treatment system design is in compliance with the Record of Decision (ROD), obviating the need for an Explanation of Significant Difference (ESD), and will be discussed in Sections 5.1 and 6.1. Several additional factors were considered with respect to each extraction well and treatment system location because of the recent residential and commercial development in the nearby area, including the following:

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availability of vacant land;

feasibility of obtaining property access agreements;

proposed groundwater extraction rates and TCE concentrations;

proposed groundwater treatment technologies and associated capital and operational costs;

limitations of available discharge options (injection and Roosevelt Irrigation District [RID] canal); and,

estimated construction costs.

3.1 EA-05 Location

Proposed groundwater extraction well EA-05 (Appendix A, Drawing 2), will be located south of existing monitor well MW-18 on the Flood Control District of Maricopa County (FCDMC) parcel just north of Interstate 10 to prevent the TCE capture by SunCor Well 38. The following subsections describe the potential location options considered for this proposed extraction that were evaluated.

3.1 .I Maricopa County Flood Control District Retention Basins

The FCDMC owns a large parcel of land between 1-10 and McDowell Road that is used as retention basins for storm water runoff (Appendix A, Drawing 2). The north portion of the parcel has adequate land and access available to construct a treatment system with minimal interference. The City of Goodyear has expressed its intent to place a park with sports fields on the property and is interested in obtaining irrigation water from the new treatment system. Access discussions for this location are ongoing.

3.1.2 West Valley Medical Campus

The West Valley Medical Campus (WVMC), located on the southwest corner of McDowell Road and Palm Valley Boulevard, has open areas of land in the southeastern portion of the campus (Appendix A, Drawing 2). The land is proximal to SunCor Well 3B; however this parcel is highly developed and construction of a new parking lot in the northeast corner of the parcel is in progress. The lack of available land and difficulty of obtaining contacts for land access discussions has made this location undesirable at this time.


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3.1.3 Target Center

The Target Center, located west of the WVMC, has a small open area of land located on the east side of the building. The lack of available land, discharge location options, and difficulty of obtaining contacts for land access discussions has made this location undesirable at this time.

3.2 EA-06 Location

Proposed extraction well EA-06 (Appendix B, Drawing 2) will be located in the vicinity of Priority 1 monitor wells EPA MW-16A and EPA MW-18A to control and manage further TCE migration in Subunit A and prevent TCE capture by Algonquin Water and COA domestic water supply wells.

As part of the Year 2 groundwater investigation, Crane Co. will install Subunit C monitor well EPA MW-22C in the vicinity of EPA MW-18A to serve as a sentinel well for the Litchfield Park Lake well LPW-894.

The City of Goodyear (COG) owns a recreational complex containing baseball fields, basketball courts, a skate park, and open grass areas on Litchfield Road immediately south of the RID canal (Appendix B, Drawing 2). This parcel of property is also the location of Priority 1 monitor well EPA MW-18A. Groundwater modeling suggests that the southeast corner of this parcel is an ideal position for extraction well EA-06. The COG land access agreements are in the final stages of approval.

3.3 Groundwater Extraction Rates

Groundwater extraction rates were estimated for each proposed location based on existing radius of capture information at existing extraction Well 33A, recent pumping tests performed at Priority 1 monitor wells, and by the PGA-North Groundwater Flow Model.

To estimate the required groundwater extraction rates to inhibit further TCE migration, a recent capture zone analysis was performed using a modified version of the PGA- North Groundwater Flow Model (ARCADIS, 2005a, 2007a). The modified flow model and corresponding capture zone analysis was presented in a Technical Memorandum dated April 13,2007 (ARCADIS, 2007b). Since groundwater flow at the PGA-North site occurs in a complex three-dimensional hydrogeologic system, a site-specific numerical model (e.g., MODFLOW) is the preferred method for capture zone


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ARCADlS

evaluation rather than an analytical or semi-analytical model (e.g., WHPA) (Blandford and Huyakorn. 1993). It should be also be noted that based on the discussions in the PGA-North Modeling Technical Group meeting on March 21, 2007, it was agreed that the current groundwater model, with modifications, is the best available tool to evaluate capture zones associated with the proposed extraction wells EA-05 and EA-06. Therefore, the modified groundwater flow model for the PGA-North site (ARCADIS, 2007b) was utilized in conjunction with particle-tracking procedures to delineate steady-state capture zones for the proposed extraction wells. Groundwater flow pathslcapture zones were simulated using the particle-tracking simulation code MODPATH (Pollock, 1994) in conjunction with the MODFLOW simulation code (McDonald and Harbaugh, 1988) utilized for the updated PGA-North flow model.

The primary objective of the capture zone analysis was to provide a design basis for EA-05 and EA-06 pumping rates (in conjunction with the existing on-site extraction wells) required to capture the current northeast extent of the Subunit A TCE plume (i.e., north of Interstate-10). Results of the capture zone analysis are presented in Appendix C. Appendix C contains the Technical Memorandum dated April 13,2007 (ARCADIS, 2007b) which simulated a single injection well in the vicinity of EA-05; however, ARCADIS has also prepared a capture analysis incorporating a two injection well system in the vicinity of EA-05. The results of the two injection well system are presented in Appendix D which serves as an addendum to Appendix C.

Note that simulated water levels in the vicinity of the proposed EA-06 location (Figure 5 in Appendix C) diverge from observed water levels. Simulated results depict a more northerly flow direction, whereas observed data indicate a northeasterly flow direction in the vicinity of EA-06. Therefore, the actual capture zone for EA-06 will likely not extend as far northeast as depicted in the simulated capture figures. Once EA-06 is installed, though, ARCADIS will collect the necessary groundwater monitoring data from nearby monitor wells to verify modeling results and determine the actual extent of capture.

Despite the discrepancy noted above, the results of this capture zone analysis (Appendix C and Appendix D) indicate that the following flow rates should establish hydraulic control of the northeast portion of the Subunit A I C E plume while providing adequate protection for the local domestic and irrigation supply wells (i.e., Litchfield Park well 61 1676, SunCor Well 3B, Suncor 27A, Algonquin Water wells, and COA wells):

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Extraction Well EA-05 pumping at approximately 500 gallons per minute

(gpm); and,

Extraction Well EA-06 pumping at approximately 1,000 gpm.

Note that the capture zone analysis and corresponding extraction rates are based on the most likely available locations for the extraction well and treatment system placement. These design parameters are subject to change based upon access agreements and the selection of the final extraction well locations.

3.4 Groundwater Discharge OptionslPlans

Five separate discharge alternatives were evaluated for the treated effluent disposal from these two sites. After evaluating the advantages and disadvantages of each of the discharge options, groundwater injection was selected for the EA-05 treatment system and discharge to the Roosevelt Irrigation District (RID) Canal, with the capability for future injection if necessary, was selected for the EA-06 groundwater treatment system. Details regarding each of the five alternatives and the basis for the selected discharge options are presented below.

3.4.1 lnjection

lnjection of treated water into the Subunit A aquifer has been effectively utilized at the Main Treatment System currently in operation at the former Unidynamics property. Additionally, treated water injection also enhances plume migration control with increased groundwater gradients as a result of groundwater mounding. The use of two, 14-inch diameter injection wells will be utilized to discharge the treated water back into the Subunit A aquifer at this location. Treated water injection was not immediately selected for the EA-06 treatment system due to the time required to construct and implement injection. The capability to injected treated water in the future was incorporated into the treatment system design at EA-06. lnjection will be reviewed as a discharge option after the EA-06 treatment system in operational.

3.4.2 RID Canal Discharge

Existing discharge agreements with the RID (RID, 2006) allow for the direct discharge of treated groundwater to the canal as long as the discharge criteria are met. This discharge option has been selected for EA-06 since it is cost effective and allows for expedited construction and start-up of the EA-06 treatment system. Consistent with the existing discharge agreement, Crane Co. is responsible for providing TCE



Implementation of Additional Subunit A Plume Control Measures in the Northeast Area Phoenix-Goodyear Airport- i North Superfund Site, Goodyear, Arizona

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treatment for water discharged to the RID canal at a concentration below the maximum Goodyear, Arizona contaminant level (MCL) of 5.0 micrograms per liter (pg/L).

3.4.3 Irrigation

At the EA-05 and EA-06 treatment system locations, the City of Goodyear has expressed interest in using treated water to irrigate existing and planned fields. At the EA-06 treatment system location, the Roman Catholic Church Diocese of Phoenix, to the east of the Goodyear Community Park, has also expressed interest in future use of treated water for sports fields that will be designed and built in the near future. The design for both treatment systems includes an area for an onsite above ground water storage tank in the event that the treated water is used for these irrigation purposes. The effluent piping will also include Tees that will be blind flanged for potential future use irrigation tie-ins.

3.4.4 Sanitary Sewer Discharge

The sanitary sewer option consists of discharging effluent from the treatment system into the City of Goodyear (COG) sanitary sewer for subsequent treatment at the publicly-owned treatment works (POW). Under the POTW pre-treatment program, the effluent discharge is required to not exceed the prescribed maximum daily discharge limit and is also required to be reported monthly. ARCADIS met with COG representatives on November 8, 2006 to discuss this discharge option for the two proposed extraction wells. COG personnel stated that presently the POTW has limited available hydraulic capacity as configured and that the sewer line carrying capacity is also limited from the ongoing development in the area. In order to accept the treatment system effluent, the P O W hydraulic capacity would require expansion, along with additional upgrades, at the expense of Crane Co. Therefore, effluent discharge to the COG P O W is not a cost-effective option at this time.

A similar meeting was held on November 10, 2006 with Litchfield Park Services Co. (LPSCO) representatives to discuss the potential for treatment system discharge to the LPSCO existing treatment system and sewer lines. LPSCO also stated that due to limited capacity, this option was not possible without system expansion and upgrades at the expense of Crane Co.



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3.4.5 Storm Sewer Discharge

Storm sewers located along McDowell Road were also considered as a potential effluent discharge option. The use of these storm sewers would minimize the length of the required discharge piping runs. The storm sewers discharge to the wash west of Palm Valley Boulevard, which lead to flood basins to the south. The Flood Control District of Maricopa County (FCDMC) drainage basin located just north of Interstate-10 could potentially accept all of the treatment system effluent; however, the FCDMC expressed concern with the proposed volume of water to be sent to the basin. The FCDMC anticipated that the intake capacity of the basin is not large enough, which would create additional hazards as a result of standing water.

4.0 Technical Approach

The following sections describe the technical approach for the drilling and installation of the groundwater extraction wells EA-05 and EA-06, selecting the appropriate treatment technology, and for the treatment system design. Each extraction well will be installed to a depth of 230 feet bgs extending 10 to 30 feet into Subunit B. This will maximize the saturated thickness (i.e., transmissivity) at each proposed extraction well while providing the hydraulic control to protect SunCor Well 38, SunCor 27A, LPW-894, and the other domestic water and irrigation supply wells mentioned previously.

4.1 Extraction Wells

Once the appropriate access agreements have been made, all appropriate permits have been obtained, and all underground utilities have been located, extraction wells EA-05 and EA-06 will be drilled and installed using reverse-flood drilling techniques within Subunit A. The reverse- flood method was selected because of the large diameter of the boreholes necessary to install the extraction wells, sized to produce the required groundwater extraction rate needed to capture the Subunit A TCE plume. Crane Co. will conduct a series of geophysical logs to identify zones of high groundwater yield. The geophysical logs will include:

Spontaneous potential;

Natural gamma, resistivity (short, normal, long, guard log);

Gamma;

Formation compensated density;

Neutron;

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Acoustic; and,

Caliper.

Prior to drilling, a 20-foot surface conductor casing will be installed at each location using a bucket auger. Descriptions of borehole surface conductor casing diameters for each location are presented in Appendix A and B, Drawing 10. Drill cuttings and any drilling waste will be containerized in roll-off bins, characterized, and disposed of at an appropriate landfill.

In order to effectively quantify production from each well and to determine the appropriate well design, 17.5-inch pilot holes will first be drilled to 230 feet bgs. This depth was selected based on the approximate Subunit N B contact and to maximize the saturated thickness within each well. Grab samples within the saturated zone will be collected from the shaker table every 10 feet for grain size analysis to determine the optimal screen slot size.

Following the completion of the geophysical logging and the identification of zones that are suspected to provide high yields, temporary wells will be installed. Brief 60 minute pumping tests will be conducted within each temporary well to determine the specific capacity of each location and ensure that the required groundwater extraction rates at each location are attainable. Once the specific capacity at each location has been determined to be satisfactory, each borehole will be reamed and the extraction well will be installed. Designs for extraction wells EA-05 and EA-06 are presented in Appendix A and B, Drawing 10. If necessary, the well designs will be modified based on the results of the pilot hole testing in order to maximize productivity of the well.

The borehole for extraction well EA-05 will be reamed with a 20-inch bit to a total depth of 235 feet bgs with reverse flood drilling techniques. The well will be constructed using 14-inch low carbon steel (LCS) blank casing. The screen portion of the well will be constructed using 14-inch stainless steel wire-wrap screen (0.050-inch slots). A dissimilar metal coupler will be installed between the LCS casing and stainless steel screen for corrosion control. The proposed screen interval for this well will be from 140 to 230 feet bgs. A blank section will be placed within the screen interval at the same depth as the pump intake to prevent the motor from overheating. The pump will be placed at approximately 180 feet bgs. Casing centralizers will be placed at approximate 40-foot intervals to ensure that the well is centered within the borehole. A 1.5-inch diameter sounding tube will be placed within the gravel pack of each well such that accurate drawdown measurements can be collected during pumping. A 1.5-inch


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diameter gravel feed tube will also be installed outside the well casing so additional material can be added after well development, if necessary.

The borehole for extraction well EA-06 will be reamed with a 24-inch bit to a total depth of 235 feet bgs with reverse flood drilling techniques. The well will be constructed using 16-inch LCS blank casing. The screen portion of the well will be constructed using 16-inch stainless steel wire-wrap screen (0.050-inch slots). As with extraction well EA-05, a dissimilar metal coupler will be installed between the LCS casing and stainless steel screen for corrosion control. The screen interval for this well will range from 140 to 225 feet bgs. A blank section will be placed within the screen interval at the same depth as the pump intake to prevent the motor from overheating. The pump will be placed at approximately 180 feet bgs. Casing centralizers will be placed at approximate 40-foot intervals to ensure that the well is centered within the borehole. A 1.5-inch diameter sounding tube will be placed within the gravel pack of each well such that accurate drawdown measurements can be collected during pumping. A 1 .5-inch diameter gravel feed tube will also be installed outside the well casing so additional material can be added after well development, if necessary.

4.1 .I Well Development

Following well installation, each well will be developed using the surge, bail and pump method. This development method is performed by surging water into the well to agitate fines, bailing to remove the fines, and pumping to remove any remaining fines. Water produced from the well development activities will be collected in 6,500 gallon temporary tanks, and later transported to and treated at the former Unidynamics Phoenix, Inc. facility Main Treatment System. If necessary; Aqua-Clear will be added to the wells to ensure proper development. An MSDS for Aqua-Clear is presented in Appendix E. An eight hour aquifer test will be conducted following development to determine the specific capacity and efficiency of each extraction well.

4.2 Treatment Technology Evaluation

Numerous treatment technologies effectively remove TCE from groundwater. Several of these technologies have been proven at full-scale and have become widely accepted in the remediation and water supply industries. Others technologies are still being developed in bench-scale and laboratory-scale studies, and will require further refinement before they can be reliably utilized as full-scale treatment options.

ARCADIS selected three technologies for further evaluation including low-profile air stripping with vapor-phase activated carbon off-gas treatment, low-profile air stripping


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without off-gas treatment, and liquid-phase activated carbon adsorption. Groundwater pump and treat was selected as the preferred method to achieve hydraulic control of the Subunit A TCE plume. Air-stripping and liquid-phase activated carbon were then evaluated because of each technology's treatment and cost effectiveness. Other technologies such as advanced oxidization and reverse osmosis were not further evaluated due to the associated increased capital and operational costs. ARCADIS evaluated the feasibility of implementing these technologies based on the project objectives and design criteria as presented in Section 3.0. A brief description of each technology is presented below.

4.2.1 Low-Profile Air Stripping With Vapor Phase Granular Activated Carbon

Air stripping has successfully been used for TCE treatment as evidenced by the Main Treatment System (MTS) at PGA-North for several years. New, low-profile air strippers effectively treat TCE with systems that are smaller than the packed tower air strippers currently utilized at the MTS, which minimizes the visual impact and footprint size of treatment systems which is a strong advantage in populated areas. Impacted groundwater is pumped to the top of the air stripping unit where it flows downward through a series of horizontal perforated trays while air is forced by a blower counter- current to the water (upwards) through the perforated trays. Volatile organic compounds (VOCs) are removed from the water by the stripping air. The number of trays in a low-profile air stripper required to achieve a high VOC removal efficiency is dependent on influent water and stripping air flow rates and temperatures, the VOCs chemical properties (e.g., water solubility and vapor pressure), and the VOC concentrations.

After the stripping air removes the VOCs from the water, the VOC laden air is conveyed from the top of the air stripper to a series of vapor-phase granular activated carbon (VGAC) vessels for treatment, or is discharged un-treated to the atmosphere.

Once the groundwater is stripped of TCE, it will drain to a holding tank at the bottom of the air stripper. A booster pump will transfer the effluent of the holding tank to the effluent discharge location.

A disadvantage of air stripping is noise generated by the air stripper blower. Disturbances created by the system may not be accepted by neighboring residents and businesses. Engineering controls will be utilized to dampen the noise at an increased capital cost. Additional disadvantages are the increased capital cost associated with vapor treatment, additional operating costs associated with injecting


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sequestering agents to reduce scaling and fouling within the air stripper and increased operation, maintenance, and monitoring (OM&M) of the system.

4.2.2 Low-Profile Air Stripping With No Further Treatment

The treatment system design for this technology would be as previously discussed in Section 4.2.1 without the vapor-phase granular activated carbon treatment. Evaluation of recent groundwater analytical data collected from nearby monitoring wells indicate that a maximum influent concentration of TCE would be approximately 260 vg/L with a maximum total VOC concentration of approximately 344 pg/L. The system emission calculations were based on operating 24 hours a day with a maximum influent flow rate of 500 gpm. Based on these maximum values as a conservative estimate approximately 1.56 pounds of TCE and 2.06 pounds of Total VOCs would be emitted per day at the EA-05 location (Table 1). This quantity is under the Maricopa County Air Pollution (MCAP) Control permit conditions requirement of less than 3 pounds per day. Further treatment of the air stream could potentially be bypassed to reduce capital and routine (OM&M) costs.

4.2.3 Liquid Phase Carbon Treatment

Liquid-phase granular activated carbon (LGAC) adsorption is a proven technology that has been widely applied to remove VOCs from water in remediation and drinking water applications across the country. This technology is applied by passing the VOC- impacted water through vessels that contain activated carbon. Generally, two (or more) vessels are connected in a series configuration where the lead or primary vessel removes the VOCs, while the lag or secondary vessel is used as a 'guard' or 'polish' vessel to ensure that VOCs are reduced to safe levels from the treatment stream prior to discharge. The major advantages of utilizing a liquid-phase carbon adsorption system in a highly-populated area are that relatively no noise is generated by the system, and there are no air emissions.

Liquid-phase activated carbon vessels would be appropriately sized for both locations to effectively remove all TCE from the influent stream, and to optimize the frequency of carbon change-outs to minimize disruptions in the vicinity of the treatment system. Once the activated carbon in the primary vessel is saturated with TCE and has no additional adsorptive capacity to remove TCE, the carbon can either be reactivated or disposed. When 80-percent breakthrough is observed in the effluent of the lead vessel, a carbon change-out will be scheduled. Upon completion of the change-out the



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former lag vessel will become the new lead vessel, and the fresh carbon will become the lag vessel. Breakthrough (B) can be calculated with the following equation:

B = Concentration of VOCs at Mid-Point Sample Port x 100%

Concentration of VOCs at Influent Sample Port

4.3 Technology Selection

Sections 5.0 and 6.0 discuss the design details of the selected treatment systems. The preferred remedies were selected as the technologies best suited for the treatment of TCE in Subunit A in the vicinity of SunCor Well 3B and EPA MW-18A, in addition to domestic water supply and irrigation wells in the northeast area. The sections provide for the following:

Proven technology for TCE treatment;

Capable of meeting the design principles and requirements; and,

Meets all of the project objectives as presented in Section 2.0 and design criteria in Section 3.0.

LGAC is the selected remedial technology for the EA-05 and €4-06 treatment systems for the following additional reasons beyond the design criteria and project objectives:

1) No air emissions associated with the treatment;

2) Low levels of noise; and

3) A proven track record of performance for treatment of groundwater from Subunit A as evidenced at the well 33A Treatment System.

5.0 EA-05 DESIGN

As outlined, the selected treatment technology to remove TCE from groundwater is LGAC adsorption. This Work Plan presents the design details for the system in the following sections.


The proposed process description for the TCE treatment system is as follows:



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1. A submersible groundwater pump will be properly sized and utilized to deliver up to 500 gpm through the system and discharge into injection wells.

2. The LGAC system will be comprised of two 10,000-pound capacity vessels in series.

3. Groundwater will be pre-filtered to remove particulate matter by a bag filter unit. The filters will be sized to catch particles greater than 10-microns.

4. A sequestering agent will be pumped from a 55 gallon drum to the effluent piping from the LGAC vessels to reduce scaling in system components and injection wells; and

5. An aboveground treated water tank for future irrigation discharge option.

After TCE treatment, the groundwater will be injected back into the Subunit A aquifer and is further discussed in Section 5.9.


Given the nature of this performance based design, it is anticipated that minor changes to the design may be required prior to, and during construction and start-up. However, the major components of the proposed TCE treatment system implementation are listed below and are discussed in the following sub-sections:

LGAC System

Pre-Treatment Particulate Filtration System;

System Connections and Piping;

Sequestering Agent and Pump;

Instrumentation and Controls;

Submersible Pump;

Treated Water Irrigation Tank

Utilities; and,

Construction and System Start-Up

Engineered drawings are provided to illustrate the conceptual design. These include a process flow diagram of the system (Appendix A, Drawing 5), piping and

Final Work Plan Implementation of Additional Subunit A

I

I Plume Control Measures in the I

I

Northeast Area I I


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instrumentation diagram (P&ID) (Appendix A, Drawing 6), and construction and elevation details (Appendix A, Drawings 8 and 9). In addition, vendor supplied information for the major process units is provided in Appendix F. All of these components are standard, off of the shelf items and are readily available, that when integrated will result in a system capable of meeting the performance and design specifications required of this Work Plan.


ARCADIS has selected two liquid-phase GAC vessels connected in series to optimize LGAC utilization while providing a reliable system to continuously reduce TCE concentrations below the MCL of 5 vg/L.

LGAC Vessels: Siemens PV10000 System (two vessels and inter-connecting piping manifold assembly).

These vessels were chosen because they provide sufficient hydraulic loading for the design flow rate of 500 gpm and they provide sufficient volume of LGAC to maximize time between change-outs and minimize treatment costs. Additional information on the carbon vessels is provided in Appendix F.

LGAC Operation: LeadILag series configuration

ARCADIS proposes to operate the two LGAC vessels in a leadllag series configuration, which will allow for efficient LGAC utilization and maintain the required effluent water quality. The vessels will be equipped with a valve manifold that will allow simple change-outs of the spent carbon and reconfiguration of the lead and lag vessel order.

LGAC: Westates Carbon Reactivated Coconut - ACNSC

The LGAC selected for this project is Westates carbon reactivated coconut carbon - ACNSC, or equivalent. Westates carbon virgin coconut - AC1230C was also evaluated for use in the treatment system. Reactivated coconut carbon was selected over the virgin coconut because of the low TCE concentrations and the O&M cost savings over virgin coconut carbon. Information on the selected carbon is provided in Appendix G.




5.2.2 Pre-treatment System

Based on the historical concentration of total suspended solids (TSS) in the influent groundwater, a pre-filtration system will be installed to prevent the LGAC vessels from plugging, reducing the need for backwashing. ARCADIS has selected a Hayward filter vessel for the system. A description of the filters is provided below:

Filter Unit: Hayward MaxilineTM Filter Vessel

Hayward bag filters have proven reliability and are well-suited for this application. Siemens recommends filtration to 10 microns for carbon applications. A filter unit will be installed upstream of the LGAC vessels. The bag filters will have to be replaced when the differential pressure across the filter increases to the maximum design pressure specified by the filter manufacturer. When this occurs the system will be shutdown briefly until the change-out is complete. Additional information on the filter units is provided in Appendix F.


To install the proposed LGAC treatment system, the following items will be required:

Svstem Influent and Effluent Connections: 6-inch diameter, Schedule 80 PVC tees, valves, and pipe will be installed as shown in Appendix A, Drawing 5. In addition, a 6- inch McCrometer flow meter will be installed prior to the bag filter unit. The flow meter will have analog outputs that will send flow rate information to the programmable logic controller for offsite monitoring. Information about the flow meter can be viewed in Appendix H.

All valves indicated in Appendix A, Drawings 5 and 6 will be Hayward valves. Appendix I provides information for butterfly, check, and ball valves shown in the drawings. The valves will be consistent with the size of piping indicated in the drawings.

The 6-inch butterfly valve prior to the injection well shown in Appendix A, Drawing 7 will serve as an isolation valve for any maintenance required at the injection well head. The valve will be equipped with a 2-inch square operating nut to allow control by means of a valve key through the surface completion and access pipe. The valve special feature is depicted in Appendix I.

Final Work Plan Implementation of I

Additional Subunit A I

Plume Control I

Measures in the I

Northeast Area Phoenix-Goodyear Airport- North Superfund Site, Goodyear, Arizona

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Final Work Plan

5.2.4 Sequestering Agent Tank and Pump

Based on analytical results of groundwater from nearby wells, a subcontractor recommended adding the AN-100NP sequestering agent to the effluent stream. Appendix J contains a brief description of the AN-100NP sequestering agent and a design figure showing proper metering of the agent to the stream. A chemical metering pump will be used to inject a low flow rate of the sequestering agent into the effluent piping after the carbon vessels. A six-inch motionless static mixer will be installed downstream of the sequestering agent injection point to effectively mix the two streams. A detailed schematic of the static mixer is provided in Appendix J.


The instrumentation and controls for the proposed TCE treatment system will be integrated into a process controller to enable the treatment system to be controlled by a common system. A programmable logic controller (PLC) will be installed with inputs and outputs to accommodate communication with the treatment system. The inputs that are monitored by the PLC are the decision logic process parameters (i.e. flow rates, water levels, and pressures) that are used by the PLC to determine and control the operation of the entire system. The outputs will be used to control specific process parameters (e.g., flow rate by controlling the Variable Frequency Drive WFD] connected to the groundwater extraction pump).

The Main Control Panel (MCP), which will house all of the process control components as well as the motor control equipment, will be equipped with a Supervisory Control and Data Acquisition (SCADA) system, which will provide the operator with graphic representation of process operation. The SCADA will also log critical system parameters to keep a record of system performance. The SCADA system will be accessible via a broadband internet connection, which will be installed at the site.

The following instrumentation and controls will be utilized by the treatment system:

An analog flow meter located at the front of the treatment train that will transmit flow rate and flow total to the PLC;

The sump will be equipped with a high-high level switch that will shut the entire system down should a high-high level be detected in the sump; and,

Rosemount pressure gauges and transmitters will be installed to monitor system pressures throughout the process - including differential pressure



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across the pre-filters and differential pressure across the LGAC vessels. A description of these gauges is provided in Appendix K. Pressure gauges will also be located at the influent, mid-point, and effluent of the pre-filter and LGAC system.

Signals from the flow and differential pressure transmitters and operational status switches for pumps, and other equipment will also be used to determine the system alarm status.

Emergency shutdown controls are illustrated in Appendix A, Drawing 6. System shutdown will occur if under the following circumstances:

If the groundwater extraction pump does not provides at least 95 gpm, the Flow Alarm Low connected to the flow meter will shut the system down to prevent damage to the pump motor.

If a pressure increase of greater than 15 pounds per square inch (psi) occurs at the bag filter influent, the Pressure Differential Alarm High will shut the system down. This pressure was determined based on observed bag filter failure at high pressures.

If a pressure greater than 75 psi occurs at any of the pressure indicators before, in-between, or after the carbon vessels, the Pressure Differential Alarm High will shut the system down. This maximum pressure is specified in the LGAC vendor supplied information located in Appendix F.

If heavy rainfall or system component leak occurs to an extent that the sump pump can not empty the sump over a two-minute period, the Level Alarm High will shut down the system. After the shutdown, field staff will verify the cause of the alarm (rainfall or component failure) and conduct the appropriate mitigation measures, as necessary.

Due to the nature of this perforrnance-based design, it is possible that some modifications to the proposed controls and instrumentation will be made during start-up and initial operation of the treatment systems. The final process control system arrangement and operating procedures will be detailed in the EA-05lEA-06 Groundwater Treatment System O&M Plan that will be completed in July 2007 prior to the EA-06 treatment system startup.

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Final Work Plan I


Plume Control Measures in the Northeast Area

I

I



A 50 horsepower submersible pump will be installed at 180 feet bgs and connected to a 6-inch vertical discharge pipe. The pump is sized to force the extracted groundwater through the entire treatment system to the final discharge location discussed in Section 5.9. A vendor supplied pump curve information for the Grundfos 4758500-5 is provided in Appendix L.


An aboveground irrigation tank will be sized and designed in the future based upon irrigation needs required by the property. A 2-inch motorized ball valve will be teed-off from the effluent line to supply treated water to the tank.

5.2.8 Utilities

Arizona Public Service (APS) was contacted to locate the nearest power tie-in for transformer location at the system. The tie-in location is shown in Appendix A, Drawing 2. A phone line and internet connection will also be installed at the site and connected to the PLC so system status, flows, and pressures can be remotely monitored.


The treatment system will be constructed on a 12-inch reinforced concrete pad designed to bear the structural load of the system. The perimeter of the pad will have 8-inch concrete berms designed to contain rain water or spilled or released extracted water. A sump will be installed to collect rainwaterlspills and the concrete pad will be sloped to facilitate collection of the water. A sump pump will be installed in the sump, and will be automatically controlled with a float mechanism. Any water collected in the sump will be pumped back into the system influent for treatment.

The system will be surrounded by a permanent structure built with 8-inch decorative masonry block. Appropriate aesthetic parameters will be stipulated in the land agreement between Crane Co. and the property owners. Access gates will be appropriately placed for carbon change-outs and general access for normal OM&M activities. The layout and details of the treatment structure is provided in Appendix A, Drawings 8 and 9.



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To ensure proper operation of the LGAC system, the following monitoring will be performed:

Weekly field collection of the system flow rates and pressures; and,

The pressure and flow transmitters will continuously monitor the process and transmit the data to the PLC. These values will be monitored manually daily and recorded periodically to ensure proper system performance. In addition, pre-set alarm condition set points will be programmed into the PLC to automatically shut-down the system and notify appropriate ARCADIS personnel in the event of an alarm condition.

The performance of the treatment system will also be assessed by the results of treatment system sampling. During system operation, treatment system samples will be collected at the influent to the LGAC system, the lead vessel effluent (mid-point), and from the lag vessel effluent for TCE and other VOC analyses.

Siemens predicted a carbon life-cycle of approximately one year. Therefore, monthly sampling of the system will be sufficient to ensurelconfirm proper system operation. However, in order to provide an additional factor of safety and to assess actual system performance versus predicted performance, an expanded monitoring program will be utilized during the first month of operation. This will include the following:

During the first week of operation, influent, mid-point, and effluent samples will be collected on three occasions (ie., every other day);

Following the first week, weekly samples will be collected for the remainder of the month (three weeks); and,

In addition, the samples collected during the first month of operation will be analyzed on an expedited turn-around basis (24 to 48 hours) so the data is available for immediate review and analysis.

All samples collected will be analyzed for TCE in accordance with the USEPA Method SW8260 as outlined in the O&M Plan for the groundwater treatment system and reported in the Groundwater Monthly and Remedial Systems Performance Report with an estimated total TCE mass removed from all treatment systems provided in the Phoenix-Goodvear Airport-North Superfund Site Weekly Update Report (ARCADIS, 2005b).



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I Final Work Plan

5.4 EA-05 Operation and Maintenance (O&M)

The O&M activities required to operate the proposed LGAC system will be similar to the existing O&M activities, according to the procedures outlined in the O&M Plan for the groundwater treatment system (ARCADIS, 2005b), performed at the MTS and Well 33A groundwater pump and treat systems. Operation will be monitored daily by the PLC and weekly by a thorough O&M review of the system. A new O&M manual will be provided for the new treatment systems prior to startup in July 2007.


The O&M activities required for the LGAC treatment system is anticipated to include the following:

Particulate Filters:

Monitor and record the pressure drop across the filter unit. This will be part of the weekly O&M duties. The pressure drop will be continuously monitored by pressure gauges and transmitters located pre- and post-filter; and,

Replace filters. The schedule for this will be determined from the weekly pressure drop measurements, and will be performed on an as needed basis.

LGAC Vessels:

Monitor and record the total volume of groundwater pumped through the vessels on a weekly basis;

Monitor and record the pressure at the system influent, mid-point, and effluent on a weekly basis;

Inspect for leaks regularly;

Estimate carbon life remaining in each vessel after each sampling event using vendor supplied correlations, accounting for total volume treated, VOC concentrations, and other process parameters; and,

Change out the LGAC as required.

5.6 LGAC Change Out

Once the absorptive capacity of the LGAC is exhausted and a change out is required, the vessels will be drained of excess water and the spent carbon will be either vacuum

Implementation of Additional Subunit A Plume Control I ~ Measures in the Northeast Area Phoenix-Goodyear Airport- North Superfund Site, Goodyear, Arizona


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transferred or water slurried from the LGAC vessels. Once removed from the vessel, the LGAC will be contained by the vendor for off-site disposal or regeneration after characterizing the spent LGAC. Prior to loading the replacement LGAC, the vessels will be partially filled with water to provide a "cushion" for the replacement LGAC.

5.7 Backwash

Following a carbon change out the fresh carbon will require backwashing to remove the carbon fines and allow for proper expansion of the carbon within the vessel. Backwashes will be performed using the submersible pump installed in the extraction well to deliver the appropriate flow rate required for backwashing. The influent water will enter through the top of the lead vessel for treatment and exit through the bottom of the vessel. The water will then enter the bottom of the lag vessel and exit the top of the lag vessel thus removing the carbon fines in the vessel and head for the effluent.

Appendix A, Drawings 5 and 6 provide the effluent design configuration for backwashing. During the backwash, the effluent valve (V-92) will be closed and all water will be routed to either a frac tank or a contractor semi for filtration. When the systems are brought online for initial startup, both vessels will receive new carbon and require backwashing. For this event, 20,000 gallon frac tanks will be rented and backwash water will be sent to the tanks and allowed to settle out. After the tanks are thoroughly backwashed and carbon fines have settled in the frac tanks, the water will be pumped to the final discharge location. The remaining carbon in the tanks will be removed and disposed of accordingly.

Future carbon change outs will be conducted differently. When only one of the vessels is changed out, two trucks will arrive onsite to conduct the change out. One truck will be loaded with the spent carbon and the other will bring the new carbon for application. After all of the new carbon is transferred to the vessel the truck with the spent carbon will be connected to the backwashing valving. Once again the effluent valve (V-92) between both backwash connections will be closed so no fines are sent to the final discharge location. Backwashing will be sent through the vessels as stated previously, but when the effluent leaves the vessels with the fines, it will leave the effluent line through the backwashing bypass and enter the top of the truck trailer containing the spent fines. The fines will collect on top of the spent carbon and the water will be filtered out through the bottom of the truck. The filtered water will then go back to the system effluent line by means of the backwash bypass and go to the final discharge location. Both bypass valving configurations will have a section of clear Schedule 80 PVC so visual inspection of the backwashing can be conducted. When the backwash

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stream clears up (determined by visual inspection), backwashing activities will conclude.

5.8 Waste Disposal

Spent filters will be transferred to a designated location within the treatment system enclosure. The bag filters will be allowed to dry and will then be stored in 55-gallon DOT drums. Waste profile samples will be collected once the 55-gallons drums are full to characterize the waste for proper disposal. It is expected that the bag filters will qualify as non-hazardous waste, however, and can be disposed as general refuse. Spent LGAC will also be characterized before transported off-site for reactivation or disposal by appropriate methods. It is anticipated that the spent LGAC will also be classified as a non-hazardous waste.

5.9 EA-05 Discharge

The treated effluent water will be injected back into Subunit A through two injection wells located east of the treatment facility. All drilling will be conducted by an ADWR licensed driller using air rotary-casing hammer (ARCH) or equivalent drilling methodology. The proposed injection wells will be drilled to a total depth of 102 feet bgs and screened within a gravel dominant zone that ranges from approximately 55 to 110 feet bgs. To accommodate any additional future increased treatment capacity, the well will be constructed using 14-inch PVC well casing from 0 to 50 feet bgs and stainless steel wire-wrap screen (0.050 slot size) from 50 to 100 feet bgs, contingent upon in-situ soil sample results. The size and number of injection wells is based on the screened interval and slot size required to deliver 250 gpm per well to the subsurface. Calculations concluded that a 14-inch well is required to deliver the effluent water at a rate that will not disrupt the existing formation. To define the coarse grained deposits, in-situ soil samples will be collected every 5 feet from 50 feet to 100 feet bgs. Selected samples from the coarse grained zones will be collected every 10 feet and submitted for geotechnical analysis (grain size analysis and permeability testing). Due to the wells proximity to each other, only one well will be sampled in this manner. All drill cuttings and in-situ samples will be logged in accordance with ASTM D2488. Although a summary of the proposed injection well construction specifications are presented in Appendix A, Drawings 7 and 11, the actual screened interval and slot size of the well will be based on field collected soil samples and expedited sieve analysis results obtained during drilling. All drill cuttings generated during the drilling will be containerized in roll-off bins for characterization and disposal.



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The injection well will be completed below grade in a precast concrete traffic rated vault as shown in Appendix A, Drawing 7. A McCrometer flow meterltotalizer will be installed at each well head to allow flow rate monitoring to each well.


6.0 EA-06 DESIGN

The selected treatment technology to remove TCE at the EA-06 treatment system is LGAC adsorption. This Work Plan presents the design details for the system in the following sections.


The following is the proposed process description for the TCE treatment system:

1. A submersible groundwater pump will be properly sized and utilized to deliver up to 1,000 gpm through the system and discharged into the RID canal;

2. The groundwater pump will pump raw water through two, 20,000-pound LGAC vessels configured in series;

3. Groundwater will be pre-filtered by a bag filter to remove particulates. The filters will be sized to remove particles greater than 10-microns; and

4. An irrigation tank for watering the fields in the Goodyear Community Park.

Treated groundwater will be discharged into the RID canal where it will be used as irrigation supply water.


Given the nature of this performance based design, it is anticipated that minor changes to the design may be required prior to, and during construction and start-up. However, the major components of the proposed TCE treatment system implementation are listed below and are discussed in the following sub-sections:

LGAC System

Pre-Treatment Particulate Filtration System;

System Connections and Piping; 1

I

I I

25


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Instrumentation and Controls;

Submersible Pump;

Irrigation Tank

Utilities; and,

Construction and System Start-Up

Engineered drawings are provided to illustrate the conceptual design. These include a process flow diagram of the system (Appendix B, Drawing 5), piping and instrumentation diagram (P&ID) (Appendix B, Drawing 6), and construction and elevation details (Appendix B, Drawings 8 and 9). In addition, vendor supplied information for the major process units is provided in Appendix M. All of these components are standard, off of the shelf items and are readily available, that when integrated will result in a system that will be capable of meeting the performance and design specifications required of this Work Plan.


ARCADIS has selected two liquid-phase GAC vessels connected in series to optimize LGAC utilization, while providing a reliable system to continuously reduce TCE concentrations below the MCL of 5 pg1L.

LGAC Vessels: Siemens HP 1220 System (two vessels and inter-connecting piping manifold assembly).

These vessels were selected because they provide sufficient hydraulic loading for the design flow rate of 1,000 gpm and they provide sufficient volume of LGAC to maximize time between change outs and minimize treatment costs. Additional information on the LGAC vessels is provided in Appendix M.

LGAC Operation: LeadILag series configuration

ARCADIS proposes to operate the two LGAC vessels in a leadllag series configuration, which will allow for efficient LGAC utilization, and maintain the required effluent water quality. The vessels will be equipped with a valve manifold that will allow simple change-outs of the spent carbon and reconfiguration of the lead and lag vessel order.


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LGAC: Westates Carbon Reactivated Coconut - ACNSC

The carbon selected for this project is Westates Carbon reactivated coconut - ACNSC, or equivalent. Westates carbon virgin coconut - AC1230C was also evaluated for use in the treatment system. Reactivated coconut carbon was selected over the virgin coconut because of the low TCE concentrations and the O&M cost savings over virgin coconut carbon. Information on the carbon is provided in Appendix G.

6.2.2 Pre-treatment System

Based on the historical concentration of TSS in the influent groundwater, a pre-filtration system will be installed to prevent the LGAC vessels from plugging, reducing the need for backwashing. ARCADIS has selected a Hayward filter vessel for the system. A description of the filters is provided below:

Filter Unit: Hayward MaxilineTM Filter Vessel

Hayward bag filters have proven reliability and are well-suited for this application. Siemens recommends filtration to 10 microns for carbon applications. A filter unit will be installed upstream of the LGAC vessels. The bag filters still have to be replaced when the differential pressure across the filter increases to the maximum design pressure specified by the filter manufacturer. Additional information on the filter units is provided in Appendix M.


To install the proposed TCE LGAC treatment system, the following items will be required:

Svstem Influent and Effluent Connections: 8-inch diameter, Schedule 80 PVC tees, valves, and pipe will be installed as shown in Appendix B, Drawing 5. In addition, an 8- inch McCrometer flow meter will be installed prior to the bag filter unit. The flow meter will have analog outputs that will send flow rate information to the PLC for offsite monitoring.

All valves indicated in Appendix B, Drawings 5 and 6 will be Hayward valves. Appendix I provides information for butterfly, check, and ball valves shown in the drawings. The valves will be consistent with the size piping indicated in the drawings.

Final Work Plan Implementation of

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5

Northeast Area j


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The 8-inch butterfly valves shown in Appendix B, Drawing 7 will serve as isolation valves if maintenance is required in section of the piping. The valve will be equipped with a 2-inch square operating nut to allow control by means of a valve key through the surface completion and access pipe. The valve special feature is depicted in Appendix I.


The instrumentation and controls for the proposed TCE treatment system will be integrated into a process control system to enable the treatment system to be controlled by a common system. A PLC will be installed with inputs and outputs to accommodate communication with the treatment system. The inputs that are monitored by the PLC are the decision logic process parameters (i.e., flow rates, water levels, and pressures) that are used by the PLC to determine the operation of the entire system. The outputs will be used to control process parameters (e.g., flow rate by controlling the VFD connected to the groundwater extraction pump).

The Main Control Panel (MCP), which will house all of the process control components as well as the motor control equipment, will be equipped with a Supervisory Control and Data Acquisition (SCADA) system, which will provide the operator with graphic representation of process operation. The SCADA will also log critical system parameters to keep a record of system performance. The SCADA system will be accessible via a broadband internet connection, which will be installed at the site.

The following instrumentation and controls will be utilized by the treatment system:

An analog flow meter located at the front of the treatment train that will transmit flow rate and flow totals to the PLC;

The sump will be equipped with a high-high level switch that will shut the entire system down should a high-high level be detected in the sump; and,

Rosemount pressure gauges and transmitters will be installed to monitor system pressures throughout the process - including differential pressure across the pre-filters and differential pressure across the LGAC vessels. A description of these gauges is provided in Appendix K. Pressure gauges will also be located at the influent, mid-point, and effluent of the pre-filter and LGAC system.


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Signals from the flow and differential pressure transmitters and operational status switches for pumps, and other equipment will also be used to determine the system alarm status.

Emergency shutdown controls are illustrated in Appendix B, Drawing 6 and system shutdown will occur if under the following circumstances:

If the groundwater extraction pump does not provides at least 95 gpm, the Flow Alarm Low connected to the flow meter will shut the system down to prevent damage to the pump motor.

If a pressure increase of greater than 15 psi occurs at the bag filter influent the Pressure Differential Alarm High will shut the system down. This pressure was determined based on observed bag filter failure at high pressures.

If a pressure greater than 75 psi occurs at any of the pressure indicators before, in-between, or after the carbon vessels, the Pressure Differential Alarm High will shut the system down. This maximum pressure is specified in the LGAC Vendor Supplied Information located in Appendix M.

If heavy rainfall or system component leak occur to an extent that the sump pump can not empty the sump over a two-minute period, the Level Alarm High will shut down the system. After the shutdown, field staff will verify the cause of the alarm (rainfall or component failure) and conduct the appropriate mitigation measures, if necessary.

Due to the nature of this performance-based design, it is possible that some modifications to the proposed controls and instrumentation design will be made during start-up and initial operation. The final control system arrangement and operating procedures will be detailed in the EA-05lEA-06 Groundwater Treatment System O&M Plan that will be completed in July 2007 prior to the EA-06 system startup.


A 125 horsepower submersible pump will be installed at 175 feet bgs and connected to a 6-inch vertical discharge pipe. The pump is sized to force the water through the entire system to the final discharge location discussed in Section 6.9. A vendor supplied pump curve information for the Grundfos 1 100S1250-3A is provided in Appendix L.

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An irrigation tank will be sized and designed once irrigation needs required by the Goodyear Community Park are determined. A 2-inch motorized ball valve will be teed- off from the effluent line to supply treated water to the tank.

6.2.7 Utilities

APS was contacted to locate the nearest power tie-in for transformer location at the system. The tie-in location is shown in Appendix B, Drawing 2. A phone line and internet connection will also be installed at the site and connected to the PLC so system status, flows, and pressures can be monitored offsite.


The treatment system will be surrounded by a 12-inch reinforced concrete pad designed to bear the structural load of the system. The perimeter of the pad will have 8-inch concrete berms that will be designed to contain rain water or spilled or released extracted water. A sump will be installed to collect rainwaterlspills and the concrete pad will be sloped to facilitate collection of the water. A sump pump will be installed in the sump, and will be automatically controlled with a float mechanism. Any water collected in the sump will be pumped back into the system influent for treatment.

The system will be enclosed within a permanent structure built with 8-inch decorative masonry block. Appropriate aesthetic parameters will be stipulated in the land agreement between Crane Co. and the property owners. Access gates will be appropriately placed for carbon change-outs and general access for normal OM&M activities. The layout of the treatment structure is provided in Appendix B, Drawings 8 and 9.


To ensure proper operation of the LGAC system, the following monitoring will be performed:

Weekly field collection of the system flow rates and pressures; and,

The pressure and flow transmitters will continuously monitor the process and transmit the data to the PLC. These values will be monitored manually daily and recorded periodically to ensure proper system performance. In addition,



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pre-set alarm condition set points will be programmed into the PLC to automatically shutdown the system and notify appropriate ARCADIS personnel in the event of an alarm condition.

The performance of the treatment system will also be assessed by the results of treatment system sampling. During system operation, treatment system samples will be collected at the influent to the LGAC system, the lead vessel effluent (mid-point), and from the lag vessel effluent for TCE and other VOC analyses.

Given the large volume of LGAC in each vessel and the low concentration of TCE in the influent water, Siemens predicted a carbon lifecycle in excess of two years. Therefore, monthly sampling of the system will be sufficient to ensurelconfirm proper system operation. However, in order to provide an additional factor of safety and to assess actual system performance versus predicted performance, an expanded monitoring program will be utilized during the first month of operation. This will include the following:

During the first week of operation, influent, mid-point, and effluent samples will be collected on three occasions (i.e., every other day);

Following the first week, weekly samples will be collected for the remainder of the month (three weeks); and,

In addition, the samples collected during the first month of operation will be analyzed on an expedited turn around basis (24 to 48 hours) so the data is available for immediate review and analysis.

All samples collected will be analyzed for TCE in accordance with the USEPA method SW8260as outlined in the O&M Plan for the groundwater treatment system and reported in the Groundwater Monthly and Remedial Systems Performance Report with an estimated total TCE mass removed form all treatment systems provided in the Phoenix-Goodyear Airport-North-Su~erfund Site Weekly Update Report (ARCADIS, 2005b).

6.4 EA-06 Operation and Maintenance

The O&M activities required to operate the proposed LGAC system will be similar to the existing O&M activities, according to the procedures outlined in the O&M Plan for the groundwater treatment system (ARCADIS, 2005b), performed at the MTS and Well 33A groundwater pump and treat systems.. Operation will be monitored daily by the

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PLC and weekly by a thorough O&M review of the system. A new O&M manual will be provided for the new treatment systems prior to startup of the system in July 2007.


The O&M activities required for the LGAC treatment system is anticipated to include the following:

Particulate Filters:

Monitor and record the pressure drop across the filter unit. This will be part of the weekly O&M duties. The pressure drop will be continuously monitored by pressure gauges and transmitters located pre- and post-filter; and,

Replace filters. The schedule for this will be determined from the weekly pressure drop measurements, and will be performed on an as needed basis.

LGAC Vessels:

Monitor and record the total volume of groundwater pumped through the vessels on a weekly basis;

Monitor and record the pressure at the system influent, mid-point, and effluent on a weekly basis;

Inspect for leaks regularly;

Estimate carbon life remaining in each vessel after each sampling event using vendor supplied correlations, accounting for total volume treated, VOC concentrations, and other process parameters; and,

Change-out the LGAC as required.

6.6 LGAC Change Out

Once the absorptive capacity of the LGAC is exhausted and a change out is required, the vessels will be drained of excess water and the spent carbon will be either vacuum transferred or water slurried from the LGAC vessels. Once removed from the vessel, the LGAC will be contained by the vendor for off-site disposal or regeneration after characterizing the spent LGAC. Prior to loading the replacement LGAC, the vessels will be partially filled with water to provide a "cushion" for the replacement LGAC.


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6.7 Backwash

Following a carbon change out the fresh carbon will require backwashing to remove the carbon fines and allow for proper expansion of the carbon within the vessel. Backwashes will be performed using the submersible pump installed in the extraction well to deliver the appropriate flow rate required for backwashing. The influent water will enter through the top of the lead vessel for treatment and exit through the bottom of the vessel. The water will then enter the bottom of the lag vessel and exit the top of the lag vessel thus removing the carbon fines in the vessel and head for the effluent.

Appendix B, Drawings 5 and 6 provide the effluent design configuration for backwashing. During the backwash, the effluent valve (V-92) will be closed and all water will be routed to either a frac tank or a contractor semi for filtration. When the systems are brought online for initial startup, both vessels will receive new carbon and require backwashing. For this event, 20,000 gallon frac tanks will be rented and backwash water will be sent to the tanks and allowed to settle out. After the tanks are thoroughly backwashed and carbon fines have settled in the frac tanks, the water will be pumped to the final discharge location. The remaining carbon in the tanks will be removed and disposed of accordingly.

Future carbon change outs will be conducted differently. When only one of the vessels is changed out, two trucks will arrive onsite to conduct the change out. One truck will be loaded with the spent carbon and the other will bring the new carbon for application. After all of the new carbon is transferred to the vessel the truck with the spent carbon will be connected to the backwashing valving. Once again the effluent valve (V-92) between both backwash connections will be closed so no fines are sent to the final discharge location. Backwashing will be sent through the vessels as stated previously, but when the effluent leaves the vessels with the fines, it will leave the effluent line through the backwashing bypass and enter the top of the truck trailer containing the spent fines. The fines will collect on top of the spent carbon and the water will be filtered out through the bottom of the truck. The filtered water will then go back to the system effluent line by means of the backwash bypass and go to the final discharge location. Both bypass valving configurations will have a section of clear schedule 80 PVC so visual inspection of the backwashing can be conducted. When the backwash stream clears up (determined by visual inspection), backwashing activities will conclude.


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6.8 Waste Disposal

Spent bag filters will be transferred to a designated location within the treatment system enclosure. The bag filters will be allowed to dry and will then be stored in 55- gallon DOT drums. Waste profile samples will be collected once the 55-gallon drums are full to characterize the waste for proper disposal. It is expected that the bag filters will qualify as non-hazardous waste, however, and can be disposed as general refuse. Spent LGAC will also be characterized before transported off-site for reactivation or disposal by appropriate methods. It is anticipated that the spent LGAC will also be classified as a non-hazardous waste.

6.9 EA-06 Discharge

Treated water from the EA-06 location will be discharged to the RID canal as discussed in Section 3.4.2. The submersible groundwater extraction pump at the EA- 06 location will be sized large enough to directly discharge treated water to the canal, considering the pressure drop associated with the treatment system components.

7.0 ACCESS, PERMITTING AND APPROVALS

7.1 Preliminary Agreements

Once the final locations are determined the following permit, notifications or approvals will be sought:

Access agreements with the City of Goodyear (EA-06);

Access agreement with the Maricopa County Flood Control District (EA-05);

Arizona Department of Water Resources Notice of Intent to Drill permits will be acquired for the groundwater extraction and injection wells; and

Roosevelt Irrigation District (RID) agreement to discharge treated effluent water to the canal;

7.2 Easements

Once access agreements are reached and discharge permits are obtained, easements must be signed. The standard easement agreement will include the site details and any stipulations of the agreement. A drawing will be created including labeled locations and distances to serve as a reference figure for the easement. The easements will

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ensure that the legal right to maintain the system is preserved even if the property ownership changes.

8.0 IMPLEMENTATION SCHEDULE

Once Crane Co. is granted approval by the USEPA to implement this Work Plan, and access agreements for each of the well sites is negotiated, ARCADIS will schedule the drilling of the extraction wells followed by the construction and installation of the recovery and treatment systems. It is anticipated that the EA-05 and EA-06 extractionltreatment systems will be installed and operating by the 3'C' Quarter of 2007.

The following is a general summary of the major elements and time frames for implementing this Work Plan;

USEPA Approval

Completion of land access agreements

Well permitting - 2 weeks following USEPA approval and granted land access,

Local building permits - 4 to 6 weeks following USEPA approval and granted land access (estimated - actual duration may vary and impact schedule)

Well installation, development, and yield tests - 4 to 6 weeks following permit approval and granted land access,

Procure equipment - 6 to 8 weeks following USEPA approval and granted land access,

Excavation of treatment site and placement of foundations - 4 weeks following permit approval and granted land access,

Assembly of equipment, piping and instrumentation - 2 to 3 weeks following placement of treatment foundation,

Obtain power drop from APS - 6 to 8 weeks following permitting approval and granted land access (actual duration may vary and impact schedule)

Start-up and shake-down - 2 weeks following completion of treatment system assembly.

A proposed implementation schedule associated with this Work Plan is provided in Appendix N.


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9.0 REFERENCES

Arizona Department of Environmental Quality (ADEQ), 1996. Arizona Administrative Code, Title 18. Environmental Quality, Chapter 11. Department of Environmental Quality Water Quality Standards, September 30, 1996.

ARCADIS. 2005a. Revised Draft Development of a Groundwater Flow Model, Phoenix- Goodyear Airport - North Superfund Site, Goodyear, Arizona. August 22,2005.

ARCADIS, 2005b, Groundwater Treatment Systems Operation and Maintenance Work Plan, Phoenix-Goodyear Airport-North Superfund Site, December 2, 2005.

ARCADIS. 2005c. Draft Final - Remedial Design Work Plan, Perchlorate Treatment Unit, Phoenix-Goodyear Airport - North Superfund Site, Goodyear, Arizona. March 31, 2005.

ARCADIS. 2006. Final - Hydrophysical investigation Summary Letter Report Suncor Well #3B, Phoenix-Goodyear Airport - North Superfund Site, Goodyear, Arizona. August 3, 2006.

ARCADIS, 2007a, Updated Development of a Groundwater Flow Model, Phoenix- Goodyear Airport - North Superfund Site, Goodyear, Arizona. January 2007.

ARCADIS 2007b, Technical Memorandum - Proposed Northeast Extraction Well (EA- 05 and EA-06) Capture Analysis, Phoenix-Goodyear Airport - North Superfund Site, Goodyear, Arizona. April 13, 2007

Blandford, T.N. and Huyakom, P.S. (1993), Well Head Protection Area (WHPA) Delineation Code, IGWMC Version 2.1 1 (FOS 41) Modeling Software

Driscoll, F.G., 1986. Groundwater and Wells. 2nd ed. Johnson Screens, St. Paul, 1089

PP.

McDonald, M.G. and Harbaugh, A.W. (1988). A modular three-dimensional finite- difference ground-water flow model. Technical Report, U.S. Geol. Survey, Reston, VA. www.usns.nov/nrp/~wsoftware/modflow.html




Pollock, D. W. (1994), "User's guide for Modpath Modpath-Plot, version 3: A particle tracking post-processing package for MODFLOW, U.S. Geological Survey Open-File Report 94-464 www.usns.nov/mr~/nwsoftware/mod~ath.htmI

Roosevelt Irrigation District (RID), 2006, Water Acceptance and Indemnity Agreement, May 2,2006.

USEPA. 1990. Amended Administrative Order for Remedial Design and Remedial Action for Phoenix-Goodyear Airport Superfund Site, Docket No. 90-20. October 1990.


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Final Work Plan i Implementation of Additional Subunit A I

I Plume Control Measures in the I

Northeast Area 1 Phoenix-Goodyear Airport- i North Superfund Site, 1 Goodyear, Arizona ;

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