Attachment 1- Basis of Design-PHASE III GWTP_BODR_Feb 26 IFB To Navy_REDACTED.pdf

Naval Facilities Engineering Systems Command Mid-Atlantic Norfolk, Virginia

Basis of Design Report Phase III – Groundwater Treatment System

Site 00001 – Former Drum Marshalling Area, OU2 Groundwater

Naval Weapons Industrial Reserve Plant Bethpage, New York

Issued for Bid - February 2026

Distribution Statement A. Approved for public release: distribution is unlimited.

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Phase III Basis of Design Report NWIRP Bethpage, New York CTO Number WE24 Table of Contents i

Table of Contents Introduction ................................................................................................................. 1-1

1.1 Background............................................................................................................... 1-1

1.2 Objective ................................................................................................................... 1-2

1.3 Report Organization .................................................................................................. 1-2

Design Basis ............................................................................................................... 2-1

2.1 Plume Characterization ............................................................................................. 2-1

2.2 Treatment Goals ....................................................................................................... 2-2

System Development .................................................................................................. 3-1

3.1 Recovery Well System .............................................................................................. 3-1

3.2 Description of Treatment System .............................................................................. 3-2

3.3 Treatment Building Common Elements ..................................................................... 3-2

3.4 Discharge ................................................................................................................. 3-3

3.5 Discharge Piping and Routing ................................................................................... 3-4

Treatment Process and Design Basis .......................................................................... 4-1

4.1 Process Summary..................................................................................................... 4-1

4.2 Design Flow and Influent Conditions ......................................................................... 4-3

4.3 Groundwater Extraction System ................................................................................ 4-3

4.4 Plant Process Flow ................................................................................................... 4-4

4.5 Equalization Tank ..................................................................................................... 4-5

4.6 Mixing System .......................................................................................................... 4-6

4.7 MMF Feed Pumps .................................................................................................... 4-6

4.8 Multimedia Filters ...................................................................................................... 4-7

4.9 Backwash Supply and Waste Tanks ......................................................................... 4-7

4.10 Cartridge Filters ........................................................................................................ 4-8

4.11 Advanced Oxidation Process (AOP) – Ozone Generation and Reactor .................... 4-9

4.12 Bench-scale testing for Ozone-Hydrogen Peroxide AOP Reactor System .............. 4-12

4.13 AOP Reactor Startup and Bypass ........................................................................... 4-12

4.14 LGAC Feed Tank and LGAC Feed Pumps ............................................................. 4-13

4.15 Liquid-Phase Granular Activated Carbon Polishing ................................................. 4-13

4.16 Gas-Phase Activated Carbon Vessel and Blower ................................................... 4-14

4.17 Building Sump and Sump Pumps ............................................................................ 4-15

CTO Number WE24 Table of Contents ii

4.18 Chemical Storage Tanks and Unloading Station ..................................................... 4-15

4.19 Treated Groundwater Discharge ............................................................................. 4-18

4.20 Process Control System.......................................................................................... 4-18

4.21 Building Services .................................................................................................... 4-20

4.22 General Logic and Alarms ....................................................................................... 4-21

4.23 Process Control Description .................................................................................... 4-22

Treatment System Building .......................................................................................... 5-1

5.1 Summary .................................................................................................................. 5-1

5.2 Site Civil .................................................................................................................... 5-1

5.3 Geotechnical ............................................................................................................. 5-2

5.4 Structural and Architectural ....................................................................................... 5-2

5.5 Heating, Ventilation, and Air Conditioning ................................................................. 5-7

5.6 Plumbing ................................................................................................................... 5-8

5.7 Electrical ................................................................................................................... 5-8

5.8 Fire Protection Life Safety Design Analysis ............................................................. 5-10

References

CTO Number WE24 Table of Contents iii

TABLES

2-1 Recovery Well Water Quality and Treatment Goals 3-1 Hydraulic Calculation Summary 4-1 Recovery Well Parameters 4-2 Treatment Plant Process Goals 4-3 Key Process Equipment List 5-1 Fire Rresistance for Building Elements 5-2 Fire Resistance Rating Requirements for Exterior Walls 5-3 Occupant Load Factor 5-4 Egress Requirements Per NFPA 101

FIGURES

1-1 General Location Map 1-2 Planned and Potential OU2 & OU3 Groundwater Infrastructure 2-1 Well Location Map 3-1 Work Location Map 4-1 Process Flow Diagram 4-2 Treatment Plant Layout

APPENDICES

A Groundwater Data, Computer Modeling, Basin Infiltration Testing, AOP Bench-Scale Testing, and Geotechnical Investigation

B Design Calculations C Key Equipment Cutsheet D Technical Specifications E Design Drawings

CTO Number WE24 Acronyms and Abbreviations iv

Acronyms and Abbreviations °F degrees Fahrenheit 1,1,2-TCA 1,1,2-Trichloroethane AASHTO American Association of State Highway and Transportation Officials ACI American Concrete Institute AOP Advanced Oxidation Process ASTM American Society for Testing and Materials bgs below ground surface CAT category BWS Back Wash Supply BWW Back Wash Waste CMU concrete mason unit COC chemical of concern CPP Control Power Plant CTO Contract Task Order Freon 113 1,1,2-trichloro-1,2,2-triflouroethane FSD fire separation distance GAC granular activated carbon gpm gallon per minute GWTS Groundwater Treatment System HDPE high-density polyethylene HMI human machine interface HP horsepower hr hour HSC Hydraulic System Center HVAC Heating, Ventilation, and Air Conditioning i/o input/output IBC International Building Code KW kilowatts LED light emitting diode LGAC liquid phase granular activated carbon LOX liquid oxygen mA milliamp MCC motor control center mg/L milligram per liter MMF multimedia filter NAPL non-aqueous phases liquid NAVFAC Naval Facilities Engineering Systems Command Navy Department of the Navy NFPA National Fire Protection Association NPDES National Pollutant Discharge Elimination System NWIRP Naval Weapons Industrial Reserve Plant

CTO Number WE24 Acronyms and Abbreviations v

NYCRR New York Code, Rules, and Regulations NYSDEC New York State Department of Environmental Conservation NYSDOH New York State Department of Health OIT operational interface terminal OSHA Occupational Safety and Health Administration OSWER Office of Solid Waste and Emergency Response OU Operable Unit P&ID piping and instrumentation diagram PLC programmable logic controller PSA pressure swing adsorption PSEGLI Public Service Electric and Gas Company Long Island psf pounds per square foot psi pounds per square inch ROD Record of Decision RW recovery well RPZ Reduced Pressure Zone SCADA supervisory control and data acquisition SCFH standard cubic feet per hour SCFM standard cubic feet per minute SPR standard penetrative resistance SPT Standard Penetration Test TDH total dynamic head Tetra Tech Tetra Tech, Inc.

µg/L microgram per liter UFC United Facilities Criteria USCS Unified Soil Classification System USEPA United States Environmental Protection Agency V volt VFD variable frequency drive VGAC vapor phase granular activated carbon VOC volatile organic compound VOIP voice over internet protocol VPN virtual private network W watt

CTO Number WE24 Acronyms and Abbreviations vi

CTO Number WE24 Introduction

1-1

Introduction This Basis of Design Report was prepared to develop a groundwater extraction, treatment, and discharge system to address the migration of the leading edge of a volatile organic compound (VOC)- and/or 1,4-dioxane-impacted groundwater plume associated with the former Naval Weapons Industrial Reserve Plant (NWIRP) Bethpage Operable Unit 2 (OU2) groundwater in Nassau County, Long Island, New York (see Figure 1-1). Groundwater from the former NWIRP Bethpage flows to the south southeast. This report was prepared by Tetra Tech, Inc. (Tetra Tech) for Naval Facilities Engineering Systems Command (NAVFAC) – Mid-Atlantic under Contract N6247216D9008, Contract Task Order (CTO) WE24.

1.1 Background

As a result of operations at the former NWIRP Bethpage, the groundwater has been impacted with several chlorinated solvents, including tetrachloroethene, trichloroethene, and 1,1,1-trichloroethane. Starting in the early 1990s, the Navy has been conducting groundwater investigations, implementing soil and groundwater remedies, and evaluating options for remediating the groundwater plume and protecting human health and the environment.

In 2003, the Navy prepared the NWIRP Bethpage OU2 Record of Decision (ROD) which identified actions that the Navy can take to address VOC-impacted groundwater that is located downgradient of the former NWIRP Bethpage, including the extraction, treatment, and discharge of groundwater (Navy, 2003). The current understanding (conceptual site model) for the OU2 plumes is presented as the background in Figure 1-2. The horizontal and vertical boundaries of the OU2 plumes are mostly defined by the presence of trichloroethene and to a lesser extent along the southern edge of the plume by 1,4-dioxane.

One part of the 2003 OU2 ROD was the extraction and treatment of the more contaminated groundwater in the area (i.e., VOCs greater than 1,000 micrograms per liter [µg/L]). Since 2003, two OU2 hotspots were identified, the GM38 Area Hotspot and the RE108 Area Hotspot. The GM38 Area Hotspot Groundwater Treatment System (GWTS) started operation in 2009 and has eliminated over 80 percent of the associated contamination. Remediation of the RE108 Area Hotspot was divided into phases.

Phase I addresses the northern portion of this hotspot and consists of two recovery wells (RW4 and RE137). The associated treatment systems are in operation. Recovery well RW4 and RE137 groundwaters are pumped to the GM38 GWTS. An upgrade to increase capacity at the GM38 GWTS is ongoing. The Phase II GWTS is intended to address the balance of the RE108 Area Hotspot (recovery wells RW5 and RW6). This system is under construction, with initial startup and testing in 2025 and continuous operation in 2026.

In 2021, the 2003 ROD was modified by an Explanation of Significant Differences (ESD) (Navy, 2021). This ESD allows for groundwater extraction and treatment of groundwater with lower concentrations of VOCs (e.g., 150 µg/L) and incorporated an extension of the Phase II (recovery well RW7). In addition, the ESD identified 1,4-dioxane as a chemical of concern and the installation and operation of up to four recovery wells and one or two treatment systems to

CTO Number WE24 Introduction

1-2 capture, or intercept, as practicable, the OU2 plumes to maintain their approximate current footprint. An area near the Southern State Parkway was identified as the location of these recovery wells and treatment plant(s). The recovery wells and treatment plant(s) are referred to the Phase III GWTS and include recovery wells RW8, RW9, RW10A, and potentially RW11.

This report develops the design of the Phase III GWTS. In addition, one interim groundwater treatment system is currently operating at RW8 well location and a second interim groundwater treatment system at the RW9 well location is anticipated to start operation in Spring 2026.

Because the Phase III recovery wells are located downgradient of the OU2 plumes, the concentrations of VOCs and 1,4-dioxane in the extracted groundwater are anticipated to start low, increase over time, and eventually decrease to less than cleanup levels. For the first 10 to 20 years of operation, the VOCs in the extracted groundwater may remain undetected, or at very low concentrations relative to the cleanup goals. Based on the effectiveness of groundwater activities being conducted to the north, VOC concentrations are estimated to increase to a maximum concentration of 10 µg/L, before decreasing.

Initially, the 1,4-dioxane concentration is anticipated to be approximately 0.5 µg/L, peak at 1.5 µg/L, and then decrease to less than 1 µg/L. In addition, although iron is naturally present and not a chemical of concern in the OU2 plume, the Phase III GWTS will need to remove it to control adverse impacts to the treatment equipment and sedimentation in the recharge basins.

During early stages of operation, groundwater monitoring of the Phase III recovery wells and other wells in the area will be conducted. This data will be used to help evaluate the plume migration into the area. Based on an evaluation of this data, pumping rates at individual recovery wells may be reduced or suspended, until the OU2 plumes move into the area.

As discussed in Section 2.0, Table 2-1 summarizes the anticipated average and maximum concentrations of organics and inorganics in the Phase III groundwater.

1.2 Objective

The objective of the Phase III GWTS is to capture, or intercept, as practicable, the OU2 plumes to maintain their approximate current footprint. These activities would be conducted in close proximity to the Southern State Parkway. This report documents the basis for this design.

1.3 Report Organization

This report is divided into five sections and is organized as follows:

• Section 1.0 - Introduction

• Section 2.0 - Provides the design basis and describes the plume characteristics

• Section 3.0 - Develops the extraction, treatment, and discharge system

• Section 4.0 - Provides a summary of the process design

• Section 5.0 - Provides details on the layout and design of the treatment building

SOUTH

OYSTER BAY

ATLANTIC OCEAN

GREAT

SOUTH BAY

³ 0 1 20.5

Miles

Former Northrop Grumman Facility

New York

New Jersey

Connecticut

Rhode Island

Atlantic Ocean

Long Island Sound

NWIRP

Bethpage

Sunrise Hwy

State H w y

135Hempstead Tnpk

Southern State Pkwy

Former NWIRP Bethpage Facility

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GENERAL LOCATION MAP

NWIRP BETHPAGE, NEW YORK

CTO

1-1

FIGURE NUMBER

DATEDRAWN BY

N62470-16-D-9008 WE13

MC 03/31/20

DATECHECKED BY

EW 03/31/20

BWD-6-1

BWD-6-2

RW10A

RW4

RE137

Well 17 Well 18 Well 19

RW-4

RW-20

RW-21

Well 3R

RW5A RW5B

RW6B

RW7B

RW8

RW9

GM38-RW01

RW-22

Well 1

RW-3

RW-2

RW-1

RW6A

RW7A

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Legend Existing Navy Recovery Well

Existing NG Recovery Well

Regional Groundwater Flow

Existing Navy Treatment Plan

Proposed Navy Treatment Plan

2022 TCE Plume (All Depths) Plus 1,4- Dioxane

5 to100 µg/L TCE, > 1.0 µg/L 1,4-Dioxane

>1,000 µg/L TCE

>1,000 µg/L TCE

Boundaries Bethpage Community Park (BCP)

Hooker Ruco Superfund Site (HR)

Former Northrop Grumman Facility (NG)

NWIRP

NG

NWIRP

BCP

HR

NG

Deep Western Plume (OU2)

RE108 Area Hotspot (OU2)

2,000 2,0000 Feet

Deep Eastern Plume (OU3)

RW21 Area Hotspot (OU3)

Former GM38 Area Hotspot (OU2)

Shallow Plume

(OU3)

South Oyster Bay ~ 3.6 Miles

RE108 Phase II Treatment Plant

GM38 Groundwater Treatment Plant

RW8 Interim Treatment System

CTO

FIGURE NUMBER

DATEDRAWN BY

CHECKED BY DATE

WE16I. CHAPMAN

R. MOORE 1-2

EXISTING AND PROPOSED OU2 AND OU3 GROUNDWATER INFRASTRUCTURE

NAVAL WEAPONS INDUSTRIAL RESERVE PLANT

BETHPAGE, NEW YORK

Notes:

µg/L

NWIRP

OU

RW

TCE

Microgram per liter Former Naval Weapons Industrial Reserve Plant Operable Unit Recovery Well Trichloroethene

Shallow Plumes (OU2)

OU2 and/or OU3 Plumes

PWD-7438

12/30/2025

12/30/2025

CTO Number WE24 Design Basis

2-1

Design Basis This section presents and summarizes environmental investigations that describe plume characteristics. Also presented are criteria and guidelines used to establish treatment requirements for the extracted groundwater.

2.1 Plume Characterization

Vertical profile borings in the area are used to establish the geology and horizontal and vertical distribution of VOCs in groundwater. Analysis of groundwater samples from monitoring wells are then used to confirm the vertical profile boring data and to monitor plume migration. In addition, measured and estimated hydrogeological parameters are used to calculate plume migration direction and rates. This data in combination with groundwater modeling is used to define the boundaries of the OU2 Plume (Figure 1-2) and project contaminant migration.

The quality of groundwater projected to migrate into and be captured by the Phase III GWTS are characterized by several monitoring wells in the area identified below (see Figure 2-1 for all of the area wide monitoring wells). For those wells identified as current, associated data represents groundwater that is in the area and depth of the recovery wells. For those wells identified as future, groundwater is anticipated to require 10 to 30 years to reach the recovery wells. Recent analytical data for these wells, one vertical profile boring, and the RW8 interim groundwater treatment system are presented in Appendix A.

Recovery Wells RW8 and RW9 (Deep Western Plume): Recovery Wells RW8 and RW9 target an area that is an extension of the RE108 Area Hot Spot plume not captured by the Phase I, Phase II, or Phase II Extension recovery wells or water supply wells. The groundwater in the area of recovery wells RW8 and RW9 is currently free of VOCs but may contain 1,4-dioxane at a concentration up to 0.5 µg/L (one half the New York State Department of Health [NYSDOH] drinking water standard).

During pumping tests for RW8 and RW9, the groundwater was tested for VOCs, 1,4-dioxane, and inorganic constituents. VOCs and 1,4-dioxane were not detected in this groundwater.

Except for iron, the concentrations of each of inorganics was low enough that treatment is not required. The iron concentrations ranged from 0.605 to 1.44 milligrams per liter (mg/L). A secondary NYSDOH drinking water standard for iron is 0.3 mg/L. Also important for the Phase III GWTS is that precipitates of iron can foul advanced oxidation process (AOP) lamps, plug granular activated carbon units, and reduce infiltration rates in recharge basins.

In the future, the 1,4-dioxane concentration is anticipated to increase to a maximum of 1.5 µg/L.

VOCs are anticipated to be limited to several chlorinated compounds, primarily trichloroethene.

These VOCs are present in narrow and thin finger of the plume moving at depth of 730 to 755 feet below ground surface (bgs), typical of groundwater in monitoring well RE117D1. The peak trichloroethene concentration in this well was 150 µg/L. Because of the large capture zone of the recovery wells relatively to the plume associated with RE117D, this maximum concentration is anticipated to reduce by a factor of at least 6 for an individual recovery well and then further reduced via dilution from the other recovery wells.

CTO Number WE24 Design Basis

2-2

Representative Monitoring Wells for RW8 and RW9 Characterization:

• BPOW 5-1 through 5-7 (future)

• BPOW 6-1 through 6-6 (current)

• RE117D1 and D2 (future)

• RW8-MW01D1 through D3 (current)

• RW9-MW01D1 through D3 (current)

• RW8-PT-IN01 and IN02 (current)

• RW9PT-IN01 and IN02 (current)

• TT102D1 and D2 (current)

Recovery Well RW10A: Recovery Well 10A targets a relatively wide area of VOC- and 1,4-dioxane-impacted groundwater. The plume is relatively thin, approximately 20 to 50 feet thick and found at a depth of approximately 200 to 250 feet bgs. Under current conditions (see VPB- RW10), several chlorinated VOCs are present in the area of RW10A, including tetrachloroethene and breakdown products. The maximum concentration detected in one of the vertical profile boring groundwater grab samples was tetrachloroethene at 8.8 µg/L. The corresponding 1,4 -dioxane concentration was 0.22 µg/L. Groundwater upgradient of this area contains similar concentrations of VOCs and the 1,4-dioxane concentrations vary from not detected to one half the NYSDOH drinking water standard (0.5 µg/L).

Representative Vertical Profile Boring and Monitoring Well for RW10A Characterization:

• VPB-RW10 (current)

• TT119S1 (future)

2.2 Treatment Goals

The primary treatment goals for the Phase III GWTS are based on the NYSDOH drinking water standards as shown in Table 2-1. Under current conditions, the extracted groundwater is not anticipated to exceed these drinking water standards. Overtime, as the OU2 plume continues to migrate southward, several OU2 plume-related VOCs, including trichloroethene, tetrachloroethene, Freon 113 (1,1,2-trichlorotrifluoroethane), 1,1-dichloroethene, cis-1,2-dichlorothane, and 1,4-dioxane may be detected in the extracted groundwater. Over time, some of these constituents may exceed discharge goals.

In addition, the New York State Department of Environmental Conservation (NYSDEC) has established groundwater quality standards for the local aquifer. The local aquifer is classified as Class GA, with its primary use as a supply of drinking water. For the VOCs, the NYSDEC groundwater (Class GA) and NYSDOH drinking water standards are the same. For 1,4-dioxane, the NYSDOH drinking water standard is 1.0 µg/L and the NYSDEC groundwater standard is 0.35 µg/L. Practical target treatment levels for the VOCs will be 1 µg/L and for 1,4-dioxane will be 0.1 to 0.3 µg/L. These treatment goals are coordinated with the NYSDEC through a State Pollutant Discharge Elimination System permit equivalent.

CTO Number WE24 Design Basis

2-3

Iron, which is natural in this area, is evaluated as a secondary drinking water standard. The NYSDOH has established a goal of 0.3 mg/L, with the primary basis of the standard is staining.

The Phase III Groundwater Treatment Plant is being designed to achieve this goal, but with an emphasis on protecting downstream equipment and the recharge basins from the buildup of suspended solids and reduced efficiency. In practice, the iron levels should be controlled to much lower concentrations (e.g., less than 0.1 mg/L).

The Phase III GWTS is anticipated to operate until site related VOCs and 1,4-dioxane have stabilized at concentrations less than the NYSDOH drinking water standards in upgradient groundwater, such that the mass of residual contaminants in the groundwater would not result in the exceedance of NYSDOH drinking water standards in downstream public water supplies.

CTO Number WE24 Design Basis

2-4

TABLE 2-1

RECOVERY WELL WATER QUALITY AND TREATMENT GOALS

Parameter Unit RW8 (Avg/Max)

RW9

(Avg/Max)

RW10A

(Avg/Max)

Combined (Avg/Max)

Treatment Goal1

Organics Trichloroethene µg/L 1/5 5/25 0.2/1 1.8/10 5 Tetrachloroethene µg/L ND ND 0.2/5 ND/1 5 Freon 113 µg/L ND 0.2/0.5 ND ND/0.5 5 1,1-Dichloroethene µg/L ND 0.2/0.5 ND ND/0.5 5 cis-1,2-Dichloroethene µg/L ND 0.2/0.5 0.5/2 ND/0.5 5 1,4-Dioxane µg/L 0.5/1.5 0.5/1.5 0.5/1.5 0.5/1.5 0.35 Inorganics pH (Range) Standard Unit 4.8 to 5.5 4.6 to 5.4 4.5 to 5.5 4.5 to 5.5 6.5 to 8.0 Sodium mg/L NA NA NA 3/10 NA Calcium mg/L NA NA NA 3/6 NA Iron mg/L NA NA NA 1.5/2.5 0.6 Manganese mg/L NA NA NA 0.02/0.03 NA Alkalinity mg/L NA NA NA 4/15 NA Chloride mg/L NA NA NA 5/12 NA Ammonia mg/L NA NA NA ND/0.2 NA Nitrate/Nitrite mg/L NA NA NA 0.2/0.5 NA Sulfate mg/L NA NA NA 7/15 NA Total Dissolved Solids mg/L NA NA NA 25/60 NA Total Organic Carbon mg/L NA NA NA 0.6/1.5 NA Total Suspended Solids mg/L NA NA NA 1/2 NA Phosphorus mg/L NA NA NA 0.04/0.06 NA

1. The treatment goals presented are based on New York State Department of Health drinking water standards and New York State Department of Environmental Conservation Class GA groundwater standards. Practical target treatment levels for VOCs will be 1 µg/L and for 1,4-dioxane 0.1 to 0.3 µg/L.

µg/L - Microgram per liter. mg/L - Milligrams per liter.

RW - Recovery Well. GPM - Gallon per minute.

NA - Not applicable. ND - Not detected.

CTO Number WE24 Design Basis

2-6

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CTO Number WE24 Design Basis

2-8

CTO Number WE24 System Development

3-1

System Development

3.1 Recovery Well System

The objective of the Phase III GWTS is to capture, or intercept, as practicable, the OU2 plumes to maintain their approximate current footprint. These activities would be conducted in close proximity to the Southern State Parkway.

As presented in Section 2.0, delineation of the OU2 plume Hotspot is based on analytical data from groundwater samples collected through 2025. The location of the recovery well and treatment plant are based on the current delineation of the OU2 plumes coupled with its migration, and the availability of space within that area, see Figure 1-2.

The extraction system design is based on the hydraulic properties of the aquifer coupled with the width and thickness of the OU2 plume (s). These factors allow a calculation of the plume flow-through rate and serves as the basis for the minimum required pumping rates. Additional factors are applied to the estimate to account for uncertainties in the aquifer properties and the need to intercept OU2 plume. Pumping at higher rates will intercept groundwater that has not been impacted, but is in close horizontal and vertical proximity to the impacted groundwater.

These calculations are supported by computer modeling efforts coordinated for the larger OU2 plume area. The layout for the recovery wells is presented in Figure 3-1. The exact location, screen depth, and pumping rates of the recovery wells are based on numerical modeling. Using the numeric model results (Appendix A) and estimated OU2 properties, associated hydraulic calculations are summarized in Table 3-1.

Table 3-1: Hydraulic Calculation Summary

Parameter Deep Western Plume

Shallow Eastern Plume

Associated Recover Wells RW8 and RW9 RW10A

Plume Width (feet) 3,300 2,800

Plume Thickness (feet) 200 40

Hydraulic Conductivity (feet/day) 1031 70

Hydraulic Gradient (foot-V/foot-H) 0.002 0.002

Calculated Plume Flow Through Rate (each well, gallons per minute) 350 80

Design Extraction Rate (each well, average/maximum, gallons per minute) 450/600 600/700

1. Thickness-weighted average using 200 feet per day using a 50-foot-thick gravel zone and 70 feet per day using a 150-foot-thick sand zone.

A comparison of the design extraction rate with the calculated plume flow through rates for recovery wells RW8 and RW9 provides an approximate safety factor of 1.3 to 1.7 (i.e., over

CTO Number WE24 System Development

3-2 pumping of 30 to 70 percent). These two wells work together to incept the Deep Western Plume. RW10A has a safety factor of approximately 7.5 to 8.8, (i.e., over pumping of 650 to 780 percent). This magnitude of over pumping is required because one single well will be used to capture a relatively thick portion of the aquifer in order to capture the thin Shallow Plume.

The Phase III GWTS is anticipated to operate until site related VOCs and 1,4-dioxane have stabilized at concentrations less than the NYSDOH drinking water standards in upgradient groundwater, such that the mass of residual contaminants in the groundwater would not result in the exceedance of NYSDOH drinking water standards in downstream public water supplies. The treatment duration is based on groundwater extraction rates, the groundwater seepage velocity, VOC retardation within the plume, and on limited biodegradation mechanisms. Based on these factors, the amount of groundwater plume to be extracted and treated, and the limited viability of degradation, the treatment system is expected to operate for more than 30 years.

3.2 Description of Treatment System

The treatment elements selected from the Phase III GWTS consist of the following processes (See Figure 4-1 in Section 4.0).

• Flow rate and water quality equalization: A tank will be used to blend groundwater from the three recovery wells (RW8, RW9, and RW10A), as well as water from the building sump, and potentially recycle water from the process units.

• Iron oxidation: Air- and sodium hypochlorite-based oxidation of iron at a neutral pH to convert soluble ferrous iron to insoluble ferric hydroxide.

• pH adjustment: Ventilation and carbon dioxide off gassing coupled with the addition of sodium hydroxide. A neutral pH is required for aquifer discharge and iron oxidation.

• Filtration: Multimedia units to remove precipitated iron hydroxide and other suspended solids. Also, cartridge filters will be used to protect downstream equipment from the potential release of suspended solids from the multimedia filters.

• Advanced oxidation process: Unit is used to remove 1,4-dioxane and most of the VOCs anticipated to be in the extracted groundwater. Because of the presence of iron in the water and likely staining of the UV lamp sleeves, ozone- and hydrogen-peroxide based units will be required. If practical, a UV- and hydrogen peroxide-based AOP system may be evaluated during startup.

• Ventilation/Mixing: To remove low levels of VOCs (e.g., Freon 113) that may not be effectively removed by the AOP system or granular activated carbon (GAC).

• Granular activated carbon: Polishing to remove residual ozone, hydrogen peroxide, hypochlorite, and VOCs prior to discharge.

3.3 Treatment Building Common Elements

A building is used to house the equipment and chemicals, and would consist of several components, as follows:

• The treatment building and support structures size as per design drawings.

CTO Number WE24 System Development

3-3

• The building is provided with lighting, a security system, workspace, telemetry system, heater, and vent fans.

• Equipment is installed with secondary containment and sump, with associated precautions and containment required for chemical feed systems.

• Standard instrumentation and controls including flow and pressure switches, alarms, and level switches are included.

3.4 Discharge

Following treatment, existing storm water (recharge) basins will be used to re-infiltrating treated groundwater back into the aquifer. In order to minimize interference with the recovery wells, the treated water should be injected downgradient of the recovery wells. For the Phase III GWTS, five planned discharge basins are presented in Figure 3-1.

Recharge basins are large open depressions in the ground surface used to infiltrate water into the aquifer. In the Hempstead area, basins are commonly used to manage stormwater (stormwater basins). As a stormwater basin, it provides a reservoir to initially accumulate storm surges and then allow infiltration of accumulated water into the aquifer. Recharge basins are used to infiltrate clean (non-contact) or treated water on a continuous basis at production and groundwater remediation facilities.

In preparation for this system, short-term and long-term infiltration testing on four of these basins were conducted in 2022.

The short-term double ring tests found no evidence of shallow soils that would inhibit infiltration.

While these short-term tests provide valuable information, the primary method for determining continuous high rate is by conducting infiltration rates uses high volume storm water events.

For the long-term tests, piezometers were set into the bottom of the basin and data loggers were used to measure water level during and after storm events. This data then allowed infiltration rates to be directly measured as the water level decreased in the basin after the storm event.

During these long-term tests, water levels were measured in Basins 3 and 4 (identified as Basins 2 and 3 in the Appendix) during one or more events. These tests found infiltration rates of approximately 12 feet per day. Based on the area of each basin, the calculated infiltration rate for these basins are 940 gpm and 1,300 gpm, respectively. Basin 2 and Basin 4 (identified as Basins 1 and 3 in the Appendix) did not have any measurable water levels recorded during the testing. Therefore, the capacity of these basins is uncertain.

Basin 1 was not originally considered as a viable basin because of its small size. During pumping tests of recovery well RW8, this basin was found to be able to effectively infiltrate 1,000 gpm over three consecutive days. In addition, this basin has been consistently infiltrating approximately 400 to 500 gpm on a continuous basis for several months without issue, which is equal to approximately 14 feet per day.

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3.5 Discharge Piping and Routing

Discharge pipe routing is presented on Figure 3-1. This routing shows five recharge basins south of the Phase III Groundwater Treatment Plant. Basin 1 is just south of the east of the GWTS building. Basins 2 and 3 are 900 and 1600 feet south of the GWTS building in the neighborhood off Ruth Court and Twin Lane East and Basins 4 and 5 are 2800 feet southeast of the GWTS building near the corner of Seamans Neck Road and Jerusalem Avenue. To maintain the existing capacity of the storm water basins, two feet would be removed from the bottom of each basin. There would be three discharge lines from the GWTS building. One gravity discharge line would discharge directly to Basin 1. The second gravity line would divert the water to Basins 2 and 3, with a diversion manhole used to split the flow. The third discharge line would discharge into Basin 4 and 5. These basins would be interconnected to allow flow to both basins.

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CTO Number WE24 Treatment Process and Design Basis

4-1

Treatment Process and Design Basis This section describes the processes that will be used for treatment of groundwater at the site and presents the design basis for these processes. Calculations used in this design are presented in Appendix B and key equipment cut sheets are presented in Appendix C. The specifications are provided in Appendix D and the design drawings are presented in Appendix E.

4.1 Process Summary

The Phase III GWTS consists of three (3) new recovery wells (RW8, RW9, RW10A), a treatment system, and a discharge system using up to five existing storm water basins. The process flow schematic for the Phase III GWTS is presented in Figure 4-1

Within the new treatment building, there will be the following processes:

• Equalization Tank, with agitation and active venting

• Iron Oxidation

• Multi Media and Cartridge Filtration

• Advance Oxidation Process (AOP) system, using ozone and hydrogen peroxide

• Liquid-Phase Granular Activated Carbon (LGAC)

• Tank Ventilation and Treatment System to control off gas emissions.

The building layout is presented in Figure 4-2. The new building will be approximately 145 feet by 85 feet (12,300 square feet).

Groundwater from the aquifer will be extracted using three recovery wells. Based on modeling, over the long term, RW8 and RW9 will pump at an average flow rate of 450 gpm each and RW10A will pump at an average rate of 600 gpm, resulting in a design average flow rate of 1,500 gpm. Information on the recovery wells and associated pumps are presented in Table 4-1

Because the OU2 plumes will move through the target capture area at different rates and times, the recovery wells will be designed to pump at a maximum rate of 600 gpm (RW8 and RW9) and 700 gpm (RW10A). The combined peak flow from all three (3) recovery wells be 1800 gpm, i.e., not all of the pumps will be able to pump at the maximum rate at the same time. Existing monitoring wells, coupled with modeling, will serve to monitor the capture of the groundwater by the recovery wells. Some existing monitoring wells also serve to monitor water quality. The locations of the wells are shown on Figure 2-1.

The Phase III GWTS building will be located on New York State-owned property adjacent to Southern State Parkway, within the Navy easement. The setback for the new site and Phase III GWTS building and layout plan for the Phase III GWTS is shown in Appendix E.

The groundwater influent pipes from the recovery wells enter the Phase III GWTS building through the floor in the southwest corner (Figure 4-2). The Equalization Tank is also located in the south-west corner of the building. The Equalization Tank will include a side mounted aerator

CTO Number WE24 Treatment Process and Design Basis

4-2 that will help with oxygen transfer and reduce any chemical oxidant demand downstream for iron removal. Active venting of the Equalization Tank will also assist in stripping out any excess carbon dioxide (CO2) to raise the pH and Freon 113 that might be present in the recovery wells raw water. Approximately 200 cubic feet per minute (CFM) of continuous air flow through the Equalization Tank will be required. Sodium hydroxide (25 percent) will be fed upstream of the Equalization Tank to provide enough contact time for pH adjustment from 4.5 to 5.0 to approximately 7.0. This will assist with iron removal through oxidation.

The multimedia filter (MMF) feed pumps (P-100A/100B) are mounted on a pad at finished floor elevation. These pumps convey flow from Equalization Tank into three (3) high-rate vertical MMF containing anthracite, sands, and gravels operating in parallel. Iron hydroxide-based suspended solids are removed using these MMF. An optimal dose of sodium hypochlorite (12 percent chlorine) will be fed upstream of the MMF as an oxidant to convert any residual iron from soluble ferrous to insoluble ferric state prior to feeding into the MMF. The sodium hypochlorite system is backup in the event the Equalization Tank ventilation is insufficient to oxidize all of the iron. A set of cartridge filters will be used downstream of the MMF to remove any remaining solids or particulates. The flow is then fed into the AOP Reactor.

The AOP system consists of a reactor, hydrogen peroxide feed system, and an ozone generation and feed system. Because local road conditions, liquid oxygen cannot be delivered to site. As a result, relatively pure and dry oxygen will be generated onsite using a compressor, air receiver tank, dryer/filter, pressure swing adsorption oxygen concentrator system, and oxygen buffer tank. From the dried and concentrated oxygen, the ozone will also be generated on site and consist of an ozone generator and distributor (feed system). Both the compressors and ozone generators produce excess heat. The compressors require moderate rate room ventilation to remove the heat and the ozone generator uses a water chiller.

The hydrogen peroxide tank (containing 27 percent peroxide) with chemical feed pumps is used to feed it upstream of the AOP reactor, whereas the ozone is fed in one or more injection points in the reactor. Following the reactor, the water is depressurized to allow residual ozone and oxygen to off gas. This off gas is treated with an ozone destructor prior to venting to the atmosphere. The AOP system is designed to treat for 1,4-dioxane and other organics to meet the treatment goals maximum contaminant limit drinking water standards as listed in Table 2-1.

The LGAC feed pumps (P-400A/400B) are mounted on a pad at finished floor elevation. Treated flow from the AOP contact tank is fed into a LGAC feed tank from where the LGAC feed pumps convey flow into three (3) LGAC vessels operating in parallel. The LGAC vessels contain virgin coconut based granular activated carbon media that will be used to remove any residue peroxide, ozone, hypochlorite, organics and suspended solids prior to final discharge.

The building sump will be located adjacent to the equalization tank, with sump pumps as shown in the mechanical plan layout in Appendix E. Curbing for the plant serves as secondary building containment and is designed to store a major leak of the largest process tank.

All doors and exits will have a 4-inch-high sloped ramp. All rooms have a 6-inch-high step. The building containment calculations are provided in Appendix B.

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The building is equipped with high overhead doors to the south of the building. There will be access doors to the outside for chemical, mechanical, control, electrical and storage rooms in the building. A separate 85-foot by 25-foot (2,125 square foot) office building will be located on west of the treatment plant.

A summary of the recovery wells pump, motor horsepower and flow rate information are provided in Table 4-1.

The new treatment facility design drawings are in Appendix E.

4.2 Design Flow and Influent Conditions

Expected design flows, influent groundwater quality conditions, and rationale for selection of those parameters for the new groundwater treatment system are discussed in Section 2.0.

The design influent concentrations are presented in Table 2-1 and are the basis for design of the groundwater treatment system. The design VOC, 1,4-dioxane, and iron influent concentrations are based on maximum anticipated concentrations. During the initial years of operation, actual concentrations may be less. In the event that higher concentrations occur, the GWTS includes units that provide redundant removal ability, plus there is excess capacity in the chemical treatment equipment to allow better performance. For example, the Equalization Tank ventilation, AOP unit, and LGAC all provide removal of VOCs and higher hydrogen peroxide and/or ozone dosages would improve removals.

The maximum capacity of the new groundwater treatment system is 1800 gpm, the treatment performance was evaluated at a maximum operating capacity of 1800 gpm. This flow consists of an anticipated maximum flow of 550 gpm from RW8 and RW9 (each) and 700 gpm from

RW10A.

A summary of the targeted treatment train concentrations for unit processes is presented in Table-4-2 and the key process equipment list is presented in Table 4-3.

4.3 Groundwater Extraction System

The groundwater extraction system for recovery wells RW8, RW9 and RW10A consists of three

(3) 6-inch recovery well submersible pumps inside a 12-inch well casing. Recovery wells RW8 and RW9 are screens at 595 to 790 feet bgs and 650 to 865 feet bgs, respectively. Recovery well 10A is screened at 217 to 310 feet bgs.

The pumps are to be installed 120 feet from the top of the well casing and the static water surface is 25 to 30 feet bgs. With a pump extraction drawdown (accounting for well fouling) of 50 feet, the water level in the well would be approximately 80 feet bgs. Groundwater pumps for the extraction system are anticipated to run at maximum flow rate of 550 to 700 gpm per pump with a motor rating of 25 to 40 horsepower (HP). The recovery wells will be equipped with submersible electric pumps (e.g., Grundfos 625S type) or equal.

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More information on the recovery wells and pumps are provided in Table 4-1. Details on recovery well pumps are included in Appendices B and C.

4.4 Plant Process Flow

The three (3) recovery well discharge pipes convey groundwater to the Phase III GWTS. The discharge piping from these three recovery wells were designed and will be installed under a separate project. Each recovery well has a dedicated well pump, valve vault and discharge pipe.

The discharge pipe from the recovery well runs independently using various fittings underground before conveying flow to the Phase III GWTS. Therefore, there are a total of three

(3) influent pipes entering the treatment building. Each recovery well extraction pipe includes adequate access through a valve vault. This valve vault is a precast concrete structure with an approximate 20 feet by 7 feet outside dimensions.

Each recovery well valve vault houses the recovery well that includes a fitting to bring the recovery well piping inside the valve vault. This fitting is on top of the well cap and provides means to access the level transmitter and recovery well pumps inside the well casing.

Equipment along each line also includes a sampling port, a check valve, butterfly valves, a combination air/vacuum release valve, a flow meter to measure the flow from each individual well, and flexible coupling inside the valve vault walls. A 2-inch drain line with drain ball valve is provided underneath the discharge pipe so the entire pipe can drain back to the well casing.

The top of the valve vault includes two (2) 36-inch by 36-inch aluminum access hatch with lifting handle and a side hinge, and a 12-inch by 12-inch opening for well pump as shown on design drawings. These hatches are H-20 loading rated for vehicular traffic.

At the Phase III GWTS, each of the three (3) influent pipes individually convey flow into the Equalization Tank and include a totalizer to indicate flow totals.

A process flow diagram is in Figure 4-1. Inside the building, the Equalization Tank receives flow from three (3) recovery well pipes individually that discharge from the top side of the tank.

The Equalization Tank includes ventilation (off gassing) and pH adjustment using sodium hydroxide. A mixer mounted on top of the Equalization Tank, or an inline three element static mixer will assist in chemical mixing and to bring the pH level at the desired level for iron oxidation and precipitation. The upstream ventilation provides for reduced dosage of chemical oxidant for iron removal using the multimedia filters. This oxidation process will be supplemented with use of optimal amount of oxidant (sodium hypochlorite) The groundwater is then pumped using MMF feed pumps into to a set of vertical MMF for the oxidized iron removal prior to being pumped into cartridge filters for removal of any solids or particulates.

The treated flow is then conveyed into the AOP reactor. The AOP reactor uses ozone and hydrogen peroxide for treating the VOCs and 1,4- dioxane below the desired target treatment goals. The ozone is generated and distributed into the AOP reactor by an air preparation, oxygen and ozone generation system. Excess ozone (unused ozone) is separated and removed by the ozone destructor downstream of the AOP reactor and LGAC units.

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The flow from the AOP reactor is then conveyed into a pumping tank. The LGAC feed pumps are used to send flow into the LGAC polishing adsorbers (LGAC-410, LGAC-420, and LGAC-

430) operating in parallel to remove residual VOCs, ozone, and hydrogen peroxide present in the groundwater. The treated effluent is tested to meet the effluent goals and monitoring requirements prior to being discharged into the recharge basins.

The AOP treatment system is downstream of the MMF and upstream of the LGAC vessels.

Piping from the AOP reactor includes a provision to recycle flow from the downstream of AOP reactor back into the reactor during start-up time.

A backwash supply (BWS) tank and a backwash waste (BWW) tank are provided to provide backwash flow for the backwash operations of the MMF and LGAC vessels and for storage for the backwash waste generated through each backwash cycle.

A building sump is provided as secondary containment. Water collected in the building sump is pumped to the Equalization Tank by two (2) submersible type pumps.

4.5 Equalization Tank

The Equalization Tank (T-100) is a prefabricated single wall fiberglass tank with a 12-foot diameter, 18-foot height, and a capacity of 15,200 gallons and flanged nozzle pipe connections, with an access manway on top. The Equalization Tank is on a concrete pad, 6 inches above the finished floor elevation. Adequate working space is provided around and above the tank to service and maintain the piping and pumps associated with the Equalization Tank.

The influent from the recovery well pipes discharge into and near the top of the Equalization Tank.

The Equalization tank will include a 8-inch line that will vent off gases from the tank through a carbon cannister C-100 prior to discharge to the atmosphere. These off gases may at times contain VOCs, ozone, and chlorine.