Geotechnical Environmental Water Resources Ecological

Groundwater Model Report

Gowanus Canal Superfund Site Brooklyn, New York EPA ID#: NYN000206222

Submitted to: National Grid 287 Maspeth Avenue Brooklyn, NY 11211

Submitted by: GEI Consultants, Inc. Mutch Associates, LLC 455 Winding Brook Drive 360 Darlington Ave. Glastonbury, CT 06033 Ramsey, NJ 07446 860-368-5300 201-669-4171

David B. Terry, P.G. Robert D. Mutch, Jr. P.Hg, P.E. Project Manager President and Principal Groundwater Hydrologist

December 2011 Project #093010-5-1506

GROUNDWATER MODEL REPORT NATIONAL GRID GOWANUS CANAL SUPERFUND SITE DECEMBER 2011

Table of Contents

Executive Summary iv

1. Introduction 1

2. Model Description 2 2.1 Conceptual Site Model 2 2.2 Assumptions 5 2.3 Model Grid 6 2.4 Boundary Conditions 7 2.4.1 Constant Head Boundaries 7 2.4.2 Recharge 7 2.4.3 Drains/Utilities 8 2.4.4 No-Flow (Inactive) Boundaries 9 2.4.5 Bulkheads 10 2.4.6 Supply Pumping 11 2.5 Hydraulic Conductivity 11 2.5.1 Fill/Shallow Sand 11 2.5.2 Marsh Deposits/Sediments 12 2.5.3 Upper Glacial Aquifer 13 2.5.4 Gardiners Clay 14 2.5.5 Jameco Gravel 15

3. Calibration 17 3.1 Shallow Zone 19 3.2 Upper Glacial Aquifer 19 3.3 Jameco Gravel 20 3.4 Sediments/Marsh Deposits 21

4. Sensitivity Analysis 22

5. Validation 23 5.1 Water Supply Pumping 23 5.2 Reduced Precipitation 24

6. Findings and Recommendations 25 6.1 Findings 25 6.1.1 Base Flow Estimate 25 6.1.2 Groundwater Contribution Area 25 6.2 Recommendations 25

References 28

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Tables 1 Soil Boring Log Summary 2 Hydraulic Conductivity Zones 3 Calibration Data Set 4 Mass Balance

Figures

1-1 Groundwater Model Location 2-1 Groundwater Model Limits 2-2 Conceptual Schematic of Hydrogeologic Units in the Vicinity of the Site 2-3 USGS Regional Contours 2-4 1766 Map of Site Vicinity 2-5 Model Grid 2-6 Model Grid – Cross Section A-A’ 2-7 Model Grid – Cross Sections B-B’ and C-C’ 2-8 Shallow Constant Head and Drain Boundaries 2-9 Jameco Gravel Constant Head Boundaries 2-10 Recharge Boundaries 2-11 Canal/Bulkhead Detail 2-12 Bulkhead Conductivity 2-13 Hydraulic Conductivity Layer 1 2-14 Hydraulic Conductivity Layer 2 2-15 Hydraulic Conductivity Layer 3 2-16 Hydraulic Conductivity Layer 3 (Canal Detail) 2-17 Hydraulic Conductivity Layer 4 2-18 Hydraulic Conductivity Layer 5 2-19 Hydraulic Conductivity Layer 6 2-20 Hydraulic Conductivity Layer 7 2-21 Cut-Away View Along Canal 2-22 Hydraulic Conductivity Cross Section A-A’ 2-23 Hydraulic Conductivity Cross Sections B-B’ and C-C’ 3-1 Calibration Curve – All Layers 3-2 Calibration Curve – Upper Glacial Aquifer (Layers 4 and 5) 3-3 Calibration Curve – Jameco Gravel (Layers 6 and 7) 3-4 Potentiometric Contours Cross Section A-A’ 3-5 Potentiometric Contours Cross Sections B-B’ and C-C’ 4-1 Sensitivity Analysis Hydraulic Conductivity 1 4-2 Sensitivity Analysis Hydraulic Conductivity 2 4-3 Sensitivity Analysis Areal Recharge 5-1 Historic Reported Well Yields 5-2 Historic Precipitation 6-1 Calculated Base Flow 6-2 Particle Flow Paths – Upper Glacial Aquifer

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Appendix

Appendix A – Model Calibration and Validation Figure A-1 USGS Groundwater Data Points Figure A-2 Calibration Points Shallow Figure A-3 Calibration Points Upper Glacial Aquifer Figure A-4 Calibration Points Jameco Gravel Figure A-5 Regional Soil Boring Data Points Figure A-6 Qualitative Calibration – Shallow North Figure A-7 Qualitative Calibration – Shallow Central Figure A-8 Qualitative Calibration – Shallow South Figure A-9 Qualitative Calibration Upper Glacial Aquifer Figure A-10 Qualitative Calibration Jameco Gravel Figure A-11 Model Validation Results – Partial Historic Pumping Figure A-12 Model Validation Results – Reduced Recharge

H:\WPROC\Project\NationalGrid\Gowanus - Confidential\GW Model Report\Submittal to EPA 12-2011\GW Model Rept 122211.docx

iii GROUNDWATER MODEL REPORT NATIONAL GRID GOWANUS CANAL SUPERFUND SITE DECEMBER 2011

Executive Summary

The United States Environmental Protection Agency (USEPA) has issued a draft remedial investigation (RI) report (EPA, 2011) and is currently performing a Feasibility Study (FS) of remedial alternatives for the Gowanus Canal Superfund Site (the Site) in Brooklyn, New York. On behalf of National Grid, GEI Consultants, Inc. (GEI), in collaboration with Mutch Associates, LLC, developed a three-dimensional numerical groundwater flow model (computer model) to be used for predicting hydraulic effects of potential remedial alternatives in support of remedy selection.

The model is a representation of hydraulic conditions within the aquifer system at the Site and the surrounding region. This report includes a description of the model, and guidance and recommendations for its use in predicting the hydraulic effects of potential remedial alternatives. The key model output parameters consist of water table elevation, potentiometric head, flow direction, velocity, and base flow rate to the canal. The model was calibrated to present-day conditions in the aquifer system. The objective functions of the model consist of:

. Quantitative estimate of present day (baseline) groundwater flow conditions. . Quantitative prediction of groundwater flow after remedy implementation for comparison to specified constraints. . Comparative evaluation of potential remedial alternatives and design variables to optimize efficiency and, if necessary, mitigate potential adverse hydraulic effects of potential remedial alternatives.

The model is a representation of the portion of the regional aquifer that is hydraulically connected to the canal. The modeled aquifer system includes a shallow (water table) unit, outwash sand and till unit (Upper Glacial Aquifer), and an underlying gravel aquifer unit (Jameco Gravel). The water table and Upper Glacial Aquifer units are separated in the area of the Site by a marsh deposit aquitard. Shallow groundwater on Site is generally perched above the marsh deposits, and discharges to the Gowanus Canal horizontally through permeable bulkheads. Groundwater discharge from the Upper Glacial Aquifer to the canal is generally upward through sediments. The Upper Glacial Aquifer and Jameco Gravel are separated in some locations by the Gardiners Clay confining unit. Groundwater within the Jameco Gravel flows upward into the Upper Glacial Aquifer in areas where the Gardiners Clay is thin, absent, or is comprised primarily of sand.

The model was developed to simulate the anticipated potential remedial components of sediment dredging, sediment capping, in-situ stabilization, and adjacent bulkhead improvements. The model can also accommodate supplemental or ancillary systems such as upland capping, relief drains, and groundwater extraction. As groundwater processes associated with remedial components would be identified as part of the FS, a computer model

iv GROUNDWATER MODEL REPORT NATIONAL GRID GOWANUS CANAL SUPERFUND SITE DECEMBER 2011 assists in quantifying the processes. The model was developed to quantitatively predict changes in water table elevation, groundwater flow direction, base flow, groundwater velocities, and potentiometric head changes in the regional aquifer system. Evaluation of the nature of these processes is essential to understanding the present and future behavior of groundwater within and near the canal. Proceeding without modeling would preclude being able to predict the effects of the remediation project on water quality and the water table elevation following remediation. Recommendations are provided as to how remedial system components may be included in the model, and how output can be interpreted to assist EPA in selecting the most appropriate, effective, and sustainable solution to the issues in the Gowanus Canal.

The approximately 1.8-mile-long canal is abutted by 80 parcels owned variously by 64 public and private entities. Given the large size of the Site and number of abutting properties physical constraints and timelines for remedy implementation are expected to vary by location within the Site . The model was developed to simulate multiple systems under multiple timelines as part of a holistic approach to Site remediation. The model can be used to evaluate system redundancy, interferences, and adverse effects associated with a remedy comprised of multiple components.

The model was developed using site-specific data collected from USEPA’s Remedial Investigation (RI) of the Site, National Grid’s investigations of former Manufactured Gas Plant (MGP) sites abutting the canal, and regional geologic and hydrogeologic data obtained from the USGS and other published sources. The model was calibrated to a groundwater elevation data set representing present conditions. The data set was seasonal- and tidal-averaged to represent long-term steady state conditions. Site and regional groundwater elevation data indicate that groundwater elevations in the regional aquifer system have remained relatively constant over the past two decades. Site groundwater elevation measurements showed no significant changes in groundwater flow patterns relative to the tide cycle or seasonal fluctuations. The calibrated model was validated by modeling historic pumping and drought events, and confirming that the calculated groundwater elevations were consistent with historically documented groundwater elevations.

This report presents quantitative output from the calibrated model to support risk characterization and hydrodynamic modeling for the Site. The model calculates a net base flow to the canal of 675 gallons per minute. Model-calculated localized upward head potential and base flow are also presented in this report. The area of contribution to the canal is an approximate 2.8 square mile area centered about ½ mile east of the Site.

v GROUNDWATER MODEL REPORT NATIONAL GRID GOWANUS CANAL SUPERFUND SITE DECEMBER 2011

1. Introduction

On behalf of National Grid, GEI Consultants, Inc. (GEI), in collaboration with Mutch Associates, LLC, developed and calibrated a numerical groundwater flow model for the area of the Gowanus Canal in Brooklyn, New York (the Site, Figure 1-1). The model was developed to characterize the relationship of the canal to the surrounding aquifer, and to provide a model for use in evaluating remedial alternatives for the canal and abutting sites. The purposes of this report are to document the groundwater model and its calibration, and to provide a quantitative description of present-day groundwater flow to serve as a baseline for risk assessment and future remediation scenarios.

The work was done in accordance with the Groundwater Model Work Plan transmitted to United States Environmental Protection Agency (USEPA) on September 13, 2010 by National Grid [GEI, 2010]. The work was performed by GEI between September 2010 and October 2011. This report is being submitted to the USEPA for inclusion in the Administrative Record for the Gowanus Canal to provide an evaluation tool for use in screening and guiding the selection of potential remedial alternatives.

This report is organized as follows. Section 2 provides a description of the structure of the model and its boundary conditions. Section 3 describes the model calibration. Section 4 describes the sensitivity analysis. Section 5 describes model validation. Section 6 provides findings and recommendations for use of the model in support of risk assessment and potential remedial alternatives for the canal and abutting sites.

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2. Model Description

A three-dimensional groundwater model was constructed using Visual MODFLOW version 2010.0 from Schlumberger Water Services (SWS). MODFLOW is an industry standard program used for numerical groundwater modeling, developed by the United States Geological Survey (USGS) [McDonald and Harbaugh, 1988]. MODFLOW is a modular finite-difference flow model, which is a computer code that solves the general groundwater flow partial differential equation. The groundwater flow equation is a mathematical relationship which is used to describe the flow of groundwater through an aquifer. Visual MODFLOW is a graphical user interface which facilitates model input and output. The model domain is discretized into a number of three-dimensional blocks (rectangular cells) and boundary conditions are applied. For each cell, MODFLOW computes the hydraulic head using a number of hydrogeologic input parameters such as hydraulic conductivity. The site MODFLOW model was run in steady-state mode. In steady-state mode, model inflows, outflows, and heads do not vary over time. Steady-state results consist of a single flow field representing a stable condition over time. Three-dimensional particle tracking was used in the model to depict the predicted flow paths and velocities within the steady-state flow field. Elevations in the model are relative to the North American Vertical Datum of 1988 (NAVD).

2.1 Conceptual Site Model

A conceptual site model (CSM) was developed to describe regional and local groundwater flow for the purpose of constructing the model and defining boundary conditions. The CSM was developed using information obtained during Remedial Investigation for activities for the Gowanus Canal Site, abutting former Manufactured Gas Plant (MGP) sites, and regional publications as cited below.

The model area is shown in Figure 2-1. Groundwater flow within the model area occurs in two regional aquifers: The Upper Glacial Aquifer and the Jameco Gravel. Groundwater elevation contours for the Upper Glacial Aquifer reported by USGS are shown in Figure 2-1. The bulk of the Upper Glacial Aquifer consists of outwash sand with till lenses, but is also considered to include overlying post-glacial deposits such as marsh deposits and fill [USGS, 1999]. The Upper Glacial Aquifer is separated from the Jameco Gravel by the Gardiners Clay confining unit in the eastern portion of the model area. Groundwater flows from the Jameco Gravel upward to the Upper Glacial Aquifer through locations where the Gardiners Clay is not present. A conceptual profile of the aquifer components is shown in Figure 2-2.

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Regional flow in the Upper Glacial and Jameco Gravel Aquifers in the area of the Site is westerly to southwesterly as can be inferred from the regional groundwater contours shown in Figure 2-3 [USGS 1997; USGS, 1999]. Groundwater approaching the Site within the Upper Glacial Aquifer discharges to the canal or flows relatively parallel to the canal with regional flow. Historic measurements shown in Appendix A, Figure A-1 indicate that water levels in the Upper Glacial Aquifer have remained stable over the past decade.

Groundwater elevation measurements and soil boring observations indicate that the marsh deposits at the Site are a significant confining or semiconfining unit. The water table near the Site appears to be mounded (perched) above the marsh deposits. Groundwater elevations at the water table (Figure A-2) in wells screened above the marsh deposits are higher than the potentiometric surface observed within the Upper Glacial Aquifer beneath the marsh deposits (Figure A-3). The historical extent of the marsh deposits is shown in Figure 2-4. Relatively high mounding was observed at the former Citizens MGP site, in the area of the former holders along 5th Street, which has been partially attributed to buried debris and structures. Groundwater elevation heads in the Jameco Gravel (Fig. A-4) are generally slightly higher than heads in the Upper Glacial Aquifer, indicating the potential for upward flow where the Jameco Gravel is in direct contact with the Upper Glacial Aquifer.

Groundwater flow in the computer model is controlled by four sources and sinks:

Sources

. Recharge (rain and snowmelt) . Regional Aquifer

Sinks

. Surface water (Gowanus Canal, East River, Gowanus Bay) . Regional Aquifer . Utility corridors

The Upper Glacial Aquifer is fed by local recharge and by upward flow from the Jameco Gravel. The horizontal model limits were defined to represent approximate natural groundwater divides within the Upper Glacial Aquifer. Radially outward flow from the area of Prospect Park generally dominates the groundwater flow trends within in the eastern portion of the model (Fig. 2-3).

The Jameco Gravel is fed by recharge zones in northern Long Island, flows southerly, and discharges at locations within and downgradient of the model area (Fig. 2-3). Within the model, groundwater in the Jameco Gravel discharges at locations where the Gardiners Clay is absent.

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Utility corridors that influence the water table are located in the model at the Fulton Former MGP Site and in a low-lying area surrounding Wallabout Bay (see Section 2.4.3). Regionally, utility infiltration and exfiltration are expected to be present throughout urban areas. The effects are assumed to be evenly spread, and as such can be incorporated in the model as part of the soil hydraulic conductivity (for infiltration) or as a component of recharge (for exfiltration).

The regional aquifer system was used historically as a significant water supply source until the 1960s. As a result of pumping, the water table was drawn down as much as 35 feet within the model area. The water table has returned to its approximate original elevation (Cartwright, 2002), and periodic gauging results reported by USGS indicates that water levels have been stable over the last decade (USGS, 2011). No active pumping of groundwater is reportedly occurring near the Site (Roux Associates, 1990). USGS (1998) reports subway tunnel dewatering occurs near the northern model boundary. Localized drawdown in the area of dewatering was found to not significantly affect either the modeled regional groundwater flow or model calibration.

The CSM for the regional aquifer system has five stratigraphic units: fill or native sand at the surface, underlain by the silt/peat marsh deposits (where present), the Upper Glacial Aquifer, the Gardiners Clay, and the Jameco Gravel. Underlying bedrock is assumed to be impervious. Soil type and extent of the five stratigraphic units in the model are described in Section 2.5. Regional lithology and hydrogeologic conditions were obtained for purposes of developing the CSM from Buxton et al. (1981), Cartwright (2002), and EPA (2010b). Strata break elevations used in defining model layers were interpreted from Former MGP and Gowanus Canal site boring logs (GEI, 2005; EPA, 2010); and historic boring logs compiled by the New York State Department of Environmental Conservation (NYSDEC) as made available by USGS (NYSDEC, 1937; NYSDEC, 1944). Historic soil boring and Former MGP Site locations are shown in Figure A-5. Soil boring logs used in development of the model are shown with the interpreted strata break elevations in Table 1. Monitoring well locations for the Gowanus Canal and Former MGP investigations are shown in Figures A-2, A-3, and A-4. Model grid development is described in Section 2.3. Each CSM stratigraphic unit was assigned at least one numerical layer in the computer model. The numerical model grid is shown in plan view in Figure 2-5, and in cross-section in Figures 2-6 and 2-7.

The Upper Glacial Aquifer was divided into two numerical layers (4 and 5) for vertical discretization and to allow for partially-penetrating cutoff walls to be modeled in potential remediation scenarios. The marsh deposit layer was divided into two numerical layers to accommodate sediments beneath the canal, and canal head boundaries above the sediments. MODFLOW requires that the layer splits throughout the entire model, for continuity of the finite-difference grid. For strata that are discontinuous within the model (marsh deposits, sediments, the Gardiners Clay, and the Jameco Gravel), the numeric layers were extended

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beyond the strata extent as described in Section 2.3. The following seven numerical layers were assigned in the numerical model:

. Model Layer 1: Zone above the top of the silt/peat unit (primarily fill in the area of the canal; native sand in upland areas further from the canal. . Model Layer 2: Marsh deposits where present; open water within the canal, Gowanus Bay, and the East River; Upper Glacial sand elsewhere. . Model Layer 3: Same as layer 2, except includes sediments within the canal, Gowanus Bay, and the East River. . Model Layers 4 and 5: Upper Glacial Aquifer. . Model Layer 6: Gardiners Clay where present; Upper Glacial Aquifer elsewhere. . Model Layer 7: Jameco Gravel where present; Upper Glacial Aquifer elsewhere.

Bedrock observed at the Site is the Fordham Gneiss, which is described as a metamorphosed, medium to coarse-grained igneous rock unit of Precambrian Age (P.C. Brock and P.W.G. Brock, 2001). Regional down-warping of bedrock beneath the Site and the vicinity has resulted in a southeast-dipping bedrock surface (EPA, 2003; Cartwright, R.A., 2002).

2.2 Assumptions General assumptions inherent to MODFLOW are:

. Groundwater flow occurs within a three-dimensional heterogeneous, anisotropic, saturated porous medium. . Groundwater flow is laminar. . Groundwater is incompressible.

Assumptions used in the development of the groundwater model that are specific to the Site are:

. Groundwater flow conditions are at steady-state for calibration purposes. . The calibration data set and interpreted groundwater flow directions and gradients represent conditions typical of long-term present-day conditions, and are adequate for evaluation and comparison of potential future remedial alternatives. . The calibration data set is assumed to represent mid-tide conditions. For model calibration purposes, groundwater levels taken at high and low tides were averaged to represent a mid-tide level. Tidal fluctuations in ground water were measured during the 2005 Carroll Gardens/Public Place RI and during the 2010 Gowanus Canal RI. Tidal fluctuations adjacent to the canal were assumed to not affect net long-term flow directions or discharge rates to the canal.

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. To model the net long-term effect of the canal surface elevation on groundwater, the head boundary within the canal, Gowanus Bay, and the East River was assumed to be Mean Sea Level. . The calibration data set includes water level elevations taken during the 2005 Carroll Gardens/Public Place RI and during the 2010 Gowanus Canal RI. Several monitoring wells present in each respective investigation were not present during the other investigation; therefore, not all wells in the data set could be gauged during the same event. It is assumed that groundwater flow trends have remained stable over this period, and the calibration data set adequately represents steady state long term conditions at the Site for purposes of modeling the long-term effect of remedial systems on groundwater. . Each stratigraphic layer can be modeled as a homogeneous and horizontally isotropic unit, with the following localized variations in hydraulic conductivity - Fill material in the area of the canal consists of sand containing silt, debris, gravel, and buried structures. It is assumed that the net effect of this condition can be represented as zones with varying hydraulic conductivity. - The hydraulic effects of inter-bedding (e.g. sand inter-bedded with layers of silt) within each layer can be approximated in the model by assigning a vertical anisotropy to hydraulic conductivity values. . Temporary variations in canal surface water elevations due to combined sewer overflow (CSO) discharges were assumed to not affect the long term static conditions present within the aquifer system. . It is assumed that bedrock is impermeable and contributes no significant groundwater flow or pressure head to the overburden aquifers modeled.

2.3 Model Grid The model is comprised of a grid 18,400 by 25,250 feet (3.5 by 4.75 miles) in area with depths ranging from 100 to 250 feet deep as defined by the top of the Fordham Gneiss (Figures 2-5, 2- 6, and 2-7). Horizontal grid spacing ranges from 23 to 32 feet on site and 460 to 630 feet off site. The grid was designed so that approximately 100-foot-wide canal would have at least five model cells across its width to model partial dredge or cap scenarios. Vertical grid layer thicknesses ranges from 1 to 108 feet, as defined by the stratigraphic units described in Section 2.1. A zone of inactive cells was assigned in the northeast corner of the model to represent a groundwater divide as described in Section 2.4.4.

The model grid is defined in North American Datum (NAD) 1983 New York State Plane East. The model axis is rotated 42.5 degrees east of north. The model axis was rotated so that the canal alignment was approximately parallel to the Y-axis.

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Model layer elevations were defined by mapping the observed top and bottom elevations of each stratigraphic unit. For discontinuous units, dummy layer elevation points were assigned for numerical layer continuity where the geological unit is absent. The point elevations were imported to MODFLOW to define the numeric layers by interpolation.

2.4 Boundary Conditions Boundary conditions were assigned to represent the sources and sinks sources described in Section 2.1 (regional aquifers, canal, utilities, and recharge).

2.4.1 Constant Head Boundaries Constant head boundaries (CHBs) were assigned along the model limits to represent surface water, and the interface with the surrounding regional aquifer system in areas where divides were not considered to be present. Groundwater divides are described in Sections 2.1 and detailed in Section 2.4.4. CHBs consist of potentiometric head elevations assigned to specific cells in the model. Groundwater can flow into and out of CHB cells, depending upon whether the neighboring groundwater is under a higher or lower potentiometric head, respectively.

Constant head cells were assigned in Layer 1 with head values at elev. 0.0 NAVD (Mean Sea Level) within the Gowanus Canal, Gowanus Bay, and the East River (Fig. 2-8). CHB cells allow groundwater to enter the canal vertically from cells representing sediments and the underlying aquifer, and horizontally from fill through the bulkhead wall boundary.

A CHB was assigned along the southeastern model boundary in Layer 4 (Upper Glacial Aquifer) to represent a southerly component of flow toward Gowanus Bay consistent with regional trends. A linear gradient was ranging from head elevation 1.0 to 6.75 NAVD was assigned where shown in Figure 2-8.

CHBs were assigned at the northern and southern extents of the model in the Jameco Gravel layer (Layer 7) to represent flow to and from the regional aquifer. The USGS contours (Fig. 2-3) indicate potentiometric heads in the Jameco Gravel at the northern and southern model limits of approximately 7 and 5 NAVD, respectively. CHBs of 7 and 5 were assigned in the Jameco Gravel near the northern model limit (south of the inactive zone) and the southern model limit, respectively, where shown in Figure 2-9.

2.4.2 Recharge Four aquifer recharge zones were established for the model, to represent variations in ground cover (Fig. 2-10). Aquifer recharge was set at:

. Commercial/Industrial 4 inches/year . Urban Residential 7 inches/year

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. Urban Undeveloped 9 inches/year . Parkland 10 inches/year

The modeled recharge rates are consistent with estimated recharge rates for urban areas in the northeastern United States. Recharge in undeveloped areas of Long Island was estimated to equal about 50 percent of mean annual precipitation, but recharge from precipitation in the highly urbanized and industrialized areas of Kings and Queens Counties is reported to be far less because the large amounts of impervious surfaces impede infiltration (Cartwright, 2002). Buxton and Shernoff (1995) reported an annual recharge for Kings County of 15 percent of precipitation. Average annual precipitation for the New York City area for the years 1961 through 1991 was reported to be 40 to 50 inches per year [USGS, 2005]. Fifteen percent of annual precipitation would yield 6 to 7.5 inches/year of recharge to the aquifer system. Recharge rates in the model vary relative to the reported county-wide values to reflect local changes in infiltration rates based on ground cover. Other values reported from studies of urban areas in the region are similar, where recharge in urbanized areas near Pennsauken, New Jersey, and Allentown, Pennsylvania, were reported to range from 0 to 9 inches per year, and 0.11 to 11 inches per year, respectively [New Jersey Department of Environmental Protection (NJDEP), 2000; USGS, 2008].

2.4.3 Drains/Utilities Drains and utilities can affect the water table by infiltration or exfiltration. Infiltration may include leakage of groundwater into utility conduits beneath the water table (leaking pipes, coarse trench backfill, or bedding material). Exfiltration includes leakage from water or sewer mains. Two areas of infiltration were included in the model: drainage within the filled-in inlet and wetlands around Wallabout Bay, and a sewer main along DeGraw Street near 3rd Avenue (Fig. 2-8). Infiltration is modeled as “drain” cells with assigned head elevations, where surrounding groundwater at higher head elevations can enter the drain cells, causing a flow gradient toward the drain cells.

Within the Wallabout Bay/Navy Yard area, a drain boundary was included to represent drainage occurring within a backfilled former inlet and wetlands. The lower observed water table near Wallabout Bay may also be a result of higher-conductivity fill in the area allowing the water table to equalize with surface water elevations in the East River. The drain cells were assigned an elevation value of 1.0 NAVD, to represent the water table approaching sea level in the area. Drain cells would have the same effect on regional flow in the model as relatively high conductivity fill in the area, which is to create a groundwater divide north of the canal.

Groundwater elevations in three monitoring wells near a 36-inch sewer along DeGraw Street were relatively low, based on observed drawdown trends. Groundwater elevations observed at monitoring wells FW-MW05, MW-MW5R, and FW-MW12 approach elevation 4 NAVD,

8 GROUNDWATER MODEL REPORT NATIONAL GRID GOWANUS CANAL SUPERFUND SITE DECEMBER 2011 indicating a relatively flat water table along DeGraw Street. A line of cells was assigned an elevation value of 4.0 NAVD along the segment of DeGraw Street shown in Figure 2-8, to represent drainage into the sewer.

Infiltration/exfiltration is common in urban areas, and is expected to occur throughout most of the model area. USGS reports that aquifers in urban areas may gain 3 inches per year as artificial returns. Other than Wallabout Bay and the DeGraw Street sewer, no evidence of relatively high infiltration or exfiltration was apparent in the model area, based on observed groundwater elevations. It is assumed that background levels of infiltration/exfiltration are uniformly distributed within the model. Background levels of infiltration would be accounted for in the model as part of the calibrated hydraulic conductivity values in fill. Background levels of exfiltration would be accounted for as part of the calibrated areal recharge rates.

2.4.4 No-Flow (Inactive) Boundaries No-Flow (Inactive) boundaries are located at the model limits where no head boundaries are present, and at the base of the model. At the model limits and the base of the model, where head boundaries are not present, no groundwater flow occurs in or out of the model. Flow occurs parallel to or radially outward from the inactive boundaries.

The western model limit is inactive, where outward (easterly) flow occurs because recharge accrues along the model limit and can only flow parallel to or away from the model limit. Along the eastern model limit, groundwater flows radially outward, representing regional flow as shown in Figure 2-3. Along the northern model limit, flow is generally outward, representing regional flow toward Wallabout Bay. The northeastern corner of the model is inactive, to represent a regional divide to the north. Groundwater north of the model flows north or northwesterly away from the terminal moraine, towards the East River or the Newtown Creek basin.

The western, northwestern, and southwestern portions of the model located within Gowanus Bay, the East River, Governor’s Island, and Manhattan are inactive boundaries. Groundwater elevations in these areas of the model are controlled by the constant head boundaries representing surface water. Groundwater flows outward from these boundaries toward the East River. The East River is assumed to be a groundwater divide. The southern model boundary within Gowanus Bay and the lower East River was placed far enough from the canal such that any sea bed discharges from the Site occurs within the model.

Bedrock is modeled as an inactive boundary. The top of bedrock comprises the base of the model. Bedrock is considered to be a relatively impermeable crystalline metamorphic rock, with water contained in joints and fracture zones (USGS, 1998). Groundwater flow occurs along or upward from the base of the model, driven primarily by head boundaries assigned in the Jameco Gravel.

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2.4.5 Bulkheads Bulkheads along the Gowanus Canal may inhibit groundwater flow to and from the canal, where the bulkhead materials are less permeable than the adjacent upland soil. Bulkheads along the canal are modeled as Horizontal Flow Boundaries (“wall” boundaries). Wall boundaries were placed in the model between cells representing the canal (and sediments), and cells representing upland soil. Hydraulic conductivities were assigned to the bulkhead, and adjusted as calibration parameters.

The bulkhead boundary structure relative to the canal and sediment model cells is illustrated in Figure 2-11. Groundwater enters the canal by three mechanisms:

. Upland of the canal above the mudline elevation, groundwater flows horizontally from fill adjacent to the bulkhead, through the wall boundary and into cells representing canal surface water. . Upland of the canal beneath the mudline elevation, groundwater can flow horizontally from marsh deposits through the wall boundary, then into cells representing sediments, then upward into cells representing canal surface water. . Beneath the canal sediments, groundwater from the regional aquifer can flow upward through the sediments then into cells representing surface water.

Groundwater entering CHB cells exit the computational model. The flow rate into the canal as calculated by MODFLOW represents the model-calculated estimate of groundwater flow from the aquifer system to the canal.

The bulkheads along the canal are constructed of various materials and include timber cribbing, timber sheet piling, riprap embankments, and steel sheet piling (NEA, 2004). The bulkhead conductivities assigned in the model represents the net effect of three processes potentially occurring along the bulkhead:

. Groundwater leakage through cribbing, between timbers, and through sheet pile joints. . Decreases of leakage due to siltation within the bulkhead, and increases of leakage due to channeling or washing out of silt or fine-grained material. . Increase of leakage due to potential historic removal or partial removal of marsh deposits during bulkhead construction.

Hydraulic conductivities for the bulkhead were assigned during the calibration process. During model calibration, bulkhead hydraulic conductivities were adjusted so that the model-calculated heads for monitoring wells screened in fill near the canal matched the observed heads. Bulkhead conductivities in the model range between 0.001 and 10 ft/day. Figure 2-12 depicts the modeled bulkhead conductivity in plan view.

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In general, observed heads in shallow wells near the bulkheads ranged from elevation 2 to 3, indicating moderate resistance to flow toward the CHB of zero NAVD water-side of the bulkhead (Fig. A-2). Figure 2-11 illustrates idealized water table behavior relative to bulkhead conductivity. Shallow wells adjacent to the bulkhead with lower observed head elevations (1 to 2 ft NAVD) and strong tidal response, where the marsh deposit aquitard is present, indicate a higher-permeability bulkhead.

2.4.6 Supply Pumping No supply pumping was included in the model. Roux Associates, Inc. (1990) reported that there are no public or private water supply wells within a 3-mile radius of the Citizens Former MGP site. The NYSDEC Phase II Report prepared by Roux Associates, Inc. cites the New York State Department of Health (NYSDOH) New York State Atlas of Community Water Systems Sources 1982 as the source of this information. A USGS model for water supply pumping on Long Island indicates that ongoing subway tunnel dewatering occurs in the area of downtown Brooklyn, near the northern model boundary (USGS, 1998). The subway system is located outside the zone of groundwater contribution to the canal (Section 6.1.2). Model calibration is not sensitive to localized drawdown in the area of reported dewatering. USGS (1998) reports that ongoing supply pumping in Kings and Queens counties presently occurs in eastern areas of the counties, outside the model area to the north and northeast.

2.5 Hydraulic Conductivity Hydraulic conductivities were assigned to each stratigraphic unit as listed in Table 2. The spatial location of assigned hydraulic conductivities for each layer are shown in Figures 2-13 through 2-20. Figure 2-21 is a cut-away view showing the model structure with conductivity zones along the canal. Cross-sections of the model showing hydraulic conductivity zones are shown in Figures 2-22 and 2-23. Hydraulic conductivities were selected based on slug test results, published values for the regional formations, published ranges for the observed soil types [Anderson, 1992; USGS, 1999], and calibration of the model to observed water level elevations. Hydraulic conductivity values used in the model are listed with slug test results and published values in Table 2. In general, the water table mounding and variability in water level elevations in the shallow groundwater zone on Site is attributed to a combination of areal recharge, fill heterogeneity, and variability in bulkhead permeability along the canal. In the intermediate and deep zones of the Upper Glacial Aquifer, and within the Jameco Gravel, less spatial variability was observed in observed potentiometric heads (e.g. a flatter potentiometric surface was apparent), indicative of relatively higher permeability soil.

2.5.1 Fill/Shallow Sand The area of the Gowanus Creek was artificially filled as part of the construction of the Gowanus Canal in the 1860s. In the area of the canal, above the marsh deposits, fill consists of

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loose, non-cohesive silt, sand and little gravel mixed with brick, concrete, coal, wood, metal, ash, and clinkers. Within portions of the Citizens Former MGP site, fill also contains concrete debris and foundation remnants from the former facility. We assumed that fill within other industrialized areas within the model are of a similar nature, and that in residential areas, fill is comprised mainly of reworked native sand. At relatively high topographic elevations including Cobble Hill and Prospect Hill, the nature of the fill within the model is not significant because fill would be located above the water table.

A uniform hydraulic conductivity of 10 ft/day (horizontal) and 1 ft/day (vertical) was assigned to most of the upper layer of the model to represent fill, or the upper fringe of native soil outside the limits of the filled-in former wetlands complex. Localized areas of fill, referred to herein as subunits, near the canal were assigned different conductivity values during model calibration (Section 3.1). Hydraulic conductivities assigned to the subunits range from 0.1 to 35 ft/day. The conductivity values used are consistent with literature values for soil ranging from silty sand to medium-coarse sand (Anderson, 1992). The lower values reflect areas where higher water table elevations were observed, where the rate of groundwater travel is relatively limited due to lower hydraulic conductivity. The higher values reflect areas where the observed water table is flatter, because water can easily travel between the gravel particles. As a result, groundwater elevations within relatively coarse material tend to equalize with potentiometric heads at downgradient discharge points, and the water table becomes relatively flat. In addition to the fill subunits in Layer 1, an apparent till deposit north and northeast of the canal was assigned a lower conductivity value as described in Section 2.5.3.

2.5.2 Marsh Deposits/Sediments Marsh deposits consisting of silt, clay, peat, and sand are represented in the model within former wetland areas. Prior to development, wetlands were located around the Gowanus Canal, the southern end of the Red Hook neighborhood, and Wallabout Bay, as shown in Figure 2-4. The modeled extent of silt/peat marsh deposits shown in Figures 2-14 and 2-15 can be compared to the mapped extent shown in Figure 2-4.

The marsh deposits are modeled as a semiconfining unit with relatively low hydraulic conductivity. Water table elevations above the marsh deposits (potentiometric heads ranging in elevation from 3 to 10 ft.) are higher than the potentiometric surface beneath the marsh deposits (elevation heads approximately 1 to 3 ft.). The generally higher overlying water table elevation is indicative that the marsh deposits function as a semiconfining unit. The absence of the water table mound outside the marsh deposit footprint (the northwest corner of the Citizens Former MGP site and the southwestern area of the Fulton Works Former MGP site), suggests that recharge retained above the marsh deposits contributes to the formation and stability of the higher water table.

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Canal sediments include soft recent organic deposits and, where present, underlying native silt and peat. In the model, the sediment column is represented as a single layer. Model cells within the sediment layer were assigned hydraulic conductivity values that were determined based on presence or absence of underlying native silt and peat, and whether evidence of local groundwater upwelling was apparent based on potentiometric heads in adjacent wells screened in the Upper Glacial Aquifer. Evidence of local groundwater upwelling was considered to be apparent at locations where observed potentiometric heads within the Upper Glacial Aquifer were relatively low.

Sediment core data indicates that marsh deposits are variably present beneath the canal (Figure 2-11) [GEI, 2009; EPA, 2011]. Native silt and peat was generally present beneath the southern two-thirds of the canal (south of 3rd Street). The silt and peat was absent in borings beneath the canal North of 3rd Street, adjacent to the Red Hook area, and near 4th Street. The areas where native peat and silt are absent were assumed to have been removed by dredging. In the three areas where native peat and silt are absent, the potentiometric surface in the Upper Glacial Aquifer was observed to be relatively low, below elevation 2.0 in some monitoring wells. The potentiometric surface in the Upper Glacial Aquifer observed along the remainder of the canal was generally observed to be between 2.0 and 2.5 NAVD.

Hydraulic conductivity values were assigned based on the presence or absence of silt and peat below the soft sediments, and indications of upwelling based on potentiometric heads in monitoring wells adjacent to the canal. The following sediment hydraulic conductivities were assigned in the model:

Marsh deposits present, no evidence of local upwelling: 0.01 – 0.1 ft/d Marsh deposits present, evidence of local upwelling: 0.5 ft/d No marsh deposits present: 4 – 40 ft/d

The above values are typical for fine-grained soil, but are higher than those used for marsh deposits in the model. Channeling may occur on a smaller scale through low-permeability silt and peat due to upward hydraulic pressure and erosion as a result of long-term upward discharge.

2.5.3 Upper Glacial Aquifer The Upper Glacial Aquifer is the predominant geologic unit through which groundwater flows within the model. In the model, all groundwater flow toward the canal passes at some point through the Upper Glacial Aquifer, except for shallow recharge above the marsh deposits that may discharge to the canal laterally through bulkheads. Within the model area, the Upper Glacial Aquifer is predominantly comprised of sandy glacial outwash occasionally containing silty sand or interbedded with clayey till, but also contains two subunits containing predominantly till. Cartwright (2002) reports that the Upper Glacial Aquifer has a relatively

13 GROUNDWATER MODEL REPORT NATIONAL GRID GOWANUS CANAL SUPERFUND SITE DECEMBER 2011 high but locally variable permeability, and that the aquifer is generally unconfined but is confined locally by layers of silt and clay within moraine deposits. The Site is located at the western terminus of the east-west trending Ronkonkoma-Harbor Hill terminal moraine.

The Upper Glacial Aquifer is modeled primarily as a zone of uniform hydraulic conductivity where the aquifer is predominantly glacial outwash sand (40 ft/day horizontal and 4 ft/day vertical). Fetter (1994) reports a hydraulic conductivity range of approximately 3 to 300 ft./day for glacial outwash. The order of magnitude of the horizontal hydraulic conductivity in the model (40 ft/day) is in the approximate middle of the order of magnitude range reported by Anderson (1992) for clean sand, and at the high end of the reported range for silty sand. The hydraulic conductivity used for the Upper Glacial Aquifer is indicative of a productive aquifer and is consistent with its use historically as a water supply source. Wells in the area of the Site have been reported to yield between 60 and 300 gallons per minute (NYSDEC, 1937; NYSDEC, 1944). The maximum historic groundwater withdrawal rate reported for Kings County was 33 million gallons per day in 1910, at a time when the Upper Glacial Aquifer was the predominant source aquifer (Cartwright, 2002).

Extensive areas of till within the Upper Glacial Aquifer, referred to herein as till subunits, were modeled as zones of lower hydraulic conductivities (1 to 5 ft/day horizontal and 0.05 to 0.1 ft/day vertical). The till subunits (north and south subunits, Fig 2-17) are located at the base of the Prospect Hill moraine, and extends southeast of the canal. Thick till deposits were not observed at some shallow locations adjacent to the canal, between the east and west zones, and may represent a scour zone ancestral to the Gowanus Canal. As a result, a gap in the till unit is apparent in model Layer 4 as shown in Figure 2-17, and the till unit remains continuous in Layer 5 as shown in Figure 2-18. The area between the two till subunits is comprised of interbedded sand and till similar to other locations within the aquifer.

Local variations in hydraulic conductivity within the Upper Glacial Aquifer may be caused by discontinuous silt/clay lenses. A 5:1 vertical anisotropy ratio was used to represent interbedded silt and clay within the sand unit, which would inhibit vertical groundwater flow. It is assumed that till lenses are uniformly distributed in the aquifer such that at the scale of the model, bulk horizontal and vertical hydraulic conductivity values for the upper glacial aquifer represent the combined effect of the outwash and till.

2.5.4 Gardiners Clay The Gardiners Clay is a major confining unit in the regional aquifer system, with hydraulic conductivities significantly lower than the adjoining sand and gravel units. The clay is a lagoonal marine deposit and consists of greenish-gray clay and silt with inter-bedded sand and sea shells. The Gardiners Clay has been observed to be comprised of silty sand at some locations near the fringes of the formation. The clay is reported to range in thickness from

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absent in northern Kings County to upwards of 100 feet to areas to the southeast and east of the Site (Cartwright, 2002).

The Gardiners Clay is present in the eastern two-thirds of the model area, and pinches out on the western edge where the bedrock surface approaches the relatively flat Gardiners Clay unit. The extent of the Gardiners Clay within the model was determined based on the approximate regional extent reported by USGS (2007) and soil boring logs from the Site and from USGS records. The Gardiners Clay was observed in the southern area of the canal (Site boring GCMW-40D2) as a 9.5-foot-thick layer of gray fine sand mixed with clay approximately 140 feet below ground surface. In the central area of the canal (Citizens Former MGP Boring CGMW-07D), the Gardiners Clay was observed as a 3.5-foot-thick layer of gray, very dense clay with shells, at approximately 130 feet below ground surface. Beneath the Fulton Works Former MGP site, the Gardiners Clay was apparent as silty sand with sea shells. The Gardiners Clay was found to be absent in some areas of the Citizens Former MGP site.

The Gardiners Clay is modeled in Layer 7. Layer 8 contains a thin line of Gardiners Clay to represent contact with bedrock at the base of the numerical model (Fig. 2-20). Discharge zones for the Jameco Gravel to the Upper Glacial Aquifer are present in Layer 8 where the Gardiners Clay is absent.

The Gardiners Clay was assigned a hydraulic conductivity of 0.008 ft/day, consistent with published literature, where the clay was reported by Franke and Cohen (1972) to have vertical hydraulic conductivity of about 0.001 ft/day. Sand zones at the fringes were assigned a vertical hydraulic conductivity of 0.2 ft/day.

North of the canal area, the Gardiners clay contacts bedrock, thus confining the underlying Jameco Gravel laterally. West and south of the canal area, no contact between the Gardiners Clay and bedrock was apparent based on available boring logs, suggesting no lateral confinement of the Jameco Gravel. Therefore, in the approximate southern half of the model, the Gardiners clay does not contact bedrock, forming a lateral discharge zone for the Jameco Gravel to the Upper Glacial Aquifer, as described in Section 2.5.5.

2.5.5 Jameco Gravel

The Jameco Gravel is described as a Pleistocene-era channel fill deposit associated with the ancestral Hudson River channel scour of southern Kings and Queens Counties (Soren, 1978; EPA, 2010b). The unit consists of dark coarse sand and gravel with cobbles and boulders and ranges in thickness from absent at some locations to approximately 200 feet thick in Queens County (Cartwright, 2002). The Jameco Gravel in the model has a horizontal hydraulic conductivity of 300 ft/day, consistent with published literature, where the Gardiners Jameco Gravel was reported by Soren (1978) to have vertical hydraulic conductivity of in exceedance of 270 ft/day. The approximate elevation of the surface of the Jameco Gravel ranges between

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–100 feet NGVD and –150 feet NGVD beneath the Site and vicinity and slopes toward the southeast (Buxton, Soren, Posner and Shernoff, 1981).

The extent of the Jameco Gravel is similar to that of the Gardiners Clay (Cartwright, 2002). In the model, the extent of the Jameco Gravel was assigned the same extent as the modeled extent of the overlying Gardiners Clay (Figs. 2-19 and 2-20). The Jameco Gravel is located between the Gardiners Clay and bedrock. The top and bottom elevations of the Jameco Gravel were assigned as to be bottom of Gardiners clay and top of bedrock, based on available borings and mapped USGS elevations.

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3. Calibration

The calibrated model provides a calculated steady-state groundwater flow field representing mid-tide groundwater elevations. The objectives of model calibration consisted of matching model-calculated heads to observed heads at monitoring wells; qualitatively matching model- calculated groundwater elevation contours to contours interpolated based on observed heads, and comparison of model-calculated base flow into the canal to a literature-reported value. The model was calibrated by soil, sediment, and bulkhead hydraulic conductivities, and areal recharge. The calibration data set is provided in Table 3. Observed and final (calibrated) water level elevations for each calibration point are shown in Table 3. Calibration residuals plots for the entire model, the Upper Glacial Aquifer, and the Jameco Gravel are shown in Figures 3-1 through 3-3. Calibration data points are shown in Figures A-1 through A-4. Model-predicted and observed (interpolated) contours are shown in Figures A-5 through A-9, where it should be noted that the model calculates groundwater elevations within the entire active model space, as compared to the observed contours which are only interpolated between observation points. Potentiometric head contours are shown in cross-section in Figures 3-4 and 3-5.

The calibration data set consists of tidally averaged static groundwater elevations for the Site and Former MGP gauging events, and single (non-tide specific) elevations for Parcel III of the Citizens Site and USGS monitoring wells. Groundwater elevations were measured at high tide in Site monitoring wells on July 26 and September 29, 1010; and at low tide on August 23 and October 22, 2010. Groundwater elevations were measured at both high and low tides on May 5, 2003, April 4, 2005, and April 11, 2005 at Citizens Former MGP monitoring wells. Tidal measurements were averaged as described in Table 3, and the average measured elevation for each monitoring well were used as calibration data points. For Citizens Former MGP Parcel III wells, readings from measurements taken October 24, 2008 were used. For wells in the USGS monitoring well network, the approximate average of elevations reported through the past decade were used as calibration data points. Groundwater elevations over time as reported by USGS are shown in Appendix A, Figure A-1.

The time-averaged groundwater elevations shown in Table 3 represent regional conditions for model development and calibration. Tidal variation (difference between average measured high tide and average measured low tide elevations in each well) wells ranged from 4.43 to - 3.5 feet, however, tide variation in most wells was less than 1 foot. The averaged high tide elevations were equal to or within 1 foot greater than the averaged low tide elevations at 108 of 200 measurement locations. The averaged high tide elevations exceeded the averaged low tide elevations (positive tidal response) by greater than one foot at 17 of the 200 locations, most located near bulkheads. At 75 of the 200 locations, the averaged low tide groundwater

17 GROUNDWATER MODEL REPORT NATIONAL GRID GOWANUS CANAL SUPERFUND SITE DECEMBER 2011 elevations were equal to or greater than the averaged high tide elevations by as much as 3.5 feet, where the exceedances are attributed to seasonal fluctuations.

Shallow zone monitoring wells exhibiting a strong positive tidal response were located close to bulkheads. Monitoring wells screened in the Upper Glacial Aquifer exhibiting a strong tidal response were located in areas with slightly lower observed tidally-averaged groundwater elevations (below elevation 2.0 NAVD) within the Upper Glacial Aquifer. The relatively strong tidal response and slightly lower potentiometric heads were interpreted to represent upward discharge zone areas, or areas where a relatively larger volume of water flows upward and discharges to the canal. Three such zones were apparent, and are described in Section 3.2.

The MODFLOW output calibration residuals plot for all data points in the model is presented in Figure 3-1. On the calibration plot it can be seen that high heads were predicted by the model where high heads where observed (at shallow depths within the mound on Parcel I) and low heads were predicted where low heads were observed (in intermediate/deep groundwater and along the canal). The primary statistical goal for model calibration was to obtain a normalized root mean square of the residuals of less than 10%. The normalized RMS for the model calibration is approximately 5.4%, which is well below this statistical objective, and thus shows that the model is well calibrated.

Calibration residuals plots for the Upper Glacial and Jameco Gravel are shown in Figures 3-2 and 3-3. The significant trends in the regional aquifers are being qualitatively met: upward preferential discharge zones with relatively low heads in the Upper Glacial Aquifer are represented by the lower observed and calculated heads (Fig. 3-2), while the remainder of the potentiometric surface within the Upper Glacial Aquifer on and near the Site is relatively flat, ranging primarily between elevations 2 and 3 NAVD. Similarly, the calibration residuals plot for the Jameco Gravel indicates that significant regional trends are quantitatively met in the model: groundwater elevations near discharge zones along the western fringe of the Gardiners Clay are generally lowest. A water budget is presented in Table 4. As shown in Table 4, the percent difference between calculated flow rates entering and leaving the model, for the calibration run and three predictive runs, are below 0.1%, which is considered generally acceptable. The model was run with head change and residual criterion between numerical iterations set to 0.01 feet.

USGS (1998) developed a regional model developed for assessing historic and current groundwater resource use on Long Island. In the USGS model a base flow of groundwater to the Gowanus Canal was estimated to be 1,122 GPM prior to industrial development, zero during aquifer recovery in 1983 (one to two decades after cessation of pumping), and 134 GPM as of 1991. The groundwater model described herein calculates a base flow to the canal of 675 GPM. The USGS model incorporates a coarser grid, where assumptions regarding the extent of the terminal moraine and Jameco Gravel are more generalized. Both of these model elements would affect estimates of net flow through the modeled systems.

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3.1 Shallow Zone Shallow zone model-calculated and observed (interpolated) contours are shown for the northern, central, and southern portions of the canal in Figures A-6 through A-8. Shallow groundwater elevations generally range from elevation 1 to 8 NAVD on properties adjacent to the canal. Calculated groundwater elevations were primarily affected by the hydraulic conductivity of fill material and sediments. Baseline hydraulic conductivities of 10 ft/day and 0.1 ft/day were used for shallow zone soil and bulkhead permeability, at the start of model calibration. The hydraulic conductivity values were varied locally to match observed conditions. A relatively high fill hydraulic conductivity value (35 ft/day) was assigned to areas where the water table was relatively flat. Relatively low (0.1 to 0.5 ft/day) hydraulic conductivities were assigned where steeper gradients were observed or where the groundwater table was relatively high. The baseline bulkhead hydraulic conductivity was increased in areas where observed groundwater elevations were relatively low (generally less than elevation 2 NAVD), or where relatively high positive tidal response was observed. Areal recharge was also adjusted as part of calibration refinement, to the values shown in Figure 2-10.

As shown in Figure A-6 through A-8, model-calculated groundwater elevations generally approximate the tidally-averaged observed elevations. At the former MGP sites, where there are a greater density of data, groundwater flow trends generally approximate observed flow directions and gradients. Further from the canal (outside the approximate extent of the marsh deposits), the water table is considered part of the Upper Glacial Aquifer for calibration purposes and is described in Section 3.2. Adjacent to the canal, shallow groundwater is mounded above the marsh deposit aquitard (where present) to elevations generally ranging from 1 to 4 NAVD. Groundwater preferentially flows toward the canal, with a relatively minor component of flow into the marsh deposits. At the Citizens Former MGP site, the water table mounds to approximately elevation 10. The mound is in the location of former gas holders and buried structures. Along the western extent of the mound, the shallow contours indicate that groundwater flows westerly, away from the canal. Once the mounded groundwater passes the western extent of the aquitard, it enters the Upper Glacial Aquifer and becomes part of the regional flow discharging to the canal further downstream from the Citizens MGP Former site.

3.2 Upper Glacial Aquifer Model-calculated and observed (interpolated) contours are shown for the Upper Glacial Aquifer on Figure A-8. Groundwater elevations generally range from elevation 2 to 3 at the Site, and up to elevation 10 north of the Site. Calculated groundwater elevations in the Upper Glacial layers were affected by the hydraulic conductivity of formation, sediment conductivity, and areal recharge. A baseline hydraulic conductivity of 40 ft/day was used for the Upper Glacial Aquifer permeability, at the start of model calibration, and was varied in specific locations as described below.

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Relatively high recharge over Prospect Park, and relatively low-permeability till west of Prospect Park (north till subunit, Fig. 2-17) contribute to the higher potentiometric surface in the eastern portion of the model. The potentiometric surface in the Upper Glacial Aquifer along the canal is relatively flat (generally between 2 and 3 NAVD) along the length of the canal, with three localized areas of lower potentiometric head (below 2 NAVD; Fig. A-8). The till subunits described in Section 2.5.3 were assigned lower hydraulic conductivity values. The presence of the south till subunit (Fig. 2-17) results in a slight increase in potentiometric heads near the lower third of the canal, while the absence of marsh deposits at the northern end of the canal contributes to a slight lowering of the potentiometric surface at the northern end of the canal. A relatively high fill hydraulic conductivity value (35 ft/day) was assigned to areas where the water table was relatively flat. Relatively low (0.1 to 0.5 ft/day) hydraulic conductivities were assigned where steeper gradients were observed or where the groundwater table was relatively high. The baseline bulkhead hydraulic conductivity was increased in areas where observed groundwater elevations were relatively low (generally less than elevation 2 NAVD), or where relatively high positive tidal response was observed. Localized zones of varying conductivity were assigned where potentiometric heads indicate the presence of increased or reduced upwelling (Fig. 2-17).

Model-calculated contours are compared with contours reported by Buxton and Shernoff (1997) for groundwater head elevations within the Upper Glacial Aquifer on Fig. A-8. Groundwater flow is shown to flow outward (westerly) from the eastern divide and southerly from areas of downtown Brooklyn and Cobble Hill, converging to the canal, Gowanus Bay, and the East River. The three upwelling zones in the northern, central, and southern portions are indicated by the elevation 2 contours. An offset between the observed and calculated contours for the central upwelling area is attributed to localized zones of channeling. The regional contour reported by Buxton and Shernoff representing elevation 5 NAVD is largely inferred, and no data points support the exact location of the reported contour. The model- calculated contours are considered validated and consistent with Buxton and Shernoff.

3.3 Jameco Gravel Model-calculated and observed (interpolated) contours are shown for the Jameco Gravel on Figure A-9. Groundwater potentiometric heads in the Jameco Gravel range from elevations 5 and 8 NAVD as defined by the CHBs described in Section 2.4.1. Calculated groundwater elevations in the Jameco Gravel were affected by the presence and location of zones of hydraulic communication between the Jameco Gravel and Upper Glacial Aquifer. As can be seen in Figure A-9, a major component of groundwater flow in the modeled Jameco Gravel is westerly, towards discharge zones and preferential flow paths through relatively thin deposits of the Gardiners Clay where the clay pinches out at its western limit. At the western model boundary, groundwater flow becomes more southerly, consistent with regional flow depicted in Figure 2-3. Comparison of model-predicted contours in Figures A-9 and A-10 shows that potentiometric heads within the Jameco Gravel (model layer 7) are higher than those shown in

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Figure A-9 for the Upper Glacial Aquifer (layer 4), indicating a general upward vertical head potential consistent with observed heads.

3.4 Sediments/Marsh Deposits Canal sediment hydraulic conductivity, including underlying native marsh deposits (where present), primarily affects upward flow from the underlying Upper Glacial Aquifer. Sediment hydraulic conductivities in the model (layer 3, Fig. 2-16) represent a weighted average of soft sediments and native marsh deposits. A baseline hydraulic conductivity of 0.5 ft/day (vertical) was used for the sediment permeability, at the start of model calibration. Four additional conductivity zones were created, to represent locations where marsh deposits are absent beneath the canal, and areas where sediment conductivity appears to be lower, based on relatively higher potentiometric heads in nearby wells screened in the Upper Glacial Aquifer. Along a portion of the canal adjacent to the Citizens Former MGP site, the canal is actively used for barge docking. Gravel with little to no soft sediment, and no marsh deposits are present. In the barge docking area, the same conductivity value used for the Upper Glacial Sand was used in layer 3 to represent a sediment layer with little to no resistance to upward vertical flow from the aquifer.

Marsh deposits in the model primarily affect the extent and degree of water table mounding or perching in overlying fill. A baseline vertical hydraulic conductivity of 0.5 ft/day was used for the sediment permeability, at the start of model calibration. Three minor areas of varying marsh deposit conductivity were defined, to refine calibration at individual shallow groundwater data points indicating that marsh deposit conductivities may be lower or higher.

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4. Sensitivity Analysis

An analysis was performed to evaluate the sensitivity of hydraulic conductivities and recharge rates on model calibration. These parameters would have the greatest effect on modeled groundwater flow at the Site. The analysis was performed by comparing the change in calibration residuals with changes in hydraulic conductivity and recharge. Calibration error, as measured by the normalized root mean square (NRMS) of the calibration residuals (calculated minus observed heads) for the sensitivity runs are shown in Figures 4-1 through 4-3. The NRMS is a measure of the correlation between observed and predicted heads. In general, the NRMS varies as the parameters change, and the lowest NRMS value corresponds to the most accurate parameter value for the model. Therefore, as the parameter is varied further from its most accurate value, the NMRS increases, and the plot of NRMS vs. parameter value would be a curve where the low point corresponds to the value most appropriate for use in the system modeled. However, if the calibrated model is not sensitive to a parameter, the NMRS may not change, and a sensitivity analysis for the subject parameter would be recommended for the predictive model.

Hydraulic conductivity for key strata in the model (fill, marsh deposits, sediments, and glacial sand, and the till subunits) were increased and decreased to values within ranges reasonable for the soil type. Calibration was most sensitive to variation in sediment and glacial sand conductivity, because changes in these units affect a large number of data points.

The recharge rate for each recharge zone in the model was varied over a range of several inches, depending on effect. The model was roughly equally sensitive to changes in the commercial/industrial, residential, and undeveloped areas. The NRMS was not significantly affected by changes in the recharge value used for parks; however, the model was qualitatively affected in the eastern portion of the model where no data points exist. The water table elevation along the eastern site boundary was sensitive to recharge applied to Prospect Park, and a recharge value of 10 in./year was selected because it resulted in the approximate water table elevation reported by USGS in the area. Based on the quantitative sensitivity analysis results shown on Figures 4-1 through 4-3, and qualitative model calibration where no data points exist, the most accurate input parameter values were used in the model.

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5. Validation

Confidence that a model calibration is uniquely correct can be improved (although never fully achieved) if the model can be shown to adequately predict water levels and other calibration targets, such as groundwater discharge rates, for a wholly different set of hydrogeologic stresses than the steady-state conditions to which the model has been initially calibrated. Examples of a different set of hydrogeologic stresses include a major aquifer test that stresses a significant portion of the model or a period of drought. This process is often referred to as “verification” or “validation.”. Toward this end, an analysis was performed to assess that the model properly calculates past observed changes in groundwater elevations due to historic events. Available data indicate that periods of historic pumping and lower precipitation resulted in lower potentiometric surfaces within the Upper Glacial Aquifer.

5.1 Water Supply Pumping The public water supply is currently provided to the Site and surrounding area by the New York City Water Department. The water supply comes from a series of aqueducts from a watershed located 125 miles north of New York City.

Historic pumping for previous water supply purposes resulted in significant drawdown of the regional aquifer system, which has recovered since pumping ceased between the 1960s and 1970 (Cartwright, 2002). The water table was reported to have been decreased to as low as elevation -35 in some areas, or about 37 feet below its current potentiometric surface. The model was used to assess whether pumping from known wells within the model at their reported yield would produce drawdowns equal to or less than those reported by Cartwright (2002) for the year 1951. Although not a perfect simulation since a majority of pumping occurred outside the model boundary a model-calculated drawdown with partial pumping that is less than the observed drawdown under full pumping conditions represents a validation of the model’s predictive abilities.

Several pumping wells were located within the model limits and have been documented by the USGS (Figure 5-1). Pumping from a subset of these wells at their reported yield (14 wells for a total of 3,656 GPM (5 Mgal/day)) was modeled at steady-state to assess whether the model- predicted drawdown is within range of reported historic drawdowns. Wells close to the model limits were not included in the validation to avoid boundary effects. The model calculated drawdowns to elevation -5 within the immediate vicinity of the wells, and a larger zone of 2 to 4-foot drawdowns extending approximately one-half mile from the wells (Fig. A-11). Historically-reported drawdowns were deeper and widespread in these areas (elevation -15 to - 25 NAVD). The model-predicted drawdown under partial pumping conditions was less than

23 GROUNDWATER MODEL REPORT NATIONAL GRID GOWANUS CANAL SUPERFUND SITE DECEMBER 2011 the observed drawdown under full pumping conditions. The comparatively lower drawdown calculated by the model represents a validation of the model’s predictive abilities.

5.2 Reduced Precipitation Historical data indicate that an extended period of reduced groundwater recharge occurred between approximately 1999 and 2003. USGS long-term monitoring data indicate a 1.5 to 2- foot decrease in groundwater elevations within the Upper Glacial Aquifer in several observation wells during this period (Fig. A-12). Meteorological data suggests that an extended period of rainfall generally below the annual average, a reduction in rainfall events exceeding 0.1-inches (0.1-Years), and below-average snowfall, are contributing factors (Fig. 5-2). Observed drawdowns, based on an estimation of an annual average elevation over the affected period shown for area wells in Figure A-1, are shown in Figure A-11. No spatial variation in trends was apparent that would suggest an artificial localized source of drawdown.

From Figure 5-2, an extended approximate 10% decrease in days with rainfall exceeding 0.1- inches is apparent, and a 10 to 30% decrease in snowfall is apparent. We assumed that the aquifer was at steady state during the period of reduced precipitation. Model-calculated drawdown contours with a 20% reduction in annual recharge are shown for the Upper Glacial Aquifer (model layer 4) on Figure A-12. The drawdown contour values are relative to the steady-state potentiometric surface for layer 4 in the calibrated model. The model predicted drawdown ranges of between 0.2 and 1.8 feet, which is consistent with the observed values. The pattern of greater drawdown within eastern portions of the model was similar to the observed pattern of drawdown. The similarity between model-predicted and observed drawdown associated with reduced recharge is considered a validation of the model’s predictive abilities.

24 GROUNDWATER MODEL REPORT NATIONAL GRID GOWANUS CANAL SUPERFUND SITE DECEMBER 2011

6. Findings and Recommendations

6.1 Findings

A groundwater flow simulation model was constructed to quantify the regional aquifer system contributing to the Gowanus Canal. Findings presented in this section consist of model- calculated estimates of base flow from the aquifer system to the canal, and delineation of the estimated area of groundwater contribution to the canal.

6.1.1 Base Flow Estimate Base flow estimates were calculated to support human health and ecological risk assessments associated with the canal and adjacent upland sites, to provide input data for hydrodynamic analysis of flow within the canal, and for use in evaluating potential remedial alternatives for the Site.

Base flow estimates were calculated using the Zone Budget interface of Visual MODFLOW. For the purpose of estimating base flow, the canal was divided in to six segments. For each segment, zone budget cells were assigned within, alongside, and beneath the canal, to quantify both horizontal contribution through bulkheads, and vertical contribution from the regional aquifer. The estimated base flow is presented in Figure 6-1.

6.1.2 Groundwater Contribution Area The zone of contribution of groundwater to the Gowanus Canal was estimated for purposes of identifying resources that may be affected by remedial alternatives or that may affect the potential alternatives. The zone of contribution was estimated using particle flow paths calculated by MODFLOW. The contribution area for the Upper Glacial Aquifer is estimated to be 2.8 square miles as shown in Figure 6-2. The area of shallow zone contribution would be similar, because shallow zone and the Upper Glacial Aquifer water table surface are identical outside the former marsh deposit area, as described in Section 3.1.

6.2 Recommendations

The groundwater model is provided for use in evaluation of potential remedial alternatives within the canal and abutting upland sites. The groundwater model as described herein is a representation of regional flow. The model was calibrated to match groundwater elevations at locations of existing wells, and to match published regional groundwater flow patterns. The model has been validated and is generally suitable for use in evaluating interactions of remedial components on a comparative and holistic basis. At former MGP locations with a

25 GROUNDWATER MODEL REPORT NATIONAL GRID GOWANUS CANAL SUPERFUND SITE DECEMBER 2011 greater density of calibration data, the model may be used for more detailed remedial design evaluations. For potential remedial scenarios at specific properties where data are sparse, additional detail and a refinement of calibration in the area of concern may be appropriate to understand and adequately model site-specific conditions.

Potential remedies that may be modeled are described below, followed by recommendations for interpretation of results:

. Dredging: Dredging programs that involve removal of native silt and peat deposits may alter upward flow patterns to the canal and therefore be increasing hydraulic communication between the canal and the Upper Glacial Aquifer. The impacts of potential dredging projects may be modeled by increasing the hydraulic conductivity of the sediment layer in the proposed dredging areas. . Sediment Capping or In-Situ Stabilization/Solidification: Sediment capping using impervious or low-permeability material, or in-situ stabilization/solidification resulting in a lower sediment hydraulic conductivity than the existing sediments and underlying marsh deposits, may cut off or deflect upward flow of groundwater to the canal. The impacts of sediment capping or in-situ stabilization/solidification may be modeled by decreasing the hydraulic conductivity of the sediment layer in proposed capping areas. . Bulkhead Improvements/Cutoff Walls: Reconstruction of bulkheads or installation of groundwater or Non-Aqueous Phase Liquid (NAPL) cutoffs may be modeled by reducing the hydraulic conductivity of the wall boundary in the affected area. The effect of cutoff walls of varying depths and types may be modeled. The depth of the cutoff wall should be extended to the appropriate layer in the model. . Remedial Excavation: Soil excavation and backfill with clean material may be modeled by changing the hydraulic conductivity within the excavation volume to a value representative of the backfill material. Excavation dewatering rates may be modeled using drain cells or pumping wells; likewise, excavation support may be modeled as wall boundaries. . Pavement Caps or Impervious Liners: Capping or lining of an upland site may be modeled as areas of reduced areal recharge. . Groundwater Extraction: Groundwater extraction systems may be modeled as pumping wells. . Relief Drains: Relief drains are generally an ancillary component to remedial systems. Relief drains may be modeled as drain cells, or as cells of specified hydraulic conductivities connected to a head boundary or drain representing an outlet, filter media, or pump chamber.

26 GROUNDWATER MODEL REPORT NATIONAL GRID GOWANUS CANAL SUPERFUND SITE DECEMBER 2011

The model indicates that the canal is a significant discharge zone of groundwater from the regional aquifer. Changes in bulkhead or sediment hydraulic conductivity would affect groundwater flow directions and head elevations. Modeling should be performed at a minimum to quantify the potential for basement and utility flooding, and for the migration of dissolved contaminants to previously unimpacted areas. The effects of alternative remedial systems on groundwater hydraulics should be evaluated; including:

. Alteration of groundwater flow direction should be analyzed using particle flow paths and interpretation of model-calculated groundwater contours. . Water table mounding should be analyzed by interpretation of model-calculated groundwater elevation contours, and comparison of predicted groundwater elevation contours to basement and utility elevations. . The effect of remedial systems on base flow to the canal should be quantified using particle flow paths and zone budget. . The effect of remedial systems on the quantity of groundwater flow entering or exiting specific properties or areas of concern quantified using particle flow paths and zone budget. . The potential for NAPL migration should be assessed in part by mapping groundwater velocities. NAPL may be mobilized by shear or by significant changes in groundwater flow direction, and lower-viscosity NAPL would have a greater potential to be mobilized by changes in groundwater flow patterns. DNAPL (dense NAPL; or NAPL with a density greater than water) generally flows under its own gradient along confining units, and the use of calculated velocities to estimate the potential for DNAPL migration should be evaluated in consideration of the stability of the subject DNAPL pool. . The capture zone for extraction wells and funnel systems may be estimated using particle flow paths and model-calculated drawdown contours.

The model presented in this report quantifies flow under steady-state conditions. Predictions for potential remedial systems under steady-state are intended to represent the long-term hydraulic effects of the systems being modeled. Transient analyses also may be performed to assess the hydraulic effects of short-term changes in boundary conditions (like doing remedial construction) or temporally varying remedial systems such as cyclical pumping. Potential climatic effects on recharge and mean sea level may be evaluated by adjusting the appropriate boundary conditions. Sensitivity analyses are recommended to assess whether predicted results (with proposed remedial components in place in the model) change when model inputs (soil properties or boundary conditions) are varied within reasonable ranges. Safety factors should be incorporated into the design if predicted hydraulic effects could potentially exceed design tolerances. Monitoring programs should be implemented after remedial construction to confirm that water level elevations are within predicted ranges.

27 GROUNDWATER MODEL REPORT NATIONAL GRID GOWANUS CANAL SUPERFUND SITE DECEMBER 2011

References

Anderson, 1992. Applied Groundwater Modeling: Simulation of Flow and Advective Transport. Anderson M.P. and Wossner, W.W., Academic Press, Inc., 1992.

Brock, P. C. and P. W. G. Brock, undated. “Bedrock Geology of New York City: More than 600 m.y. of geologic history” Field Guide for Long Island Geologists Field Trip October 27, 2001”. Pp. 17. http://pbisotopes.ess.sunysb.edu/reports/NYCity/. Accessed September 16, 2003.

Buxton, H. T., J. Soren, A. Posner, and P. K. Shernoff, 1981. Reconnaissance of the Ground- Water Resources of Kings and Queens Counties, New York. United States Geological Survey Open-File Report 81-1186.

Cartwright, R. A., 2002. History and Hydrologic Effects of Ground-Water Use in Kings, Queens, and Western Nassau Counties, Long Island, New York, 1800s through 1997. United States Geological Survey Water-Resources Investigations Report 01-4096.

Fetter, 1994. Applied Hydrogeology, Third Edition. Fetter, C.W. Prentice-Hall, Inc., 1994.

Franke and Cohen, 1972. Regional rates of ground-water movement on Long Island, New York in Geological Survey Research 1972: U.S. Geological Survey Professional Paper 800-C, Franke, O.L., and Cohen, Philip, 1972.

GEI, 2005. Final Remedial Investigation Report, Carroll Gardens/Public Place, GEI Consultants, Inc., October, 2005.

GEI, 2007. Final Remedial Design Work Plan, Carroll Gardens/Public Place, GEI Consultants, Inc., September, 2007.

GEI, 2009. Gowanus Canal Superfund Site, Final Remedial Investigation Report, GEI Consultants, Inc., December 2009.

GEI, 2010. Groundwater Model Work Plan, Groundwater Model Work Plan, Brooklyn, New York, September 2010.

EPA, 2011 Gowanus Canal Remedial Investigation Report, Volume 1, Prepared for USEPA by HDR Engineering and CH2M Hill, January 2011

28 GROUNDWATER MODEL REPORT NATIONAL GRID GOWANUS CANAL SUPERFUND SITE DECEMBER 2011

EPA, 2010b. Brooklyn-Queens Aquifer System, statement in support of designation of areas dependent upon ground water supplies. USEPA Region 2, http://www.epa.gov/region2/water/aquifer/brooklyn/brooklyn.htm#I22 Updated October 5, 2010.

LIHJ, 2011. Brooklyn’s Thirst, Long Island’s Water: Consolidation, Local Control, and the Aquifer. J. A. Kroessler, Center for Global & Local History, Stony Brook University, NY, Winter 2011.

McDonald and Harbaugh, 1988. A modular three-dimensional finite-difference ground-water flow model, Techniques of Water-Resources Investigations 06-A1, USGS.

NEA, 2004. Final Report, National Register of Historic Places, Eligibility Evaluation and Cultural Resources Assessment for the Gowanus Canal, Borough of Brooklyn, Kings County, New York, in Connection with the Proposed Ecosystem Restoration Study. North. Prepared for U.S. Army Corps of Engineers. Northern Ecological Associates, Inc., May 2004 (Revised December 2004).

NJDEP, 2000. Ground-Water-Recharge Rates and Selected Open Space in the Rancocas, Pennsauken and Cooper Watersheds, New Jersey, Open-File Map OFM-32, Mark A. French and Jeffrey L. Hoffman, New Jersey Department of Environmental Protection, 2000.

NYSDEC, 1937. Record of Wells in Kings County, N.Y., State of New York Department of Conservation, by the United States Geological Survey, Bulletin GW-3, 1937.

NYSDEC, 1944. Record of Wells in Kings County, N.Y., State of New York Department of Conservation, by R.M. Leggette and M.L. Brashears, Jr., Bulletin GW-8, 1944.

Roux Associates, Inc., 1990. Engineering Investigation at Inactive Hazardous Waste Sites, Phase II Investigations, Carroll Gardens, Site No: 224012, Borough of Brooklyn, Kings County, Final – September 1990.

Soren, 1978. Subsurface geology and paleogeography of Queens County, Long Island, New York: U.S. Geological Survey Water-Resources Investigation Open-File Report 77-34, Soren, Julian 1978.

USACE, 2009. Water Resource Policies and Authorities Incorporating Sea-Level Change Considerations in Civil Works Programs, Expires 1 July 2011. U.S. Army Corps of Engineers, Circular No. 1165-2-211, July 1, 2009.

29 GROUNDWATER MODEL REPORT NATIONAL GRID GOWANUS CANAL SUPERFUND SITE DECEMBER 2011

USGS, 1987. Thickness and hydrogeology of aquifers and confining units below the upper glacial aquifer on Long Island, New York. Soren, J. and Simmons, D. L., United States Geological Survey, Publication No. 86-4175.

USGS, 1997. Water Table of the Upper Glacial Aquifer on Western Long Island, New York, in March-April 1997, R. Busciolano et. al., U.S. Geological Survey.

USGS, 1999. Simulation of Ground-Water Flow and Pumpage in Kings and Queens Counties, Long Island, New York, Water-Resources Investigations Report 98-4071, U.S. Geological Survey.

USGS, 2005. New York Average Annual Precipitation, 1961-1990, in National Atlas of the United States, http://nationalatlas.gov

USGS, 2008. Spatial Distribution of Ground-Water Recharge Estimated with a Water-Budget Method for the Jordan Creek Watershed, Lehigh County, Pennsylvania. Scientific Investigations Report 2008-5041, U.S. Geological Survey, 2008.

USGS, 2011. National Water Information System Map, http://wdr.usgs.gov/nwisgmap/ U.S. Geological Survey., accessed June 2011.

30 GROUNDWATER MODEL REPORT NATIONAL GRID GOWANUS CANAL SUPERFUND SITE DECEMBER 2011

Tables

Table 1 Soil Boring Log Summary Grounwater Model Gowanus Canal Superfund Site Brooklyn, New York

Observed Strata Break Elevations (ft. NAVD 88) Ground Bottom Boring/Monitoring Well Surface Borehole Top Marsh Bottom Marsh Top Upper Top Gardiner's Top Jameco Facility Easting Northing Top Bedrock Elevation of Location ID Elevation Depth (ft.) Deposits Deposits Glacial Sand Clay Gravel Boring (NAVD 88) Citizens Fmr MGP CG-MW01 631797 672021 29.59 157 N N 30 -105 -112 -- -127.41 Citizens Fmr MGP CG-MW02 632142 671726 13.56 130 -3 -12 -12 N P -- -116.44 Citizens Fmr MGP CG-MW03 631936 671620 15.93 149 -4 -19 -19 N P -- -133.07 Citizens Fmr MGP CG-MW04 632448 671754 9.87 137 -4 -12 -12 N P -- -127.13 Citizens Fmr MGP CG-MW06 631830 671211 10.54 140 -7 -16 -16 -116.5 138.5 -- -129.46 Citizens Fmr MGP CG-MW07 632274 671589 11.01 138 -9 -10 -10 117 -120.5 -- -126.99 Citizens Fmr MGP CG-MW08 631958 671278 9.55 138 -8 -24 -24 121.5 -- -- -128.45 Citizens Fmr MGP CG-MW10 632018 671569 12.45 48 -6 -16 -16 ------35.55 Citizens Fmr MGP CGP4SB-01 632326 671889 15 30 -4 -8 -8 ------15 Citizens Fmr MGP CGP4SB-02 632293 671826 13.5 30 -5.5 -10.2 -10 ------16.5 Citizens Fmr MGP CGP4SB-03 632250 671854 16 37 -7 -9 -9 ------21 Citizens Fmr MGP CGP4SB-04 632170 671899 19.5 40 0.2 -3.5 -4 ------20.5 Citizens Fmr MGP CGP4SB-05 632142 671933 22.25 50 N N 22 ------27.75 Citizens Fmr MGP CGSB-04 632016 671801 27.93 109 -4 -12 -12 ------81.07 Citizens Fmr MGP CGSB-05 631880 671837 29.93 79 -6 -8 -8 ------49.07 Citizens Fmr MGP CGSB-07 631809 671677 26.8 49 -5 -14 -14 ------22.2 Citizens Fmr MGP CGSB-08 632309 671606 19.53 39 -9 -19 -19 ------19.47 Citizens Fmr MGP CGSB-10 632140 671807 29.59 157 -4 -14 -14 -- -112.41 -- -127.41 Citizens Fmr MGP CGSB-105 632114 671659 19.5 27 -5.5 ------7.5 Citizens Fmr MGP CGSB-107 631720 671817 24.5 41 N -2.5 -3 ------16.5 Citizens Fmr MGP CGSB-108 631743 671892 28.25 41 N 0.25 0 ------12.75 Citizens Fmr MGP CGSB-109 631804 672036 29.5 42 N 2.5 3 ------12.5 Citizens Fmr MGP CGSB-110C/CGSB-110E 631901 671976 28.77 41 N -0.23 0 ------12.23 Citizens Fmr MGP CGSB-111/CGPZ-05 631972 671944 26.28 51 N -0.72 -1 ------24.72 Citizens Fmr MGP CGSB-112R/CGSB-112R2 632027 671889 26.53 51 N -5.47 -5 ------24.47 Citizens Fmr MGP CGSB-113 632123 671846 18.14 42 -4.86 -8.16 -8 ------23.86 Citizens Fmr MGP CGSB-114 632179 671798 16.12 42 -8.58 -9.88 -10 ------25.88 Citizens Fmr MGP CGSB-116/CGCPT-116 631984 671318 9.8 88 -4.2 -25.2 -25 ------78.2 Citizens Fmr MGP CGSB-117 632020 671793 26.94 87 -6.06 -12.06 -12 ------60.06 Citizens Fmr MGP CGSB-119 632158 671757 13.44 70 -6.56 -17.56 -18 ------56.56 Citizens Fmr MGP CGSB-120/CGCPT-120 631923 671233 9.76 100 0.76 -20.24 -20 ------90.24 Citizens Fmr MGP CGSB-121/CGSB-121R 631987 671323 9.78 101 -5.22 -17.22 -17 ------91.22 Citizens Fmr MGP CGSB-122R 632048 671415 9.64 100.3 -13.36 -21.36 -21 ------90.66 Citizens Fmr MGP CGSB-123/CGCPT-123 632116 671491 10.94 84 -5.86 -21.06 -21 ------73.06 Citizens Fmr MGP CGSB-124/CGSB-124C 632196 671551 13.65 67 -6.35 -18.35 -18 ------53.35 Citizens Fmr MGP CGSB-125 631955 671279 9.76 62 -4.24 -21.54 -22 ------52.24 Citizens Fmr MGP CGSB-126 632266 671585 11.5 91 -8.5 -27.5 -28 ------79.5 Citizens Fmr MGP CGSB-127 632355 671623 10.42 101.3 -8.58 -15.68 -16 ------90.88 Citizens Fmr MGP CGSB-128 632420 671649 9.21 59 -5.79 -10.79 -11 ------49.79

H:\WPROC\Project\NationalGrid\Gowanus - Confidential\GW Model Report\Submittal to EPA 12-2011\Tables\ Page 1 of 9 Tables Table 1 Soil Boring Log Summary Grounwater Model Gowanus Canal Superfund Site Brooklyn, New York

Observed Strata Break Elevations (ft. NAVD 88) Ground Bottom Boring/Monitoring Well Surface Borehole Top Marsh Bottom Marsh Top Upper Top Gardiner's Top Jameco Facility Easting Northing Top Bedrock Elevation of Location ID Elevation Depth (ft.) Deposits Deposits Glacial Sand Clay Gravel Boring (NAVD 88) Citizens Fmr MGP CGSB-129 632529 671648 7.8 65.6 -13.2 -21.2 -21 ------57.8 Citizens Fmr MGP CGSB-13 631936 671620 15.93 149 -17.07 -17 ------133.07 Citizens Fmr MGP CGSB-130/CGCPT-130 632611 671651 7.15 100 -2.85 -20.85 -21 ------92.85 Citizens Fmr MGP CGSB-131/CGCPT-131 632347 671620 10.56 68 -8.44 -15.44 -15 ------57.44 Citizens Fmr MGP CGSB-132 632569 671707 7.35 101 -5.65 -18.65 -19 ------93.65 Citizens Fmr MGP CGSB-133/CGCPT-133 632493 671745 11.21 71 0.21 -11.79 -12 ------59.79 Citizens Fmr MGP CGSB-134 632352 671795 11.26 101 -0.74 -11.54 -12 ------89.74 Citizens Fmr MGP CGSB-14 632598 671662 9 67 -8 -18 -18 ------58 Citizens Fmr MGP CGSB-15 632362 671752 10.92 77 -4 -11.08 -11 ------66.08 Citizens Fmr MGP CGSB-17 632292 671850 14.48 68 -5.52 -18 -18 ------53.52 Citizens Fmr MGP CGSB-18 632210 671946 21.42 67 N N 21 ------45.58 Citizens Fmr MGP CGSB-19 632217 672052 26.4 77 N N 26 ------50.6 Citizens Fmr MGP CGSB-20 631745 671761 22.72 48 -5.28 -11.28 -11 ------25.28 Citizens Fmr MGP CGSB-22 632559 671698 9 108 -5 -19 -19 ------99 Citizens Fmr MGP CGSB-24 632020 671472 10.41 106 -7.59 -15.59 -16 ------95.59 Citizens Fmr MGP CGSB-25 632106 671469 10.4 98 -3.1 -22.6 -23 ------87.6 Citizens Fmr MGP CGSB-26 631830 671211 10.54 140 -12.46 -22.96 -23 ------129.46 Citizens Fmr MGP CGSB-27 632012 671412 10.06 78 -4 -7 -7 ------67.94 Citizens Fmr MGP CGSB-31 631570 671546 19.4 48 -11 -12 -12 ------28.6 Citizens Fmr MGP CGSB-32 631627 671711 22.51 138 -6.99 -7.49 -7 -110.00 -114.49 -- -115.49 Citizens Fmr MGP CGSB-33 631700 671924 28.65 48 N N 29 ------19.35 Citizens Fmr MGP CGSB-37 632110 671854 18.98 146.5 -6.02 -8.02 -8 -110.00 -114.02 -127.02 -127.52 Citizens Fmr MGP CGSB-39 632393 671912 14.33 78 -2.67 -6.67 -7 ------63.67 Citizens Fmr MGP CGSB-40 632268 671935 23.58 59 4.58 3.58 4 ------35.42 Citizens Fmr MGP CGSB-41 632188 671981 18.86 58 N N 19 ------39.14 Citizens Fmr MGP CGSB-42 632463 671957 16.35 58 -2 -5 -5 ------41.65 Citizens Fmr MGP CGSB-44 632890 671670 5.86 108 -4.64 -22.14 -22 ------102.14 Citizens Fmr MGP CGSB-45 632225 671651 12.06 158 -5 -14 -14 -- P -145.94 -145.94 Citizens Fmr MGP CGSB-46 632122 671666 13.98 182 -9.02 -19.02 -19 -- -138.02 -152.02 -168.02 Citizens Fmr MGP CGSB-47 632021 671785 27.74 169 -6 -8 -8 -116 -118 -- -141 Citizens Fmr MGP CGSB-48 632502 671287 6.64 164 -6.36 -14 -14 -123 -124 -155.78 -157 Citizens Fmr MGP CGSB-49 632366 670896 8.5 128 -4 -11 -11 -110 -120 -- -120 Citizens Fmr MGP CGSB-52 631973 671002 6.05 108 -6.45 -20 -20 ------102 Citizens Fmr MGP CGSB-57/CGMW-27 632584 671910 12.55 45 -5.95 -8.95 -9 ------32.45 Citizens Fmr MGP CGSB-58 632970 671759 7.31 69 -12.19 -20.69 -21 ------61.69 Citizens Fmr MGP CGSB-59/CGMW-29 632989 670749 8.93 45 -4 -10.57 -11 ------36.07 Citizens Fmr MGP CGSB-60/CGMW-32 632059 670722 5.24 49 -13.5 -21.26 -21 ------43.76 Citizens Fmr MGP CGSB-62/CGPZ-42S/CGMW-42I 631946 671526 15.36 86 -10.64 -16.64 -17 ------70.64 Citizens Fmr MGP CGSB-63/-63B 631892 671519 14.72 81 -3.78 -17.28 -17 ------66.3

H:\WPROC\Project\NationalGrid\Gowanus - Confidential\GW Model Report\Submittal to EPA 12-2011\Tables\ Page 2 of 9 Tables Table 1 Soil Boring Log Summary Grounwater Model Gowanus Canal Superfund Site Brooklyn, New York

Observed Strata Break Elevations (ft. NAVD 88) Ground Bottom Boring/Monitoring Well Surface Borehole Top Marsh Bottom Marsh Top Upper Top Gardiner's Top Jameco Facility Easting Northing Top Bedrock Elevation of Location ID Elevation Depth (ft.) Deposits Deposits Glacial Sand Clay Gravel Boring (NAVD 88) Citizens Fmr MGP CGSB-64/CGMW-34S 631918 671463 14.7 86 -1.3 -15.3 -15 ------71.3 Citizens Fmr MGP CGSB-65 631813 671497 14.38 46 -6.52 -13.62 -14 ------31.62 Citizens Fmr MGP CGSB-66 631934 671399 14.24 86 -1.76 -19.76 -20 ------71.76 Citizens Fmr MGP CGSB-67/CGMW-40D 631820 671337 15.07 114 -3 -8 -8 ------98.93 Citizens Fmr MGP CGSB-68/CGMW-35 631818 671579 15 34 -4 -15 -15 ------19 Citizens Fmr MGP CGSB-69/CGMW-36 631781 671479 14.62 35 -1 -13.38 -13 ------20.38 Citizens Fmr MGP CGSB-70 631674 671489 14.4 42 1.5 -13.6 -14 ------27.6 Citizens Fmr MGP CGSB-71/CGMW-37 631668 671620 15.2 40 -6.8 -8.8 -9 ------24.8 Citizens Fmr MGP CGSB-72/CGMW-38 631628 671519 14.4 40 -8.9 -14.6 -15 ------25.6 Citizens Fmr MGP CGSB-73 631605 671452 14.42 40 -9.58 -11.58 -12 ------25.58 Citizens Fmr MGP CGSB-74 631613 671343 14.42 90 -8.88 -13.58 -14 ------75.58 Citizens Fmr MGP CGSB-75/CGMW-39 631678 671320 14.1 92.8 -4 -14.6 -15 ------78.7 Citizens Fmr MGP CGSB-77 631886 671254 15.22 114 -4.78 -16.78 -17 ------98.78 Citizens Fmr MGP CGSB-78 631647 671366 15.04 36 -7.96 -13.46 -13 ------20.96 Citizens Fmr MGP CGSB-79 632685 671652 6.42 64 -10.58 -23.38 -23 ------57.58 Citizens Fmr MGP CGSB-81/CGPZ-1I 632019 671867 27.36 52.5 NE -6.04 -6 ------25.14 Citizens Fmr MGP CGSB-82/CGPZ-2I 631982 671825 28.2 52.5 -5.7 -8.8 -9 ------24.3 Citizens Fmr MGP CGSB-83/CGPZ-3 631944 671796 29.56 37 N N 30 ------7.44 Citizens Fmr MGP CGSB-99/-99A 632180 671426 -16.5 105 -16.5 -21.5 -22 -120.3 -120.5 -- -121.5 Citizens Fmr MGP CGSB-100 631965 671210 -12 65 -12 -22 -22 ------77 Citizens Fmr MGP FW-MW-01 634200 673049 10.18 66 N N 10 ------55.82 Fulton Works Fmr MGP FW-MW-02 634302 673012 13.26 75 N N 13 ------61.74 Fulton Works Fmr MGP FW-MW-03 634429 673010 12.17 65 N N 12 ------52.83 Fulton Works Fmr MGP FW-MW-04 634626 672850 14.99 50 -4 -4 -4 ------35.01 Fulton Works Fmr MGP FW-MW-05 634844 672930 21.15 50 -4 -10 -10 ------28.85 Fulton Works Fmr MGP FW-MW-06 634940 673074 22.38 60 -4 -15 -15 ------37.62 Fulton Works Fmr MGP FW-MW-07 635050 673083 23.18 55 N N 23 ------31.82 Fulton Works Fmr MGP FW-MW-08 634905 673257 15.11 65 -4 -13 -13 ------49.89 Fulton Works Fmr MGP FW-MW-09 634724 673387 11.22 75 -4 -14 -14 ------63.78 Fulton Works Fmr MGP FW-MW-10 634416 673445 10.65 98 -4 -18 -18 ------87.35 Fulton Works Fmr MGP FW-MW-12 635199 672856 22.62 50 -4 -17 -17 ------27.38 Fulton Works Fmr MGP FW-MW-13 635149 672983 24.2 50 N N 24 ------25.8 Fulton Works Fmr MGP FW-MW-14 635298 673052 24.33 50 N N 24 ------25.67 Fulton Works Fmr MGP FW-MW-16 634959 673198 21.4 65 -6 -13 -13 ------43.6 Fulton Works Fmr MGP FW-SB-01 634358 673208 13.05 50 N N 13 ------36.95 Fulton Works Fmr MGP FW-SB-02 634345 673163 12.99 50 N N 13 ------37.01 Fulton Works Fmr MGP FW-SB-03 634330 673120 13.03 25 N N 13 ------11.97 Fulton Works Fmr MGP FW-SB-04 634373 673187 13.03 50 N N 13 ------36.97 Fulton Works Fmr MGP FW-SB-05B 634297 673150 13.01 50 N N 13 ------36.99

H:\WPROC\Project\NationalGrid\Gowanus - Confidential\GW Model Report\Submittal to EPA 12-2011\Tables\ Page 3 of 9 Tables Table 1 Soil Boring Log Summary Grounwater Model Gowanus Canal Superfund Site Brooklyn, New York

Observed Strata Break Elevations (ft. NAVD 88) Ground Bottom Boring/Monitoring Well Surface Borehole Top Marsh Bottom Marsh Top Upper Top Gardiner's Top Jameco Facility Easting Northing Top Bedrock Elevation of Location ID Elevation Depth (ft.) Deposits Deposits Glacial Sand Clay Gravel Boring (NAVD 88) Fulton Works Fmr MGP FW-SB-06 634345 673241 11.58 98 N N 12 ------86.42 Fulton Works Fmr MGP FW-SB-07/FW-MW-17 634401 673207 12.08 73 N N 12 ------60.92 Fulton Works Fmr MGP FW-SB-08 634476 673103 11.97 100 N N 12 ------88.03 Fulton Works Fmr MGP FW-SB-09 634460 672934 12.19 65 N N 12 ------52.81 Fulton Works Fmr MGP FW-SB-10 634575 673126 11.8 65 -4 -5.2 -5 ------53.2 Fulton Works Fmr MGP FW-SB-11/-11A 634596 673038 15.43 75 N N 15 ------59.57 Fulton Works Fmr MGP FW-SB-16 634674 672943 18.16 75 -3 -6 -6 ------56.84 Fulton Works Fmr MGP FW-SB-17B 634869 673042 22 60 -2 -13 -13 ------38 Fulton Works Fmr MGP FW-SB-18 634886 673101 20.86 70 -2 -13 -13 ------49.14 Fulton Works Fmr MGP FW-SB-19 634854 673201 21.34 60 -9 -13 -13 ------38.66 Fulton Works Fmr MGP FW-SB-20 634745 673182 16.91 75 -2 -9 -9 ------58.09 Fulton Works Fmr MGP FW-SB-21 634786 673094 21.76 75 -4 -9 -9 ------53.24 Fulton Works Fmr MGP FW-SB-22 634728 673145 16.91 80 -5 -8 -8 ------63.09 Fulton Works Fmr MGP FW-SB-23 634827 673158 21.48 100 -4 -17 -17 ------78.52 Fulton Works Fmr MGP FW-SB-24 634792 673235 17.05 75 -4 -6 -6 ------57.95 Fulton Works Fmr MGP FW-SB-25 634705 673253 16.99 110 -8 -16 -16 ------93.01 Fulton Works Fmr MGP FW-SB-26 634644 673171 16.91 75 -3 -8 -8 ------58.09 Fulton Works Fmr MGP FW-SB-27 634488 673177 10.72 11 N N 11 ------0.28 Fulton Works Fmr MGP FW-SB-28 634749 673337 11.84 75 -4 -13 -13 ------63.16 Fulton Works Fmr MGP FW-SB-29 634545 673254 11.51 65 N N 12 ------53.49 Fulton Works Fmr MGP FW-SB-30 634646 673331 14.87 80 -4 -9 -9 ------65.13 Fulton Works Fmr MGP FW-SB-31 634615 673268 15.27 75 N N 15 ------59.73 Fulton Works Fmr MGP FW-SB-32 634582 673205 15.47 100 -4 -7 -7 ------84.53 Fulton Works Fmr MGP FW-SB-33A 635240 672904 24.25 20.3 N N 24 ------3.95 Fulton Works Fmr MGP FW-SB-34 635274 672955 24.42 31 N N 24 ------6.58 Fulton Works Fmr MGP FW-SB-35 634460 673228 11.54 105 N N 12 ------93.46 Fulton Works Fmr MGP FW-SB-36 634967 673268 16.45 55 -5.55 -12.55 -13 ------38.55 Fulton Works Fmr MGP FW-SB-37 634151 672802 14.3 80 N N 14 ------65.7 Fulton Works Fmr MGP FW-SB-38 634221 672766 13.32 68 N N 13 ------54.68 Fulton Works Fmr MGP FW-SB-39 635075 673207 22.64 55 -2.96 -6.86 -7 ------32.36 Fulton Works Fmr MGP FW-SB-40 634992 673500 17.24 60 -8 -9.96 -10 ------42.76 Fulton Works Fmr MGP FW-SB-41 634842 673578 17.56 70 -2 -8 -8 ------52.44 Fulton Works Fmr MGP FW-SB-42 634561 673716 14.79 79 -5 -9 -9 ------64.21 Fulton Works Fmr MGP FW-SB-43 635330 672906 24.1 50 -5 -10 -10 ------25.9 Fulton Works Fmr MGP KSF-SB-01 634661 673209 16.81 20 -2.69 -7 -7 ------3.19 Fulton Works Fmr MGP KSF-SB-02 634677 673243 16.89 20 -2.11 -8 -8 ------3.11 Fulton Works Fmr MGP KSF-SB-03 634738 673213 16.99 8 N N 17 ------8.99 Fulton Works Fmr MGP KSF-SB-07 634699 673274 16.79 20 N N 17 ------3.21 Fulton Works Fmr MGP KSF-SB-08 634721 673321 12.66 24 -8.34 -10 -10 ------11.34

H:\WPROC\Project\NationalGrid\Gowanus - Confidential\GW Model Report\Submittal to EPA 12-2011\Tables\ Page 4 of 9 Tables Table 1 Soil Boring Log Summary Grounwater Model Gowanus Canal Superfund Site Brooklyn, New York

Observed Strata Break Elevations (ft. NAVD 88) Ground Bottom Boring/Monitoring Well Surface Borehole Top Marsh Bottom Marsh Top Upper Top Gardiner's Top Jameco Facility Easting Northing Top Bedrock Elevation of Location ID Elevation Depth (ft.) Deposits Deposits Glacial Sand Clay Gravel Boring (NAVD 88) Fulton Works Fmr MGP KSF-SB-09 634788 673110 21.76 27.5 -1.74 -9 -9 ------5.74 Fulton Works Fmr MGP KSF-SB-11 634864 673246 21.5 28 -2.5 ------6.5 Fulton Works Fmr MGP KSF-SB-12 634873 673078 21.22 18 N N 21 ------3.22 Fulton Works Fmr MGP KSF-SB-13 634902 673127 20.86 19 N N 21 ------1.86 Fulton Works Fmr MGP KSF-SB-14 634560 673283 11.24 20 -7.26 -8.26 -8 ------8.76 Fulton Works Fmr MGP KSF-SB-15 634990 672962 21.42 20 N N 21 ------1.42 Fulton Works Fmr MGP KSF-SB-16 634748 673095 17 20 N N 17 ------3 Fulton Works Fmr MGP KSF-SB-17 634674 673131 13.9 20 -2.1 -7 -7 ------6.1 Fulton Works Fmr MGP KSF-SB-18 634583 673171 15.47 12 -4 -8 -8 ------3.47 Fulton Works Fmr MGP KSF-SB-19 634834 672994 18.24 14.5 N N 18 ------3.74 Fulton Works Fmr MGP KSF-SB-21 634626 673100 12.92 16 N N 13 ------3.08 Fulton Works Fmr MGP KSF-SB-22 634572 673128 11.6 16 N N 12 ------4.4 Fulton Works Fmr MGP KSF-SB-23 634313 673257 11.26 23.5 -6.74 -7.74 -8 ------12.24 Fulton Works Fmr MGP KSF-SB-24 634407 673205 12.08 24 N N 12 ------11.92 Fulton Works Fmr MGP KSF-SB-25 634497 673165 10.72 2 N N 11 ------8.72 Fulton Works Fmr MGP KSF-SB-26 634463 673079 12.23 24 N N 12 ------11.77 Fulton Works Fmr MGP KSF-SB-27 634425 672912 12.21 26 N N 12 ------13.79 Fulton Works Fmr MGP KSF-SB-28 634628 672871 14.99 20 -2 -6 -6 ------5.01 Fulton Works Fmr MGP KSF-SB-29 634747 672804 14.99 20 -2 -6 -6 ------5.01 Gowanus Canal (EPA) EPA-MW03 634047 673057 6.62 43 -3 -8 -8 ------42.38 Gowanus Canal (EPA) EPA-MW04 633870 673236 8.6 39 -4 -9 -9 ------30.4 Gowanus Canal (EPA) EPA-MW05 633628 672013 5.85 35 -4 -12 -12 ------21.15 Gowanus Canal (EPA) EPA-MW06 633498 672097 7.2 35 -3 -18 -18 ------33.8 Gowanus Canal (EPA) EPA-MW11 631568 670748 9.75 45 -7 -15 -15 ------31.25 Gowanus Canal (EPA) EPA-MW13 630820 669229 5.83 56 -4 -36 -36 ------36.17 Gowanus Canal (EPA) EPA-MW14 630796 669472 7.05 56 -10 -24 -24 ------34.95 Gowanus Canal (EPA) EPA-MW15 630055 668535 7.45 60 N N 7 ------33.55 Gowanus Canal (EPA) EPA-MW20 631986 671026 6.03 39 -4 -17 -17 ------44.97 Gowanus Canal (EPA) EPA-MW21 632234 670897 6.27 38 -4 -9 -9 ------44.73 Gowanus Canal (EPA) EPA-MW24 632863 671082 8.71 40 -4 -12 -12 ------33.29 Gowanus Canal (EPA) EPA-MW25 633803 671880 22.25 43 -11 -19 -19 ------19.75 Gowanus Canal (EPA) EPA-MW26 633980 671881 21.44 39 N N 21 ------17.56 Gowanus Canal (EPA) EPA-MW27 633954 671949 17.41 47 -3 -12 -12 ------70.59 Gowanus Canal (EPA) EPA-MW28 633902 672417 7.77 37 -3 -25 -25 ------79.23 Gowanus Canal (EPA) EPA-MW29 633997 672325 8.83 37 -3 -10 -10 ------61.17 Gowanus Canal (EPA) EPA-MW33 634668 673484 7.28 39 -8 -17 -17 ------93.72 Gowanus Canal (EPA) EPA-MW34 634107 673163 5 33 -4 -7 -7 ------95 Gowanus Canal (EPA) EPA-MW35 633995 672616 7.6 35 -3 -11 -11 ------93.4 Gowanus Canal (EPA) EPA-MW36 633718 672276 5.28 38 -3 -10 -10 ------95.02

H:\WPROC\Project\NationalGrid\Gowanus - Confidential\GW Model Report\Submittal to EPA 12-2011\Tables\ Page 5 of 9 Tables Table 1 Soil Boring Log Summary Grounwater Model Gowanus Canal Superfund Site Brooklyn, New York

Observed Strata Break Elevations (ft. NAVD 88) Ground Bottom Boring/Monitoring Well Surface Borehole Top Marsh Bottom Marsh Top Upper Top Gardiner's Top Jameco Facility Easting Northing Top Bedrock Elevation of Location ID Elevation Depth (ft.) Deposits Deposits Glacial Sand Clay Gravel Boring (NAVD 88) Gowanus Canal (EPA) EPA-MW37 633518 671259 12.02 42 -8 -12 -12 ------71.98 Gowanus Canal (EPA) EPA-MW38 633788 671082 11.33 39 -2 -17 -17 ------55.67 Gowanus Canal (EPA) EPA-MW39 633983 670859 18.15 43 -16 -24 -24 ------43.85 Gowanus Canal (EPA) EPA-MW42 632315 671008 6.81 38 -15 -18 -18 ------84.19 Gowanus Canal (EPA) EPA-MW43 633691 672247 5.4 38 -2 -10 -10 ------95.9 Gowanus Canal (EPA) EPA-MW44 631636 670459 4.73 45 -3 -25 -25 ------54.27 Gowanus Canal (EPA) EPA-MW45 631766 670642 4.5 41 -4 -18 -18 ------61.1 Gowanus Canal (EPA) EPA-MW46 631739 670581 4.76 57 -5 -22 -22 ------144.24 Gowanus Canal (NG) GC-GP-05 634184 673348 4.96 40 -4.29 -10.04 -10 ------35.04 Gowanus Canal (NG) GC-GP-07 634063 673099 3.71 40 -3.01 -12.79 -13 ------36.29 Gowanus Canal (NG) GC-GP-13 633714 672124 4.99 40 -7.24 -23.01 -23 ------35.01 Gowanus Canal (NG) GC-GP-15 633584 671897 3.76 40 -7.24 -18.24 -18 ------36.24 Gowanus Canal (NG) GC-MW23I 632487 671276 7.03 39 -2 -10 -10 ------39 Gowanus Canal (NG) GC-MW30D2/D1 634218 673042 8.56 167 N N 9 -115.4 -115.9 -159 -167 Gowanus Canal (NG) GC-MW40D2/D1 630563 669197 12.40 157 -3 -13 -13 -137 -147 -- -145 Gowanus Canal (NG) GC-MW41I 630343 669305 7.92 58 -4 -6 -6 ------58 Gowanus Canal (NG) GCMW-41S 630336 669306 7.94 13.5 N N 8 ------13.5 Gowanus Canal (NYC) NYC-MW01 634476 673671 9.57 40 N N 10 ------30.43 Gowanus Canal (NYC) NYC-MW02 634302 673621 5.57 39 -6 -13 -13 ------33.43 Gowanus Canal (NYC) NYC-MW09 631759 670959 10.32 40 -18 -25 -25 ------29.68 Gowanus Canal (NYC) NYC-MW10 631573 671266 13.74 45 N N 14 ------31.26 Gowanus Canal (NYC) NYC-MW17 631226 669638 10.32 46 -6 -16 -16 ------35.68 Gowanus Canal (NYC) NYC-MW18 631153 669308 11.08 58 -11.5 -21.5 -22 ------46.92 Gowanus Canal (NYC) NYC-MW19 631437 669332 12.14 62 -13 -17 -17 ------49.86 Gowanus Canal (NYC) NYC-MW47 631766 670692 4.6 47 -12.4 -18.4 -18 ------42.4 Metropolitan Fmr MGP MT-MW1 632319 669756 11.99 72 -3 -23 -23 ------60.01 Metropolitan Fmr MGP MT-MW2 632036 669756 10.26 72 -5 -17 -17 ------61.74 Metropolitan Fmr MGP MT-MW3 631831 669867 8.61 60 -4 -20 -20 ------51.39 Metropolitan Fmr MGP MT-MW4 631428 670144 6.86 150 -5 -21 -21 -121 -135 -- -143.14 Metropolitan Fmr MGP MT-MW5 631373 669935 9.79 72 -10 -19 -19 ------62.21 Metropolitan Fmr MGP MT-MW6 631658 669756 9.81 50 -6 -16 -16 ------40.19 Metropolitan Fmr MGP MT-MW7 631768 669683 10.36 50 -3 -17 -17 ------39.64 Metropolitan Fmr MGP MT-MW8 631617 670073 7.48 50 -8 -17 -17 ------42.52 Metropolitan Fmr MGP MT-MW9 631498 670280 9.29 80 -16 -21 -21 ------70.71 USGS K10.1 633303 671953 9.0 161.0 N N 9 -- -128.0 -- -152.0 USGS K1012.1 626956 663315 16.0 175.0 N N 16 -100.0 -124.0 -- -159 USGS K1018.1 639579 678972 18.0 116.0 0.0 -18.0 -18 ------98 USGS K1051.1 639884 679379 14.0 80.0 N N 14 ------66 USGS K1069.1 629839 671427 8.0 53.0 N N 8 ------45

H:\WPROC\Project\NationalGrid\Gowanus - Confidential\GW Model Report\Submittal to EPA 12-2011\Tables\ Page 6 of 9 Tables Table 1 Soil Boring Log Summary Grounwater Model Gowanus Canal Superfund Site Brooklyn, New York

Observed Strata Break Elevations (ft. NAVD 88) Ground Bottom Boring/Monitoring Well Surface Borehole Top Marsh Bottom Marsh Top Upper Top Gardiner's Top Jameco Facility Easting Northing Top Bedrock Elevation of Location ID Elevation Depth (ft.) Deposits Deposits Glacial Sand Clay Gravel Boring (NAVD 88) USGS K1091.1 630380 671228 18.0 124.0 N N 18 -105 -113 -- -106 USGS K110.1 632180 679738 72.0 160.0 N N 72 -- -- -88.0 -88.0 USGS K1130.1 648334 682974 18.0 89.0 N N 18 -63.0 -- -- -71 USGS K1148.1 628187 663727 11.0 150.0 N N 11 -86.0 -100.0 -- -139 USGS K1160.1 645038 680524 10.0 155.0 0.0 -6.0 -6 -69.0 -86.0 -- -145 USGS K1190.1 628978 673851 10.0 74.0 0.0 -4.0 -4 -54.0 -- -- -64 USGS K1192.1 630057 673756 30.0 112.0 2 -10 -10 ------82 USGS K12.1 634570 679347 49.0 112.0 N N 49 -- -- -50.0 -63.0 USGS K1271.1 627260 664127 5.0 153.0 N N 5 -96.0 -134.0 -207.0 -148 USGS K1274.1 645114 680626 10.0 165.0 N N 10 N -140.0 -- -155 USGS K1287.1 642222 662494 50.0 161.0 N N 50 -82.0 -97.0 -- -111 USGS K1288.1 639427 678668 30.0 102.0 N N 30 -72.0 -73.0 -- -72 USGS K1302.1 635741 676723 41.0 79.0 N N 41 ------38 USGS K1305.1 644653 680420 10.0 166.0 -17.0 -32.0 -32 -72.0 -96.0 -- -156 USGS K1313.1 640426 678978 31.0 161.0 N N 31 -72.0 -129.0 -- -130 USGS K1329.1 645357 666561 46.0 162.0 N N 46 ------116 USGS K1331.1 646358 666567 50.0 145.0 N N 50 ------95 USGS K1332.1 632696 670431 10.0 168.0 0.0 -10.0 -10 -121.0 -129.0 -- -158 USGS K1338.1 641962 667147 79.0 200.0 N N 79 -116.0 -- -- -121 USGS K1340.1 640350 678876 35.0 145.0 N N 35 -72.0 -110.0 -120.0 -110 USGS K1344.1 644653 680420 10.0 171.0 N N 10 -85.0 -118.0 -- -161 USGS K1354.1 637747 663276 60 180.0 N N 60 -105.0 -120.0 -- -120 USGS K15.1 636112 679154 15.0 114.0 -23.0 -25.0 -25 -93.0 -99.0 -- -99.0 USGS K167.1 628032 663929 13.0 150.0 N N 13 -73.0 -82.0 ??? -137.0 USGS K20.1 638301 673703 40.0 136.0 N N 40 -94.0 -96.0 -- -96.0 USGS K23.1 640226 673815 73.0 152.0 N N 73 no info no info -170.0 -79.0 USGS K245.1 630599 659794 127.0 178.0 NE NE 127 ------51.0 USGS K249.1 646058 677596 36.0 101.3 N N 36 no info no info -- -65.3 USGS K256.1 642826 676968 50.0 112.0 N N 50 no info no info -- -62.0 USGS K259.1 635589 676318 40.0 113.0 N N 40 -73.0 no info -- -73.0 USGS K261.1 634276 676917 50.0 110.0 N N 50 no info no info -59.0 -60 USGS K277.1 635975 676117 37.0 146.0 NE -13.0 -13 -97.0 N -109.0 -109 USGS K285.1 632082 656463 63.0 127.0 N N 63 no info no info -- -64 USGS K290.1 635514 676013 45.0 110.0 N N 45 -58 -59 -59.0 -65 USGS K320.1 635744 676217 38.0 114.0 N N 38 -65 -77 -75.0 -76 USGS k3301 637079 671874 65 69.7 N N 65 ------4.7 USGS K501.1 636699 658008 47.0 112.0 N N 47 ------65 USGS K503.1 636766 659729 63.0 110.0 N N 63 ------47 USGS K508.1 638451 661459 50.0 116.0 N N 50 ------66

H:\WPROC\Project\NationalGrid\Gowanus - Confidential\GW Model Report\Submittal to EPA 12-2011\Tables\ Page 7 of 9 Tables Table 1 Soil Boring Log Summary Grounwater Model Gowanus Canal Superfund Site Brooklyn, New York

Observed Strata Break Elevations (ft. NAVD 88) Ground Bottom Boring/Monitoring Well Surface Borehole Top Marsh Bottom Marsh Top Upper Top Gardiner's Top Jameco Facility Easting Northing Top Bedrock Elevation of Location ID Elevation Depth (ft.) Deposits Deposits Glacial Sand Clay Gravel Boring (NAVD 88) USGS K510.1 634919 659212 63.0 120.0 N N 63 ------57 USGS K512.1 638998 660349 48.0 106.0 N N 48 ------58 USGS K517.1 644119 667262 78.0 303.0 N N 78 -110.0 -165.0 -- -225 USGS K525.1 636623 657906 47.0 400.0 N N 47 -173.0 -288.0 -- -353 USGS K526.1 641962 667147 82.0 400.0 N N 82 -146.0 -208.0 -291.0 -318 USGS K528.1 644215 664328 61.0 360.0 N N 61 -159.0 -195.0 -298.0 -299 USGS K529.1 636610 660031 62.0 220.0 N N 62 -151.0 -- -- -158 USGS K615.1 644395 672424 80.0 140.0 N N 80 ------60 USGS K 638. 1 632696 670431 9.0 175.0 N N 9 -135.0 -136.0 -166.0 -166 USGS K639.1 632472 669115 28.0 190.0 N N 28 -122.0 -142.0 no info -162 USGS K64.2 645114 680626 10.0 168.0 3.0 -22.0 -22 -85.0 -90.0 -- -158.0 USGS K641.1 630168 681346 NR NR NR NR NR -- -- -64.3 NR USGS K646.1 634854 670343 10.0 194.0 -20.0 -45.0 -45 -97.0 -144.0 -- -184 USGS K648.1 634393 670138 38.0 197.0 18.0 16.0 16 -112.0 -114.0 -- -159 USGS K650.1 634164 669732 10.0 195.0 N N 10 -111.0 -167.0 -- -185 USGS K654.1 632981 674481 25.0 158.6 N N 25 -- -- -100.0 -133.6 USGS K655.1 635596 675204 39.0 214.0 N N 39 -- -- -147.0 -175 USGS K656.1 635823 675813 43.0 159.4 N N 43 -- -- -89.0 -116.4 USGS K657.1 637222 673797 44.0 227.8 N N 44 -- -- -162.0 -183.8 USGS K658.1 639431 677858 61.0 201.8 N N 61 -103.0 -120.0 -120.3 -140.8 USGS K659.1 636596 675413 38.0 170.0 N N 38 -- -- -106.0 -132 USGS K660.1 636052 676219 35.0 125.0 N N 35 -- -- -67.0 -90 USGS K661.1 637047 677338 62.0 147.0 N N 62 -63 -66 -74.0 -85 USGS K663.1 639113 679577 14.0 195.2 N N 14 -101.0 -121.0 -151.0 -181.2 USGS K666.1 642178 682125 55.0 214.0 2 -10 -10 -- -- -139.0 -159 USGS K668.1 631907 673665 57.0 199.7 2 -10 -10 -- -- -123.0 -142.7 USGS K669.1 630831 673153 48.0 182.1 2 -10 -10 -- -- -114.0 -134.1 USGS K670.1 643326 683246 30.0 165.5 N N 30 -- -- -115.5 -135.5 USGS K671.1 635021 681273 37.0 135.0 N N 37 -- -- -76.4 -98 USGS K672.1 643551 684259 20.0 170.8 N N 20 -- -- -130.8 -150.8 USGS K676.1 634749 675098 28.0 162.8 N N 28 -- -- -127.4 -134.8 USGS K684.1 632401 681561 5.0 104.0 -27.0 -46.0 -46 -- -- -98.0 -99 USGS K685.1 634478 681978 7.0 91.0 2 -10 -10 -- -- -73 -84 USGS K687.1 641719 681617 46.0 200.3 N N 46 ------129.7 USGS K690.1 645381 687205 12.0 193.8 N N 12 ------162.3 USGS K691.1 644694 686290 20.0 186.5 N N 20 ------147.3 USGS K694.1 634134 674791 16.0 106.6 N N 16 ------90.6 USGS K698.1 627867 665850 0.0 100.0 -32.0 -47.0 -47 ------100 USGS K700.1 629763 671325 6.0 127.0 -7.0 -11.0 -11 -- -- -110.0 -121

H:\WPROC\Project\NationalGrid\Gowanus - Confidential\GW Model Report\Submittal to EPA 12-2011\Tables\ Page 8 of 9 Tables Table 1 Soil Boring Log Summary Grounwater Model Gowanus Canal Superfund Site Brooklyn, New York

Observed Strata Break Elevations (ft. NAVD 88) Ground Bottom Boring/Monitoring Well Surface Borehole Top Marsh Bottom Marsh Top Upper Top Gardiner's Top Jameco Facility Easting Northing Top Bedrock Elevation of Location ID Elevation Depth (ft.) Deposits Deposits Glacial Sand Clay Gravel Boring (NAVD 88) USGS K701.1 628852 668790 0.0 83.0 -8 -19 -19 ------83 USGS K702.1 632752 674075 31.0 136.3 2 -10 -10 -- -- -85.0 -105.3 USGS K703.1 629834 672338 18.0 141.2 N N 18 -93.0 -104.0 -110.0 -123.2 USGS K704.1 628605 671724 7.0 130.0 -3 -11 -11 -51 -121 -121.0 -123 USGS K705.1 626289 672622 10.0 151.0 2 -2 -2 -- -- -112.0 -141 USGS K708.1 630267 677501 6.0 120.0 -24.0 -34.0 -34 -- -- -82.0 -114 USGS K709.1 634797 679956 58.0 139.0 2 -10 -10 -- -- -60.0 -81 USGS K720.1 630457 671127 13.0 103.0 -8.0 -20.0 -20 -83.0 -- -- -90 USGS K723.1 634409 680561 57.0 141.0 N N 57 -- -- -72.0 -84 USGS K725.1 633827 674688 14.0 114.8 N N 14 -- -- -79.0 -100.8 USGS K728.1 635034 679047 36.0 131.7 N N 36 -- -- -81.0 -95.7 USGS K729.1 638118 678458 45.0 175.2 N N 45 -90.0 -- -108.0 -130.2 USGS K730.1 635349 677935 36.0 134.3 N N 36 -- -- -68.0 -98.3 USGS K731.1 634441 674995 23.0 210.0 N N 23 -- -- -160.0 -187 USGS K82.1 639963 679076 20.0 120.0 N N 20 -- -- -100.0 -100.0 USGS K880.1 637727 652293 30 71 N N 30 ------41 USGS K884.1 649788 668978 120 172 N N 120 ------52 USGS K894.1 649727 681971 30.0 282.0 22.0 8.0 8 -57.0 -- -- -252 USGS K898.1 644007 685274 7.0 84.0 N N 7 ------77 USGS K907.1 633789 667908 80.0 130.0 N N 80 ------50 USGS K916.1 633930 670135 13.0 162.0 -26.0 no info 13 -118.0 -128.0 -- -149 USGS K917.1 635081 671052 10.0 105.5 N N 10 ------95.5 USGS K 920. 1 633853 670236 15.0 164.0 N N 15 -117.0 -122.0 -- -149 USGS K922.1 628879 664034 12.0 150.0 N N 12 -87.0 -102.0 -- -138 USGS K923.1 634694 659653 67 121 N N 67 ------54 USGS K925.1 653981 668999 41 87 N N 41 ------46 USGS K930.1 635230 671964 20.0 180.0 10.0 -20.0 -20 -123.0 -129.0 -- -160 USGS K952.1 649207 679033 67.0 122.0 N N 67 ------55 USGS K956.1 635152 671964 22.5 182.0 6.5 -28.5 -29 -96.0 -130.0 -- -159.5

Footnotes -- = Boring terminated at insufficient depth to determine strata break; or insufficient data. N = Not Present / Not Observed P = Strata break present at boring location based on local geology, but unable to discern strata break from soil boring log.

H:\WPROC\Project\NationalGrid\Gowanus - Confidential\GW Model Report\Submittal to EPA 12-2011\Tables\ Page 9 of 9 Tables Table 2 Hydraulic Conductivity Zones Groundwater Model Gowanus Canal Superfund Site Brooklyn, New York

Hydraulic Conductivity (ft./day) Published USGS Horizontal Used Vertical Used in Regional Anisotropy Ratio Literature Value Stratigraphic Unit in Model (a) Model (a) Slug Test Results (b) (b) Used in Model for Soil Type Fill See Below See Below 0.6 - 17 -- 0.5 - 50 Fill 1 / Shallow Sand 10 1 10:1 Fill 2 35 3.5 10:1 Fill 3 0.5 0.05 10:1 Fill 4 0.1 0.01 10:1 Fill 5 2 0.2 10:1 Marsh Deposits 0.01 0.001 10:1 10-6 - 1.0 (c) Canal sediment 0.1 0.1 10:1 Sediment 2 4 4 1:1 Sediment 3 0.5 0.5 1:1 Upper Glacial Aquifer 40 8 0.5 - 172 20-80 (moraine) 5:1 Till Subunit 1 5 0.1 -- 50:1 Till Subunit 2 1 0.05 0.58 -- 20:1 Gardiner's Clay 0.008 0.008 0.001-0.0029 1:1 10-6 - 0.005 (d) Sand Fringe 2 0.2 10:1 0.1 - 20 Jameco Gravel 300 30 232-811 200-300 10:1 200-20000 (e)

Footnotes: a. Source: Slug testing results for Carroll Gardens/Public Place and Gowanus Canal Superfund Site monitoring wells, GEI, 2005; GEI, 2010. b. Source: USGS, 1999. c. Published range for silt and clay (Anderson, 1992) d. Published range for clay (Anderson, 1992) e. Published range for coarse grained deposits (Anderson, 1992)

References: GEI, 2005. Final Remedial Investigation Report, Carroll Gardens/Public Place, Site No. V00360-2, GEI Consultants, Inc., October 2005. GEI, 2010. Monitoring Well Installation and Sampling Report, Gowanus Canal Superfund Site, EPA ID#NYN000206222, GEI Consultants, Inc., November 2010. Anderson, 1992. Applied Groundwater Modeling: Simulation of Flow and Advective Transport. Anderson M.P. and Wossner, W.W., Academic Press, Inc., 192. USGS, 1999. Simulation of Groundwater Flow and Pumpage in Kings and Queens Counties, Long Island, New York.

H:\WPROC\Project\NationalGrid\Gowanus - Confidential\GW Model Report\Submittal to EPA 12-2011\Tables\ Page 1 of 1 Tables Table 3 Calibration Data Set Groundwater Model Gowanus Canal Superfund Site

Measured Averages Measurement Date/Tide Cycle (c)

Model- Center Calibration Tidally Tidal Facility Location Strata Easting Northing Calculated 5/5/03 4/4/05 4/11/05 7/26/10 9/29/10 5/5/03 7/10/03 4/4/05 4/11/05 8/23/10 10/22/10 Screen Elev. Residual (a) Heads Averaged Static Avg High Tide Avg Low Tide Fluctuation Avg GW Elev.(b) High - Low Tide

H H H H H L L L L L L Citizens CG-MW01D UG 631797 672021 -99.4 2.92 0.70 2.23 2.27 2.18 0.09 0.79 2.49 2.61 2.86 2.6 0.78 1.81 2.45 2.62 2.84 2.58 Citizens CG-MW01I UG 631797 672021 -46.4 2.92 0.68 2.24 2.23 2.26 -0.03 0.74 2.43 2.58 2.82 2.56 0.75 1.76 2.4 2.59 3.48 2.55 Citizens CG-MW01S S 631797 672021 -1.4 3.21 0.75 2.46 2.46 2.47 -0.02 0.77 2.47 2.54 2.88 3.62 0.77 1.81 2.46 2.65 3.54 3.61 Citizens CG-MW02D J 632142 671726 -124.5 2.97 0.73 2.24 2.48 2.01 0.47 1.56 2.87 3 1.43 1.1 2.68 2.81 Citizens CG-MW02I UG 632142 671726 -45.1 2.27 0.36 1.91 2.10 1.72 0.38 1.21 2.51 2.57 1.01 1.71 2.23 1.92 Citizens CG-MW02S S 632142 671726 -0.2 10.16 -0.25 10.41 10.41 10.42 -0.01 11.33 11.06 10.78 9.46 9.4 11.32 9.84 11.1 10.74 9.36 10.15 Citizens CG-MW03D J 631936 671620 -121.1 3.09 -0.21 3.30 2.59 3.83 -1.23 1.89 2.88 3.01 1.43 8.4 2.66 2.81 Citizens CG-MW03I UG 631936 671620 -53.3 2.45 0.76 1.69 1.91 1.53 0.38 0.92 2.35 2.45 0.66 1.41 1.95 2.08 Citizens CG-MW03S S 631936 671620 2.8 7.68 -0.06 7.74 7.48 7.94 -0.46 7.4 7.57 7.48 7.46 9.15 7.55 7.6 Citizens CG-MW04D UG 632448 671754 -120.1 2.80 0.61 2.19 2.20 2.19 0.01 1.66 2.92 2.02 1.56 2.15 2.19 2.86 Citizens CG-MW04I UG 632448 671754 -52.7 1.90 0.24 1.66 1.66 1.66 0.01 1.18 2.38 1.43 0.91 1.37 2.43 1.92 Citizens CG-MW04S S 632448 671754 -3.2 3.37 -1.20 4.57 4.58 4.57 0.01 4.81 4.43 4.5 4.82 4.56 4.42 4.48 Citizens CG-MW05I UG 632217 672052 -32.9 2.69 0.54 2.15 2.19 2.12 0.07 1.16 2.64 2.77 1.19 1.96 2.57 2.77 Citizens CG-MW05S S 632217 672052 -4.3 2.71 0.30 2.41 2.44 2.39 0.05 1.46 2.89 2.96 1.48 2.14 2.91 3.01 Citizens CG-MW06 S 631830 671211 -4.9 2.68 -0.62 3.30 3.57 3.04 0.54 3.68 3.31 3.73 3.67 3.42 1.26 3.79 Citizens CG-MW07D UG 632286 671579 -112.3 1.73 -0.47 2.20 2.32 2.08 0.24 1.41 2.68 2.87 1.24 1.99 2.45 2.64 Citizens CG-MW07I UG 632286 671579 -55.5 1.51 -0.47 1.98 2.29 1.67 0.62 1.52 2.63 2.72 1 1.47 2.01 2.2 Citizens CG-MW07S S 632286 671579 -5.1 -0.04 0.64 -0.68 1.85 -2.58 4.43 1.44 1.73 2.39 -1.93 -2.78 -3.01 -2.6 Citizens CG-MW08S S 631969 671268 -4.4 0.91 1.80 -0.89 1.58 -2.74 4.32 1.29 1.56 1.89 -2.12 -2.85 -2.94 -3.03 Citizens CG-MW08D UG 631969 671268 -108.7 2.18 0.60 1.58 1.76 1.44 0.32 0.82 2.17 2.3 0.58 1.39 1.9 1.89 Citizens CG-MW09 S 632078 671513 -1.7 2.39 0.66 1.73 1.74 1.73 0.01 1.58 NM 1.66 1.97 1.63 1.25 NM 1.74 2.33 1.7 Citizens CG-MW10 S 632018 671569 0.3 6.46 -0.66 7.12 7.16 7.08 0.08 7.23 7.13 7.13 7.25 6.77 7.11 7.19 Citizens CG-MW11 UG 632890 671670 -53.1 1.82 -0.43 2.25 2.58 1.92 0.66 2.59 2.57 1.88 1.96 Citizens CG-MW12 S 632686 671817 -4.0 3.04 0.57 2.48 2.66 2.29 0.38 3.62 3.67 2.44 0.92 3.39 3.64 0.97 1.15 Citizens CG-MW14 CH2 S 632110 671854 -1.7 9.81 -1.33 11.14 11.10 11.19 -0.10 11.17 11.02 11.33 11.05 Citizens CG-MW14 CH3 UG 632110 671854 -14.3 2.51 -0.37 2.88 2.91 2.86 0.05 2.8 3.01 2.8 2.91 Citizens CG-MW14 CH4 UG 632110 671854 -46.7 2.51 -0.05 2.56 2.59 2.52 0.07 2.49 2.69 2.33 2.71 Citizens CG-MW14 CH5 UG 632110 671854 -106.7 2.53 -0.22 2.75 2.72 2.78 -0.06 2.67 2.77 2.77 2.79 Citizens CG-MW14 CH6 UG 632110 671854 -112.3 2.53 -0.22 2.75 2.78 2.72 0.07 2.68 2.88 2.7 2.73 Citizens CG-MW14 CH7 J 632110 671854 -119.6 3.04 0.33 2.71 2.73 2.69 0.04 2.56 2.89 2.64 2.74 Citizens CG-MW15CH1 S 631553 671372 -5.2 5.89 -0.60 6.49 6.92 6.06 0.86 6.05 6.07 5.93 9.62 5.95 6.09 5.84 6.36 Citizens CG-MW15CH3 UG 631553 671372 -17.9 2.73 -0.20 2.93 3.83 2.04 1.80 2.09 2.11 2.3 8.83 1.84 1.9 2.37 2.03 Citizens CG-MW15CH6 UG 631553 671372 -110.2 2.73 0.56 2.17 2.68 1.66 1.02 1.44 1.53 1.92 5.83 1.51 1.51 1.71 1.92 Citizens CG-MW15CH7 J 631553 671372 -130.2 3.30 0.14 3.16 3.31 3.05 0.26 2.84 2.76 4.32 2.83 3 3.39 2.98 Citizens CG-MW16 CH2 UG 632502 671287 -11.5 1.44 -0.01 1.45 1.24 1.66 -0.43 1.32 1.15 1.98 1.34 Citizens CG-MW16 CH3 UG 632502 671287 -22.5 1.44 -0.35 1.79 2.38 1.21 1.17 2.42 2.33 1.22 1.19 Citizens CG-MW16 CH4 UG 632502 671287 -41.6 1.44 -0.77 2.21 2.80 1.63 1.17 2.86 2.73 1.73 1.52 Citizens CG-MW16 CH5 UG 632502 671287 -62.4 1.44 -0.38 1.82 0.96 2.68 -1.72 0.19 1.72 3.13 2.22 Citizens CG-MW16 CH7 UG 632502 671287 -133.5 3.94 0.97 2.98 3.01 2.94 0.07 2.88 3.14 2.74 3.14 Citizens CG-MW17CH1 S 631627 671711 5.2 6.03 -1.09 7.12 7.31 7.00 0.31 7.16 7.46 7.05 7.51 6.44 Citizens CG-MW17CH4 UG 631627 671711 -52.4 2.83 0.50 2.33 2.31 2.36 -0.05 2.11 2.25 2.56 2.18 2.29 2.61 Citizens CG-MW17CH5 UG 631627 671711 -62.2 2.83 0.40 2.43 2.44 2.42 0.01 2.32 2.42 2.57 2.25 2.42 2.6 Citizens CG-MW17CH6 UG 631627 671711 -102.4 2.83 0.51 2.33 2.32 2.33 0.00 2.22 2.3 2.45 2.1 2.32 2.56 Citizens CG-MW17CH7 J 631627 671711 -119.6 3.27 -0.80 4.07 2.77 5.04 -2.27 2.82 2.29 3.19 2.81 10.94 3.26 3.15 Citizens CG-MW18CH1 S 632393 671912 0.8 3.52 -0.14 3.66 3.45 3.87 -0.42 2.45 2.57 3.87 4.92 2.34 2.54 5.45 5.15 Citizens CG-MW18CH2 S 632393 671912 -8.2 2.66 0.13 2.53 2.63 2.44 0.19 2.43 2.38 2.82 2.88 1.96 2.23 2.96 2.61 Citizens CG-MW18CH5 UG 632393 671912 -41.2 2.37 -0.56 2.93 2.94 2.92 0.02 2.78 2.65 3.25 3.07 2.67 2.75 3.22 3.03 Citizens CG-MW18CH6 UG 632393 671912 -56.3 2.37 -0.56 2.93 2.96 2.90 0.06 2.73 2.84 3.16 3.09 2.7 2.72 3.2 2.97 Citizens CG-MW18CH7 UG 632393 671912 -63.2 2.37 -0.50 2.87 2.87 2.86 0.01 2.78 2.85 2.99 2.65 2.8 3.13 Citizens CG-MW19CH1 S 632366 670896 -2.5 2.21 0.55 1.66 1.73 1.60 0.13 1.99 1.91 1.3 1.47 1.63 1.85 1.45 Citizens CG-MW19CH2 S 632366 670896 -15.5 2.07 0.27 1.80 2.21 1.39 0.82 2.23 2.16 1.98 2.46 1.13 1.1 2.11 1.22 Citizens CG-MW19CH3 UG 632366 670896 -22.5 2.07 -0.16 2.23 2.43 2.02 0.41 2.41 2.19 2.61 2.51 1.88 1.91 2.41 1.88 Citizens CG-MW19CH4 UG 632366 670896 -66.5 2.07 -0.52 2.59 2.59 2.60 -0.01 2.66 2.56 2.54 2.64 2.57 2.62 2.57 Citizens CG-MW19CH5 UG 632366 670896 -76.5 2.46 -0.98 3.44 3.62 3.31 0.31 2.8 2.66 5.4 2.82 2.67 4.41 3.33 Citizens CG-MW19CH6 UG 632366 670896 -107.5 2.46 -0.86 3.32 3.30 3.33 -0.03 3.37 3.24 3.29 3.38 3.21 3.37 3.35 Citizens CG-MW22CH1 S 631973 671002 -6.3 1.93 0.92 1.01 1.42 0.61 0.81 1.38 1.57 1.35 1.36 0.63 0.5 1.05 0.26 Citizens CG-MW22CH2 UG 631973 671002 -22.4 2.25 0.62 1.63 1.74 1.53 0.21 1.65 1.49 1.84 1.97 1.47 1.29 1.86 1.49 Citizens CG-MW22CH3 UG 631973 671002 -34.3 2.25 0.40 1.85 2.32 1.38 0.94 2.21 2.3 2.37 2.4 1.2 1.2 1.92 1.19 Citizens CG-MW22CH4 UG 631973 671002 -46.4 2.25 0.34 1.91 2.20 1.63 0.57 2.06 2.18 2.29 2.27 1.45 1.47 2.09 1.5 Citizens CG-MW22CH5 UG 631973 671002 -58.5 2.25 0.15 2.10 2.53 1.68 0.85 2.11 2.18 2.54 3.27 1.58 1.51 2.41 1.21 Citizens CG-MW22CH6 UG 631973 671002 -76.4 2.27 0.21 2.06 2.25 1.88 0.38 2.03 2.1 2.44 2.44 1.62 1.68 2.31 1.89 Citizens CG-MW22CH7 UG 631973 671002 -91.4 2.27 0.25 2.02 2.33 1.71 0.62 1.95 2.88 2.15 1.34 1.64 2.15 1.7 Citizens CG-MW26 S 632429 672057 1.0 4.42 -1.05 5.47 5.47 5.47 5.47 Citizens CG-MW27 S 632584 671910 4.3 5.88 -0.80 6.68 6.57 6.80 -0.23 8.97 4.16 4.72 8.87

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Measured Averages Measurement Date/Tide Cycle (c)

Model- Center Calibration Tidally Tidal Facility Location Strata Easting Northing Calculated 5/5/03 4/4/05 4/11/05 7/26/10 9/29/10 5/5/03 7/10/03 4/4/05 4/11/05 8/23/10 10/22/10 Screen Elev. Residual (a) Heads Averaged Static Avg High Tide Avg Low Tide Fluctuation Avg GW Elev.(b) High - Low Tide

H H H H H L L L L L L Citizens CG-MW29 S 632989 670749 0.5 4.58 0.82 3.76 4.27 3.26 1.01 2.43 6.1 2.94 3.57 Citizens CG-MW32 S 632059 670722 -2.0 3.52 0.19 3.34 3.05 3.62 -0.57 3.37 2.73 3.85 3.39 Citizens CG-MW34I UG 631925 671455 -37.8 2.31 -0.25 2.56 2.37 1.80 0.57 2.53 2.21 2.04 1.56 Citizens CG-MW34S S 631925 671455 1.5 4.95 -1.20 6.15 0.00 Citizens CG-MW35 S 631818 671579 6.3 7.13 -2.18 9.31 6.66 6.78 -0.12 7.24 6.07 6.94 6.61 Citizens CG-MW36 S 631781 671479 8.1 6.52 -2.31 8.83 6.33 6.51 -0.18 6.78 5.88 6.58 6.44 Citizens CG-MW37 S 631668 671620 8.2 6.63 -2.89 9.52 6.65 6.78 -0.13 7.01 6.28 6.76 6.79 Citizens CG-MW38 S 631634 671518 8.4 6.65 -3.37 10.02 6.91 7.55 -0.64 7.06 6.76 7.34 7.76 Citizens CG-MW39 S 631682 671314 5.4 4.67 -3.50 8.17 4.60 5.35 -0.75 4.67 4.53 4.86 5.83 Citizens CG-MW40D UG 631820 671337 -79.5 2.41 -0.81 3.22 0.93 0.99 -0.06 0.66 1.19 1.29 0.69 Citizens CG-MW41 UG 631886 671254 -37.7 2.30 0.13 2.17 Citizens CG-MW42 UG 631955 671517 -21.2 2.31 0.07 2.24 Citizens CG-MW43 UG 631796 671292 -71.3 2.43 -0.08 2.51 Citizens CG-PZ03 S 631944 671796 1.8 8.18 0.10 8.08 8.05 8.12 -0.07 8.63 7.46 8.11 8.12 Citizens CG-PZ04 S 631779 671761 6.8 7.55 -0.35 7.9 Citizens CG-PZ05 S 631973 671944 -10.4 2.73 0.24 2.49 2.27 2.72 -0.45 2.89 1.64 2.85 2.58 Citizens CG-PZ06 S 632063 671522 3.2 2.80 0.57 2.23 0.00 2.23 Citizens CG-PZ1I UG 632019 671867 -18.2 2.62 -0.15 2.77 3.37 2.17 1.21 2.97 3.77 2.96 1.37 Citizens CG-PZ2 S 631982 671825 3.7 8.42 -1.29 9.71 Citizens CG-PZ2I UG 631982 671825 -17.0 2.61 0.56 2.05 Citizens CG-PZ42 S 631946 671526 -0.2 5.80 -0.27 6.07 6.34 5.81 0.54 7.84 4.84 6.27 5.34 Fulton FW-MW01 S 634213 673042 -0.6 1.53 0.24 1.29 1.81 0.78 1.03 1.75 1.86 1.22 0.33 Fulton FW-MW02 S 634308 673009 1.0 1.97 0.16 1.81 1.87 1.75 0.12 1.84 1.9 2.03 1.47 Fulton FW-MW03 S 634429 673010 0.9 2.34 0.55 1.79 1.89 1.70 0.19 1.89 1.88 1.71 1.69 Fulton FW-MW03R S 634460 673072 0.0 2.29 0.09 2.20 2.35 2.04 0.31 1.86 2.84 2.27 1.81 Fulton FW-MW04 S 634626 672850 6.5 3.16 -0.31 3.47 3.45 3.50 -0.04 3.49 3.41 3.43 3.56 Fulton FW-MW04R S 634435 672905 1.0 2.53 0.75 1.78 1.98 1.59 0.39 1.9 2.05 2.3 0.88 Fulton FW-MW05 S 634844 672930 3.9 3.40 -3.63 7.03 0.00 3.82 Fulton FW-MW5R S 634970 672980 5.9 3.67 -0.40 4.07 3.93 4.21 -0.28 3.95 3.9 4.05 4.36 Fulton FW-MW06 S 634934 673077 3.8 4.24 -0.97 5.21 5.00 5.42 -0.42 5.12 4.87 5.21 5.62 Fulton FW-MW07 S 635044 673085 7.8 5.60 0.11 5.50 5.28 5.71 -0.43 5.37 5.19 5.39 6.03 Fulton FW-MW09 S 634729 673388 1.2 2.49 -0.01 2.50 2.34 2.66 -0.32 2.38 2.3 2.61 2.7 Fulton FW-MW10 S 634418 673443 0.3 1.55 0.40 1.15 1.15 Fulton FW-MW12 S 635205 672853 6.1 4.21 -0.67 4.88 4.84 4.93 -0.09 4.84 4.83 4.83 5.02 Fulton FW-MW13 S 635149 672983 1.6 4.03 2.09 1.94 0.17 3.71 -3.54 3.55 -3.21 3.74 3.67 Fulton FW-MW14 S 635304 673049 8.8 7.49 -0.39 7.88 7.91 7.86 0.04 7.91 7.9 7.86 7.86 Fulton FW-MW16 S 634955 673200 6.0 4.04 -1.52 5.56 5.31 5.80 -0.49 5.41 5.21 5.5 6.1 Fulton FW-MW17 S 634395 673210 -1.2 1.50 -0.47 1.97 1.88 2.06 -0.18 1.88 1.87 2.24 1.87 Fulton FW-MW18 S 634151 672802 -0.5 1.88 -0.49 2.37 2.36 2.39 -0.02 2.32 2.4 2.54 2.23 Fulton FW-MW19 S 634842 673578 7.6 6.23 -0.85 7.08 6.93 7.24 -0.31 6.91 6.95 7.1 7.37 Fulton FW-MW20 S 634561 673716 2.1 1.88 -0.21 2.09 2.02 2.17 -0.16 1.96 2.07 2.15 2.19 Fulton FW-MW23S S 634483 673572 -2.0 1.92 -1.33 3.25 Fulton FW-MW23I UG 634483 673572 -26.0 2.07 -1.20 3.27 Fulton FW-MW23D1 UG 634483 673572 -108.0 2.46 -0.79 3.25 Fulton FW-MW23D2 J 634483 673572 -143.0 3.58 0.26 3.32 Fulton KSF-MW2 S 634560 673283 6.1 2.31 0.14 2.17 2.11 2.23 -0.12 2.15 2.07 2.4 2.06 Fulton KSF-MW6 S 634674 673131 1.3 -6.31 6.31 6.18 6.44 -0.26 7.08 5.28 7.08 5.79 Fulton KSF-MW7 S 634626 673100 7.8 2.26 -0.22 2.48 2.47 2.50 -0.04 2.59 2.34 2.5 Metropolitan MT-MW1D UG 632319 669756 -52.9 4.48 0.19 4.29 4.24 4.35 -0.11 4.26 4.21 4.34 4.35 Metropolitan MT-MW1I UG 632319 669756 -23.4 -4.56 4.56 4.77 4.36 0.41 4.79 4.74 4.98 3.74 Metropolitan MT-MW1S S 632319 669756 4.0 7.47 -0.32 7.79 7.74 7.84 -0.11 7.99 7.48 8.02 7.66 Metropolitan MT-MW2D UG 632036 669756 -55.0 3.67 0.72 2.95 3.08 2.83 0.25 3.04 3.11 3.14 2.52 Metropolitan MT-MW3I UG 631831 669867 -28.9 3.10 -0.97 4.07 4.20 3.95 0.25 4.17 4.22 4.26 3.63 Metropolitan MT-MW3S S 631831 669867 0.6 5.05 -0.52 5.57 5.57 5.56 0.01 5.66 5.48 5.60 5.52 Metropolitan MT-MW4I UG 631428 670144 -30.6 2.58 0.10 2.48 2.53 2.44 0.10 2.98 2.08 2.95 1.92 Metropolitan MT-MW4S S 631428 670144 -1.1 1.12 -0.62 1.74 1.72 1.77 -0.05 1.86 1.57 2.15 1.38

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Measured Averages Measurement Date/Tide Cycle (c)

Model- Center Calibration Tidally Tidal Facility Location Strata Easting Northing Calculated 5/5/03 4/4/05 4/11/05 7/26/10 9/29/10 5/5/03 7/10/03 4/4/05 4/11/05 8/23/10 10/22/10 Screen Elev. Residual (a) Heads Averaged Static Avg High Tide Avg Low Tide Fluctuation Avg GW Elev.(b) High - Low Tide

H H H H H L L L L L L Metropolitan MT-MW4D1 UG 631428 670144 -110.0 2.71 -0.49 3.20 Metropolitan MT-MW4D2 J 631428 670144 -137.0 4.45 1.25 3.20 Metropolitan MT-MW5D UG 631373 669935 -55.2 2.61 -0.02 2.64 2.92 2.35 0.57 2.84 3.00 2.69 2.01 Metropolitan MT-MW5I UG 631373 669935 -33.2 2.61 0.05 2.56 2.81 2.31 0.50 2.74 2.88 2.61 2 Metropolitan MT-MW5S S 631373 669935 1.8 2.41 0.17 2.24 2.27 2.22 0.04 2.39 2.14 2.50 1.94 Metropolitan MT-MW6I UG 631658 669756 -25.2 2.87 0.05 2.82 3.09 2.56 0.53 3.03 3.15 3.04 2.07 Metropolitan MT-MW6S S 631658 669756 1.8 4.71 0.75 3.96 3.91 4.02 -0.11 4.01 3.80 4.03 4 Metropolitan MT-MW7I UG 631768 669683 -24.6 3.01 0.01 3.00 3.23 2.77 0.46 3.16 3.29 3.21 2.33 Metropolitan MT-MW7S S 631768 669683 2.4 5.47 0.72 4.76 4.58 4.93 -0.35 4.73 4.43 4.84 5.02 Metropolitan MT-MW8I UG 631617 670073 -27.5 2.68 0.04 2.64 2.85 2.43 0.42 2.76 2.94 2.78 2.08 Metropolitan MT-MW8S S 631617 670073 -0.5 3.23 0.56 2.67 2.71 2.64 0.07 2.81 2.60 2.72 2.55 Metropolitan MT-MW9D UG 631498 670280 -56.2 2.60 0.02 2.59 3.08 2.09 0.99 NS 3.08 NS 2.09 Metropolitan MT-MW9I UG 631498 670280 -28.7 2.60 0.54 2.06 2.07 2.05 0.02 NS 2.07 NS 2.05 Metropolitan MT-MW9S S 631502 670284 -1.0 0.37 0.16 0.21 2.36 -1.95 4.31 NS 2.36 NS -1.95 Gowanus Canal GC-MW23I UG 632487 671276 -24.9 1.47 -0.53 2.00 2.31 1.69 0.62 2.16 2.45 1.74 1.63 Gowanus Canal GC-MW23S S 632487 671276 3.8 1.10 -1.11 2.21 2.13 2.29 -0.16 2.05 2.21 2.07 2.51 Gowanus Canal GC-MW30I UG 634223 673055 -23.1 1.54 -0.34 1.88 2.18 1.58 0.60 2.13 2.23 2.04 1.12 Gowanus Canal GC-MW30D1 UG 634223 673055 -102.6 1.92 -0.99 2.91 3.18 2.65 0.54 3.64 2.72 2.92 2.37 Gowanus Canal GC-MW30D2 J 634223 673055 -133.0 3.22 0.34 2.88 2.71 3.05 -0.35 2.37 3.04 3.17 2.93 Gowanus Canal GC-MW31I UG 634422 673448 -22.3 1.71 -0.52 2.23 0.00 2.23 Gowanus Canal GC-MW32I UG 634650 673200 -22.3 2.74 -0.26 3.00 2.95 3.04 -0.09 2.94 2.96 3.18 2.9 Gowanus Canal GC-MW40D1 UG 630551 669189 -79.5 2.52 -0.26 2.78 3.25 2.32 0.93 3.07 3.42 2.55 2.09 Gowanus Canal GC-MW40D2 J 630563 669197 -142.0 4.47 0.33 4.14 4.42 3.86 0.56 4.26 4.57 4.01 3.71 Gowanus Canal GC-MW40I UG 630563 669197 -44.0 2.15 0.79 1.36 2.39 0.34 2.05 2.25 2.52 0.69 -0.02 Gowanus Canal GC-MW40S S 630563 669197 1.9 2.62 -0.30 2.92 4.47 1.37 3.10 4.22 4.71 4.43 -1.69 Gowanus Canal GC-MW41I UG 630343 669305 -44.0 2.34 0.69 1.65 2.35 0.95 1.40 2.25 2.45 1.65 0.25 Gowanus Canal GC-MW41S S 630343 669305 2.8 5.43 1.03 4.40 4.38 4.42 -0.04 4.27 4.49 4.13 4.71 Gowanus Canal EPA-MW14I UG 630796 669472 -46.2 2.40 0.09 2.31 2.52 1.89 0.63 2.4 2.64 1.89 NR Gowanus Canal EPA-MW14S S 630796 669472 -0.7 2.23 -0.59 2.82 2.81 2.83 -0.02 2.67 2.95 2.83 NR Gowanus Canal EPA-MW24I UG 632863 671082 -28.0 2.55 0.09 2.46 3.45 1.96 1.49 NR 3.45 2.48 1.44 Gowanus Canal EPA-MW24S S 632863 671082 -1.5 1.89 -0.73 2.62 2.54 2.66 -0.12 NR 2.54 2.57 2.74 Gowanus Canal EPA-MW25I UG 633803 671880 -29.0 1.84 -0.60 2.44 2.69 2.19 0.50 2.61 2.76 2.48 1.9 Gowanus Canal EPA-MW25S S 633803 671880 0.9 2.62 0.95 1.67 1.59 1.71 -0.12 NR 1.59 1.75 1.67 Gowanus Canal EPA-MW34I UG 634107 673163 -26.0 1.51 -0.62 2.13 2.43 1.83 0.60 2.42 2.43 2.31 1.34 Gowanus Canal EPA-MW34S S 634107 673163 -2.5 0.96 -0.81 1.77 1.94 1.61 0.33 1.79 2.08 1.55 1.66 Gowanus Canal EPA-MW35I UG 633995 672616 -22.4 1.66 -0.77 2.43 2.43 2.44 -0.02 2.15 2.7 3.06 1.82 Gowanus Canal EPA-MW35S S 633995 672616 0.1 2.19 -0.87 3.06 3.07 3.06 0.01 2.36 3.77 3.93 2.18 Gowanus Canal NYC-MW01I UG 634458 673647 -27.7 2.23 -0.35 2.58 2.58 2.52 0.06 2.58 2.58 2.7 2.34 Gowanus Canal NYC-MW01S S 634458 673647 0.3 2.19 1.73 0.46 0.31 0.62 -0.32 0.13 0.48 0.98 0.26 Gowanus Canal NYC-MW08I UG 633285 671659 -13.8 2.04 -0.57 2.61 2.85 2.37 0.48 2.82 2.88 2.54 2.19 Gowanus Canal NYC-MW08S S 633285 671659 -2.6 1.63 -0.98 2.61 3.80 4.71 -0.91 3.75 3.85 5.08 4.34 Gowanus Canal NYC-MW09I UG 631759 670959 -27.0 2.46 0.17 2.29 2.46 2.12 0.34 2.44 2.47 2.39 1.85 Gowanus Canal NYC-MW09S S 631759 670959 2.9 1.71 -0.58 2.29 1.53 1.54 -0.01 1.36 1.7 1.85 1.22 Gowanus Canal NYC-MW10I UG 631573 671266 -28.8 2.68 0.20 2.48 2.51 2.32 0.19 2.48 2.53 2.52 2.11 Gowanus Canal NYC-MW10S S 631573 671266 3.6 3.51 0.30 3.21 3.21 3.76 -0.55 3.21 3.21 ‐0.69 3.76 Gowanus Canal NYC-MW11I UG 631568 670748 -32.0 1.37 -0.98 2.35 2.52 2.18 2.5 2.54 2.43 1.92 Gowanus Canal NYC-MW11S S 631568 670748 1.1 2.62 0.45 2.17 2.10 2.24 2.03 2.17 2.35 2.13 Gowanus Canal NYC-MW17 S 631226 669638 0.4 2.54 0.04 2.5 Gowanus Canal NYC-MW17 UG 631226 669638 -31.5 2.82 0.40 2.42 Gowanus Canal NYC-MW18 S 631153 669308 1.8 2.45 -2.69 5.14 Gowanus Canal NYC-MW18 UG 631153 669308 -43.1 4.59 2.33 2.26 Gowanus Canal NYC-MW19 S 631437 669332 2.1 2.82 -3.82 6.64 Gowanus Canal NYC-MW19 UG 631437 669332 -44.5 5.21 2.80 2.41 Gowanus Canal NYC-MW21I UG 634302 673621 -9.1 2.68 2.18 1.95 2.71 2.19 0.53 2.66 2.76 2.45 1.92 Gowanus Canal NYC-MW21S S 634302 673621 1.9 2.90 2.48 3.33 2.96 3.70 -0.74 2.89 3.03 3.32 4.07

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Measured Averages Measurement Date/Tide Cycle (c)

Model- Center Calibration Tidally Tidal Facility Location Strata Easting Northing Calculated 5/5/03 4/4/05 4/11/05 7/26/10 9/29/10 5/5/03 7/10/03 4/4/05 4/11/05 8/23/10 10/22/10 Screen Elev. Residual (a) Heads Averaged Static Avg High Tide Avg Low Tide Fluctuation Avg GW Elev.(b) High - Low Tide

H H H H H L L L L L L Gowanus Canal NYC-MW47I UG 631766 670692 -20.8 2.53 0.14 2.39 2.56 2.23 0.33 2.55 2.56 2.51 1.94 Gowanus Canal NYC-MW47S S 631766 670692 4.2 2.75 1.73 1.02 1.12 0.92 0.20 0.62 1.62 1.36 0.48 Gowanus Canal EPA-MW03I UG 634047 673057 -33.4 1.54 -0.58 2.12 2.44 1.81 0.64 2.42 2.46 2.25 1.36 Gowanus Canal EPA-MW03S S 634047 673057 -2.9 1.88 -0.48 2.36 0.00 2.04 2.67 ‐0.65 ‐0.07 Gowanus Canal EPA-MW04I UG 633870 673236 -27.5 2.31 -0.23 2.54 2.66 2.43 0.23 2.69 2.62 2.74 2.12 Gowanus Canal EPA-MW04S S 633870 673236 1.1 3.37 0.03 3.34 3.20 3.48 -0.28 3.16 3.24 3 3.95 Gowanus Canal EPA-MW05I UG 633628 672013 -26.2 2.45 0.13 2.32 2.65 1.99 0.66 2.59 2.7 2.42 1.56 Gowanus Canal EPA-MW05S S 633628 672013 -1.7 2.46 -0.07 2.53 2.51 2.56 -0.05 2.42 2.59 2.57 2.55 Gowanus Canal EPA-MW06I UG 633498 672097 -25.1 2.49 0.14 2.35 2.59 2.12 0.48 2.47 2.71 2.44 1.79 Gowanus Canal EPA-MW06S S 633498 672097 -0.6 3.20 -1.10 4.30 4.06 4.54 -0.48 3.82 4.3 4.52 4.55 Gowanus Canal EPA-MW07I UG 633216 671575 -24.4 1.99 -0.51 2.50 2.47 2.53 -0.07 2.48 2.45 2.99 2.07 Gowanus Canal EPA-MW07S S 633216 671575 -0.9 0.98 0.78 0.20 2.18 -1.78 3.96 1.83 2.53 -0.79 -2.77 Gowanus Canal EPA-MW12I UG 631490 670880 -30.3 2.67 0.28 2.39 2.56 2.23 0.33 2.54 2.57 2.46 1.99 Gowanus Canal EPA-MW12S S 631490 670880 3.3 2.40 -0.10 2.5 2.46 2.54 -0.08 2.49 2.43 2.47 2.61 Gowanus Canal EPA-MW13I UG 630820 669229 -47.1 2.17 0.37 1.80 1.95 1.51 0.44 1.31 2.59 1.51 NR Gowanus Canal EPA-MW13S S 630820 669229 -1.6 2.15 0.18 1.97 1.90 2.10 -0.20 1.79 2.01 2.1 NR Gowanus Canal EPA-MW15I UG 630055 668535 -49.6 1.38 -0.40 1.78 2.41 0.54 1.87 2.14 2.67 0.54 ‐1.38 Gowanus Canal EPA-MW15S S 630055 668535 -0.1 2.40 1.00 1.40 1.14 1.92 -0.79 0.89 1.38 1.92 ‐1.99 Gowanus Canal EPA-MW16I UG 629985 668982 -49.4 2.05 -0.04 2.09 2.49 1.31 1.18 2.29 2.68 1.31 ‐0.19 Gowanus Canal EPA-MW16S S 629985 668982 -0.9 2.86 0.29 2.57 2.55 2.60 -0.04 2.51 2.59 2.52 2.67 Gowanus Canal EPA-MW20I UG 631986 671026 -30.2 2.23 -0.24 2.47 2.57 2.37 0.20 2.68 2.45 2.34 2.39 Gowanus Canal EPA-MW20S S 631986 671026 -1.7 1.98 0.26 1.72 1.78 1.66 0.12 1.56 2 2 1.32 Gowanus Canal EPA-MW26I UG 633980 671881 -17.7 2.70 0.25 2.45 2.65 2.26 0.40 2.59 2.71 2.51 2 Gowanus Canal EPA-MW26S S 633980 671881 -0.2 2.97 0.61 2.37 2.48 2.26 0.22 2.4 2.55 2.46 2.05 Gowanus Canal EPA-MW27I UG 633954 671949 -22.5 2.64 0.21 2.43 2.63 2.24 0.40 2.55 2.71 2.5 1.97 Gowanus Canal EPA-MW27S S 633954 671949 -3.0 2.99 0.86 2.14 1.81 2.46 ‐0.44 ‐1.30 Gowanus Canal EPA-MW28I UG 633902 672417 -26.3 1.76 -0.52 2.28 2.47 2.10 0.38 2.41 2.53 2.34 1.85 Gowanus Canal EPA-MW28S S 633902 672417 0.2 2.17 -0.23 2.40 1.89 2.91 -1.02 0.59 3.18 3.24 2.57 Gowanus Canal EPA-MW29I UG 633997 672325 -25.3 2.30 0.05 2.25 2.40 2.10 0.30 2.29 2.51 2.45 1.75 Gowanus Canal EPA-MW29S S 633997 672325 1.2 2.99 0.44 2.55 2.16 2.94 -0.79 1.37 2.94 2.77 3.11 Gowanus Canal EPA-MW33I UG 634668 673484 -28.7 2.68 0.21 2.47 2.47 2.47 0.00 2.49 2.45 2.65 2.29 Gowanus Canal EPA-MW33S S 634668 673484 -0.2 2.18 -0.86 3.04 2.97 3.11 -0.14 2.96 2.98 3.12 3.09 Gowanus Canal EPA-MW36I UG 633718 672276 -29.9 2.19 -0.24 2.43 2.79 2.08 0.72 2.63 2.95 2.46 1.69 Gowanus Canal EPA-MW36S S 633718 672276 -2.4 1.53 -0.17 1.70 1.76 1.64 0.13 1.5 2.02 1.74 1.53 Gowanus Canal EPA-MW37I UG 633518 671259 -30.2 2.18 -0.51 2.69 3.06 2.33 0.74 2.98 3.14 2.62 2.03 Gowanus Canal EPA-MW37S S 633518 671259 -5.7 1.73 0.01 1.72 1.56 1.89 -0.33 1.5 1.61 1.92 1.85 Gowanus Canal EPA-MW38I UG 633788 671082 -28.4 2.28 -0.73 3.01 3.21 2.82 0.39 3.15 3.26 3.11 2.53 Gowanus Canal EPA-MW38S S 633788 671082 0.2 1.34 -0.95 2.29 1.68 2.89 -1.21 1.49 1.87 2.79 2.99 Gowanus Canal EPA-MW39I UG 633983 670859 -19.1 3.58 0.50 3.08 3.03 3.13 -0.09 3 3.06 3.28 2.97 Gowanus Canal EPA-MW39S S 633983 670859 2.4 3.82 -1.20 5.02 4.85 5.19 -0.34 4.77 4.93 5.44 4.93 Gowanus Canal EPA-MW42I UG 632315 671008 -28.5 1.90 -0.52 2.42 2.82 2.03 0.80 2.79 2.85 2.36 1.69 Gowanus Canal EPA-MW42S S 632315 671008 -1.0 1.44 -0.72 2.16 1.83 2.48 ‐0.40 ‐2.91 Gowanus Canal EPA-MW43I UG 633691 672247 -29.3 2.28 -0.06 2.34 2.61 2.07 0.54 2.58 2.63 2.5 1.64 Gowanus Canal EPA-MW43S S 633691 672247 -2.3 2.01 -0.38 2.39 1.97 2.82 -0.85 1.74 2.2 3.04 2.59 Gowanus Canal EPA-MW44I UG 631636 670459 -37.3 2.59 0.20 2.40 2.56 2.23 0.33 2.54 2.58 2.51 1.95 Gowanus Canal EPA-MW44S S 631636 670459 -2.8 1.19 -0.18 1.37 1.42 1.32 0.10 1.33 1.5 1.68 0.96 Gowanus Canal EPA-MW45I UG 631766 670642 -33.6 2.54 0.08 2.46 2.65 2.28 0.37 2.63 2.66 2.56 2 Gowanus Canal EPA-MW45S S 631766 670642 -4.1 2.82 1.11 1.71 1.49 1.93 -0.44 1.19 1.79 2.03 1.82 Gowanus Canal EPA-MW46I UG 631739 670581 -46.9 2.57 0.09 2.48 2.65 2.32 0.33 2.64 2.65 2.57 2.06 USGS K19 UG 637066 674100 -49.6 6.87 -1.63 8.5 USGS K3259 UG 635526 673888 -5.7 12.32 -0.68 13 USGS K3301 UG 637079 671874 -2.2 13.77 -3.23 17

Page 4 of 5 H:\WPROC\Project\NationalGrid\Gowanus - Confidential\GW Model Report\Submittal to EPA 12-2011\Tables\Table 3 Table 3 Calibration Data Set Groundwater Model Gowanus Canal Superfund Site

Measured Averages Measurement Date/Tide Cycle (c)

Model- Center Calibration Tidally Tidal Facility Location Strata Easting Northing Calculated 5/5/03 4/4/05 4/11/05 7/26/10 9/29/10 5/5/03 7/10/03 4/4/05 4/11/05 8/23/10 10/22/10 Screen Elev. Residual (a) Heads Averaged Static Avg High Tide Avg Low Tide Fluctuation Avg GW Elev.(b) High - Low Tide

H H H H H L L L L L L Data Not Used Tar/NAPL Impacted Citizens CGMW-06I I 631830 671211 -54.7 -- -- 0.49 0.58 0.41 0.58 NM NM 0.11 0.7 NM NM Citizens CGMW-08I I 631969 671268 -54.8 -- -- -0.83 -0.61 -0.94 -0.61 NM NM -1.21 -0.68 NM NM Citizens CGMW-06D D 631830 671211 -108.9 -- -- 1.12 1.28 0.95 0.29 1.69 1.87 0.09 0.69 1.42 1.6 Redundant Location Citizens CG-MW16 CH1 S 632502 671287 -5.5 -- -- 3.04 3.02 3.07 -0.04 3.12 2.92 3.13 3 Citizens CG-MW19CH7 UG 632366 670896 -108.5 -- -- 3.44 3.45 3.43 0.01 3.59 3.37 3.38 3.66 3.6 3.4 3.07 Citizens CGMW18 I 632393 671912 0.8 -- -- 5.12 4.92 5.32 5.14 5.28 4.8 4.45 5.12 5.33 5.46 5.37 Fulton FW-MW01R S 634320 673253 0.4 -- -- 5.41 5.14 5.67 5.12 5.16 6.26 5.08 Fulton KSF-MW1 S 634313 673257 6.1 -- -- 4.82 4.62 5.03 4.08 5.15 5.25 4.8 USEPA EPA-MW32S S 634955 673200 -- -- 8.77 8.52 9.01 8.62 8.42 8.71 9.31 USEPA EPA-MW31S S 634418 673443 -- -- 4.36 4.36 NR NR NR Fulton KSF-MW3 S 634463 673079 7.2 -- -- 5.17 5.03 5.24 5.03 5.36 5.11 Fulton KSF-MW4 S 634433 672906 7.2 -- -- 4.95 5.16 4.75 5.07 5.24 5.4 4.09 USEPA EPA-MW30S S 634213 673042 -- -- 4.50 5.02 3.99 4.96 5.07 4.43 3.54 Erratic Readings/Well Screen Plugged Citizens CG-PZ1S S 632014 671871 12.6 -- -- 21.21 21.20 21.22 -0.02 21.67 20.72 21.12 21.31 Citizens CGMW13 S 631929 671976 -0.7 -- -- 8.87 8.98 8.76 13.4 13.5 5.06 3.94 13.21 13.58 4.48 3.76 Citizens CGMW18 S 632393 671912 -16.2 -- -- 4.01 4.06 3.97 5.16 5.25 2.97 2.84 5.14 5.32 2.89 2.51 Citizens CGMW-16 CH6 UG 632502 671287 -- -- 4.35 4.34 4.36 4.33 4.35 4.21 4.51 Citizens CGMW-14 CH1 S 632110 671854 -- -- 12.78 13 12.45 13.14 12.54 Citizens CGMW-15CH4 UG 631553 671372 -41.7 -- -- 5.19 3.86 6.52 2.03 2.15 9.16 2.09 2.35 2.06 9.03 12.63 Citizens CGMW-15CH5I UG 631553 671372 -51.7 -- -- 2.07 2.06 2.08 2.03 1.97 2.35 1.88 1.96 1.96 2.32 2.06

Footnotes: a. Calibration residual = calculated - observed heads, where observed head is tidally averaged static groundwater elevation. b. Calibration data set, represents average of all high tide readings minus average of all low tide readings. Where measurements were not tide-specific or taken on the above dates shown, the average of available data were used in its place. c. Groundwater elevation measurement in feet relative to the North American Vertical Datum (NAVD) of 1988. H / L indicates measurements taken within 2 hours of high / low tide, respectively.

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Sources (GPM) Sinks (GPM) % Error Constant Constant Discharge Total Recharge Total Into Head Cells Drains Out (sources - sinks) Water Balance Head Cells to Canal Out of Into Model Model Out of of Model (d) Into Model From Model Model Model MGD 1.2 4.7 5.2 5.2 1.2 0.004 5.2 0.04% GPM 680.6 2726 2988 2984 681 2.4 2986 0.04%

Notes: Flow calculated by Modflow using Mass Balance and Zone Budget. Units shown in gallons per minute (GPM). Percent Error shown for difference between model-calculated total flow in and total flow out, for check of numeric mass balance calculation. GPM = Gallons per minute MGD = Million gallons per day

H:\WPROC\Project\NationalGrid\Gowanus - Confidential\GW Model Report\Submittal to EPA 12-2011\Tables\ Page 1 of 1 Tables GROUNDWATER MODEL REPORT NATIONAL GRID GOWANUS CANAL SUPERFUND SITE DECEMBER 2011

Figures

MODEL BOUNDARY

GOWANUS CANAL

NEW YORK QUADRANGLE LOCATION SOURCE: 1. TOPO! (c) 2011 NATIONAL GEOGRAPHIC SOCIETY ACCESSED THROUGH ARCGIS GROUNDWATER MODEL REPORT ONLINE (http://www.arcgis.com) GOWANUS CANAL SUPERFUND SITE GROUNDWATER MODEL 0 3,500 7,000 BROOKLYN, NEW YORK LOCATION

Consultants SCALE, FEET Project 093010-5-1506 December 2011 Figure 1-1

J:/Projects/National_Grid/Gowanus/Regional_GW_Model/GW_Model_Location.mxd 5

1 5 0 5

5

MODEL BOUNDARY 0 1

0

1

5

5 15

10

5

5

GOWANUS CANAL

5

5

PARALLEL FLOW

5

LEGEND

LOCATION OF SCHEMATIC 5 CROSS-SECTION (SEE FIG. 2-2)

SOURCE: 1. AERIAL IMAGERY BING MAPS (c) 2011 MICROSOFT CORPORATION ACCESSED GROUNDWATER ELEVATION CONTOUR THROUGH ARCGIS ONLINE 5 FOR UPPER GLACIAL AQUIFER (http://www.arcgis.com) REPORTED BY BUXTON AND SHERNOFF (1997) 5 2. GROUNDWATER ELEVATION CONTOUR FOR UPPER GLACIAL AQUIFER REPORTED BY 5 BUXTON AND SHERNOFF (1997). GROUNDWATER MODEL REPORT GOWANUS CANAL SUPERFUND SITE GROUNDWATER MODEL 0 3,000 6,000 BROOKLYN, NEW YORK LIMITS

Consultants SCALE, FEET Project 093010-5-1506 December 2011 Figure 2-1

J:/Projects/National_Grid/Gowanus/Regional_GW_Model/GW_Model_Limit.mxd

SITE

SITE

MEASURED 1997 WATER TABLE OF UPPER SIMULATED 1991 POTENTIOMETRIC GLACIAL AQUIFER [USGS, 1997]. SURFACE OF JAMECO AND UPPER MAGOTHY AQUIFERS [USGS, 1999]. SOURCES:

USGS, 1997. WATER-TABLE ALTITUDE IN KINGS AND QUEENS COUNTIES, NEW YORK, IN MARCH1997, FACT SHEET FS 134- 97, USGS, NOVEMBER 1997.

USGS, 1999. SIMULATION OF GROUND- WATER FLOW AND PUMPAGE IN KINGS AND QUEENS COUNTIES, LONG ISLAND, NEW YORK, WATER-RESOURCES GROUNDWATER MODEL REPORT USGS REGIONAL INVESTIGATIONS REPORT 98-4071, U.S. GOWANUS CANAL SUPERFUND SITE GEOLOGICAL SURVEY. BROOKLYN, NEW YORK GROUNDWATER Consultants CONTOURS Project 093010-5-1506 December 2011 Figure 2-3

H:\TECH\project\Regional Modflow model\Report\Figures.pptx GOWANUS CREEK

ESTIMATED HISTORICAL EXTENT OF FORMER WETLANDS COMPLEX/MARSH DEPOSITS

GROUNDWATER MODEL REPORT GOWANUS CANAL SUPERFUND SITE 1766 MAP OF SITE SOURCE: PLAN OF THE CIT OF NEW YORK, BROOKLYN, NEW YORK IN NORTH AMERICA: SURVEYED IN THE VICINITY YEARS 1766 & 1767. FADEN AND Consultants FEFFERYS, PRINTER. Project 093010-5-1506 December 2011 Figure 2-4

H:\TECH\project\Regional Modflow model\Report\Figures.pptx 23 115 257 460 A’

630

313

100 FT. 160

B B’

SEE INSET INSET GRID SPACING RELATIVE TO GOWANUS CANAL 32 CANAL

C C’ LEGEND

GRID LINES

32 GRID SPACING (FT.)

LOCATION OF CROSS- SECTION (FIGURE 2-6) A

GROUNDWATER MODEL REPORT GOWANUS CANAL SUPERFUND SITE MODEL GRID BROOKLYN, NEW YORK Consultants Project 093010-5-1506 December 2011 Figure 2-5

H:\TECH\project\Regional Modflow model\Report\Figures.pptx GOWANUS BAY (2nd AVE. DOCK AREA) CANAL/MARSH DEPOSIT AREA A’ GOWANUS CANAL WILLIAMSBURG LAYER 1 – FILL

LAYERS 2 & 3 – MARSH NAVY DEPOSITS / SEDIMENTS YARD BOERUM HILL EAST LAYERS 4 & 5-SAND (UPPER RIVER GLACIAL AQUIFER) B B’

COBBLE PROSPECT HILL HILL MATCH LINE A LINE MATCH RED HOOK LAYER 6 – GARDINERS CLAY(b) C C’

GOWANUS 2ND AVE LAYER 7 – JAMECO GRAVEL BAY DOCK AREA MODEL BOTTOM (BEDROCK) A CROSS SECTION LOCATIONS A-A’ (west)

BOERUM HILL NAVY YARD

LAYER 1 – FILL 0 4,000 8,000 LAYERS 2 & 3 – MARSH DEPOSITS / SEDIMENTS SCALE, FEET LAYERS 4 & 5-SAND (UPPER GLACIAL AQUIFER)

LAYER 6 – GARDINERS CLAY(b) 20:1 VERTICAL EXAGGERATION LAYER 7 – JAMECO GRAVEL MATCH LINE A LINE MATCH

MODEL BOTTOM (BEDROCK)

LEGEND A-A’ (east) MODEL GRID LINES FOOTNOTES:

(a) SILT/PEAT MARSH DEPOSITS INCLUDED IN LAYERS 3 AND 4 WITHIN FOOTPRINT OF FORMER WETLANDS GROUNDWATER MODEL REPORT ONLY. SAND IS MODELED IN THESE GOWANUS CANAL SUPERFUND SITE MODEL GRID LAYERS OUTSIDE THE FORMER WETLANDS.. BROOKLYN, NEW YORK CROSS SECTION A-A’ Consultants Project 093010-5-1506 December 2011 Figure 2-6

H:\TECH\project\Regional Modflow model\Report\Figures.pptx EAST RIVER COBBLE HILL CANAL PROSPECT HILL A’ (DEGRAW ST.) WILLIAMSBURG LAYER 1 – FILL

LAYERS 2 & 3 – MARSH NAVY DEPOSITS / SEDIMENTS YARD BOERUM HILL EAST LAYERS 4 & 5-SAND RIVER (UPPER GLACIAL B B’ AQUIFER) COBBLE HILL PROSPECT RED HOOK HILL C C’ LAYER 6 – GARDINERS CLAY(b) GOWANUS 2ND AVE BAY DOCK AREA

LAYER 7 – JAMECO A GRAVEL CROSS SECTION LOCATIONS B-B’

EAST RIVER RED HOOK CANAL PROSPECT HILL (BAY ST.) LAYER 1 – FILL

LAYERS 2 & 3 – MARSH DEPOSITS / SEDIMENTS

LAYERS 4 & 5-SAND (UPPER GLACIAL AQUIFER)

LAYER 6 – GARDINERS CLAY(b) MODEL BOTTOM: (BEDROCK SURFACE) LAYER 7 – JAMECO GRAVEL 0 3,000 6,000

SCALE, FEET

C-C’ 20:1 VERTICAL FOOTNOTES: EXAGGERATION

(a) SILT/PEAT MARSH DEPOSITS INCLUDED IN LAYERS 3 AND 4 WITHIN FOOTPRINT OF FORMER WETLANDS ONLY. SAND IS MODELED GROUNDWATER MODEL REPORT IN THESE LAYERS OUTSIDE THE FORMER MODEL GRID WETLANDS. GOWANUS CANAL SUPERFUND SITE CROSS SECTIONS B-B’ (b) GARDINERS CLAY IS MODELED IN LAYER 7 BROOKLYN, NEW YORK EXCEPT IN AREAS WHERE GARDINERS CLAY IS Consultants AND C-C’ MODELED TO BE ABSENT; SAND IS MODELED IN LAYER 7 WHERE CLAY IS ABSENT. Project 093010-5-1506 December 2011 Figure 2-7

H:\TECH\project\Regional Modflow model\Report\Figures.pptx LEGEND NAVY YARD BASIN DRAINAGE CONSTANT HEAD NETWORK = 1.0 BOUNDARY

DRAIN BOUNDARY

INACTIVE (NO-FLOW) CELL

DEGRAW STREET UTILITIES = 4.0 FOOTNOTES:

(a) SOUTHEAST CONSTANT HEAD BOUNDARY (CHB) ISCONTINUOUS ALONG MODEL LIMITS FROM ELEV. 1 (WEST END) TO ELEV. 8 (EAST END). (b) CHB ELEVATIONS ARE RELATIVE TO NAVD 88. MEAN SEA LEVEL IS 0.22 FT. BELOW 0 NAVD 88.

0 3,000 6,000 CANAL/SURFACE SOUTHEAST UPLAND LINEAR CHB = WATER CHB = 1 TO 8 NAVD(a) (UPPER GLACIAL -0.22(b) AQUIFER) SCALE, FEET

GROUNDWATER MODEL REPORT GOWANUS CANAL SUPERFUND SITE SHALLOW CONSTANT HEAD BROOKLYN, NEW YORK AND DRAIN BOUNDARIES Consultants Project 093010-5-1506 December 2011 Figure 2-8

H:\TECH\project\Regional Modflow model\Report\Figures.pptx LEGEND

NORTHERN CONSTANT HEAD BOUNDARY = 8.0 BOUNDARY

INACTIVE (NO-FLOW) CELL

NOTE:

(a) CONSTANT HEAD BOUNDARY ELEVATIONS ARE RELATIVE TO NAVD 88. MEAN SEA LEVEL IS 0.22 FT. BELOW 0 NAVD 88.

SOUTHERN BOUNDARY = 5.0 0 3,000 6,000

SCALE, FEET

GROUNDWATER MODEL REPORT GOWANUS CANAL SUPERFUND SITE JAMECO GRAVEL CONSTANT BROOKLYN, NEW YORK HEAD BOUNDARIES Consultants Project 093010-5-1506 December 2011 Figure 2-9

H:\TECH\project\Regional Modflow model\Report\Figures.pptx AREAL RECHARGE RATES

COMMERCIAL/INDUSTRIAL 4 INCHES/YEAR (a)

RESIDENTIAL 7 INCHES/YEAR

UNDEVELOPED 9 INCHES/YEAR

PARKS 10 INCHES/YEAR

INACTIVE (NO-FLOW) CELLS

FOOTNOTE:

(a) COMMERCIAL/INDUSTRIAL RECHARGE USED AS DEFAULT OVER SURFACE WATER. APPLIED RECHARGE OVER SURFACE WATER DOES NOT AFFECT MODEL. GOWANUS CANAL

0 3,000 6,000

SCALE, FEET

GROUNDWATER MODEL REPORT GOWANUS CANAL SUPERFUND SITE RECHARGE BROOKLYN, NEW YORK BOUNDARIES Consultants Project 093010-5-1506 December 2011 Figure 2-10

H:\TECH\project\Regional Modflow model\Report\Figures.pptx HIGH HYDRAULIC CONDUCTIVITY IN CANAL CELLS (500 FT.DAY) ALLOWS UNINHIBITED FLOW TO CANAL HEAD BULKHEAD (HORIZONTAL BOUNDARY CELLS. GROUNDWATER FLOW BOUNDARY) LIMITS ENTERING CHB CELLS EXITS THE HORIZONTAL FLOW TO MODEL. HEAD BOUNDARY MUST BE AT CANAL SCHEMATIC WATER OR BELOW HEAD ELEVATION (ZERO TABLE SURFACE FOR: NAVD) IN MODEL) LOW-CONDUCTIVITY GROUND SURFACE BULKHEAD(a)

HIGH-CONDUCTIVITY FILL (LAYER 1) CANAL BULKHEAD(a) CELLS MEAN SEA LEVEL

MARSH DEPOSITS (LAYER 2)

MARSH DEPOSITS (LAYER 3) SEDIMENT CELLS (LAYER 3)

LEGEND

CONSTANT HEAD UPPER GLACIAL AQUIFER (LAYER 4) BOUNDARY NOTE: SEDIMENT THICKNESS SHOWN REPRESENTS SOFT SEDIMENTS AND WALL BOUNDARY UNDERLYING NATIVE MARSH DEPOSITS (WHERE PRESENT). SEDIMENT CONDUCTIVITY AND LAYER 3 TRANSVERSE CROSS- THICKNESS BENEATH CANAL SECTION ACROSS CANAL MODEL LAYER REPRESENT NET CONDUCTANCE OF SEDIMENTS AND MARSH DEPOSITS. GROUNDWATER FLOW (a) SCHEMATIC WATER TABLE DIRECTION REPRESENTS CONDITIONS WHERE GROUNDWATER IS PERCHED ABOVE MARSH DEPOSIT AQUITARD. GROUNDWATER MODEL REPORT GOWANUS CANAL SUPERFUND SITE CANAL/BULKHEAD BROOKLYN, NEW YORK DETAIL Consultants Project 093010-5-1506 December 2011 Figure 2-11

H:\TECH\project\Regional Modflow model\Report\Figures.pptx LEGEND

MODELED BULKHEAD HYDRAULIC CONDUCTIVITY (FT./DAY)

1 – 10

0.1 – 1.0

0.01 – 0.1

0.001 – 0.01

NOTE: MODELED BULKHEAD THICKNESS = 1.0 FT.

0 3,000 6,000

SCALE, FEET

GROUNDWATER MODEL GOWANUS CANAL SUPERFUND SITE BULKHEAD BROOKLYN, NEW YORK CONDUCTIVITY Consultants Project 093010-5-1506 December 2011 Figure 2-12

H:\TECH\project\Regional Modflow model\Report\Figures.pptx HYDRAULIC CONDUCTIVITY ZONES

FILL OR SHALLOW NATIVE SAND KH = 10, KV = 0.1

UPPER GLACIAL- NORTH TILL SUBUNIT

(KH = 1.0, KV = 0.05)

OPEN WATER (KH = KV = 500)

LOCALIZED AREAS OF VARIOUS HYDRAULIC CONDUCTIVITIES (HETEROGENOUS FILL OR NATIVE SOIL)

FILL 2 KH = 35, KV = 3.5

FILL 3 KH = 0.5, KV = 0.05

FILL 4 KH = 0.1, KV = 0.01

FILL 5 KH = 2.0, KV = 0.2

0 3,000 6,000

SCALE, FEET

NOTES: GROUNDWATER MODEL KH = HORIZONTAL HYDRAULIC CONDUCTIVITY GOWANUS CANAL SUPERFUND SITE HYDRAULIC

KV = VERTICAL HYDRAULIC CONDUCTIVITY BROOKLYN, NEW YORK CONDUCTIVITY LAYER 1 Consultants HYDRAULIC CONDUCTIVITY VALUES ARE IN FEET PER DAY (FT./DAY) Project 093010-5-1506 December 2011 Figure 2-13

H:\TECH\project\Regional Modflow model\Report\Figures.pptx HYDRAULIC CONDUCTIVITY ZONES

FILL 1 (FILL OR SHALLOW NATIVE SAND, OR

DISCONTINUITY IN MARSH DEPOSITS) KH = 10, KV = 0.1

FILL HETEROGENEITY; MARSH DEPOSITS

ABSENT, KH = 35, KV = 3.5

MARSH DEPOSITS (KH = 0.01, KV = 0.0008)

UPPER GLACIAL- NORTH TILL SUBUNIT (KH = 1.0, KV = 0.05)

OPEN WATER (KH = KV = 500)

MARSH DEPOSIT HETEROGENEITIES

MARSH 2 KH = 0.01, KV = 0.0001

MARSH 3 KH = 0.1, KV = 0.01

0 3,000 6,000

SCALE, FEET

NOTES: GROUNDWATER MODEL REPORT KH = HORIZONTAL HYDRAULIC CONDUCTIVITY GOWANUS CANAL SUPERFUND SITE HYDRAULIC

KV = VERTICAL HYDRAULIC CONDUCTIVITY BROOKLYN, NEW YORK CONDUCTIVITY LAYER 2 Consultants HYDRAULIC CONDUCTIVITY VALUES ARE IN FEET PER DAY (FT./DAY) Project 093010-5-1506 December 2011 Figure 2-14

H:\TECH\project\Regional Modflow model\Report\Figures.pptx HYDRAULIC CONDUCTIVITY ZONES

SEDIMENT 1 K = 0.1

SEDIMENT 2 K = 0.01

SEDIMENT 3 K = 4

SEDIMENT 3 K = 0.5

UPPER GLACIAL SAND (KH = 40, KV = 4)

UPPER GLACIAL- NORTH TILL SUBUNIT (KH = 1.0, KV = 0.05)

MARSH DEPOSITS (KH = 0.01, KV = 0.0008)

MARSH 3 KH = 0.1, KV = 0.01

0 3,000 6,000

SCALE, FEET

NOTES: GROUNDWATER MODEL REPORT KH = HORIZONTAL HYDRAULIC CONDUCTIVITY GOWANUS CANAL SUPERFUND SITE HYDRAULIC

KV = VERTICAL HYDRAULIC CONDUCTIVITY BROOKLYN, NEW YORK CONDUCTIVITY LAYER 3 Consultants HYDRAULIC CONDUCTIVITY VALUES ARE IN FEET PER DAY (FT./DAY) Project 093010-5-1506 December 2011 Figure 2-15

H:\TECH\project\Regional Modflow model\Report\Figures.pptx HYDRAULIC CONDUCTIVITY ZONES

SEDIMENT 1 K = 0.1

SEDIMENT 2 K = 0.01

SEDIMENT 3 K = 4

SEDIMENT 3 K = 0.5

UPPER GLACIAL SAND (KH = 40, KV = 4)

UPPER GLACIAL- NORTH TILL SUBUNIT (KH = 1.0, KV = 0.05)

MARSH DEPOSITS (KH = 0.01, KV = 0.0008)

MARSH 3 KH = 0.1, KV = 0.01

NOTES: GROUNDWATER MODEL REPORT HYDRAULIC KH = HORIZONTAL HYDRAULIC CONDUCTIVITY GOWANUS CANAL SUPERFUND SITE CONDUCTIVITY LAYER 3 KV = VERTICAL HYDRAULIC CONDUCTIVITY BROOKLYN, NEW YORK Consultants (CANAL DETAIL) HYDRAULIC CONDUCTIVITY VALUES ARE IN FEET PER DAY (FT./DAY) Project 093010-5-1506 December 2011 Figure 2-16

H:\TECH\project\Regional Modflow model\Report\Figures.pptx HYDRAULIC CONDUCTIVITY ZONES

UPPER GLACIAL SAND (KH = 40, KV = 4)

UPPER GLACIAL TILL SUBUNITS

UPPER GLACIAL- NORTH TILL SUBUNIT (KH = 1.0, KV = 0.05)

UPPER GLACIAL - SOUTH TILL SUBUNIT KH = 5.0, KV = 0.1

UPPER GLACIAL SAND 2 (KH = 40, KV = 40)

UPPER GLACIAL SAND 3 (KH =0.5, KV = 0.05)

0 3,000 6,000

SCALE, FEET

NOTES: GROUNDWATER MODEL REPORT KH = HORIZONTAL HYDRAULIC CONDUCTIVITY GOWANUS CANAL SUPERFUND SITE HYDRAULIC

KV = VERTICAL HYDRAULIC CONDUCTIVITY BROOKLYN, NEW YORK CONDUCTIVITY LAYER 4 Consultants HYDRAULIC CONDUCTIVITY VALUES ARE IN FEET PER DAY (FT./DAY) Project 093010-5-1506 December 2011 Figure 2-17

H:\TECH\project\Regional Modflow model\Report\Figures.pptx HYDRAULIC CONDUCTIVITY ZONES

UPPER GLACIAL SAND (KH = 40, KV = 4)

UPPER GLACIAL TILL SUBUNITS

UPPER GLACIAL- NORTH TILL SUBUNIT (KH = 1.0, KV = 0.05)

UPPER GLACIAL - SOUTH TILL SUBUNIT KH = 5.0, KV = 0.1

UPPER GLACIAL SAND 2 (KH = 40, KV = 40)

UPPER GLACIAL SAND 3 (KH =0.5, KV = 0.05)

0 3,000 6,000

SCALE, FEET

NOTES: GROUNDWATER MODEL REPORT KH = HORIZONTAL HYDRAULIC CONDUCTIVITY GOWANUS CANAL SUPERFUND SITE HYDRAULIC

KV = VERTICAL HYDRAULIC CONDUCTIVITY BROOKLYN, NEW YORK CONDUCTIVITY LAYER 5 Consultants HYDRAULIC CONDUCTIVITY VALUES ARE IN FEET PER DAY (FT./DAY) Project 093010-5-1506 December 2011 Figure 2-18

H:\TECH\project\Regional Modflow model\Report\Figures.pptx HYDRAULIC CONDUCTIVITY ZONES

UPPER GLACIAL SAND (KH = 40, KV = 4)

GARDINERS CLAY (KH =0.008, KV = 0.008)

GARDINERS CLAY SAND FRINGE (KH =2, KV = 0.2)

0 3,000 6,000

SCALE, FEET

NOTES: GROUNDWATER MODEL REPORT KH = HORIZONTAL HYDRAULIC CONDUCTIVITY GOWANUS CANAL SUPERFUND SITE HYDRAULIC

KV = VERTICAL HYDRAULIC CONDUCTIVITY BROOKLYN, NEW YORK CONDUCTIVITY LAYER 6 Consultants HYDRAULIC CONDUCTIVITY VALUES ARE IN FEET PER DAY (FT./DAY) Project 093010-5-1506 December 2011 Figure 2-19

H:\TECH\project\Regional Modflow model\Report\Figures.pptx INACTIVE HYDRAULIC CONDUCTIVITY ZONES

GARDINERS UPPER GLACIAL SAND (KH = 40, KV = 4) CLAY CONTACT WITH BEDROCK GARDINERS CLAY (KH = 0.008, KV = 0.008)

GARDINERS CLAY SAND FRINGE (KH =2, KV = 0.2)

JAMECO GRAVEL JAMECO GRAVEL (KH = KV = 300)

0 3,000 6,000

SCALE, FEET

NOTES: GROUNDWATER MODEL REPORT KH = HORIZONTAL HYDRAULIC CONDUCTIVITY GOWANUS CANAL SUPERFUND SITE HYDRAULIC

KV = VERTICAL HYDRAULIC CONDUCTIVITY BROOKLYN, NEW YORK CONDUCTIVITY LAYER 7 Consultants HYDRAULIC CONDUCTIVITY VALUES ARE IN FEET PER DAY (FT./DAY) Project 093010-5-1506 December 2011 Figure 2-20

H:\TECH\project\Regional Modflow model\Report\Figures.pptx WESTERN MODEL LIMIT

SOUTHERN MODEL LIMIT EAST RIVER

GOWANUS BAY RED HOOK COBBLE HILL

CANAL

GARDINERS CLAY

GARDINERS CLAY UPPER GLACIAL (SAND FRINGE) AQUIFER JAMECO GRAVEL

BEDROCK SURFACE (FORDHAM GNEISS)

20:1 VERTICAL EXAGGERATION CUT-AWAY VIEW (LOOKING WEST)

GROUNDWATER MODEL REPORT GOWANUS CANAL SUPERFUND SITE CUT-AWAY VIEW ALONG BROOKLYN, NEW YORK CANAL Consultants Project 093010-5-1506 December 2011 Figure 2-21

H:\TECH\project\Regional Modflow model\Report\Figures.pptx GOWANUS BAY CANAL/MARSH HYDRAULIC CONDUCTIVITY ZONES (2nd AVE. DOCK AREA) DEPOSITS FILL OR SHALLOW NATIVE SAND (KH = 10, KV = 0.1)

OPEN WATER (KH = KV = 500)

MARSH DEPOSITS (KH = 0.01, KV = 0.0008)

SEDIMENT 1 K = 0.1

SEDIMENT 2 K = 0.01

MATCH LINE A LINE MATCH SEDIMENT 3 K = 4

SEDIMENT 3 K = 0.5

UPPER GLACIAL SAND (KH = 40, KV = 4)

A-A’ (WEST) NORTH TILL SUBUNIT (KH = 1.0, KV = 0.05)

SOUTH TILL SUBUNIT KH = 5.0, KV = 0.1

BOERUM HILL NAVY YARD GARDINERS CLAY (KH =0.008, KV = 0.008)

GARDINERS CLAY SAND FRINGE (KH =2, KV = 0.2)

JAMECO GRAVEL (KH = KV = 300)

A’ WILLIAMSBURG

NAVY YARD BOERUM HILL EAST RIVER B B’

COBBLE MATCH LINE A LINE MATCH HILL PROSPECT RED HILL C HOOK C’

GOWANUS 2ND AVE BAY DOCK AREA A-A’ (EAST) A 0 2,000 4,000 CROSS SECTION LOCATIONS

GROUNDWATER MODEL REPORT HYDRAULIC SCALE, FEET GOWANUS CANAL SUPERFUND SITE BROOKLYN, NEW YORK CONDUCTIVITY 20:1 VERTICAL CROSS SECTION A-A’ EXAGGERATION Consultants Project 093010-5-1506 December 2011 Figure 2-22

H:\TECH\project\Regional Modflow model\Report\Figures.pptx HYDRAULIC CONDUCTIVITY ZONES EAST RIVER COBBLE HILL CANAL PROSPECT HILL (DEGRAW ST.) FILL OR SHALLOW NATIVE SAND (KH = 10, KV = 0.1)

OPEN WATER (KH = KV = 500)

MARSH DEPOSITS (KH = 0.01, KV = 0.0008)

SEDIMENT 1 K = 0.1

SEDIMENT 2 K = 0.01

SEDIMENT 3 K = 4

SEDIMENT 3 K = 0.5

UPPER GLACIAL SAND (KH = 40, KV = 4)

NORTH TILL SUBUNIT (KH = 1.0, KV = 0.05) B-B’ SOUTH TILL SUBUNIT KH = 5.0, KV = 0.1

CANAL GARDINERS CLAY (KH =0.008, KV = 0.008) EAST RIVER RED HOOK (BAY ST.) PROSPECT HILL GARDINERS CLAY SAND FRINGE (KH =2, KV = 0.2)

JAMECO GRAVEL (KH = KV = 300)

A’ WILLIAMSBURG

NAVY YARD BOERUM HILL EAST B RIVER B’

COBBLE HILL RED PROSPECT HILL C HOOK C’

GOWANUS 2ND AVE BAY DOCK C-C’ AREA A CROSS SECTION LOCATIONS

0 3,000 6,000 GROUNDWATER MODEL REPORT HYDRAULIC GOWANUS CANAL SUPERFUND SITE CONDUCTIVITY SCALE, FEET BROOKLYN, NEW YORK CROSS SECTIONS B-B’ Consultants AND C-C’ Project 093010-5-1506 December 2011 Figure 2-23

H:\TECH\project\Regional Modflow model\Report\Figures.pptx CALIBRATION POINT BY MODEL LAYER

GROUNDWATER MODEL REPORT GOWANUS CANAL SUPERFUND SITE CALIBRATION CURVE – BROOKLYN, NEW YORK ALL LAYERS Consultants Project 093010-5-1506 December 2011 Figure 3-1

H:\TECH\project\Regional Modflow model\Report\Figures.pptx CALIBRATION POINT BY LAYER

GROUNDWATER MODEL REPORT CALIBRATION CURVE – GOWANUS CANAL SUPERFUND SITE UPPER GLACIAL AQUIFER BROOKLYN, NEW YORK (LAYERS 4 AND 5) Consultants Project 093010-5-1506 December 2011 Figure 3-2

H:\TECH\project\Regional Modflow model\Report\Figures.pptx CALIBRATION POINT BY LAYER

GROUNDWATER MODEL REPORT CALIBRATION CURVE – GOWANUS CANAL SUPERFUND SITE BROOKLYN, NEW YORK JAMECO GRAVEL Consultants (LAYERS 6 AND 7) Project 093010-5-1506 December 2011 Figure 3-3

H:\TECH\project\Regional Modflow model\Report\Figures.pptx BOERUM HILL NAVY YARD WILLIAMSBURG

A’

WILLIAMSBURG

UPPER GLACIAL AQUIFER NAVY YARD

BOERUM HILL EAST RIVER MATCH LINE A LINE MATCH GARDINERS CLAY B B’ COBBLE PROSPECT JAMECO GRAVEL HILL HILL

RED HOOK C C’ BEDROCK GOWANUS 2ND AVE BAY DOCK AREA A CROSS SECTION LOCATIONS A-A’ (NORTH)

GOWANUS BAY CANAL/MARSH DEPOSIT AREA (2nd AVE. DOCK AREA) . ST. BASIN . ST. . ST. BASIN . ST. BOND ST. BOND TH BAY ST. BAY TH BRYANT ST. BRYANT UNION/ CARROLL ST. 6 LEGEND 7

MODELCALCULATED POTENTIOMETRIC CONTOUR (FT. NAVD 88)

MODEL LAYER UPPER GLACIAL AQUIFER SURFACE WATER / CONSTANT-HEAD

MATCH LINE A LINE MATCH CELLS GARDINERS CLAY GROUNDWATER FLOW DIRECTION JAMECO GRAVEL BEDROCK

A-A’ (SOUTH)

20:1 VERTICAL GROUNDWATER MODEL REPORT EXAGGERATION POTENTIOMETRIC GOWANUS CANAL SUPERFUND SITE BROOKLYN, NEW YORK CONTOURS Consultants CROSS SECTION A-A’ Project 093010-5-1506 December 2011 Figure 3-4

H:\TECH\project\Regional Modflow model\Report\Figures.pptx CANAL LEGEND EAST RIVER COBBLE HILL (DEGRAW ST.) PROSPECT HILL

MODELCALCULATED POTENTIOMETRIC CONTOUR (FT. NAVD 88)

MODEL LAYER

SURFACE WATER / CONSTANT-HEAD CELLS

GROUNDWATER FLOW DIRECTION

B-B’

EAST RIVER RED HOOK CANAL PROSPECT HILL (BAY ST.)

A’

WILLIAMSBURG

NAVY YARD

BOERUM HILL EAST RIVER B B’ COBBLE PROSPECT HILL HILL

RED HOOK C C’

GOWANUS 2ND AVE BAY DOCK AREA A CROSS SECTION LOCATIONS C-C’

GROUNDWATER MODEL REPORT POTENTIOMETRIC GOWANUS CANAL SUPERFUND SITE CONTOURS BROOKLYN, NEW YORK CROSS SECTIONS B-B’ Consultants AND C-C’ Project 093010-5-1506 December 2011 Figure 3-5

H:\TECH\project\Regional Modflow model\Report\Figures.pptx NOTES:

HORIZONTAL HYDRAULIC CONDUCTIVITY SHOWN, EXCEPT FOR SEDIMENTS, MARSH DEPOSITS, AND GARDINERS CLAY, WHERE VERTICAL HYDRAULIC CONDUCTIVITY SHOWN. HORIZONTAL AND VERTICAL CONDUCTIVITIES ADJUSTED GROUNDWATER MODEL REPORT SENSITIVITY ANALYSIS BY SAME PROPORTIONS IN SENSITIVITY ANALYSIS. GOWANUS CANAL SUPERFUND SITE NORMALIZED RMS = NORMALIZED ROOT MEAN SQUARE BROOKLYN, NEW YORK HYDRAULIC ERROR OF CALIBRATION RESIDUAL (CALCULATED - OBSERVED HEADS). Consultants CONDUCTIVITY 1 Project 093010-5-1506 December 2011 Figure 4-1

H:\TECH\project\Regional Modflow model\Report\Figures.pptx NOTES:

HORIZONTAL HYDRAULIC CONDUCTIVITY SHOWN, EXCEPT FOR SEDIMENTS, MARSH DEPOSITS, AND GARDINERS CLAY, WHERE VERTICAL HYDRAULIC CONDUCTIVITY SHOWN. GROUNDWATER MODEL REPORT SENSITIVITY ANALYSIS HORIZONTAL AND VERTICAL CONDUCTIVITIES ADJUSTED GOWANUS CANAL SUPERFUND SITE BY SAME PROPORTIONS IN SENSITIVITY ANALYSIS. BROOKLYN, NEW YORK HYDRAULIC NORMALIZED RMS = NORMALIZED ROOT MEAN SQUARE Consultants CONDUCTIVITY 2 ERROR OF CALIBRATION RESIDUAL (CALCULATED - OBSERVED HEADS). Project 093010-5-1506 December 2011 Figure 4-2

H:\TECH\project\Regional Modflow model\Report\Figures.pptx NOTE: GROUNDWATER MODEL REPORT NORMALIZED RMS% = NORMALIZED ROOT MEAN GOWANUS CANAL SUPERFUND SITE SENSITIVITY ANALYSIS SQUARE ERROR OF CALIBRATION RESIDUAL BROOKLYN, NEW YORK AREAL RECHARGE (CALCULATED - OBSERVED HEADS). Consultants Project 093010-5-1506 December 2011 Figure 4-3

H:\TECH\project\Regional Modflow model\Report\Figures.pptx K 1305 K 1160 400 350 K 881 134-163 135-155 650 K 1288 115-140 125 79-92 K 249 K 912 300 69 K 1102 87-101 71-83 485 K 457 74-94 235 K 276 35-55 600 K 917 69-94 107 K 1190 90-106 K 615 512 K 930 69 44-64 300 125-140 K 1069 154-180 69K 638 K 1332 41-5169 300 160-175 160-168 K 916 K 920 69 69 150-162 142-164 K 531 K 1338 2255 710 K 1329 K 1331 290-350 150-190 700 790 122-162 105-145

K 922 K 1189 K 167 500 450 750 129-150 123-144 K 1287 69 K 1012 K 1148 153-161 200 540 142-157 129-150 K 245 260 145-170

K 244 225 99-114

LEGEND SOURCE: 1. AERIAL IMAGERY BING MAPS (c) 2011 MICROSOFT CORPORATION ACCESSED K 638 - USGS WELL ID THROUGH ARCGIS ONLINE 69 - REPORTED YIELD (GPM) (http://www.arcgis.com) 160-175 - SCREEN DEPTH 2. WELL YIELD DATA OBTAINED FROM USGS AS ORIGINALLY REPORTED BY NYSDEC (1937); NYSDEC (1944). GROUNDWATER MODEL REPORT GOWANUS CANAL SUPERFUND SITE HISTORIC REPORTED BROOKLYN, NEW YORK 0 3,500 7,000 WELL YIELDS

Consultants SCALE, FEET Project 093010-5-1506 December 2011 Figure 5-1 Path: J:\Projects\National_Grid\Gowanus\regional_GW_model\Well_Yield.mxd HISTORIC ANNUAL PRECIPITATION, LAGUARDIA AIRPORT

100

90

80

70 LEGEND

60 PRCP (IN.)

50 SNOW (IN.)

40 PRCP > 0.1 IN. (DAYS)

AVG PRCP (IN.) 30 AVG SNOW (IN.)

INCHES OR DAYS (SEE LEGEND) INCHES DAYS (SEE OR 20 AVG PRCP > 0.1 IN. (DAYS) 10

0 1954 1956 1958 1960 1962 1964 1966 1968 1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 2014

YEAR PERIOD OF LOWER WATER TABLE REPORTED BY USGS

NOTES: GROUNDWATER MODEL REPORT PRCP = ANNUAL PRECIPITATION GOWANUS CANAL SUPERFUND SITE HISTORIC PRECIP > 0.1 IN. = NUMBER OF DAYS IN YEAR THAT PRECIPITATION EXCEEDED 0.1 INCH. BROOKLYN, NEW YORK PRECIPITATION SNOW = ANNUAL SNOWFALL Consultants AVG = AVERAGE OVER YEARS SHOWN Project 093010-5-1506 December 2011 Figure 5-2

H:\TECH\project\Regional Modflow model\Report\Figures.pptx 1 LEGEND

2 CANAL SEGMENT FOR BASE FLOW 2 CALCULATION 3

4 MODEL-CALCULATED BASE FLOW TO CANAL

5

6

BASE FLOW CALCULATED USING MODFLOW ZONE BUDGET

GROUNDWATER MODEL REPORT NOTE: GOWANUS CANAL SUPERFUND SITE CALCULATED BASE BROOKLYN, NEW YORK GPM = GALLONS PER MINUTE FLOW Consultants Project 093010-5-1506 December 2011 Figure 6-1

H:\TECH\project\Regional Modflow model\Report\Figures.pptx LEGEND

MODEL-CALCULATED GROUNDWATER CONTOUR (FT. NAVD)

GROUNDWATER FLOW DIRECTION

DOWNWARD PARTICLE FLOW PATH (10-YR TICK SPACING)

UPWARD PARTICLE FLOW PATH (10-YR TICK SPACING)

APPROXIMATE UPPER GLACIAL AREA OF GROUNDWATER CONTRIBUTION DISCHARGING TO GOWANUS CANAL

1,870 Ac. (2.8 sq. mi.) 0 1,500 3,000

SCALE, FEET

GROUNDWATER MODEL REPORT PARTICLE FLOW PATHS GOWANUS CANAL SUPERFUND SITE BROOKLYN, NEW YORK – UPPER GLACIAL Consultants AQUIFER Project 093010-5-1506 December 2011 Figure 6-2

H:\TECH\project\Regional Modflow model\Report\Figures.pptx GROUNDWATER MODEL REPORT NATIONAL GRID GOWANUS CANAL SUPERFUND SITE DECEMBER 2011

Appendix A

Model Calibration and Validation

JAMECO AQUIFER SCRN ELEV. -139 FT. NGVD UPPER GLACIAL AQUIFER 29 SCRN ELEV. -16FT. NGVD 29

UPPER GLACIAL AQUIFER SCRN ELEV. -30 FT. NGVD 29 UPPER GLACIAL AQUIFER SCRN ELEV. -20 FT. NGVD 29

UPPER GLACIAL AQUIFER SCRN ELEV. -7FT. NGVD 29

UPPER GLACIAL AQUIFER SCRN ELEV. -10FT. NGVD 29

LLOYD AQUIFER SCRN ELEV. -298FT. NGVD 29

UPPER GLACIAL AQUIFER SCRN ELEV. 0 FT. NGVD 29 UPPER GLACIAL AQUIFER SCRN ELEV. -18 FT. NGVD 29

DATUM CONVERSION: NGVD 1929 ELEV. (FT.) – 1.08 FT. = NAVD 1988 ELEV. (FT.)

K3430 MAGOTHY AQUIFER SCRN - SCRN ELEV. -303 FT. NGVD 39 29 WL 11 FW-MW20 NYC-MW01 2.09 0.46 NYC-MW21 FW-MW19 5.13 EPA-MW33 7.08 3.04 FW-MW10 1.15 FW-MW09 KF-MW2 2.5 EPA-MW04 2.17 FW-MW17 FW-MW16 KF-MW6 3.34 MW-34 1.97 5.56 FW-MW07 1.77 FW-MW03R 6.31 FW-MW06 FW-MW01 2.2 KF-MW7 FW-MW14 EPA-MW03 1.29 2.48 5.21 5.5 FW-MW13 7.88 2.36 FW-MW02 FW-MW5R FW-MW03 2.1 1.81 1.79 4.07 FW-MW04R FW-MW05 FW-MW12 1.78 4.88 FW-MW18 FW-MW04 3.82 2.37 3.47 MW-35 3.06

EPA-MW28 2.4 EPA-MW36 EPA-MW29 2.55 EPA-MW43 1.7 2.39 CGMW-05 EPA-MW06 CGMW-01 CGMW13 CGMW-26 4.3 2.41 EPA-MW05 8.87 5.47 2.47 CG-PZ05 EPA-MW27 CGMW27 2.53 CGPZ-04 2.49 2.14 CG-PZ2 CGMW-14 6.68 7.9 9.71 MW-25 EPA-MW26 CG-PZ03 11.14 CGMW18 CGMW12 1.67 2.37 CGMW-17 8.08 CGMW02 3.66 2.48 8.62 10.41 CGMW23 CGMW09 CGMW-04 CGMW-11 NYC-MW08 CGMW37 CGMW35 CGMW-03 2.58 1.73 4.57 2.25 6.71 6.72 7.74 2.61 CGPZ06 CGMW38 CGMW-07 EPA-MW70 CGMW-34 2.23 7.23 -0.22 2.18 4.2 CGMW-10 CGMW15 CGMW36 CG-PZ42 7.12 6.49 6.42 CGMW-16 6.07 EPA-MW37 NYC-MW10 CGMW-40 GC-MW23 3.04 3.21 0.96 CG-MW08 1.21 1.72 -0.22 CGMW39 CG-MW06 MW-24 EPA-MW38 3.27 4.97 EPA-MW20 2.62 EPA-MW42 2.29 NYC-MW09 1.72 CGMW22 2.16 EPA-MW12 2.29 EPA-MW39 1.01 CGMW19 2.5 1.66 CGMW29 5.02 CGMW32 NYC-MW11 NYC-MW47 2.17 3.34 3.76 1.02 EPA-MW45 1.71 EPA-MW44

1.37 MT-MW9

0.79 MT-MW4 MT-MW8 1.83 2.99 MT-MW5 MT-MW3 2.29 MT-MW6 5.77 MT-MW1

NYC-MW17 4.07 8.17 4.96 2.5 MT-MW7 MW-14

2.82 NYC-MW19 GC-MW41 NYC-MW18 EPA-MW13 6.64 4.4 GC-MW40 5.14 1.97 2.92

EPA-MW16

2.57

EPA-MW15

1.4

LEGEND

FW-MW01 CALIBRATION POINT GROUNDWATER ELEVATION 2.61 USED FOR CALIBRATION SOURCE: (NAVD 88) 1. AERIAL IMAGERY BING MAPS (c) 2011 MICROSOFT CORPORATION ACCESSED GROUNDWATER MODEL REPORT THROUGH ARCGIS ONLINE GOWANUS CANAL SUPERFUND SITE (http://www.arcgis.com) CALIBRATION POINTS BROOKLYN, NEW YORK 0 600 1,200 SHALLOW

Consultants SCALE, FEET Project 093010-5-1506 December 2011 Figure A-2 Path: J:\Projects\National_Grid\Gowanus\regional_GW_model\Calibration_Shallow.mxd K3259

13

NYC-MW01I NYC-MW021I 2.58 1.95 GC-MW31I EPA-MW33I 2.23 2.47

EPA-MW04I GC-MW32I EPA-MW32I 2.54 GC-MW34I 3 6 2.13 EPA-MW03I GC-MW30I 2.12 1.88

GC-MW35I 2.43

EPA-MW28I 2.28 EPA-MW36I EPA-MW29I 2.43 2.25 EPA-MW43I EPA-MW06I 2.34 CGMW-01I CGMW-05I 2.35 EPA-MW05I 2.15 2.24 EPA-MW27I CGMW-14 CGMW-18CH7 2.32 CG-PZ1I GC-MW25I 2.43 CH4 2.87 2.77 EPA-MW26I 2.56 2.44 CG-PZ2I CGMW-04I 2.45 CGMW-17CH4 2.05 1.66 2.33 NYC-MW08I CGMW-03I CGMW02 CGMW-07I 1.69 1.88 EPA-MW07I 2.61 1.98 2.5 CGMW-42 CGMW-34I CGMW15 2.56 2.24 CGMW-16 2.93 CGMW-40D CH4 2.21 CGMW-43 3.22 EPA-MW37I 2.51 CGMW-41 GC-MW23I 1 2.69 NYC-MW10I 2.17 2.48 GC-MW24I EPA-MW38I EPA-MW20I EPA-MW42I 2.46 NYC-MW09I 2.47 3.01 2.42 EPA-MW12I 2.29 CGMW-22CH4 EPA-MW39I 2.39 CGMW-19CH4I 1.91 NYC-MW11I 2.59 3.08 2.35 NYC-MW47I EPA-MW45I 2.39 2.46 EPA-MW46I 2.48 EPA-MW44I 2.4 MT-MW9I 2.74 MT-MW4I

2.45 MT-MW8I 2.59 MT-MW5I MT-MW3I 2.52 4.17 MT-MW6I MT-MW1I 2.72 MT-MW7I NYC-MW17 5.15 1.98 2.42 GC-MW14I

2.31 GC-MW41I NYC-MW18 NYC-MW19 1.65 GC-MW40I 2.26 2.41 EPA-MW13I 1.36 1.8

EPA-MW16I

2.09

EPA-MW15I

1.78

LEGEND

FW-MW01 CALIBRATION POINT GROUNDWATER ELEVATION 2.61 USED FOR CALIBRATION SOURCE: (NAVD 88) 1. AERIAL IMAGERY BING MAPS (c) 2011 MICROSOFT CORPORATION ACCESSED GROUNDWATER MODEL REPORT THROUGH ARCGIS ONLINE GOWANUS CANAL SUPERFUND SITE CALIBRATION POINTS (http://www.arcgis.com) BROOKLYN, NEW YORK UPPER GLACIAL 0 600 1,200 AQUIFER Consultants SCALE, FEET Project 093010-5-1506 December 2011 Figure A-3 Path: J:\Projects\National_Grid\Gowanus\regional_GW_model\Calibration_UG.mxd FW-MW23D2 3.89

GC-MW30D2

2.88

CGMW-14 CH7

CGMW-17CH7 2.71 CGMW02 4.07 2.21 3.3 CGMW-03D CGMW-15CH7

3.16

MT-MW4D2 3.2

GC-MW40D2

4.14

LEGEND

FW-MW01 CALIBRATION POINT GROUNDWATER ELEVATION 2.61 USED FOR CALIBRATION SOURCE: (NAVD 88) 1. AERIAL IMAGERY BING MAPS (c) 2011 MICROSOFT CORPORATION ACCESSED GROUNDWATER MODEL REPORT THROUGH ARCGIS ONLINE GOWANUS CANAL SUPERFUND SITE (http://www.arcgis.com) CALIBRATION POINTS BROOKLYN, NEW YORK 0 600 1,200 JAMECO GRAVEL

Consultants SCALE, FEET Project 093010-5-1506 December 2011 Figure A-4 Path: J:\Projects\National_Grid\Gowanus\regional_GW_model\calibration_jameco.mxd MODEL BOUNDARY

GOWANUS CANAL

K 1305 K 1160

K 881 K 1051 K 1313

K 1288 K 1340 K 249 K 271 K 261 K 260 K 256 K 276 K 1102 K 935 K 1302 K 1073 K 117 K 943 K 269 K 937 K 457 K 290 K 18 FULTON FORMER K 1190 K 1192 MGP SITE

K 873

K 615 K 3301 K 930 K 1069 K 917 K 1091 K 931 K 6381332 K 920

K 916 K 1010

CITIZENS FORMER K 907 MGP SITE

K 1339 METROPOLITAN K 531 K 1338 FORMER MGP SITE

K 1352 K 922 K 1189 K 167 K 1046 K 1012 K 1148 K 1355 K 1287

K 245

K 244 LEGEND

USGS BORING LOCATION

SOURCE: FORMER MGP SITE 1. AERIALIMAGERY BING MAPS (c) 2011 MICROSOFT CORPORATION, ACCESSED THROUGH ARCGIS BOUNDARY ONLINE (http://www.arcgis.com) 2. UNITED STATES GEOLOGICAL SURVEY AND NEW YORK STATE DEPARTMENT OF CONSERVATION, RECORD OF WELLS IN KINGS COUNTY, N. Y. GROUNDWATER MODEL REPORT GOWANUS CANAL SUPERFUND SITE REGIONAL SOIL BORING 0 3,500 7,000 BROOKLYN, NEW YORK DATA POINTS

Consultants SCALE, FEET Project 093010-5-1506 December 2011 Figure A-5

J:/Projects/National_Grid/Gowanus/Regional_GW_Model/Regional_SB_DataPoints.mxd LEGEND MODEL-CALCULATED GROUNDWATER ELEVATION 1.0 CONTOUR (FT.)

GROUNDWATER CONTOURS BASED ON TIDALLY-AVERAGED 1.0 OBSERVED GROUNDWATER ELEVATIONS

APPROXIMATE EXTENT OF MARSH DEPOSITS

GROUNDWATER MODEL REPORT GOWANUS CANAL SUPERFUND SITE QUALITATIVE SOURCE: Map created with TOPO! ® BROOKLYN, NEW YORK CALIBRATION – ©2001 National Geographic (www.nationalgeographic.com/topo) Consultants SHALLOW NORTH Project 093010-5-1506 December 2011 Figure A-6

H:\TECH\project\Regional Modflow model\Report\Figures.pptx LEGEND MODEL-CALCULATED GROUNDWATER ELEVATION 1.0 CONTOUR (FT.)

GROUNDWATER CONTOURS BASED ON TIDALLY-AVERAGED 1.0 OBSERVED GROUNDWATER ELEVATIONS

APPROXIMATE EXTENT OF MARSH DEPOSITS

GROUNDWATER MODEL REPORT GOWANUS CANAL SUPERFUND SITE QUALITATIVE SOURCE: Map created with TOPO! ® BROOKLYN, NEW YORK CALIBRATION – ©2001 National Geographic (www.nationalgeographic.com/topo) Consultants SHALLOW CENTRAL Project 093010-5-1506 December 2011 Figure A-7

H:\TECH\project\Regional Modflow model\Report\Figures.pptx LEGEND MODEL-CALCULATED GROUNDWATER ELEVATION 1.0 CONTOUR (FT.)

GROUNDWATER CONTOURS BASED ON TIDALLY-AVERAGED 1.0 OBSERVED GROUNDWATER ELEVATIONS

APPROXIMATE EXTENT OF MARSH DEPOSITS

GROUNDWATER MODEL REPORT GOWANUS CANAL SUPERFUND SITE QUALITATIVE SOURCE: Map created with TOPO! ® BROOKLYN, NEW YORK CALIBRATION – ©2001 National Geographic (www.nationalgeographic.com/topo) Consultants SHALLOW SOUTH Project 093010-5-1506 December 2011 Figure A-8

H:\TECH\project\Regional Modflow model\Report\Figures.pptx LEGEND

MODEL-CALCULATED GROUNDWATER ELEVATION CONTOUR 1.0 (FT.)

GROUNDWATER CONTOURS BASED ON TIDALLY-AVERAGED OBSERVED GROUNDWATER ELEVATIONS (ELEV. 2 AND 3 1.0 CONTOURS) AND AS REPORTED BY BUXTON AND SHERNOFF (1997) (ELEV. 5 AND 10 CONTOURS).

GROUNDWATER MODEL REPORT QUALITATIVE GOWANUS CANAL SUPERFUND SITE SOURCE: Map created with TOPO! ® BROOKLYN, NEW YORK CALIBRATION – UPPER ©2001 National Geographic GLACIAL AQUIFER (www.nationalgeographic.com/topo) Consultants Project 093010-5-1506 December 2011 Figure A-9

H:\TECH\project\Regional Modflow model\Report\Figures.pptx 8

UPPER GLACIAL JAMECO AQUIFER GRAVEL

5

LEGEND NOTE: MODEL-CALCULATED FLOW IS MORE EASTERLY THAN THE FLOW DIRECTION MODEL-CALCULATED GROUNDWATER INFERRED FROM USGS CONTOURS. VARIANCE IS DUE TO PRESENCE OF 1.0 ELEVATION CONTOUR (FT.) DISCHARGE ZONEs ALONG WESTERN EXTENTOF GARDINER’S CLAY.

GROUNDWATER CONTOURS INFERRED 1.0 FROM USGS (1999)

WESTERN LIMIT OF JAMECO GRAVEL IN MODEL

GROUNDWATER MODEL REPORT QUALITATIVE GOWANUS CANAL SUPERFUND SITE SOURCE: Map created with TOPO! ® BROOKLYN, NEW YORK CALIBRATION – JAMECO ©2001 National Geographic GRAVEL (www.nationalgeographic.com/topo) Consultants Project 093010-5-1506 December 2011 Figure A-10

H:\TECH\project\Regional Modflow model\Report\Figures.pptx 125 K1288

650 K881 600 K276

69 K912 482 K1102 107 K917

300 K930

235 K457

69 K920 69 69 K916 K638 512 300 K1130 K1332

69 K1069

LEGEND

69 REPORTED WELL YIELD (GPM) / USGS WELL ID K705

1.0 MODEL-CALCULATED GROUNDWATER ELEVATION CONTOUR (FT.)

1.0 DRAWDOWN CONTOURS FOR 1951 REPORTED BY CARTWRIGHT (2002)

NOTE: REPORTED HISTORIC GROUNDWATER CONTOURS REPRESENT PERIOD OF EXTENSIVE PUMPING OF UPPER GLACIAL AQUIFER. MODEL-CALCULATED CONTOURS IN RED SHOW DRAWDOWN FOR A SMALL SUBSET OF HISTORIC PUMPING WELLS. A SIGNIFICANTLY GREATER AMOUNT OF PUMPING WAS OCCURRING NORTH OF THE MODEL, AND ACROSS KINGS AND QUEENS COUNTIES, THAT RESULTED IN THE HISTORIC CONTOURS SHOWN. THESE RESULTS SUPPORT MODEL VALIDATION, BECAUSE CALCULATED WATER TABLE BASED ON THE PUMPING WELLS SHOWN ABOVE DOES NOT EXCEED THE REGIONAL DRAWDOWN BASED ON PUMPING FROM A GREATER NUMBER OF WELLS.

GROUNDWATER MODEL REPORT MODEL VALIDATION GOWANUS CANAL SUPERFUND SITE SOURCE: Map created with TOPO! ® BROOKLYN, NEW YORK RESULTS – PARTIAL ©2001 National Geographic HISTORIC PUMPING (www.nationalgeographic.com/topo) Consultants Project 093010-5-1506 December 2011 Figure A-11

H:\TECH\project\Regional Modflow model\Report\Figures.pptx K3483 (2.5)

K3482 (1.5)

K3276 (0.5)

K3301 (2.0)

LEGEND

K3301 (2.0) USGS WELL LOCATION / OBSERVED DRAWDOWN (FT.)

1.0 MODEL-CALCULATED DRAWDOWN (FT.)

NOTE: DRAWDOWN CONTOURS REPRESENT UPPER GLACIAL AQUIFER RESPONSE TO MILD DROUGHT 1999-2002. RESULTS SHOWN ABOVE SUPPORT MODEL VALIDATION BECAUSE CALCULATED DRAWDOWN GENERALLY MATCHES OBSERVED DRAWDOWN.

GROUNDWATER MODEL REPORT MODEL VALIDATION GOWANUS CANAL SUPERFUND SITE SOURCE: Map created with TOPO! ® BROOKLYN, NEW YORK RESULTS – REDUCED ©2001 National Geographic RECHARGE (www.nationalgeographic.com/topo) Consultants Project 093010-5-1506 December 2011 Figure A-12

H:\TECH\project\Regional Modflow model\Report\Figures.pptx