Since 2004, the Pebble Par tnership has worked with a number of Alaska-based consultants to manage an ongoing program

of groundwater hydrology data collection and analysis at key locations throughout the Pebble Project area. Groundwater is

water found beneath surface in overburden pore spaces and in the fractures of bedrock formations.

Companies contributing to Pebble Project groundwater hydrology (or hydrogeology) studies between 2004 and 2007 include:

• Water Management Consultants Inc.; • Paug Vik Development Corp.;

• SLR Alaska; • Bristol Environmental & Engineering Services Corp.; and

• HDR Alaska; • CH2M Hill Inc.

Groundwater hydrology studies are designed to characterize the groundwater regime in the Pebble Project area, including

water quantity, flow rates and flow directions. The study also includes an evaluation of the interaction between groundwater

and surface water.

Pre-Permitting Environmental/ Socio-Economic Data Report Series

Report Series D: Groundwater Hydrology

1,310,000

1,310,000

1,320,000

1,320,000

1,330,000

1,330,000

1,340,000

1,340,000

1,350,000

1,350,000

1,360,000

1,360,000

1,370,000

1,370,000

1,380,000

1,380,000

1,390,000

1,390,000

1,400,000

1,400,000

1,410,000

1,410,000

1,420,000

1,420,000

1,430,000

1,430,000

1,440,000

1,440,000

1,450,000

1,450,000

2,09

0,00

02,

100,

000

2,11

0,00

02,

120,

000

2,13

0,00

02,

140,

000

2,15

0,00

02,

160,

000

2,17

0,00

02,

180,

000

2,19

0,00

02,

200,

000

\\Manu\projects\Pebble\reporting\2008 Pebble Data Report\Site Plan.mxd

Legend

Canada

ARCTIC OCEAN

PebbleProject Area

GULF OF A LASKA

Russia

BERING SEA

0 10,000 20,000 30,000Feet

Alaska State Plane Zone 5 (units feet)1983 North American Datum

Date: June 16, 2008

Author: WMC-LC

1:150,515Scale

Project No: 7126

Version: 1

General Deposit LocationWetland Piezometer (WL)Monitoring Well (MW)Piezometer (P, GH, I, M)Pumping Well (PW)

WatershedNorth Fork Koktuli RiverSouth Fork Koktuli RiverUpper Talarik Creek

Pre-permitting Environmental/Socioeconomic

Data Report Series

Report Series D: Groundwater Hydrology

Site Plan

0 3,000 6,000 9,000Meters

LakesRivers50-ft Contour Interval

Pebble Project groundwater hydrology data collection occurred at 259 monitoring wells and piezometers at 196 sites throughout the South Fork Koktuli River, North Fork Koktuli River and Upper Talarik Creek watersheds.

levels are recorded hourly in some wells. Piezometers are constructed in the same way as monitoring wells but are used to

measure only groundwater levels.

Elements of the Pebble Project groundwater hydrology study include:

• characterization of the subsurface geology to identify fine-grained materials (silts and clays) versus coarse

grained materials (such as sands and gravels);

• 94 rising and falling head tests to measure hydraulic conductivity or the rate at which soil or rock allows

water to flow;

• seven pumping tests where one well is pumped and several near-by wells are monitored for changes in

water level;

• hourly and monthly groundwater elevation monitoring;

• a seep inventory of groundwater discharges to surface (including location and size classification) and flow-

rate monitoring at selected seeps throughout the study area.

The information being released as par t of the Pebble Par tnership’s Pre-Permitting Environmental & Socio-Economic Data

Repor t Series in June 2008 includes data and associated figures gathered between 2004 to early 2007 and is organized into

the following data groups:

• well, piezometer and drillhole locations; • pumping tests;

• monthly groundwater elevations; • seep inventory;

• hourly groundwater elevations; • seep flow rates.

• response tests;

Additional hydrogeology investigations are planned for 2008.

The data from the 2008 field program will be available in 2009.

Complete copies of the groundwater

hydrology data reports released as

part of the Pebble Partnership’s

Pre-Permitting Environmental &

Socio-Economic Data report

Series are available online at

www.pebblepartnership.com.

The study area for Pebble’s

groundwater hydrology program

includes the North Fork Koktuli River

watershed, the South Fork Koktuli

River watershed and Upper Talarik

Creek watershed. The study included

the installation of 259 monitoring

wells and piezometers at 196 sites

throughout these watersheds.

Monitoring wells are utilized to collect

groundwater samples and monitor

groundwater levels. Groundwater

Drainage

South Fork Koktuli

North Fork Koktuli

Upper Talarik Creek

TOTAL

Piezometersand

MonitoringWells

160

65

34

259

Piezometerand

MonitoringWell Sites

113

42

20

175

MonitoringWells

24

8

6

38

MonitoringWell Sites

12

5

4

21

Table 1: Summary of Monitoring Wells and Piezometers by Drainage

Hydrogeology studies provide valuable input to the Par tnership’s engineering team, in par t by identifying potential

changes to the groundwater regime resulting from construction, operation and closure of future mine development.

A comprehensive understanding of groundwater conditions will allow project engineers to design a project that minimizes

groundwater impacts and incorporates measures to mitigate residual effects.

Groundwater characterization is being under taken at multiple locations throughout the project area to identify optimal

locations for various mine facilities, including the mill, tailings storage area and other mine components. Project facility design

and location will also be substantially influenced by related environmental considerations – including effects on surface

water, fish habitat and wetlands.

Program Overview: Study Area