Groundwater Development for Public Water Supply

ASCE – Philadelphia Section

Environmental & Water Resources Technical Group

February 27, 2014

Groundwater Development for Public Water Supply

Presenters:

R. Scott Hughes, P.E. and Thomas Waddington, P.G.

GF Valley Forge, PA GF Camp Hill, PA

Agenda

1. Need for New Groundwater Supply

2. Well Site Selection

3. Well Drilling and Construction

4. Well Development

5. Aquifer Pumping Tests

6. Permitting

Need for New Groundwater Supply

Need for New Groundwater Supply Sources

• New Community or Non-Community System

• Increasing Demands (Existing System)

• Replace an Existing Public Supply Source

– Poor Yielding Source

– Poor Quality Source

– Higher Cost Source

New Well Site Selection

New Well Site Selection Study

• Well Siting Considerations

– Regulatory Requirements

– Hydrogeological Conditions

– Property

Regulatory Considerations

• Will the aquifer offer good water quality?

– PA Code - Prior to the development of a new source, the

water supplier shall make reasonable efforts to obtain the

highest quality source available.

Regulatory Considerations

• Is there sufficient land for wellhead protection?

– PA Code - The water supplier must own or substantially control

a Zone I wellhead protection area.

• Are there any groundwater withdrawal allocation restrictions?

– Certain areas may be protected by regulatory agencies because

of limited resources.

• Are there any local government restrictions/requirements?

Hydrogeological Considerations

• Aquifer Yielding and Water Quality Characteristics

– What are the geologic formation types and structure?

– What is the general water quality of formations?

– We typically use existing well data and published reports

• Aquifer Recharge Basin Characteristics

– What are the groundwater recharge and withdrawal rates?

– What are the potential pollution sources?

– Could it capture an existing groundwater contaminant plume?

• Potential Groundwater Withdrawal Impacts

– Could the new source impact wells, wetlands, or surface water?

Recommended Well Development Areas

ID Properties and Rank Well Sites within Areas

Rank Potential Test Well Sites

Proposed Test Well Sites within Property

Property Considerations

• What is the size and proximity to the system?

• What is the land use and zoning?

• Will the property owner enter and agreement for

well drilling access and the right to purchase?

• Is there a need to use Eminent Domain?

Potential Well Site Access and WHP Area

Surface Geophysics

VLF-EM Geophysics

Electrical Resistivity Imaging

Electrical Resistivity Imaging

Electrical Resistivity Imaging

ERI Results

ERI Results

Contact and Coordinate with Regulatory Agencies

• Complete a sanitary survey at the proposed

test well sites

• Prepare and submit a Pre-Drilling Plan to

regulatory agencies for approval

– In Pennsylvania, a registered professional geologist

must prepare the Pre-Drilling Plan

Pre-Drilling Plan Should Describe:

• Existing or proposed water system and the purpose of

the well development project

• Hydrogeologic and topographic setting

• Groundwater availability

• Land use, zoning, and potential pollution sources

• Potential wellhead protection area

• Proposed well depth and anticipated yield

• Potential impacts of the new groundwater withdrawal

• Threatened or endangered species

• Well construction and testing specifications

Existing System and Property Overview

Topographic and Geologic Map

Pre-Drilling and Testing Plan

Well Drilling and Construction

Well Drilling and Construction

• Procure licensed well driller

• Obtain drilling permit from local government

• Check for underground utilities

• Provide for drilling equipment access (road)

• Address erosion and sediment control

Well Drilling and Construction

Erosion and Sediment Control Measures

Erosion and Sediment Control Measures

Erosion and Sediment Control Measures

Erosion and Sediment Control Measures

Well Drilling and Construction

Well Construction Logging and Design

• A geologist must log:

– Soil and Bedrock Types

– Water-Bearing Opening

Depths and Yields

– Water Quality

– Well Casing Depth and

Diameter

Well Construction Design and Logging

Well Discharge Estimates

Well Construction Design and Logging

Well Discharge Estimates

Well Discharge Estimates

Well Discharge Estimates

Well Development

• Compressed Air-lift

• Surge Block

• Bailing

• Pumping

Air-Lift Well Development

Air-Lift Well Development

Air-Lift Well Development

Sediment Control Basins

Detention and Coagulant Treatment

Treated Discharge

Submersible Pump Development

Aquifer Pumping Tests

Aquifer Pumping Test Plan Describes:

• Hydrogeologic Setting – Geologic Fms., Structure, & Permeability

• Aquifer Boundaries – Recharge Boundaries & Barrier Boundaries

• Groundwater Elevation Map – Field-Measured Water Levels

• Hydrogeological Cross-Sections

• GW Availability Analysis – Precip. Recharge & Withdrawal Rates

• The Well Construction & Estimated Blown Yield

• Test Pumping Equipment & Water Conveyance

• Proposed Pumping Rates & WL Monitoring Procedures

• Well, Wetland, & Surface Water Monitoring Points

Generalized Block Diagram

Geology and Groundwater Recharge Basin

Hydrogeological Cross-Section

Hydrogeological Cross-Section

Well Construction Detail

Groundwater Recharge Basin & Elevations

Estimated Area of Influence & Observation Points

Tasks to Complete Aquifer Pumping Tests

• Pumping Equipment Installation

• Install Monitoring Instruments

• Background Monitoring Period

• Variable-Rate Pumping Test

• Recovery Monitoring Period

• Monitor Weather Conditions

• Constant-Rate Pumping Test

• Water Quality Samples

• Recovery Monitoring Period

Test Well Pumping Equipment

Test Well Pumping Equipment

Flow Meter

Water Conveyance Pipe

Electric Power

Test Well Pumping Equipment

Test Well Pumping Equipment

Test Well Pumping Equipment

Simultaneous Pumping Test

Artesian Well

Setting Pump in Artesian Well

Monitor Water Levels in Supply Wells

Shallow Wetland Piezometers

Surface Water Weir and Shallow Piezometer

Surface Water Weir

V-Notch Weir

Rectangular Weir

Cut-Throat Flume

Well Water Quality Samples

• PADEP New Public Supply Source Parameters

Tested by a Certified Laboratory

– Coliform Bacteria

– Volatile Organic Compounds

– Synthetic Organic Compounds

– Inorganic Chemicals

– Radionuclides

– Secondary Contaminants

– Microscopic Particulate Analysis

Hydrogeological Report

Hydrogeological Report Should Describe:

• Water System Demands and Source Needs

• Hydrogeologic Setting

• GW Availability Analysis - Normal & Below Normal Precipitation

• Well Construction and Development Details

• Results of the Aquifer Tests

– Well Pumping Rates and Sustainable Well Yield

– Water Level Drawdown Results

– Areas of Withdrawal Influence and Contribution

– Aquifer Hydraulic Characteristics – K, T, S, & Specific Capacity of Well

– Withdrawal Impacts to Neighboring Wells, Wetlands, Surface Water

– Well Water Quality Results

Variable-Rate Pumping Test

Variable-Rate Pumping Test

Variable-Rate & Constant-Rate Pumping Tests

Constant-Rate Drawdown Data

Pumping Well Residual Drawdown Data

Projection of Pumping Well Water Level

Observation Well Water Level Data

Observation Well Drawdown Data

Tabulation of Observation Point Data

Estimated Areas of Influence and Contribution

State Public Water Supply Permit

• Preliminary Conference

• Construction Permit Application

– General Information Form

– Hydrogeological Report

– Basis of Design/Engineer’s Report

– Permit Modules

– Drawings and Technical Specifications

• Operation Permit Application

– Engineer’s Certification

– Operation & Maintenance Information

River Basin Groundwater Withdrawal Permit

• Applications Include:

– Standard forms to provide system/source information

Location, characteristics, and capabilities of system sources

Demands and projected demands

– Hydrogeological report

– Design report, drawings & specs. for proposed source

– Other potential requirements, including mitigation

Questions ?