Tetra Tech, Inc.

10306 Eaton Place, Suite 340

Fairfax, VA 22030

phone 703-385-6000

fax 703-385-6007

DATE: November 14, 2008

TO: Paul Shriner, EPA

FROM: Christine Wong

SUBJECT: Substratum intake

Introduction

Tetra Tech conducted a limited

impingement and entrainment (I&E) reduction 

substratum intake technologies

intended to inform the development of 

information for the revised rule

Tetra Tech performed general Web searches using combinations of search terms

subfloor water intake structure system, 

desalination, seafloor, beach well, sea well, 

bed and basin. 

Tetra Tech (Tt) also researched a proposed project at the Shoreham site

Preliminary Findings

In general, the search yielded

detailed information. Desalination drinking water facilities 

industry utilizing substratum

States, operation of desalination facilities ha

MEMORANDUM

10306 Eaton Place, Suite 340

November 14, 2008

Paul Shriner, EPA

Christine Wong and Kelly Meadows, Tetra Tech

Substratum intakes

conducted a limited search of Internet resources to identify size, cost, and 

impingement and entrainment (I&E) reduction performance data for facilities using 

substratum intake technologies (also known as filter beds). The information recovered 

development of performance standards and supporting background 

rule.

Tetra Tech performed general Web searches using combinations of search terms

subfloor water intake structure system, subsurface, substratum, cooling water, 

desalination, seafloor, beach well, sea well, impingement, entrainment, and infiltration

Tetra Tech (Tt) also researched a proposed project at the Shoreham site in New York.

ed a moderate number of resources with a limited amount of

Desalination drinking water facilities appear to be the predominant 

intakes in their operations. While extant in the United 

States, operation of desalination facilities has so far been concentrated in Europe, N

identify size, cost, and 

performance data for facilities using 

tion recovered is 

performance standards and supporting background 

Tetra Tech performed general Web searches using combinations of search terms such as 

cooling water, 

and infiltration

in New York.

with a limited amount of

he predominant 

operations. While extant in the United 

r been concentrated in Europe, North 
Africa, and the Middle East. Some non-desalination drinking water facilities also use 

substratum water intakes. At the present, the use of substratum intakes for cooling water 

intake structures (CWIS) is mostly in the design and pilot stage. Tetra Tech identified 

one facility that is seriously considering using a substratum intake to supply its cooling 

water (see below).

Intake flow and intake structure type are the most readily available information; there is 

little information on cost and concerns regarding I&E of aquatic organisms. Most large 

desalination facilities use surface water intakes; only a few of the world’s larger 

desalination plants use substratum or subsurface water intakes. In general, “subsurface 

intakes are considered to be cost-competitive for plants of capacity smaller than 1 million 

gallons per day (mgd).”

1

 These facilities most commonly make use of vertical or 

horizontal beach wells, which are shallow shoreline intake wells that use the overlying 

rock or sand layers as a filter medium. As of 2005, “there were only four worldwide 

operational seawater reverse osmosis desalination facilities with capacity larger than 5.3 

mgd using beach well intakes.”

2

 For these intake structures, concerns regarding I&E of 

aquatic organisms are not typically addressed; where they are mentioned, I&E is assumed 

to be zero and is considered to be part of the desired baseline performance of the intake 

design. 

There are studies and pilot projects being conducted to investigate the viability of 

subsurface or substratum CWIS. Early investigations have yielded positive results, 

including 100% reduction of I&E of aquatic organisms.3 Only a few vendors appear to 

be working on substratum intake technologies for CWISs. At least one manufacturer is 

pursuing or has obtained patents for substratum technology intended for use as CWIS. 

Product and company contact information is available for at least one English-language 

manufacturer in Canada.

Many desalination facilities using surface water intakes in the United States are sited, or 

planned to be sited, along existing power plants or other facilities with water intake

operations, so the water withdrawals may be conducted through existing water intake 

structures. Poseidon Resources, a company that develops, invests in and manages water 

infrastructure projects throughout North America, is connected to many of the recent and 

ongoing desalination facility projects (using both surface and subsurface intakes) in the 

United States. 

The attached chart details the main facilities, studies, and manufacturers identified in this 

search.

 

1 Voutchkov, N. 2005. SWRO desalination process: on the beach – seawater intakes. Filtration &

Separation (42):8, October 2005, pp. 24-27.

2

Pankratz, T. An Overview of Seawater Intake Facilities for Seawater Desalination. 

http://texaswater.tamu.edu/readings/desal/Seawaterdesal.pdf; Voutchkov, 2005.

3 EEA, Inc. 2005. Keyspan Generation LLC studies the substratum intake system: An Innovative water 

intake system for power generation facilities. Environmental Consulting Insights Newsletter. Spring, 2005.
Shoreham

Tt contacted the New York Department of Environmental Conservation (NYDEC),4 who 

would regulate the proposed intake. Kevin Kispert at NYDEC acknowledged that 

NYDEC had received an application for a substratum intake (including conducting a pilot 

study) but directed Tt to contact Energy & Environment Analysts (EEA) who is the 

primary consultant for the project.

On January 2, 2008, Tt spoke with Roy Stoecker and Jim McAleer from EEA regarding 

the proposal to install a substratum intake at the Shoreham Site which has appropriate and 

typical geological conditions.5 EEA has been working with Keyspan Energy (a National 

Grid Company) for several years and initially conducted a feasibility study using existing 

technical, geological, and hydrological data. In order to operate a 400MW power plant, it 

was assumed that a withdrawal rate of approximately 170,000 gallons per minute (gpm) 

would be required. The study concluded that the aquifer could support such withdrawals, 

given a sufficiently large intake field.

The next step is to conduct a pilot study. EEA developed a proposal and, through a 

funding program from a combination of KeySpan, LIPA and NYSERDA, the pilot study

is scheduled to be conducted in the spring of 2008. Currently, EEA, KeySpan and LIPA 

are awaiting approval of several permits to begin the testing.

EEA’s staff generally assumes that the substratum intake will eliminate impingement and 

entrainment, as well as offer other benefits: reduced operations and maintenance costs, 

minimal downtime required at installation, and expected fuel savings in the summer.

As of November 14, 2008, EEA’s website (via its sister company SIS Water Systems, 

http://www.siswatersystems.com/) indicates that the pilot project will begin construction 

in the fall of 2008. Other projects are also under development.

 

4 On December 20, 2007.

5 This site is utilized by KeySpan for combustion turbine and diesel generation.
Facility/Study/

Manufacturer

Location Size

(flow)

Cost I&E reduction 

strategy/technology

I&E reduction 

performance

Long Island Sound Substratum 

CWIS Feasibility Study

Long Island, 

NY

Intake -700,000 gpm Significant cost reduction of 

typical CWIS costs

Substratum Intake Structure to 

draw water from underneath the 

Long Island Sound

100% reduction

Initial Evaluation of the 

SWISS vs. Conventional 

Multimedia Pretreatment 

Techniques

USA Estimated ~ 20-32% 

reduction of typical SWRO 

facility total costs

Subfloor Water Intake Structure 

System (SWISS); no I&E 

technology mentioned

100% reduction

Long Beach Desalination 

Prototype 

Facility

Long Beach, 

CA

300,000 gpd Design and construction phase of 

Under Ocean Floor Seawater Intake 

and Discharge Demonstration 

System

100% reduction 

planned

Elmosa Marine Works Ontario, 

Canada

Max capacity - 60,000 gpm; 

intake flow - ~ 0.3 fps

“fractional cost” of other 

intake systems

Offshore and onshore infiltration 

intake systems

100% reduction

New Infiltration Intake System 

for Zebra Mussel Control and 

Larval Exclusion

Maximum intake - 3 m3/s 30% or less of conventional 

intake systems

Filtration bed intake system 100% reduction

Marine Coast Water District 

Seawater Desalination Facility

Monterey, CA Intake - 450,000 gpd; 

Produces -300,000 gpd

Beach wells; no I&E technology 

mentioned

Cirkewwa Reverse Osmosis 

Desalination Plant

Malta Intake - 4.9 mgd; Produces -

2 mdg

Beach wells; no I&E technology 

mentioned

Pembroke Reverse Osmosis 

Desalination Plant

Malta Intake - 14.3 mgd; Produces 

- 6.4 mdg

Beach wells; no I&E technology 

mentioned

Ghar Lapsi - Reverse Osmosis 

Desalination Plant

Malta Intake - 6.3 mgd; Produces -

2 mgd

Beach wells; no I&E technology 

mentioned

Kalaeloa Desalination Plant Honolulu, HI Planned intake - 11 mgd; 

planned production - 5 mgd

Estimated at $45 million Deep basal wells; no I&E 

technology mentioned

Bay of Palma Desalination 

Plant 

Mallorca, 

Spain

Intake - 11 mgd 16 vertical beach wells; no I&E 

technology mentioned

Pemex Salina Cruz Refinery Mexico Intake - 3.8 mgd Beach wells; no I&E technology 

mentioned

Tampa Bay Seawater 

Desalination Plant

Hillsborough 

County, FL

Intake- 44 mgd; Produces -

25 mgd

$75.5 million Co-location with existing plant 

utilizing fine mesh screens

No additional I&E 

opportunity created