                                       
                                       

                                  MEMORANDUM



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 and Kelly Meadows, Tetra Tech

SUBJECT:	Substratum intakes

Introduction

Tetra Tech 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 is intended to inform the development of performance standards and supporting background information for the revised rule.

Tetra Tech performed general Web searches using combinations of search terms such as  subfloor water intake structure system, subsurface, substratum, cooling water, desalination, seafloor, beach well, sea well, impingement, entrainment, and infiltration bed and basin. 

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

Preliminary Findings

In general, the search yielded a moderate number of resources with a limited amount of detailed information.  Desalination drinking water facilities appear to be the predominant industry utilizing substratum intakes in their operations.  While extant in the United States, operation of desalination facilities has so far 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)."  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."  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.  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.

 
Shoreham

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


                                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 m[3]/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

