Document ID: EPA-HQ-OW-2008-0667-0642
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2011-04-20T04:00Z

MEMORANDUM

Tetra Tech, Inc.
10306 Eaton Place, Suite 340
Fairfax, VA 22030
phone	703-385-6000
fax	703-385-6007

DATE: 		February 28, 2011

TO:			Paul Shriner, EPA
	
FROM:		Kelly Meadows, Tetra Tech

SUBJECT:	Space Constraints for Cooling Tower Retrofits

The size of the property plays an important role in determining whether a retrofit to cooling towers is feasible.  EPA previously addressed the issue of land availability for cooling tower retrofits in its final effluent limitation guideline (ELG) for steam electric facilities (39 FR 36186, October 8, 1974).  In this ELG, the Agency stated that it had determined that "28 acres per 1000 megawatts (MW) generating capacity is ample land on which any existing plant can construct a mechanical draft cooling tower." (See 39 FR 36190.)  The ELG also required a facility to consider relocating existing uses (such as parking areas), alternative cooling tower designs (e.g., natural draft towers, which require approximately 40% less land area), or the acquisition of adjacent land in its consideration of whether sufficient space is available.  Since land uses have likely changed since the early 1970's, EPA collected new data on the acreage and production capacity of power plant properties from site visits, regional offices, draft permits, and other sources.  This memo then explores the uncertainty over land availability and other space constraints to retrofitting wet cooling towers on an existing facility.  

This memo primarily documents those sites EPA has visited in support of the 2011 proposed section 316(b) rulemaking, and is not intended to provide a statistical analysis. However, the data collected suggests that power plants where the ratio of facility size (expressed in MW) to facility acreage is equal to or exceeds 160 should have ample space to construct retrofit cooling towers.  EPA bases this ratio on the observation that approximately 95 percent of the 47 sites with a ratio of 160 and above would have sufficient acreage to retrofit mechanical draft cooling towers.  For the 25 observed sites with a ratio less than 160 MW per 1000 acres, as many as 20 percent of the facilities would likely be space constrained.  This memo documents only the observations of each site visit team, and does not reflect a detailed engineering feasibility assessment for each site.  For example, the configuration of the existing facility, topography, existing structures or uses, neighboring properties and uses, and other site-specific details may constrain the potential locations for siting cooling towers. 

The table below summarizes the data collected (see Attachment A). EPA obtained most of the acreage data from facility's stated property boundaries during site visits.  Other site data was provided from facility permit applications, by EPA regions and state permitting authorities, or other site reports. This acreage includes the power block itself, transmission yards, parking areas, coal piles, and all other existing equipment or land uses.  Next, the land area was normalized by dividing the acres by the facility's generating capacity.  In doing so, a ratio of acres per 1000 MW was generated for all sites, thereby allowing for a comparison of facilities of all sizes and types. 

                                 Facility Type
                                    Range 
                                (acres/1000 MW)
                         Average Ratio (acres/1000 MW)
                         Median Ratio (acres/1000 MW)
All Site Visit Facilities
7  -  6216
858
350
Sites With Retrofit Cooling Towers
160 - 6216
2235
1920
Sites With Non-Retrofit Cooling Towers
83  -  5657
2318
1266

EPA also collected data on the facility size of plants with existing closed-cycle cooling systems (i.e. the cooling towers were not a retrofit).  EPA was able (through basic internet searches) to find information on facility acreage for an additional 25 facilities with either partial or full closed-cycle systems.  

                                 Facility Type
                                    Range 
                                (acres/1000 MW)
                         Average Ratio (acres/1000 MW)
                         Median Ratio (acres/1000 MW)
Partial CCRS
202  -  16,667
3077
1304
Closed-Cycle Cooling
117  -  5654
1285
850

Case Studies

Two facilities are worth discussing in greater detail as case studies for space constraints to cooling tower retrofits.

Brayton Point: Brayton Point Station in Massachusetts is currently constructing two natural draft cooling towers as part of a closed-cycle cooling system retrofit.  EPA Region I and Dominion Energy conducted thorough analyses on all aspects of the retrofit before Dominion Energy determined the final design.  Space constraints at the site was not identified as a feasibility issue in retrofitting to cooling towers.  In this analysis, Brayton Point's ratio was 160 acres/1000 MW.

McDonough: McDonough Power Plant in Georgia converted an older coal-fired plant to closed-cycle cooling (with a wet cooling tower) in 2008 as part of a broader plan to repower the site to use multiple natural gas combined cycle generating units.  To install the towers, Georgia Power demolished the adjacent Atkinson Plant to create space to construct the cooling towers.  Georgia Power also faced a number of challenges in retrofitting the towers, including relocating maintenance buildings, burying cooling water pipes, and adding pump stations.  According to data collected during the site visit, the ratio for McDonough (using the current coal-fired generating capacity and the original dimensions of the site) is 612 acres/1000 MW.  However, given the construction of the two new combined cycle units on other parts of the property, the effective acreage of the McDonough site could be as little as 80 acres, making the facility's ratio 163.