Merrimack Station Revised Draft Permit 

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UNITED STATES ENVIRONMENTAL PROTECTJftN:...,:W~~v---------, 

NEW ENGLAND - REGION I 

5 POST OFFICE SQUARE- SUITE 10 .tH.P.U.C. 

BOSTON, MASSACHUSETTS 02109-39 2 

Exhibit '"~__,.;:::;'-'--~--·---

FACT SHEET 

DRAFT NATIONAL POLLUTANT DISCHARGE ELIMINATION SYSTEM (NPDES) 

PERMIT TO DISCHARGE TO WATERS OF THE UNITED STATES 

PURSUANT TO THE CLEAN WATER ACT (CWA) 

NPDES PERMIT NO.: NH0001465 

PUBLIC COMMENT PERIOD: April 18, 2014- June 17, 2014 

June 17, 2014- July 22, 2014 

PUBLIC NOTICE NO.: NH-002 -14 

NAME AND ADDRESS OF APPLICANT: 

Public Service of New Hampshire (PSNH) 

P.O. Box330 

Manchester, NH 03105-0330 

NAME AND ADDRESS OF FACILITY WHERE DISCHARGE OCCURS: 

Merrimack Station 

97 River Road 

Bow, NH 03301 

SIC CODE: 4911- Electric Power Generation NAICS Code(s): 221112 

RECEIVING WATER: Merrimack River (Hydrologic Basin Code: 01070002) 

CLASSIFICATION: Class B 

CURRENTLY EFFECTIVE PERMIT ISSUED: June 25, 1992 
Merrimack Station Revised Draft Permit 

2014 Fact Sheet 

Table of Contents 

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1.0 SUMMARY OF PROPOSED ACTION •.•.••••••••••.•.•••.•.•.•.•••••.•••.•••••.•••.••••..•.•••••.•••.•.••••••••.•.•.••••.•••.•.•.•••••••.•.•..••••. 3 

2.0 TYPE OF FACILITY, DISCHARGE LOCATION, AND QUANTITY OF WASTES •..•.•.•.••••••••.•.••..••••••.•.••••.••••.•.•.•...•••. 7 

3.0 RECEIVING WATER DESCRIPTION .................................................................................................................. 9 

4.0 BASIS OF PERMIT LIMITS .............................................................................................................................. 9 

4.1 BACKGROUND .••••••.••.••••••.••.••••••••..•.••••.•••.•••••••.•..••.•.•.•••••••••••.•.•.•..••••••••..•..•.•.•.••••.•••••.••••••••••••.•.•.••••••••••..•.•• 9 

4.1.1 MERRIMACK STATION'S FGD SCRUBBER SYSTEM ••.••••••.•..•.•.•••••••.••••..•.•••••••••.•.•.•..••••••••••.•••.•.•...•.•.•••.•.••••••..••.••••• 9 

4.1.2 Wastewater from FGD Systems ........................................................................................................... 11 

4.1.3 NPDES Permitting of FGD Wastewater Discharges .............................................................................. 12 

4.1.4 Determination of BAT for Controlling FGD Wastewater for 2011 Draft Permit... ................................ 13 

4.2 LEGAL REQUIREMENTS AND CONTEXT .............................................................................................................. 14 

4.3 AVAILABILITY OF VCE/CRYSTALLIZER TECHNOLOGY ............................................................................................ 16 

4.4 BAT FOR FGD WASTEWATER AT MERRIMACK STATION ...................................................................................... 19 

4.4.1 The Primary and Secondary Wastewater Treatment Systems Currently In Use at Merrimack Station 

19 

4.4.2 BAT Determination .............................................................................................................................. 26 

4.4.3 Conclusion ............................................................................................................................................ 47 

5.0 RE-NOTICED DRAFT PERMIT CONDITIONS .................................................................................................. 48 

5.1 REMOVAL OF OUTFALL 003C IN DRAFT PERMIT BASED ON REVISED BAT DETERMINATION ........................................ 48 

5.2. REMOVAL OF CERTAIN LIMITS FOR OUTFALL 003A ............................................................................................. 52 

6.0 ENDANGERED SPECIES ACT (ESA) .................................................................. : ............................................. 54 

7.0 ESSENTIAL FISH HABITAT (EFH) ................................................................................................................... 54 

8.0 MONITORING AND REPORTING .................................................................................................................. 55 

9.0 STATE CERTIFICATION REQUIREMENTS ....................................................................................................... 55 

10.0 COMMENT PERIOD, PUBLIC HEARING, AND PROCEDURES FOR FINAL DECISIONS .................................. 56 

11.0 REGION 1 CONTACT INFORMATION ....................................................................................................... 57 
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1.0 Summary of Proposed Action 

Proposed Action 

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Pursuant to 40 C.F.R. § 124.14, the Region 1 office ofthe United States Environmental 

Protection Agency (referred to either as Region 1 or the Region ) is reopening the public 

comment period for certain provisions of the Draft National Pollutant Discharge Elimination 

System (NPDES) Permit that the Region issued to Public Service ofNew Hampshire's (referred 

to either as PSNH, the Permittee or the Company) Merrimack Station power plant (hereinafter as 

either Merrimack Station, the Station or the Facility) on September 30, 2011. Region 1 is reopening the comment period because information, data and/or arguments submitted during the 

initial comment period, as well as information gathered by the Region during or since the initial 

comment period, appear to raise substantial new questions with regard to certain permit 

requirements. See 40 C.F.R. § 124.14(b). Furthermore, Region 1 is proposing to revise these 

particular permit requirements in response to this new information and has prepared a Revised 

Draft Permit so that the public may review and comment on the revisions. See 40 C.F.R. §§ 

124.14(a)(2), (b) and (c). 

The September 2011 Draft Permit included technology-based requirements limiting pollutant 

discharges from Merrimack Station's flue gas desulfurization (FGD) system based on Region 1 's 

site-specific, Best Professional Judgment (BPJ) application ofthe Best Available Technology 

economically achievable (BAT) standard. See 33 U.S.C. § 1311(b)(2)(A); 40 C.F.R. § 

125.3(a)(2)(iv) and (v), (c). Specifically, for the 2011 Draft Permit, Region 1 determined on a 

BP J basis that the BAT for controlling FGD wastewater discharges at Merrimack Station was a 

particular combination of physical/chemical and biological treatment technologies. In light of 

new information obtained during or after the comment period, Region 1 is now revising this BP J 

determination of the BAT, along with various permit requirements associated with it. 

The particular provisions of the September 2011 Draft Permit now being reconsidered and 

revised are the effluent limits and reporting requirements for Outfall 003C at Part I.A.4 

and for Outfall 003A at Part I.A.2. Region 1 has prepared a Revised Draft Permit and this 

Fact Sheet that includes certain changes to these provisions from the September 30, 2011, Draft 

Permit. In addition, the Region has compiled the administrative record associated with this 

action and is making it available for public review either on Region 1 's website or in person at 

Region 1 's offices in Boston, MA. The Agency is now seeking comment on the Revised Draft 

Permit provisions as well as on Region 1 's analysis supporting the revisions. 

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provisions of the Draft Permit if the comments raise issues that are inextricable from issues 

raised by the Region's revised BPJ determination ofthe BAT for controlling FGD wastewater 

discharges and/or the Region's Revised Draft Permit requirements. 

The September 20 11 Draft Permit also included condition I.A.2, which sets water quality and 

technology-based effluent limits for pollutant discharges from the slag settling pond. The 

determination of several water quality-based permit requirements was based on the discharge of 

pollutants in FGD wastewater into the slag settling pond. Because condition I.A.2 was informed 

by the potential discharge of FGD wastewater into the slag settling pond, and this scenario would 

be altered by the revised BAT determination, Region 1 is also proposing to revise some aspects 

of that provision at this time. This is discussed in Section 5.2 of this Fact Sheet. 

Region 1 is reopening the public comment period on cetiain revised provisions of Merrimack 

Station's Draft Permit under 40 C.F.R. §§ 124.14(a) and (b) and has determined that applying the 

procedures of 40 C.F.R. § 124.14(a) could expedite the decision-making process. The Region 

has decided that this is the case because numerous complex and conflicting comments have been 

submitted by a variety of interested persons about what technology or combination of 

technologies should be determined to be the BAT for controlling Merrimack Station's FGD 

wastewater discharges. Using the procedures of§ l24.14(a) may expedite the decision-making 

process by applying procedures to ensure that interested persons submit information in a timely 

way and have an opportunity to review and respond to the submissions by other persons, if they 

wish to do so. 

Under 40 C.F.R. § 124.14(a)(l), the follovving procedures will apply for the re-opened comment 

period: 

... all persons, including applicants, who believe [the revised conditions of the] ... 

draft permit ... [are] inappropriate ... must submit all reasonably available factual 

grounds supporting their position, including all supporting material, by a date, not 

less than 60 days after public notice ... , set by the Regional Administrator. 

Thereafter, any person may file a written response to the material filed by any 

other person, by a date, not less than twenty days after the date set for'filing of the 

material, set by the Regional Administrator. 

!d. The first stage of the newly re-opened comment period will extend two months (60 

days) from issuance date of the Revised Draft Permit. 

Region l currently deems this to be an adequate comment period based on the following 

considerations: (1) this is a re-opened comment period, so that interested persons have already 
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controlling FGD wastewater discharges is being revised (the revised determination retains the 

same physical/chemical treatment components as part of the BAT, but replaces biological 

treatment with vapor compression evaporation (VCE) and crystallizer technology); and ( 4) 

interested persons already had one opportunity to comment on VCE technology because the 

Region discussed it as a possible BAT option in the Fact Sheet issued in support of the 2011 

Draft Permit. Any person may ask that the 60-day comment period be extended, but a part of 

any such request will need to demonstrate why such an extension would be necessary (i.e., why 

the 60 days would not provide a reasonable opportunity to comply with the provisions of 40 

C.F.R. § 124.14(a)(l)). 

In addition, consistent with 40 C.F .R. § 124.14(a)(l ), Region 1 will provide an additiona135-

day comment period -extending from the close of the first comment period described 

above- during which any interested person may file a written response to the material 

filed by any other person. Although the regulations require a minimum period of 20 days for 

such responsive comments, Region 1 concluded that it would be reasonable to round that time 

period up to one full month (i.e., 30 days) and add five more days to allow the Region time to 

assemble the public comments and make them available on the Region's website at 

http://www.epa.gov/region l/npdes/merrimackstation/index.html. At the same time, Region 1 

does not feel that any further time should be needed, given the limited scope of this particular 

comment period (i.e., interested persons are permitted to file comments that respond to 

submissions by other persons during the initial, already targeted comment period). As before, 

any request for an extension of time will need to demonstrate why this 35-day period does not 

provide a reasonable opportunity to provide comments and an extension is needed. 

Relevant Background Information Regarding Merrimack Station's Drcift Permit 

The Outfall 003C requirements in the Draft Permit for Merrimack Station, issued on September 

30, 2011 (hereinafter, 2011 Draft Permit), were imposed under CWA §§ 301(b)(l)(C), and 

40l(a)(l) and (d), and were developed using BPJ. See 33 U.S.C. § 1342(a)(1)(B); 40 C.F.R. § 

125.3(c)(2). While the Region considered a variety of technological and operational alternatives 

as possible BAT options, Region 1 ultimately set limits for the FGD wastewater based on the use 

of the Station's "primary treatment system" for FGD wastewater plus an added biological 

treatment stage. See Attachment E of Region 1 's September 2011 Fact Sheet, titled 

"Determination of Technology-Based Effluent Limits for the Flue Gas Desulfurization 

Wastewater at Merrimack Station in Bow, New Hampshire" (hereinafter, 2011 Fact Sheet, 

Attachment E). 

Before issuing the 2011 Draft Permit, Region 1 learned that PSNH was considering installing 

VCE technology to enable it to run its wet FGD scrubber system without needing to discharge 

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operating this system since June 2012. Richard Roy, PSNH and Patricia Scroggin, Burns & 

McDonnell, "The Thermal ZLD Experience for FGD Wastewater at PSNH's Merrimack Station" 

November 2013, International Water Conference (IWC) 13-47 (hereafter, Roy and Scroggin, 

2013 ). Basically, "[ e ]vaporators and crystallizers operate by transferring latent heat from 

condensing steam across a tube surface to cause a liquid at its boiling temperature to partially 

vaporize." Shaw, William A., Benefits of evaporating FGD purge water, POWER Magazine, 

March 15, 2008 (hereinafter, Shaw, 2008). The SWWTS system at Merrimack Station results in 

condensed vapor or distillate streams and solid waste. 

Having learned that Merrimack Station was operating a SWWTS system for treating FGD 

wastewater, Region l endeavored to obtain additional information about Merrimack Station's 

system and VCE systems generally. As patt of this effort, on February 7, 2013, Region 1 sent 

PNSH an information request letter pursuant to CW A § 308. PSNH responded to Region l with 

a letter dated March 26, 2013 (hereinafter, March 2013 CW A § 308 Response), which is partially 

designated as confidential business information (CBI) by PSNH. 

In Region 1 's BP J analysis for the September 20 II Draft Permit, Region 1 evaluated VCE and 

determined that: 

[i]t simply is not clear at the present time whether or not this technology is feasible for 

application at Merrimack Station. EPA is continuing to review information characterizing 

operational factors and pollutant removal efficacy for vapor compression evaporation and 

depending on the results of further evaluation of this technology, EPA could potentially 

find it to be part of the BAT for Merrimack Station for the final NPDES permit. 

In an earlier report from·october 2010, PSNH raised a number of questions and concerns about 

using VCE technology for treating FGD wastewater, but also noted that a number of plants had 

begun using VCE technology for that purpose. See 2011 Fact Sheet, Attachment E, pp. 20-21. 

Yet, at the time of the Draft Permit, Region 1 reported having received information that PSNH 

was considering the potential for using VCE at Merrimack Station, but that the company had not 

as of that time submitted a modified permit application proposing to use the technology. 

After issuing the Draft Permit, Region 1 received a number of comments on the suitability of 

VCE for Merrimack Station during the public comment period. Region 1 has also gathered 

additional information in response to those comments. After considering all this material in 

connection with an evaluation of the BAT factors specified in the statute and regulations, see 33 

U.S.C. § 1314(b)(2)(B) and 40 C.F.R. §§ l25.3(c)(2) and (d)(3), Region 1 has concluded, based 

on its BP J, that the combined primary and secondary FGD WWTS currently operating at the 

Facility is the BAT for treating the FGD wastewater generated at 1Vferrimack Station. This is a 
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conditions, Region 1 has decided to exercise its discretionary authority pursuant to 40 C.F.R. § 

124.14(b )(3) to re-notice for public review and comment those Revised Draft Permit conditions 

and the analysis supporting them. While Region l may not have needed to re-notice these permit 

provisions as a matter of law, the Region has the discretionary authority to take this action and 

has decided to do so to be sure that interested parties have an adequate chance to comment on 

these issues. Furthermore, Region I is hopeful that its analysis in support of the Final Permit 

will benefit from the Agency's consideration of any new public comments. Region 1 will 

consider the comments received during the comment period and then prepare final permit 

conditions and written responses to all significant comments. Interested parties do not need to 

re-submit any comments or materials that they already submitted to Region 1 during the previous 

comment period on the Draft Permit. 

In accordance with 40 C.F .R. § 124.10, Region 1 has notified PSNH and other interested patiies 

of its decision to re-notice Parts I.A.2 and I.A.4 of the Draft Permit. The Region is also making 

new administrative record materials available for review and comment, to the extent that they 

relate to the re-noticed permit provisions. While the Region is only re-noticing particular 

provisions of the Draft Permit for public comment, the entire permit and administrative record 

will also be available for review so that reviewers can examine the pertinent issues within the full 

context of the permit as they see fit. 

Basis for Re-Drafted Permit Conditions 

As stated above, the Region is specifically re-noticing as draft permit conditions for public 

comment those conditions that were based on Region I 's determination that biological treatment 

technology is a component of BAT, namely Parts I.A.4 and indirectly I.A.2. The rationale for 

these nowre-drafted permit conditions, including the Region's BAT determination for 

Merrimack Station's FGD wastewater, is presented in detail in Section 4 this Fact Sheet. 

In taking the current action, there are a number of additional documents that the Region has 

considered since it issued the 2011 Draft Permit. These additional documents have been added 

to the administrative record for this permit and may be reviewed at Region 1 's offices in Boston, 

upon request or at http://www.epa.gov/region 1/npdes/merrimackstation/index.html. 

2.0 Type of Facility, Discharge Location, and Quantity of Wastes 

Merrimack Station is a 520-megawatt (MW) fossil fuel electrical generation facility. The Station 

generates electricity by means of two coal-fired steam turbine units (producing 470 MW) and 

two oil-fired combustion turbines units (50 MW). Unit No. l generates at a rated capacity of 120 

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significantly lower, at around 30 percent. Blackman, Jeremy, "PSNH loses more customers to 

lower-priced competitors," Concord Monitor, July 16,2013. See also 12/13/13 Email from John 

Moskal, Region I to Sharon DeMeo, Region 1, including graphs of capacity factors for Units I 

and 2 at Merrimack Station from 2007 through 2013. This is the result of lower prevailing prices 

for natural gas having rendered older, less efficient coal-burning plants, such as Merrimack 

Station, less competitive within New England relative to natural gas-burning plants. As a result, 

coal-burning plants have lost market share to the region's natural gas-burning facilities. 

Merrimack Station discharges pollutants to, and withdraws water for cooling from, the Hooksett 

Pool section of the Merrimack River. The Station discharges various pollutants, including heat, 

to the river. Currently, steam turbine condenser waste heat is rejected to the river by means of a 

once-through cooling water system. Water for this cooling system is withdrawn from the river 

by the Station at a maximum rate of approximately 256 million gallons per day (MGD) through 

two cooling water intake structures and the heated water is then discharged back to the fiver 

through a 4000 foot long cooling canal. The pollutant discharges to the river from the Station 

include the following: 

once-through cooling water; 

• slag sluice water; 

• intake screen wash water; 

low volume waste (equipment and floor drains, chemical drains, polisher 

regeneration, demineralizer regeneration, miscellaneous tank drains); 

• intake bay dewatering and deicing; 

• ash landfill leachate; 

metal cleaning waste; and 

storm water. 

For information regarding the type and quantity of wastes, fluids, or pollutants which are 

proposed to be, or are being, treated, stored, disposed of, injected, emitted, or discharged, as well 

as the amount of cooling water withdrawn by the Facility's cooling water intake structures, see 

Section 5 ofthe 2011 Fact Sheet. In addition, the site plan showing the location of the outfalls 

and a schematic drawing of the flow of water at the Facility, including the various discharges, is 

presented on Attachments Band C of the 2011 Fact Sheet, respectively. Finally, the cooling 

water intake issues are discussed primarily in Attachment D of the 2011 Fact Sheet. 

In its 2010 supplement to its 1997 Permit Application, PSNH requested that the renewed 

Merrimack Station NPDES permit contain limits and conditions authorizing the discharge to the 

Merrimack River of wastewater from the Facility's newly installed wet FGD scrubber system. 

The original construction plans called for the treated effluent from the wastewater treatment 
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pollutants from the Station's FGD wastewater. 

3.0 Receiving VVater Description 

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As discussed in the 20 l l Fact Sheet, the Merrimack River is classified by the State of New 

Hampshire as a Class B water body. Receiving waters designated as Class Bin New Hampshire 

pursuant to RSA 485-A:8 are considered'· ... as being acceptable for fishing, swimming and 

other recreational purposes and, after adequate treatment, for use as water supplies." 

Section 303(d) of the CWA requires states to identify those water bodies that are not expected to 

meet surface water quality standards after the implementation of technology-based controls and, 

as such, require the development of total maximum daily loads (TMDL). 

Merrimack Station withdraws from and discharges into a segment of the Merrimack River called 

Hooksett Pool. This is an approximately 5.8-mile potiion of the river bounded to the north by 

Garvins Falls Dam and to the south by Hooksett Dam. Merrimack Station is located roughly 

mid-way between the two dams. The NHDES Water Division classifies a section in the upper 

reach of Hooksett Pool (3.476 miles) that is impaired for dissolved oxygen (D.O.) concentration 

and saturation. For other sections of the Pool, there is insufficient data to make aquatic life 

assessment determinations. 

In addition, the Merrimack River is considered not to suppoti fish consumption due to elevated 

mercury levels caused primarily by atmospheric deposition (mercury is not listed on the Section 

303(d) list because a TMDL has been developed). See Northeast Regional Mercury TMDL, 

approved by EPA in 2007, at http://www.neiwpcc.org/mercurv/mercurvdocs/FINAL%20Northeast%?0Regionai%20Mercurv%20TMDL.pdf. 

4.0 Basis of Permit Limits 

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As discussed in the 20 l 1 Fact Sheet, Attachment E, the combustion process at coal-fired plants 

such as Merrimack Station generates a variety of air pollutants that are emitted from the facility's 

smoke stacks. At Merrimack Station flue gas passes through air pollution controi equipment that 

includes selective catalytic reduction systems to reduce nitrogen oxides emissions and two 

electrostatic precipitators to reduce particulate matter emissions
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air emissions of mercury and other pollutants. 1 PSNH was required to have the wet FGD system 

fully operational by July 1, 2013, "contingent upon obtaining all necessary permits and 

approvals from federal, state, and local regulatory agencies and bodies." RSA 125-0: 13(I) 

(emphasis added). But see also RSA 125-0:17(I) (variances). Consistent with this contingency, 

PSNH stated the following in a submission to the New Hampshire Public Utility Commission 

(NHPUC) in support of its request to recover the costs of its wet FG.D scrubber system through a 

temporary Energy Service rate: 

[t]he legislature recognized that in order for the Company to install and operate 

the Scrubber, it would first need to obtain various permits and approvals to do so. 

As a result, the legislature made the July 1, 2013 operational deadline for the 

Scrubber contingent upon the receipt of those approvals . . . . RSA 125-0: 13(I), 

which contains this contingency, states that "The owner shall install and have 

operational scrubber technology to control mercury emissions at Merrimack Units 

1 and 2 not later than July 1, 2013. The achievement of this requirement is 

contingent upon obtaining all necessary permits and approvals from federal, state, 

and local regulatory agencies and bodies .... " This clearly provides that the 

Scrubber must be installed and operational no later than July 1, 2013 only if the 

Company has all of the necessary permits and approvals to do so by that date. 

PSNH, "Memorandum of Public Service Company of New Hampshire on Wastewater Permitting 

Issues Associated with the Scrubber," (Investigation of Merrimack Station Scrubber Project and 

Cost Recovery, Docket No. DE 11-250) (March 19, 2012) (hereinafter, March 2012 Submission 

to the NHPUC), p. 4 (Italics in original). 2 See also In re Stonyfield Farm, Inc. & a., 159 N.H. 

227, 229 (2009) (New Hampshire Supreme Court pointing out the same). 

The legislation also expressed the New Hampshire legislature's desire to realize the air quality 

benefits of a wet FGD scrubber system at Merrimack Station- in other words, to reduce the 

Facility's harmful emissions of mercury to the air- sooner than the July 2013 date to the extent 

practicable, and created economic incentives to encourage Merrimack Station to better that date. 

RSA 125-0:11(IV); RSA 125-0:13(III); RSA 125-0:16. Indeed, to encourage the soonest 

possible reduction in Merrimack Station's air emissions of mercury, the state law created a 

sliding scale of economic incentives with increasing benefits to the company for earlier reduction 

ofthose emissions through operation ofthe FGD scrubbers. See RSA 125-0:16(I)(a). 3 

1 Title X Public Health Chapter 125-0 Multiple Pollutant Reduction Program, Sections 125-0:11- 125-0:18. See 

http://www. gencourt.state.nh. us/rsa/html/x/125 -o/ 125-o-mrg.htm. 

2 This document can be found at http://www.puc.nh.gov/Regulatorv/CASEFILE/20 11/11-250/LETTERS-MEMOST ARIFFS/ 11

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According to PSNH, '·to incent the most expeditious installation and operation of the Scrubber, 

the Legislature enacted RSA 12-0:16, which provides Economic Performance Incentives for 

mercury reductions which are achieved prior to July 1, 2013. Because the Scrubber was placed 

into service in September, 2011, the Company will earn these incentives ... " March 2012 

Submission to the NHPUC, p. 4 . 

. 2 'Nastewater 

Coal combustion generates a host of air pollutants which enter the flue gas stream and are 

emitted to the air unless an air emissions control system is put in place. The wet FGD scrubber 

system works by contacting the flue gas stream with a liquid slurry stream containing a sorbent 

(typically lime or limestone). The contact between the streams allows for a mass transfer of 

contaminants from the flue gas stream to the slurry stream. 

Coal combustion generates acidic gases, such as sulfate, which become part of the flue gas 

stream. Not only will the liquid slurry absorb sulfur dioxide and other sulfur compounds from 

the flue gas, but it will also absorb other contaminants from the flue gas, including patiiculates, 

chlorides, volatile metals- including arsenic (a metalloid), mercury, selenium, boron, cadmium, 

and zinc -total dissolved solids (TDS), nitrogen compounds and organics. Fmihermore, the 

liquid slurry will also readily absorb hydrochloric acid, which is formed as a result of chlorides 

in the coal. The limestone in the slurry also contributes iron and aluminum (from clay minerals) 

to the FGD wastewater. The chloride concentration and clay inert fines of the FGD slurry must 

be controlled through a routine wastewater purge to minimize corrosion of the absorber vessel 

materials. Depending upon the pollutant, the type of solids separation process and the solids 

dewatering process used, the pollutants may partition to either the solid phase (i.e., FGD solids) 

or the aqueous phase. 

PSNH installed a limestone forced oxidation scrubber system and produces a saleable 

commercial-grade gypsum byproduct (e.g., wallboard). While this reduces the quantity of solid 

waste requiring disposal, the gypsum cake typically must be rinsed to reduce the level of 

chlorides in the final product. Besides the scrubber purge waste stream, gypsum processing 

generates additional wastewater requiring treatment prior to reuse or discharge. 

Many of the pollutants found in FGD wastewater pose the potential for risk of harm to the 

environment.and human health. These pollutants can occur in quantities (i.e., total mass 

baseline mercury emissions, on an annual basis, in the period prior to July l, 2013. Ratios of early 

reductions credits to pounds of mercury reduced shall be as follows: 1.5 credits per pound reduced 

prior to July I, 2008; 1.25 credits per pound for reductions between July l, 2008 and 

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released) and/or concentrations that cause or contribute to in-stream excursions of EPArecommended water quality criteria for the protection of aquatic life and/or human health. In 

addition, some pollutants in the FGD wastewater present a particular ecological threat due to 

their tendency to persist in the environment and bioaccumulate in organisms. For example, 

arsenic, mercury and selenium readily bioaccumulate in exposed biota. 

Polluted wastewater from FGD scrubber systems cannot be discharged to waters of the United 

States, such as the Merrimack River, unless in compliance with the requirements of the federal 

Clean Water Act, 33 U.S.C. §§ 1251 et seq. (CWA), and applicable state laws. More 

specifically, any such discharges must comply with the requirements of a NPDES permit. See 33 

U.S.C. §§ 131l(a) and 1342(a). 

As will be discussed in detail below, discharges of wastewater from an FGD scrubber system to 

a water of the United States must satisfy federal technology-based treatment requirements as 

well as any more stringent state water quality-based requirements that may apply. While EPA 

has promulgated National Effluent Limitation Guidelines (NELGs) which set technology-based 

limits for the discharge of certain pollutants by facilities in the Steam Electric Power Generating 

Point Source Category, see 40 C.F.R. Part 423, these NELGs do not yet include best available 

technology (BAT) limits for certain pollutants of concern in FGD wastewater. In the absence of 

applicable NELGs for FGD wastewater, technology-based limits are developed by EPA (or state 

permitting authorities administering the NPDES permit program) on a Best Professional 

Judgment (BPJ), case-by-case basis. 33 U.S.C. § 1342(a)(l)(B); 40 C.F.R. § 125.3(c) ("Where 

promulgated effluent limitations guidelines only apply to certain aspects of the discharger's 

operation, or to certain pollutants, other aspects or activities are subject to regulation on a caseby-case basis in order to carry out the provisions of the Act."). 

On June 7, 2013, EPA headquarters proposed revised NELGs for the Steam Electric Power 

Generating Point Source Category (hereinafter, Proposed Steam Electric NELGs). See 78 Fed. 

Reg. 34,432 (June 7, 2013). If finalized, the new NELGs would update effluent guidelines that 

have been in place since 1982, reflecting technology improvements in the steam electric power 

industry over the last three decades. The proposal includes a range of options to reduce 

pollutants of concern such as mercury, arsenic, lead, and selenium that are released into 

America's waterways by coal ash, air pollution control waste (including from FGD scrubber 

systems), and certain other waste streams from steam electric power plants. Under the proposal, 

new requirements for existing power plants would be phased in between 2017 and 2022. If 

finalized, the new NELGs would replace the BPI, case-by-case approach for developing 

technology-based requirements for these wastewater streams. Until the new NELGs become 

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For the 2011 Draft NPDES Permit for Merrimack Station, Region 1 evaluated eleven candidate 

technologies to determine the BAT for treating wastewater from the Station's FGD system. At 

that time, Region 1 determined, based on its BPJ, see 40 C.F.R. §§ 125.3(a)(2)(iv) and (v), 

(c)(3), that the Station's newly installed primary treatment system4 for handling wastewater 

from the FGD system, coupled with biological treatment, constitutes the BAT for limiting the 

discharge of certain FGD wastewater pollutants at Merrimack Station. See Region 1 's 2011 Fact 

Sheet, Attachment E. 

In determining effluent limits for FGD wastewater from Merrimack Station, Region I used the 

best available information to specify permit limits that, consistent with the capabilities of the 

BAT, were appropriately stringent but not infeasible. Cetiain of these limits were based on 

statistical analyses of self-monitoring data collected by plant staff at two Duke Energy power 

plants that use similar physical/chemical and biological treatment, the Allen and Belews Creek 

Stations, as well as certain data collected during a study of the Belews Creek treatment system 

conducted by the Electric Power Research Institute (EPRI). 

In addition to the sources described above, Region I also considered information presented by 

the Permittee. Specifically, in PSNH's December 3, 20IO, Report, which the Company 

submitted in response an Region I' s information request under CW A § 308( a), PSNH identified 

the concentrations of pollutants that it predicted would be present in the discharge from the new 

Merrimack Station FGD wastewater treatment system. See Merrimack Station NPDES 

Administrative Record (AR) #43. 

In addition, as mentioned above, Region 1 also evaluated VCE treatment technology, an 

emerging method of treating FGD wastewater. See Region I 's 20II Fact Sheet, Attachment E, 

pp. 20-22. Region 1 described PSNH's assessment ofVCE technology, as provided to the 

Region, and explained that the company identified a number of potential concerns and 

reservations about relying upon such technology at Merrimack Station. Id., pp. 20-21. Region 1, 

itself, also noted a number of possible concerns or difficulties with regard to the advisability and 

feasibility of using VCE at Merrimack Station, including the costs that it would entail. Id., pp. 

21-22. At the same time, however, Region 1 also noted that VCE could be compatible with the 

existing Merrimack Station operation (e.g., age of Merrimack Station would not preclude the use 

ofVCE; proposed physical/chemical treatment could be used together with VCE). !d., p. 22. 

Furthermore, Region I noted that it had recently learned that PSNH was itself further 

considering the use of VCE treatment technology for its FGD wastewater to achieve a "zero 

liquid discharge" so that it could operate its FGD scrubbers without needing an NPDES permit to 

authorize direct discharges to the Merrimack River. !d., p. 21. See also AR# 638 and AR# 303. 
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In light of all of the above, EPA has concluded that it cannot based on current 

information determine this technology to be the BAT for treating FGD 

wastewater at Merrimack Station. It simply is not clear at the present time 

whether or not this technology is feasible for application at Merrimack Station. 

EPA is continuing to review information characterizing operational factors and 

pollutant removal efficacy for vapor compression evaporation and depending on 

the results of fwther evaluation of this technology, EPA could potentially find it 

to be part of the BAT for Merrimack Station for the final NPDES permit. 

Id., p. 22. Thus, Region I explained that it was continuing to evaluate VCE- as was PSNHand that this technology could be part of the BAT for the final permit. 

The 1982 NELGs established effluent limitations based on the best practicable control 

technology currently available (BPT) standard for the "catch-all" category of "low-volume 

wastes." See 40 CFR §423.11(b). See also 33 U.S.C. § 1311(b)(l)(A). Low volume wastes 

include a variety of types of wastewater from power plants, including the wastewater from wet 

scrubber air pollution control systems (i.e., FGD scrubber systems). The 1982 rulemaking did 

not, however, establish BAT standards for FGD wastewater because EPA lacked the data 

necessary to characterize the pollutant loadings from these systems and, thus, to set a national 

standard. See the Development Document for Effluent Limitations Guidelines and Standards 

and Pretreatment Standards for the Steam Electric Power Generating Point Source Category 

(EPA 440/1-82/029), November 1982 ( 1982 Development Document), at page 248 (noting that 

"[a]dditional studies will be needed to provide this data and to confirm the current discharge 

practices in the industry"). 5 Accordingly, EPA determined that BAT standards for FGD 

wastewater were outside the scope of the rulemaking and explicitly reserved the development of 

such standards for a future rulemaking. See 47 Fed. Reg. 52,290,52,291 (Nov. 19, 1982) 

(preamble to Final Rule for 1982 Steam Electric NELGs); 1982 Development Document, pp. 3, 

7. 

While the CWA provides that existing facilities were to satisfy BPT standards by no later than 

July 1, 1977,33 U.S.C. § 13ll(b)(1)(A), a facility's discharges oftoxic pollutants and 

nonconventional pollutants were to satisfy more stringent BAT standards by no later than March 

31, 1989. See 33 U.S.C. § 1311(b)(2)(A), (C), (D) and (F); 40 C.F.R. § 125.3(a)(2)(iii), (iv) and 

(v). EPA regulations state that "where promulgated effluent limitations guidelines only apply to 

certain aspects of the discharger's operation, or to certain pollutants, other aspects or activities 

are subject to regulation on a case-by-case basis to carry out the provisions of the Act." 40 

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arsenic) for which there are no currently applicable BAT -based NELGs. As a result, it is 

appropriate to develop such limits on a case-by-case, BP J basis. See 20 ll Fact Sheet, 

Attachment E, pp. 6-7. 

The BAT standard is set forth in CWA § 30 l(b)(2)(A), 33 U.S.C. § 13ll(b)(2)(A), and applies to 

many of the pollutants in Merrimack Station's FGD wastewater, which include both toxics (e.g., 

mercury, arsenic, selenium) and non-conventional pollutants (e.g., nitrogen). See 33 U.S.C. § 

l311(b)(2)(A) & (F); 40 C.F.R. §§ l25.3(a)(2)(iii)- (v). See also 33 U.S.C. § l314(b)(2). The 

BAT standard requires achievement of: 

effluent limitations ... which ... shall require application of the best available 

technology economically achievable . .. , which will result in reasonable further progress 

toward the national goal of eliminating the discharge of all pollutants, as determined in 

accordance with regulations issued by the [EPA] Administrator pursuant to section 

1314(b )(2) of this title, which such effluent limitations shall require the elimination of 

discharges of all pollutants if the Administrator finds, on the basis of information 

available to him ... that such elimination is technologically and economically achievable 

... as determined in accordance with regulations issued by the [EPA] Administrator 

pursuant to section 1314(b )(2) of this title .... 

33 U .S.C. § 1311 (b )(2)(A) (emphasis added). In other words, the BAT standard requires EPA to 

set effluent discharge limits corresponding to the use of the best pollution control technologies 

that are technologically and economically achievable and will result in reasonable progress 

toward eliminating discharges of the pollutant(s) in question, which will include eliminating such 

discharges if doing so would be achievable. Thus, in a given case, the BAT standard might or 

might not result in limits prohibiting the discharge of certain pollutants. 

According to the CWA's legislative history, the starting point for identifying the "best available 

technology" refers to the "single best performing plant in an industrial field" in terms of its 

capacity to reduce pollutant discharges. Chemical Manufacturers. Ass 'n v. US. Envtl. Prot. 

Agency, 870 F.2d 177, 239 (5th Cir. 1989) (citing Congressional Research Service, A Legislative 

History of the Water Pollution Control Act Amendments of 1972 at 170 (1973) (hereinafter, 1972 

Legislative History) at 170).6 Thus, EPA need not set BAT limits at levels that are being met by 

6 See also Texas Oil, 161 F.3d at 928, quoting Chemicali'vfanufacturers., 870 F.2d at 226; Kennecott v. U.S. Envtl. 

Prot. Agency, 780 F.2d 445, 448 (4th Cir. 1985) ("In setting BAT, EPA uses not the average plant, but the optimally 

operating plant, the pilot plant which acts as a beacon to show what is possible."); American I'v!eat, 526 F.2d at 463 

(BAT "should. at a minimum, be established with reference to the best performer in any industrial category"). 

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most or all the dischargers in a particular point source category, as long as at least one 

demonstrates that the limits are achievable. Id. at 239, 240. This comports with Congressional 

intent that EPA "use the latest scientific research and technology in setting effluent limits, 

pushing industries toward the goal of zero discharge as quickly as possible." Kennecott, 780 F.2d 

445, 448 (4th Cir. 1984 ), citing 1972 Legislative History at 798. See also Natural Resources 

Defense Council, 863 F .2d at 1431 ("The BAT standard must establish effluent limitations that 

utilize the latest technology."). While EPA must consider the degree of pollutant reduction 

achieved by the available technological alternatives, the Agency is not required to consider or 

determine the extent of water quality improvement that will result from such reduction. 7 

Available technologies may also include viable "transfer technologies"- that is, a technology 

from another industry that could be transferred to the industry in question- as well as 

technologies that have been shown to be viable in research even if not yet implemented at a fullscale facility. 8 When EPA bases BAT limits on such "model" technologies, it is not required to 

"consider the temporal availability of the model technology to individual plants," because the 

BAT factors do not include consideration of an individual plant's lead time for obtaining and 

installing a technology. See Chemical 1\l!amifacturers, 870 F.2d at 243; American 1\lfeat Inst. v. 

US. Envtl. Prot. Agency, 526 F.2d 442, 451 (7th Cir. 1975). 

EPA has reported that "[m]echanical evaporators in combination with a final drying process can 

significantly reduce the quantity of wastewater pollutants and volume discharged from certain 

process operations at various types of industrial plants, including steam electric power plants, oil 

refineries, and chemical plants." Technical Development Document for the Proposed Effluent 

Limitations Guidelines and Standards for the Steam Electric Power Generating Point Source 

Category, EPA-821-R-13-002, April2013 (hereinafter, 2013 TDD), p. 7-13.9 Evaporation 

technology has been used for decades by the power industry to eliminate cooling tower 

blowdown and demineralizer wastewater. Id. See also Shaw, 2008. 

sufficient information and data from a relevant pilot plant or semi-works plant to provide the 

needed economic and technical justification for such new source. 

Ass 'n of Pacific Fisheries v. US. Envtl. Prot. Agency, 615 F.2d 794, 816-17 (9th Cir. 1980) (quoting 1972 

Legislative History at 170). 

7 See, e.g., American Petroleum, 858 F.2d at 265-66 ("Because the basic requirement for BAT effluent limitations 

is only that they be technologically and economically achievable, the impact of a particular discharge upon the 

receiving water is not an issue to be considered in setting technology-based limitations."). 

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In addition to these uses of evaporative treatment technologies, there are also seven known VCE 

systems currently being used specifically for FGD wastewaters, one of which is currently 

operating at JV!errimack Station. An eighth VCE system is under construction. See 78 Fed. Reg. 

34452 (Proposed Rule); Marlett, J. Michael, "Flue Gas Desulfurization (FGD) Evaporator 

Operation Report, ENEL Brindisi," International Water Conference (IWC) paper# 12-25 

(Marlett, 20 12); Nebrig H.A., Teng, Xinjun, and Downs, David, "Preliminary Assessment of a 

Thermal Zero Liquid Discharge Strategy for Coal-Fired Power Plants," IWC 11-36 (Nebrig et. 

a!., 2011); HPD, Project Profile I FGD Zero Liquid Discharge System (AR #22 and AR #136); 

Personal communication, Michael Marlett, Aquatech and Sharon DeMeo, Region 1, January 8, 

2014. 

In the preamble to EPA's Proposed Steam Electric NELGs, the Agency stated: 

EPA identified two U.S. plants [(one of which is Merrimack Station)] and four Italian 

plants that treat FGD wastewater using vapor-compression evaporation. A third U.S. 

plant is currently installing a vapor-compression evaporation treatment system; it is 

scheduled to be operational by the end of 2013. 

78 Fed. Reg. 34452 (June 7, 2013) (Proposed Rule). Region 1 also notes that there is an 

additional system treating FGD wastewater in China. Nebrig et. al., 2011. "The thermal ZLD in 

China's coal-fired power plant has been in operation to treat FGD wastewater since 2009. This 

ZLD system is unique because it does not include a brine concentrator, but applies a 4-stage 

crystallizer." !d. 

The third U.S. facility mentioned above is Duke Energy's Mayo Plant, located near Roxboro, 

North Carolina. That facility is currently in the process of installing a VCE system to treat up to 

370 gpm ofFGD waste water. The new system will replace the cutTent settling pond and 

bioreactor. The change in treatment is intended to address water quality impacts to the receiving 

water, Mayo Lake. After a thorough evaluation of options, Duke Energy selected a partial ZLD 

system consisting of two evaporators (falling film and forced circulation) that will result in a 

concentrated brine solution that, similar to Iatan Station, will be mixed with fly ash prior to 

disposal in the facility's on-site landfill. See Lowenberg, et. al., Zero-Liquid Discharge System 

at Duke Energy Mayo Plant, TWC 12-16. 

The ZLD system at Iatan Station (although no crystallizer is used) was completed in 2010. See 

Burns & McDonnell, Green to the Max Zero Liquid Discharge for Iatan 2, 2011 No.3, p. 15-16. 

In addition, the ZLD systems at five of the six power plants in Italy using VCE and crystallizer 

technology were supplied and installed by Aquatech and all but two of these have been operating 

for more than 5 years. 10 See Marlett, 2012. See also Personal communication, M. Marlett, 

Aquatech and S. DeMeo, Region 1, January 8, 2014. Furthermore, the station in Monfalcone, 
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Italy, which also uses VCE technology, began operating mid 2008. The system, designed and 

supplied by HPD "is performing as designed and running on a continuous basis." HPD, Project 

Profile I FGD Zero Liquid Discharge System (AR #22 and AR #136). 

The use ofVCE and crystallizer technology in a number of industrial wastewater treatment 

settings, including for treating FGD wastewater at a number of steam electric power plants, 

demonstrates that VCE and crystallizer treatment technology is generally available for handling 

FGD wastewater at steam electric power plants. It does not, however, demonstrate by itselfthat 

the technology is available for the industrial category as a whole. More importantly for this BP J 

determination, it also does not by itself demonstrate the technology's availability for Merrimack 

Station, in pat1icular. In other words, VCE and crystallizer systems might be technologically and 

economically available for certain facilities, but not for the industrial category as a whole or for 

the individual facility that is the subject of a BP J determination. 

To the extent that VCE and crystallizer systems are able to achieve ZLD operations, they are the 

best performing treatment systems for the purpose of reducing discharges of pollutants to the 

Nation's waters. In other words, these systems make the greatest'· ... further progress toward. 

the national goal of eliminating the discharge of all pollutants .... " 33 U.S. C.§ 1311 (b)(2)(A). 

This by itself does not, however, establish that this technology is the "best available technology 

economically achievable" either for the industry as a whole or for the individual facility that is 

the subject of a BP J determination. As mentioned above, the technology might not be 

economically or technologically available for the industrial category as a whole or for an 

individual facility that is the subject of a BP J determination. Furthermore, as discussed further 

below, the CW A specifies a variety of factors, such as cost and non-water environmental effects, 

that must be considered before determining the BAT. See 33 U.S.C. § 1314(b)(2)(B); 40 C.F.R. 

§ 125.3(d)(3). 

Yet, as described in this Fact Sheet, PSNH began installation of a VCE and crystallizer system at 

Merrimack Station in 2011 and has been operating the completed system since at least June 

2012. PSNH did this without being compelled to do so by the requirements of an NPDES 

permit. 11 Again, this does not demonstrate that the technology is available for the steam electric 

power plant industrial category as a whole. These facts do, however, establish, in effect, "a 

11 Region 1 recognizes that because Merrimack Station installed "wet" FGD scrubbers that produce a wastewater 

stream incorporating pollutants, such as mercury and arsenic, removed from the Facility's air emissions, the Facility 

could not lawfully operate the FGD scrubbers unless it either had an NPDES permit authorizing wastewater 

discharges to the Merrimack River or it had a way to eliminate such discharges. Nevertheless, as discussed above, 

the Facility was not compelled by state law to operate the FGD system until it had obtained all necessary permits. 

By finding a way to operate the scrubbers without wastewater discharges, PSNH accelerated reductions of its 

emissions of air pollutants and, as described above, qualified for economic incentives provided by the state 

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rebuttable presumption" that VCE and crystallizer technology is available for Merrimack Station 

(i.e., it is technologically and economically achievable for the Facility). This presumption might 

possibly be overcome, if, for example, the facts indicated that despite initial installation and 

operation of the technology, its use raised long-term operational costs to an extent that it was 

rendered unavailable, or that experience with the technology ultimately revealed technological 

problems undermining its viability over the long-term. These issues are further discussed below. 

ter at 

ter Use 

Plants striving to maximize removals of mercury and other metals, such as Merrimack Station, 

often include sulfiqe addition (e.g., organosulfide) as part of the physical/chemical treatment 

process. Adding sulfide chemicals in addition to the alkali can provide even greater reductions 

of heavy metals due to the very low solubility of metal sulfide compounds, relative to metal 

hydroxides. In addition, "[p] !ants can add ferric (or ferrous) chloride to the precipitation system 

to co-precipitate additional metals and organic matter. The ferric chloride also acts as a 

coagulant, forming a dense floc that enhances settling of the metals precipitate in downstream 

clarification stages." 2013 TOO, p. 7-5. 

At the time the September 2011 Draft Permit was issued, PSNH was completing the installation 

of a physical/chemical treatment system (also referred to as Merrimack Station's "primary 

treatment system" elsewhere in this Fact Sheet) to remove pollutants from the wastewater 

generated by the Station's wet FGD scrubber system. Merrimack Station's primary treatment 

facility utilizes, among other techniques, the chemical addition treatment processes identified 

above. Specifically, the Facility's primary treatment system consists of a series of reaction tanks 

in which chemicals are added to convert soluble metals to insoluble metal hydroxide or sulfide 

compounds. These compounds then precipitate out of solution and are removed as solid waste. 

Merrimack Station's primary treatment system includes the following operations in sequence: 

equalization; reaction tank# 1 (includes the addition of hydrated lime for pH adjustment, soda 

ash and organosulfide); reaction tank #2 (where ferric chloride is added); polymer addition; 

clarification; pH adjustment with hydrochloric acid; gravity filtration; and a series of proprietary 

filter cartridges containing adsorbent media targeted specifically for the removal of mercury and 

arsenic (also referred to as the "polishing step" or the Enhanced Mercury and Arsenic Removal 

System ("EMARS")). Figure 1 shows the process flow of the originally designed 

physical/chemical treatment system. PSNH designed, financed and, for the most part, 

constructed the primary treatment system without first discussing with Region 1 whether this 

WWTS would fully satisfy technology-based and water quality-based standards

See 2011 Fact 
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Figure 1- FGD Primary Treatment System Process Flow Diagram 

Wet FGD 

Purge 

Lime 

Ferric Chloride 

Equalization 

Tanks 

'Enhanced Mercur; and Arsenic Removal System (Siemens) 

Roy and Scroggin, 2013. 

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Holding 

Tanks 

Internal 

I 

Several minor changes were made to this design with the addition of the secondary treatment 

system (discussed below), including the addition of soda ash to the reaction tanks and a different 

holding tank configuration to accommodate pH adjustment in series. Figure 2 shows that the 

clarifier of the primary treatment system was converted to a lime/soda ash softener. With 

softening, the predominant calcium chloride salts are replaced with less soluble sodium chloride 

salts. The resulting solid waste does not contain hygroscopic salts that require special processing 

to reduce absorption of moisture from the atmosphere. !d. See also Sharon DeMeo, Region 1, 

notes on IWC-13-47 presentation, November 19,2013. 

Figure 2- Modified FGD Primary Treatment System Process Flow Diagram 

Organa Sulfide 

Lime 

Ferric Ch1onae 

Soda Ash 

Back'Nash 

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In late May 2011, PSNH informed Region 1 that the Company was further evaluating the 

possibility of using additional treatment technology- specifically, vapor compression 

evaporation (VCE)- to further reduce the amount of FGD wastewater generated by the Station 

and potentially achieve a zero liquid discharge (ZLD) treatment system. See AR #638 and AR 

#303. See also 2011 Fact Sheet, Attachment E. p. 21. As discussed in the Fact Sheet for the 

Draft Permit, PSNH had previously evaluated VCE for treatment of FGD wastewater but, taking 

into account the pollutant concentrations expected in Merrimack Station's specific FGD 

wastewater and the relative newness of this application of the technology, concluded that VCE 

was not the BAT for the Facility or at least that it had insufficient information to assess the 

feasibility or advisability of using VCE to treat the Station's FGD wastewater. See 2011 Fact 

Sheet, Attachment E, pp. 20-21. See also PSNH's December 3, 2010 letter in response to 

Region 1 's October 29,2010 CWA § 308 information request (AR #43). As of the time that 

Region 1 issued the Draft Permit- i.e., September 30, 2011 -the Region was not aware of 

PSNH reaching any new conclusions about using VCE technology at Merrimack Station. 

Then, as a result of comments submitted during the public comment process for the Draft Permit, 

Region 1 learned that PSNH had decided to install and operate a VCE system, including 

crystallizers, as part of a "secondary wastewater treatment system" at Merrimack Station. In 

other words, the new system would be in addition to the physical/chemical "primary treatment 

system" discussed above. Nevertheless, during the comment period, a number of parties 

submitted conflicting comments on the suitability of VCE for Merrimack Station. 

In light of these developments, Region 1 requested that PSNH discuss its use ofthe added 

technology at Merrimack Station with Region 1 's NPDES permit writers. The Region explained 

that it wanted to learn from PSNH about its experience in operating the technology at Merrimack 

Station. See Region 1 's CWA § 308 informatioQ request dated February 7, 2013 (hereinafter, 

February 7, 2013 CWA § 308 Information Request), p. 1. PSNH declined the Region's request, 

however. !d. Similarly, PSNH declined Region l 's request to conduct a site visit to see and 

learn about the Facility's VCE system. !d. Therefore, to garner more information about PSNH's 

new VCE and crystallizer technology, Region 1 subsequently issued PSNH the February 7, 2013 

CWA § 308 Information Request pursuant to Section 308(a) of the CW A. More recently, the 

Region learned that Merrimack Station has been operating the complete SWWTS since June 

2012. Roy and Scroggin, 2013. 

The Facility's SWWTS consists of two distinct stages or "effects." The first effect involves the 

use of"a vapor compression driven falling film evaporator followed by a steam driven forced 

circulation evaporator" to concentrate the effluent from the primary treatment system. !d. The 

falling-film evaporator (or brine concentrator) and the forced circulation crystallizer generate a 

concentrated brine solution and relatively clean distillate and condensate streams. "The 
Fe-ed ,_;, 

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off-site for disposal and a condensate stream. "This operational mode allowed for the 

mechanical mixing of brine with flyash, brine transport and flyash disposal." Jd. 

Both the distillate from the brine concentrator (84,600 gpd) and the condensate from the 

crystallizers (1 0,800 gpd) are reused as FGD make-up water. Industrial Wastewater Indirect 

Discharge Request Application for Lowell Regional Wastewater Utility, July 11, 2001, Figure 2. 

See also Roy and Scroggin, 2013. Figure 3 below shows the process flow diagram of the 

secondary treatment system. 

Figure 3- FGD Secondary Treatment System Process Flow Diagram 

M:::::~ 

CaustiC j 

'V u w 

BCFe:ed 8( BCF~IIing BCH·tdro- 3C Brine 

Prehcate:r 

f--3> 

Otaerator 

-7 

Firm L;;. cyclone f--3> Blowd0'.'/11 E•;aporator Seed Re.C)'cle ~ Tank 

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Tank 

t 

Crystallizer 

Hash Tank 

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Forced 

Circulation 

Heat 

Exchanger 

RyAshSilo ~ IWC 13-47 

- ~------ ------------------__ ... --. ' ' ---~---1 --------1 ___ J ____ I : 2'14 Effect 1 : Belt Fllter I : Filtrate T3nk I _ I Cr{>tallizer t_ I Press t .. I : >: Rash Tank 1 ;:.: I;:.: I 

1 I I I 1 I 

~------,--1 1 ________ 1 I ________ • 

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: : : 

: : 

!..-----~--~- ... , 

I 1 I 

l l ' \~ ! \~ :--;M-E;;--: r-c::·::--: 

I Forced Grc. I , I r-~Cc<O!ing 

: Heat r-/: ~--Water 

: __ E:c:a:g:,r _ _: : ________ : 

! ! ! ' 

. 'I' ' D \if"-' --------.:&"------------.....;;J":I"-----___;;f,\~--------------~~--.. 7 t~~!l!ate Id. Generally, the secondary treatment system was designed to treat an approximate 65 gallons 

per minute (gpm) flow of FGD wastewater containing 10,000 parts per million (ppm) chloride. 

The maximum flow rates for the first effect were guaranteed by the supplier and "based upon the 

fly ash silo total ash wetting requirements." Jd. Roy and Scroggin report that all contractual 

process guarantees were met or exceeded, including those for distillate quality and minimum 

treatment rates. Jd. 

A consultant investigating issues for the New Hampshire Public Utilities Commission (NHPUC) 

described the secondary treatment system as follows: 

[t]his system is designed to ... [receive] the effluent from the EMARS waste treatment 

system and further reduce it. Phase 1 of the secondary wastewater treatment system 

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Jacobs Consultancy, "New Hampshire Clean Air Project Final Report," prepared for NHPUC, 

September 10, 2012, p. 57. Therefore, when operating as designed, the current treatment 

technology at Merrimack Station (i.e., the combined primary and secondary wastewater 

treatment systems) is a true zero liquid discharge ("ZLD") treatment system. 12 

Prior to February 2012, PSNH hauled wastewater from the FGD primary treatment system to 

several local publically owned treatment works ("POTWs"), where it was discharged to the 

headworks of each treatment plant prior to discharge to each facility's receiving waters. After 

Merrimack Station began operating the brine concentrator component of the SWWTS in 

February 2012, see Roy and Scroggin, 2013, PSNH began hauling concentrated brine wastewater 

to local POTW s for disposal. In other words, this brine wastewater was produced after 

Merrimack Station treated FGD wastewater in the primary treatment system and the first stage of 

the secondary treatment system. See Table 4-1 below. 

The second crystallizer component (i.e., the second effect) of the SWWTS began operation in 

June 2012. Roy and Scroggin, 2013. Nevertheless, PSNH reported sending distillate to the 

Hooksett Wastewater Treatment Facility for disposal in September and October 2012. 13 Region 

1 initially thought that PSNH had stopped hauling treated FGD wastewater off-site for disposal 

after October 2012 but the Region later learned that this was not the case. This confusion 

resulted from PSNH' s unilateral decision to discontinue submitting the monthly reports 

regarding off-site disposal that were required by Region 1 's March 22, 2012 CWA § 308(a) 

information request. The Region thought that the lack of repoti submissions indicated that offsite disposal had ceased, but in August 2013, PSNH informed Region 1 that it had continued 

sending wastewater (from the primary and secondary treatment systems) to area POTWs for 

disposal during 2013. In response to various informal requests for information concerning such 

off-site disposal, the company declined to provide certain information requested by the Region. 

See Personal communication, Allan Palmer, PSNH and John King, Region I, August 13,2013 

(AR #1029). As a result, on November 8, 2013, Region 1 sent PSNH another information 

request letter under CW A § 308(a). 

12 If the distillate and/or condensate streams were to be reused as boiler make-up water, for example, the system 

would not be considered a true ZLD system because, ultimately, boiler blowdown would be discharged to the 

receiving water. In addition, if the brine concentrate and/or salt cake is mixed with fly ash and disposed of in the 

Facility's on-site landfill, the system would also not be considered a true ZLD system because the leachate from the 

landfill would ultimately discharge to the Merrimack River. This concept is explained in the 20 13 TDD, p. 7-14: 

The condensed vapor (i.e., distillate water) can be recycled back to the FGD process, used in other plant 

operations (e.g., boiler make-up water), or discharged. If the plant uses the distillate for other plant 

operations that generate a discharge stream (e.g., used as boiler make-up and ultimately discharged as 

boiler blowdown)

then the FGD 

/

t

t

t

t

t 

t

i

t t

l

di

h
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Table 4-1 presents information PSNH has submitted to date regarding the FGD wastewater that it 

has had hauled off-site to local POTW s. 

Table 4-1 FGD Wastewater Hauled from Merrimack Station -Including Certain 

Data 14 

Year 

2011 

20 II 

2011 

Month 

November 

December 

December 

20 12 January 

2012 January 

2012 February 

Date 

Sampled 

5-Dec 

7-Dec 

Source 

Treat Tank 

Treat Tank 

5-Jan Treat Tank 

22-Mar (reanalyzed} 

Treat Tank 

Treat Tank 

26-Jan 

2-Feb 

Treat Tank 

Treat Tank 

Treat Tank 

Treat Tank 

Stream A 

Stream B 

Volume 

(gallons) 

642,000 

535,500 

NA 

NA 

240,000 

89,700 

755,200 

Destination 15 

S. Portland 

Attleboro 

NA 

S. Portland 

Attleboro 

Lowell 

NR Franklin 

NR Hooksett 

NR Allenstown 

32,017 Hooksett 

112,180 Hooksett 

110,967 Allenstown 

142,834 Allenstown 

282,492 S. Portland 

1,255,000 Lowell 

240,000 Attleboro 

8,000 Franklin 

128,307 Hooksett 

548,942 Hooksett 

16,000 Franklin 

95,495 Lowell 

6,800 Lowell 

94,800 Lowell 

Ha "' (ng) 

6.7 

5.6 

Se 

(!lg) 

89 

120 

As (~tg) < 10 

4.03 

10.5 74 4.98 

68.9 8.51 

12.2 104 9.56 

36 121 12.1 

14 The "Treat Tank," "Final Effluent" and "Stream A" wastestreams are synonymous. They refer to wastewater 

taken from after the primary treatment system. Stream B is wastewater from the evaporator of the secondary 

treatment system. The Combination Wastewater (Comb WW) consists of salt cake filter press "spray wash 

water,""blowdown" from the ciystallizer, and possibly "a certain amount of Stream B." See Personal 

communication between Allan Palmer

PSNH

and Sharo

D

M

R

i

1

J

31

2014

PSNH 

ll

t

d 
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Treat Tank 118,466 Allenstown 

2012 February 9-Feb Treat Tank 47,999 Allenstown 20.9 82.2 <7.5 

360,816 Allenstown 

2012 February 15-Feb Stream B NR Lowell 45.8 498' 49.4 

14,084 S. Portland 

24,006 Attleboro 

2012 March 2-Mar Final Effluent 140,890 Hooksett 17.2 109 8.12 

Final NR Franklin Effluent 

0 Franklin 

Final 191,915 Allenstown Effluent 

Final NR Lowell Effluent 

2012 March 14-Mar Stream B NR Lowell 61.2 587 37.7 

55,042 Lowell 

Distillate NA Lowell <0.5 0.71 <0.1 5 

8,000 Attleboro 

14,084 S. Portland 

2012 August 1~Aug Stream B 48,000 Lowell 34 NR <29. 9 

2012 August 16-Aug Distillate NA Lowell <200 22 6 

2012 September 6-Sep Distillate 24,000 Hooksett <200 20 6 

2012 October 18-0ct Distillate 296,000 Hooksett <200 2 <1 

2013 January 26-Jan Stream A 72,000 Lowell 41.3 44.5 <1.5 

Stream A 80,010 Hooksett 

Stream A 64,000 Allenstown 

2013 January 18-Jan Stream B 120,000 Lowell 203 NR 13 

Stream B 14,012 S. Portland 

2013 February 4-Feb Stream B 144,000 Lowell 79.6 NR 15.1 

Stream B 8,000 S. Portland 

2013 February 16-Feb Stream A 186,000 Hooksett NR 51.7 <7.5 

Stream A 106,000 Allenstown 

2013 March 6-Mar Stream B 112,000 Lowell 80.8 NR 26.6 

2013 June 3-Jun Stream B 40,000 Lowell 157 NR <7.5 

2013 August 7-Aug Stream B 120,000 Lowell 33.9 NR 20 

2013 November 27-Nov Stream B 64,000 Lowell 50.1 NR 13.2 

2013 December 19-Dec Comb WW 16,000 Lowell <25 NR 29.9 

2014 January 29-Jan Comb WW 48,000 Lowell 25.5 NR 28.8 

Blowdown 
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Data Sources for Table 4-1: PSNH' s May 7, 2012, response to Region I' s March 22, 2012, 

CWA § 308(a) information request letter; PSNH's December 6, 2013, response to Region 1 's 

November 8, 2013, CW A § 308(a) information request letter (hereinafter, December 2013 CW A 

§ 308 Response); and emails from A. Palmer to S. DeMeo dated l/31/14, 2/24114, 3/28/14 and 

4/9/14. 

PSNH was asked to provide the reason(s) for each off-site shipment. See Region 1 's November 

8, 2013 CW A § 308(a) information request letter. Instead, PSNH responded with the following 

general statement for all occurrences: 

[i]n each case, it was a business decision reached after consideration of multiple factors 

that may have included continued optimization of the secondary wastewater treatment 

system ("SWWTS") or individual components of that system; necessary adjustments 

based on fuel blends, load changes on either unit, or changes in chemistry due to 

Absorber optimization; operation of individual components or a combination of 

components of the SWWTS; operational constraints (other than the SWWTS); 

maximizing systemic Station operation when generating for a short time period. 

December 2013 CWA § 308 Response. In summary, this response indicates that in each case 

PSNH sent FGD wastewater for off-site disposal due to a business decision based upon the 

company's consideration of a variety of different factors, 

Thus, despite having installed a ZLD treatment system, PSNH has periodically continued hauling 

FGD wastewater off-site for disposal. Moreover, PSNH has indicated that it wishes to be 

authorized to discharge its FGD wastewater to the Merrimack River after treating it only with its 

primary physical-chemical treatment system. See Comments of Public Service Company of New 

Hampshire on EPA's Draft National Pollutant Discharge Elimination System Permit No. 

NH0001465 for Merrimack Station, February 28, 2012, (hereinafter, 2012 PSNH Comments on 

Draft Permit), n. 87, p. 150. See also AR #638. Yet, Region 1 also notes that in support of 

PSNH's then pending energy service rate application, William H. Smagula, PSNH's Director of 

Generation, stated the following to the NHPUC: "[t]he secondary wastewater treatment system 

[SWWT] is a technology that will be used on a permanent basis to complement the primary 

treatment system." Public Service Company of New Hampshire, Docket No. DE 11-250, Data 

Request STAFF-01, 12/30/2011, Q-STAFF-001. 

4.4.2 
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The statute sets up a loose framework within which EPA is to take account of the BAT factors. 

2011 Fact Sheet, Att. E, pp. lO-ll. As one court explained: 

[i]n enacting the CW A, 'Congress did not mandate any pat1icular structure or 

weight for the many consideration factors. Rather, it left EPA with discretion to 

decide how to account for the consideration factors, and how much weight to give 

each factor.' 

BP Exploration & Oil, Inc. v. US. Environmental Protection Agency, 66 F.3d 784, 796 (6th Cir. 

1995), citing Weyerhauser v. Castle, 590 F.2d lOll, 1045 (D.C.'Cir. 1978) (citing Senator 

Muskie's remarks about CWA § 304(b)(l) during debate). Comparison between the factors is not 

required, merely their consideration. Weyerhauser, 590 F .2d at 1045 (explaining that CW A § 

304(b )(2) lists factors for EPA "consideration" in setting BAT limits, in contrast to § 304(b )(1)' s 

requirement that EPA compare "total cost versus effluent reduction benefits" in setting BPT 

limits). While each statutory factor must be considered, the Agency has "considerable discretion 

in evaluating the relevant factors and determining the weight to be accorded to each in reaching 

its ultimate BAT determination." Texas Oil and Gas v. EPA, 161 F.3d 923,928 (5th Cir. 1998), 

citing Natural Resources Defense Council v. EPA, 863 F.2d 1420, 1426 (9th Cir. 1988). See also 

Weyerhauser, 590 F.2d at 1045 (stating that in assessing BAT factors, "[s]o long as EPA pays 

some attention to the congressionally specified factors, [CW A § 304(b )(2),] on its face lets EPA 

relate the various factors as it deems necessary"). 

Ultimately, when setting BAT limits, EPA's consideration ofthe required factors is governed by 

a reasonableness standard. BP Exploration, 66 F.3d at 796, citing American Iron & Steel 

Institute v. US. Environmental Protection Agency, 526 F.2d 1027, 1051 (3d Cir. 1975), modified 

in other part, 560 F.2d 589 (3d Cir. 1977), cert. denied, 435 U.S. 914 (1978); Chemical 

j\;fanz{facturers Ass 'n v. US. Environmental Protection Agency, 870 F.2d 177, 250 n. 320 (5th 

Cir. 1989) (citing Congressional Research Service, A Legislative History of the Water Pollution 

Control Act Amendments of 1972 (1973), at 170) (in determining BAT, "[t]he Administrator will 

be bound by a test of reasonableness.")). As one court summarized it, "[s]o long as the required 

technology reduces the discharge of pollutants, our inquiry will be limited to whether the Agency 

considered the cost of technology, along with other statutory factors, and whether its conclusion 

is reasonable." Pacific Fisheries, 615 F.2d at 818. 

With regard to technological issues, EPA takes a number of considerations into account in 

determining the BAT. For example, EPA compares the pollutant removal capabilities of the 

candidate technologies. As mentioned above, as a starting point, the BAT is supposed to be the 

most effective treatment technology for reducing pollutant discharges. EPA also takes into 

account (1) the engineering aspects of the application of various types of control techniques, (2) 
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EPA also considers the cost of implementing a treatment technology when determining the BAT. 

I d. CW A §§ 30 I (b )(2) and 304(b )(2) require "EPA to set discharge limits reflecting the amount 

of pollutant that would be discharged by a point source employing the best available technology 

that the EPA determines to be economically feasible .... " Texas Oil and Gas, 161 F .3d at 928 

(emphasis added). See also 33 U.S.C. § l314(b)(2)(B) (when determining BAT, EPA must 

consider the "cost of achieving such effluent reduction"); 40 C.F.R. § 125.3(d)(3)(v) (same). 

The United States Supreme Court has stated that treatment technology that satisfies the CWA's 

BAT standard must "represent a commitment of the maximum resources economically possible 

to the ultimate goal of eliminating all polluting discharges." EPA v. Nat 'l Crushed Stone Ass 'n, 

449 U.S. 64,74 (1980). See also BP Exploration, 66 F.3d at 790 ("BAT represents, at a 

minimum, the best economically achievable performance in the industrial category or 

subcategory."), citing Natural Resources Defense Council, 863 F.2d at 1426. 

The Act gives EPA "considerable discretion" in determining what is economically achievable. 

Natural Resources Defense Council, 863 F.2d at 1426, citing American Iron & Steel, 526 F.2d at 

I 052. It does not require a precise calculation of the cost of complying with BAT limits. EPA 

"need make only a reasonable cost estimate in setting BAT," meaning that it must "develop no 

more than a rough idea of the costs the industry would incur." Id. Rybachekv. US. 

Environmental Protection Agency, 904 F.2d 1276, 1290-91 (9th Cir. 1990); Chemical 

i\!Janufacturers, 870 F.2d at 237-38. Moreover, CWA § 30l(b)(2) does not specify any 

particular method of evaluating the cost of compliance with BAT limits or state how those costs 

should be considered in relation to the other BAT factors; it only directs EPA to consider 

whether the costs associated with pollutant discharge reduction are "economically achievable." 

Chemical J\;Janzifacturers., 870 F.2d at 250, citing 33 U.S.C. § 13ll(b)(2)(A). Similarly, CWA § 

304(b )(2)(B) requires only that EPA "take into account" cost along with the other BAT factors. 

See Pacific Fisheries, 615 F.2d at 818. 

In the context of considering cost, EPA may also consider the relative "cost-effectiveness" of the 

available technology options. The term "cost-effectiveness" has been used in multiple ways. 

From one perspective, the most cost-effective option is the least expensive way of getting to the 

same (or nearly the same) performance goal. From another perspective, cost-effectiveness may 

refer to a comparative assessment of different options' cost per some unit of performance (e.g., 

dollars per unit of pollutant removed). 

In its discretion, EPA might decide that either or both of these approaches to cost-effectiveness 

analysis would be useful in determining the BAT in a particular case. Alternatively, EPA might 

reasonably decide that neither was useful. For example, the former approach would not be 

helpful in a case in which only one technology even comes close to reaching a particular 
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Finally, the courts, including the United States Supreme Court, have consistently read the statute 

and its legislative history to indicate that while Congress intended EPA to consider cost in setting 

BAT limits, it did not require the Agency to perform some type of cost-benefit balancing. E.g., 

Nat 'l Crushed Stone, 449 U.S. at 71 ("Similar directions [to those for assessing BPT under CWA 

§ 304(b)(1)(8)] are given the Administrator for determining effluent reductions attainable from 

the BAT except that in assessing BAT total cost is no longer to be considered in comparison to 

ejjluent reduction benefits.") (emphasis added and footnote omitted); Texas Oil & Gas, 161 F.3d 

at 936 n.9 (petitioners asked court "to reverse years of precedent and to hold that the clear 

language of the CWA (specifically, 33 U.S.C. § 1314(b)(2)(B)) requires the EPA to perform a 

cost-benefit analysis in determining BAT. We find nothing in the language or history of the 

CW A that compels such a result"); Reynolds j\lfetals Co. v. US. Environmental Protection 

Agency, 760 F .2d 549, 565 (4th Cir. 1985) (in setting BAT limits, "no balancing is requiredonly that costs be considered along with the other factors discussed previously"), citing Nat 'l 

Ass 'n ojj\;fetal Finishers v. US. Environmental Protection Agency, 719 F.2d 624, 662-63 (3rd 

Cir. 1983). 

In addition to technological and cost considerations, EPA must also consider the non-water 

quality environmental effects (and energy effects) of using the technologies in question. See 33 

U.S.C. § 1314(b)(2)(B); 40 C.F.R. § 125.3(d)(3). Again, the CWA gives EPA broad discretion 

to decide how to evaluate these non-water quality and energy effects and weigh them with the 

other BAT factors. Rybachek, 904 F.2d at 1297, citing Weyerhauser, 590 F.2d at 1049-53. In 

addition, the statute also authorizes EPA to consider any other factors that it deems appropriate. 

33 U.S.C. § 1314(b)(2)(B). 

(i) Age of the equipment and facilities involved 

As previously discussed, PSNH recently installed an FGD system for the removal of pollutants, 

principally mercury, from the Station's flue gas. In order to treat the wastewater generated from 

the FGD system and gypsum processing, PSNH installed primary and secondary wastewater 

treatment systems. The primary treatment system mainly removes solids by chemical 

precipitation, while the secondary treatment system is a two-stage system which uses a brine 

concentrator and crystallizers that generate a salt cake and reusable distillate/condensate streams. 

At the time of the 2011 Draft Permit, Region 1 concluded " ... that the age of Merrimack Station 

would neither preclude nor create special problems with using vapor compression evaporation 

technology." 2011 Fact Sheet, Attachment E, p. 22. In other words, the age of Merrimack 

Station does not impact the wastewater characteristics, the processes in place, or the Station's 

ability to install VCE technology. This conclusion has been verified by the subsequent 

installation and operation of the SWWTS since June 2012 at Merrimack Station. The age ofthe 
Merrimack Station Revised Draft Permit 

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(ii) Process employed and process changes 

NHOOOI465 

Region I also considered potential process issues with the use of VCE technology for the 2011 

Draft Merrimack Station Permit, stating the following: 

Specifically, EPA has considered engineering and process concerns related to the 

potential use of vapor compression technology, and whether it might necessitate any 

changes in Merrimack Station's primary production process or other pollution control 

processes. While effective vapor compression evaporation will require control of water 

chemistry and may necessitate pretreatment of the wastewater, EPA finds that use of 

vapor compression evaporation would not interfere with, or require changes to, the 

facility's other pollution control processes or its primary process for generating 

electricity. EPA also concludes that vapor compression evaporation technology can be 

utilized together with physical/chemical treatment. 

2011 Fact Sheet, Attachment E, p. 22. Again, this determination has been confirmed with the 

subsequent installation and operation of the SWWTS since June 2012 at Merrimack Station. 

(iii) Engineering aspects of the application of various types of control techniques 

Region 1 has not identified any engineering aspects of the application ofVCE and crystallizer 

technology that would preclude or significantly restrict its use at Men·imack Station. As 

discussed in the 2011 Fact Sheet, Attachment E, physical/chemical treatment is frequently used 

to treat FGD wastewater and PSNH decided to use it for Merrimack Station's primary FGD 

wastewater treatment system. In addition, VCE and crystallizer technology has also been used 

by power plants to treat FGD wastewater, albeit less commonly than physical/chemical 

treatment, and PSNH decided to use VCE and crystallizer technology as Merrimack Station's 

secondary wastewater treatment system. PSNH has installed and commenced operation of both 

the primary and secondary FGD wastewater treatment systems. 

Consideration of Public Comments Opposing Use of VCE Technology at Ji;Jerrimack 

Station Because of Engineering Considerations 

During the public comment period for the 2011 Draft Permit, Region 1 received comments 

expressing concern about its determination that VCE technology could potentially be the BAT 

for treating Merrimack Station's FGD wastewater, depending on the nature of any additional 

information collected during the permit development process. The comments regarding 

engineering concerns are summarized and discussed below. 
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Region 1 acknowledges that there are several differences between the Iatan VCE system and the 

system installed at Merrimack Station. Iatan has I) a brine concentrator, but no crystallizers, 2) 

fly ash that is conditioned with concentrated brine solution and disposed of in an on-site landfill, 

and 3) a different primary coal source. Nevet1heless, despite these differences, the most salient 

fact is that both the Iatan and Merrimack Station facilities have been able to apply VCE 

technology in a particular way to treat their respective FGD wastewaters. 16 In other words, while 

there are differences between the two facilities, the fact remains that both use VCE technology. 

While there may be differences between the VCE systems at different facilities because certain 

site specific considerations are taken into account when designing a VCE system to treat a 

particular FGD wastewater, 17 this does not mean that every VCE system is distinct in every 

respect from every other VCE system, or that the experience at one facility could never be 

applied (in whole or in part) to another facility. There are essential commonalities between the 

VCE systems now being used at various power plants to treat their FGD wastewater. 

Region 1 regards the fact that a number of power plants are using VCE and crystallizer 

technology to achieve ZLD of their FGD wastewater to support the view that such systems are 

the best performing technology for reducing FGD wastewater pollutant discharges. 18 It also 

supports the view that, in general, this technology is available within the industry. At the same 

time, site-specific analysis would be needed to determine whether this technology is available for 

any particular facility. Yet, there is little question that the technology is available for Merrimack 

Station because it has already been installed there and is operating. As previously discussed, this 

does not, however, mean that VCE and crystallizer technology is necessarily the BAT for 

Merrimack Station. Region 1 must consider a number of factors specified in the CW A and EPA 

regulations before making that determination. 

16 At both Merrimack and Iatan, the ZLD systems were designed by Burns & McDonnell and installed by Aquatech. 

17 The need to evaluate site-specific conditions is not unique to VCE technology (with or without crystallizers). 

Site-specific considerations also must be taken into account when designing physical/chemical treatment systems. 

As an engineer at HPD (a business unit ofVeolia Water Solutions & Technologies) has explained with regard to 

physical/chemical treatment systems for FGD wastewater: 

FGD is an evaporative process, so it concentrates these impurities. The wastewater from gypsum 

dewatering will have a pollutant content that depends mostly on the type of coal burned, the efficiency of 

the unit's electrostatic precipitator (ESP), the level and type of impurities in the makeup water, the amount 

of heavy metals and impurities in the limestone, and the choice of gypsum dewatering equipment. A good 

understanding of these parameters is necessary to properly design an effective FGD purge water treatment 

system. 

Shaw

2008
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Having said all that, Region 1 again notes that there are seven known VCE systems currently 

operating, and one more being installed, to treat FGD wastewaters. As mentioned previously, 

Aquatech installed five VCE systems (with crystallizers) at various plants in Italy. (The system 

at the Brindisi power plant in Italy was evaluated in patiicular by EPA during the recent Steam 

Electric NELG rulemaking. 19) Aquatech notes that the chemical components of the FGD 

wastewater varied among the five plants, mostly due to variations in "the composition of the coal 

burned and the limestone used to scrub the flue gas." Marlett, 2012. Generally, the type of coal 

burned can also affect the FGD wastewater flow rate. Coal with high sulfur and/or chlorides can 

increase the volume of wastewater generated by the FGD system due to the need for increased 

blowdown rates. See Steam Electric Power Generating Point Source Category: Final Detailed 

Study Report, EPA 821-R-09-008, October2009, p. 4-15.20 Each facility's system has been 

designed based on that facility's site-specific conditions and dynamics. Accordingly, thorough 

site-specific chemistry and mass balance evaluations are necessary to develop an effective 

system for a particular power plant. Ultimately, as one Aquatech official has explained, "[ e ]ach 

plant has a custom-designed treatment train." Global Water Intelligence, "From zero to herothe rise of ZLD," Vol 10, Issue 12, (December 2009). At the same time, Aquatech has explained 

that for these systems, the "[ c ]riteria for design were that the system could handle varying 

chemistries, [and] had high reliability .... " Marlett, 2012. 

Region lfinds that while Merrimack Station's SWWTS shares certain characteristics with Iatan's 

system, it more closely resembles the systems operating in Italy. Like the Merrimack system, the 

Italian ZLD systems include physical/chemical pretreatment, brine concentrators and forced 

circulation evaporators (i.e., crystallizers ). 

2) Some commenters stated that corrosive wastewater requires use of exotic construction 

materials. Otherwise, the facility would need to frequently incur the cost of replacement 

parts, labor, and downtime for repairs. Furthermore, the systems used to control 

corrosivity require extensive and continual maintenance. 

The chlorides in FGD wastewater can be extremely corrosive, especially in high concentrations. 

In the United States, FGD scrubbers are generally constructed of alloys that are designed to 

withstand a chloride concentration of20,000 parts per million (ppm) or more. 2013 TDD, p. 6-2. 

Likewise, FGD treatment systems are built to withstand the corrosive nature of the effluent. 

Specifications for VCE and crystallizer equipment should include high grade, corrosion resistant 

alloys and materials such as Hastelloy, 21 rubber-coated steel, duplex stainless steel, palladiumalloyed titanium and high nickel-chrome-molybdenum alloys. PSNH reports that corrosion 

19 EPA conducted a site visit, sampling events and data analysis of the Brindisi VCE and crystallizer system to 

support its consideration of option 5 of the proposed Steam Electric NELG. 2013 TDD, p. 3-12. 
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NH0001465 

resistant materials are used for the SWWTS at Merrimack Station. March 2013 CWA § 308 

Response (partially designated as CBI by PSNH). At the 2013 IWC, Patricia Scroggin indicated 

that Burns and McDonald spent "a lot of time on materials research" for the Merrimack Station 

secondary treatment system and ended up using alternative materials that resulted in a "six digit" 

cost savings to the company. Sharon DeMeo, Region 1, notes on fW C-13-4 7 presentation, 

November 19, 2013. 

Moreover, scale and corrosion can be controlled through process design. As one authority has 

explained: 

Seeding a falling-film evaporator avoids deposition of calcium salts on the tube 

surfaces of a brine concentrator ... [and e] liminating the mist from the vapor 

separated by a falling-film evaporator dries the input to the compressor, reducing 

the potential for corrosion and erosion. 

Shaw, 2008. In addition, this author further explained that: 

[t]he feed is typically acidified to eliminate residual alkalinity, and a deaerator is 

included to remove C02 and dissolved oxygen from the feed. That reduces the 

potential for corrosion and scaling in the evaporator vessel. 

Id. The crystallizer may also be equipped with a mist eliminator to protect the compressor from 

corrosion and erosion. Furthermore, "[t]he high velocity of the brine and the suppression of 

boiling in the tubes [of a forced-circulation crystallizer] prevent scale from forming on the 

crystallizer's tube surfaces." Id. 

Just as its SWWTS uses corrosion resistant materials, Merrimack Station has also used process 

design measures to control scale and corrosion and can continue to do so in the future. March 

2013 CWA § 308 Response (partially designated as CBI by PSNH). See also Roy and Scroggin, 

2013; Sharon DeMeo, Region l, notes on IWC-13-47 presentation, November 19,2013. 

Merrimack has a seeded system, mist eliminator, de-aerator and forced-circulation crystallizer. 

Id. Thus, the corrosiveness of FGD wastewater presents cetiain challenges to a treatment _ 

system, but there are ways to address these challenges and Merrimack Station has already done 

so for its SWWTS. Obviously, doing so was neither economically nor technologically 

infeasible. 

3) Some commenters expressed concern that mercury may be re-emitted to the ambient air or 

concentrated in the plant ifthe distillate streams are reused. Further, concern was 

expressed that bromide in the coal or added for mercury control could also end up in the 

ambient air or distillate. 
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While recognizing the limited information on this point, Region 1 expects that the majority of 

mercury captured by the FGD scrubber is removed in the primary wastewater treatment system 

prior to entering the VCE system. As previously described, the primary wastewater treatment 

system at Merrimack Station includes sulfide addition and the EMARS (or "polishing step"). 

Both of these components of the primary FGD wastewater treatment system are targeted 

specifically to remove additional mercury from the FGD effluent. Richard Roy of PSNH 

confirmed that there is "little cycling up" of metals because the vast majority of metals are 

captured in the primary treatment system and hauled to an off-site commercial landfill. Sharon 

DeMeo, Region 1, notes on IWC-13-47 presentation, November 19,2013. 

Prior to completion of the FGD system, PSNH identified the concentrations of pollutants that it 

predicted would be present in the discharge from the new Merrimack Station FGD primary 

wastewater treatment system. PSNH projected that its proposed primary treatment system would 

achieve a mercury limit of 14 ng/L. Since that time, Region 1 has obtained mercury data from 

eight samples of wastewater from the primary treatment system. This data shows mercury at low 

levels; averaging 19 ng/L.22 This amount of mercury, even if all of it was re-emitted to the 

ambient air, would be a tiny fraction ( < 0.003 %) of the total mercury previously released to the 

atmosphere in the Station's flue gas but which is now captured by the FGD scrubber and 

removed using the primary wastewater treatment system. 23 See AR # l 031 for rough calculation. 

Region 1 has reviewed PSNH's March 2013 CWA § 308 Response (partially designated as CBI 

by PSNH). Based on this review, the Region's evaluation indicates that bromide will not be a 

problem. 

4) A commenter suggested that a major ZLD system failure might result if FGD wastewater 

is not successfully crystallized, resulting in sludge that would be difficult to remove, 

handle and dispose of. 

Region 1 understands that VCE and crystallizer systems are complex and that system 

adjustments may be required based on site-specific variables. In the event that FGD wastewater 

is not successfully crystallized, facilities have several options for managing the brine solution, 

including sending it back through the physical/chemical treatment process, mixing it with fly 

ash, spray drying it, or hauling it to an off-site disposal location. Personal communication, M. 

Marlett, Aquatech, and S. DeMeo, Region 1, January 8, 2014. See also 2013 TDD, p. 7-16. 

That said, the comment identifies no particular reason to expect that crystallization will not be 

22 Eight samples of wastewater from after the primary treatment system were analyzed from 12/5/2011 to 8/7/2013. 

Results ranged between 5.6 ng/L to max 41.3 ng/L mercury, with an average of 19 ng/L. 
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successful, and the Region expects it will be successful. Any treatment system, including 

physical/chemical treatment, could potentially experience problems or malfunctions and having 

contingency plans ready to implement in the face of such issues is sound practice. Region I 

recognizes that some types of systems are more complex and may be more prone to difficulties 

than others, but these differences are a matter of degree, and we have not seen evidence 

establishing that VCE and crystallizer technology is prohibitively prone to debilitating 

malfunctions. 

5) Some commenters urged that there are many operational difficulties and uncet1ainties with 

ZLD technology and that much of this uncertainty is due to the complex composition of 

FGD wastewater primarily due to variability in coal and limestone sources. 

With any newly installed, complex technology, adjustments in chemistry and operational 

parameters are likely to be required over time to optimize performance. Region 1 expects that 

PSNH's engineers have had to perform numerous adjustments in response to Merrimack 

Station's site-specific conditions, including the charactieristics of its coal and limestone. 

Nevertheless, Merrimack Station has been operating all or part of its SWWTS for its FGD 

wastewater since June 2012. Certainly, continued adjustments are expected during the life of the 

system. As operators gain confidence and experience, however, the Region expects that they 

will be better able to make process adjustments in response to system changes, such as variations 

in limestone and coal sources. See Personal communication, M. Marlett, Aquatech and S. 

DeMeo, Region 1, January 8, 2014. Other facilities using ZLD technology have also, no doubt, 

had to make adjustments to optimize handling of their FGD wastewater. 

For example, Aquatech has repot1ed identifying, and successfully addressing, various 

maintenance issues for the ZLD system at the plant in Brindisi, Italy. These issues have been 

described as follows: 

[t]he major maintenance issue of the ... Brindisi plant has been the hydroclone and the small 

lines discharging concentrate. This has been addressed and resolved by adding additional 

flushing points and the ability to disassemble the small lines. This is still an area where 

operators are practicing vigilance. The BC had one issue with a bearing failure and that 

caused a significant amount of downtime for the repair. During startup, the Belt Filter Press 

had issues with platen seals. In addition there have been instances of premature fouling and 

scaling of the feed pre heater. During the transition to steady state operation, the dryness of 

the filter cake was not acceptable. This was resolved by the increase in drying time of the 

cake. 

Marlett, 2012. Thus, Aquatech has identified and resolved a variety of issues as the treatment 

system went through its stat1up phase. 
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that to some degree, Aquatech will apply lessons learned at its installations in Italy to its system 

at Merrimack Station. 

Roy and Scroggin (2013) reported several challenges for Merrimack Station's FGD wastewater 

treatment system that were overcome using tighter process control. First, high pH of the 

wastewater in the evaporator caused "volcanic" foam upsets that were resolved by careful 

control ofthe pH and discontinuing use of the antifoaming agent in the evaporator (still used in 

the crystallizer). Second, solid-phase sulfates were accumulating in the heat exchanger, 

deaerator, and evaporator. The engineering/vendor team made several modifications to the 

system to optimize the process, including removal of much of the sulfates prior to softening. 

Third, varying the constituents in the incoming fuel affects the quantity of the salt cake 

generated. The quantity (and quality) of salt cake affects the amount of solids that can be 

processed through the indexing belt filter over a given period of time. A plant wide material and 

water balance resulted in process optimization for the entire FGD wastewater treatment system. 

"The project overcame many challenges through teamwork and close cooperation between end 

user, engineer, and equipment supplier, resulting in a highly flexible solution which in essence 

advanced the technology in a comprehensive system-wide manner. Roy and Scroggin, 2013. 

See also Sharon DeMeo, Region 1, notes on IWC-13-47 presentation, November 19,2013. 

Finally, while variable coal and/or limestone quality may pose challenges for VCE and 

crystallizer technology, it may also pose challenges for other types of pollution control 

technologies. Thus, careful process control and the ability to make adjustments based on sitespecific conditions and performance are important for many types of pollution control processes. 

(iv) Cost of achieving effluent reductions 

Region 1 is proposing revised technology-based requirements for Merrimack Station's new 

NPDES permit to govern the facility's FGD wastewater. The new requirements are based on a 

revised BAT determination which, in turn, is based on the power plant's currently-in-place 

primary and secondary FGD wastewater treatment systems. As explained above, the primary 

system relies on physical/chemical treatment, including the EMARS filtration or "polishing" 

equipment, whereas the secondary treatment system has two stages and uses VCE and 

crystallizer technology. 

PSNH installed and began operating the various components of these treatment systems at 

Merrimack Station across a number of months: primary treatment system operations began in 

September 2011; the first stage ofthe secondary system began operations in March 2012; and the 

second stage of the secondary system commenced operations in June 20 12. Thus, Merrimack 

Station began using the complete FGD wastewater treatment system, including the second stage 
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as make-up water in the FGD scrubbers (i.e., it is a ZLD system).24 

NHOOOI465 

PSNH's successful, voluntary installation and operation of this FGD wastewater treatment 

system evidences that using this combination of technologies was not cost-prohibitive for 

Merrimack Station. This is a significant fact for this site-specific, BPJ determination of the BAT 

for controlling FGD wastewater at Merrimack Station. It does not, however, mean that VCE and 

crystallizer technology would necessarily be affordable for any other individual power plant or 

for the steam electric power plant industrial category as a whole. Region 1 's site-specific BAT 

determination for the Merrimack Station permit neither analyzes nor applies to any other facility 

or to the industrial category as a whole. 

After initially indicating to Region l (in 20 l 0) that significant fmiher evaluation of VCE 

technology would be needed prior to determining if VCE should be applied at Merrimack 

Station, (AR #40), PSNH later decided (in 20 ll) to install and use VCE as part of its secondary 

FGD wastewater treatment system (in conjunction with its previously installedprimary treatment 

system). The circumstances surrounding PSNH's decision to install this system included the 

following: (l) state law required operation ofthe FGD scrubbers by July l, 2013, but only if 

Merrimack Station had obtained all necessary permits, RSA 125-0:13(1);25 (2) PSNH could 

qualify for economic incentives provided under the New Hampshire statute if it brought the FGD 

scrubber online and achieved mercury emission reductions before July 1, 2013, RSA 125-

0: 16(I)(a); (3) the sooner PSNH cut its mercury emissions, the greater the economic incentives it 

could realize under the statute, id.; (4) ifthe FGD system generated wastewater discharges 

requiring authorization from an NDPES permit, PSNH anticipated that Region 1 's NPDES 

permitting process- including potential litigation with environmental groups over any permit 

that the Region might issue that allowed FGD wastewater discharges- would significantly delay 

Merrimack Station from commencing FGD scrubber operations and prevent it from bettering the 

July 1, 2013, deadline; and (5) in the absence of an NPDES permit allowing FGD wastewater 

discharges before the statutory deadline, PSNH would either have to forego the state economic 

incentives or have in place a method of managing the FGD wastewater without direct discharges 

to the Merrimack River so that it could lawfully commence FGD scrubber operations. 

In order to manage the FGD wastewater without direct discharges, Merrimack Station would 

24 In explaining that a certain amount of water vapor is emitted to the atmosphere from the FGD scrubber, Richard 

Roy from PSNH stated, during the 20 13 IWC, that ZLD really did not mean there is no liquid discharge but that "the 

only place we are able to discharge water is up the chimney ... that's our discharge permit." Sharon DeMeo, Region 

1, notes on IWC-13-47 presentation, November 19,2013. 

25 The state statute reads, in pertinent part, as follows: 

[t]he owner shall install and have operational scrubber technology to control mercury emissions at 
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need either to collect and haul the FGD wastewater for off-site disposal or employ a "zero 

discharge" treatment technology. As it has turned out, Merrimack Station has employed both 

approaches: first, it completed the primary treatment system and the first stage of the secondary 

system by September 2011 and March 2012, respectively, and began hauling treated FGD 

wastewater off-site for disposal; and, second, it completed the second stage of the secondary 

treatment system in June 20 I 2 so that it could operate on a ZLD basis. See Testimony of 

William H. Smagula, Director of Generation for PNSH, before the NHPUC, Docket No. DE 11-

250, June 15,2012, p. 10-11 ("The [secondary treatment system] will take the treated effluent 

from the [primary treatment system] and produce a clean water stream which is recycled into the 

station for reuse, with any remaining dry solids collected for disposal at a permitted landfill .... 

In summary, no NPDES permit changes were needed for the Clean Air Project."). 26 Even after 

June 2012, PSNH has at times continued to truck treated FGD wastewater off-site for disposal at 

various municipal sewage treatment plants. 

PSNH could have delayed operation of the FGD scrubbers while NPDES permitting issues were 

worked out, but it evidently made sense for the company to take the steps needed to eliminate 

FGD wastewater discharges so that it could bring the FGD scrubbers online well before July 1, 

2013, and maximize access to the economic incentives. See 2012 PSNH Comments on Draft 

Permit, n. 68, p. 123 ("the law provides numerous incentives to PSNH if its FGD system is 

operational prior to 2013 "). See also March 2012 Submission to the NHPUC, p. 4 (According to 

PSNH, "to incent the most expeditious installation and operation of the Scrubber, the Legislature 

enacted RSA 12-0:16, which provides Economic Performance Incentives for mercury reductions 

which are achieved prior to July 1, 2013. Because the Scrubber was placed into service in 

September, 2011, the Company will earn these incentives .... ").27 

EPA regards a facility's regulatory compliance costs attributable to a set of effluent limitations to 

be the costs that the facility would incur to install and operate plant upgrades needed to comply 

with those limitations. In other words, a facility's cost of achieving effluent reductions required 

by an Agency rule or permit under the CW A are the incremental costs (i.e., costs beyond the cost 

26 See also September 2012 Jacobs Consultancy Report for the NHPUC, p. 57 ("PSNH believed adding the 

discharge to the NPDES pennit would be an extremely long process, possibly taking many years, due to the 

statutory requirements regarding public involvement. PSNH also believed there would be litigation challenges by 

one or more of the environmental groups that could prevent the start up of the scrubber and render the Merrimack 

Power Plant useless for years. Consequently, to avoid further potential litigation and possibly years of delay in 

placing the unit into operation, PSNH elected to install the secondary wastewater treatment system. As previously 

mentioned the output of this secondary system, as designed, reduces the liquids effluent to zero, resulting in nothing 

being discharged into the river and reduces the solid effluent to a minimum that can be disposed of in existing 

licensed landfills. The original construction plans had the treated water from the wastewater treatment system 

discharging into the river. PSNH had to reconfigure the system due to permit and litigation issues during the early 

part of the system construction

This redesign eliminat

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of its existing wastewater treatment practices) that a plant would incur to meet the new 

requirements. When a plant already has technology that enables it to meet EPA's effluent limits, 

the cost of installing and operating the preexisting technology are not compliance costs 

associated with the later adopted requirements. The logic behind this approach is 

straightforward: when a facility is using a technology installed prior to a rule or permit imposing 

the requirement, the costs associated with that technology cannot reasonably be attributed to that 

rule or permit. 

For example, EPA explained in the preamble to the Proposed Rule for the new Steam Electric 

Power Plant NELGs: 

[a] portion ofthe steam electric industry has already implemented processes or 

treatment technologies that serve as the basis for the regulatory options 

considered for the proposed rule; as a result, these facilities would not incur costs 

to comply with the proposed rule, or would incur costs lower than they would be 

if the processes/technologies had not already been implemented. In such cases, 

EPA assigned no compliance cost associated with the discharge of that particular 

wastestream other than compliance monitoring costs. 

78 Fed. Reg. 34,481 (June 7, 20 13) (Proposed Rule, Steam Electric NELGs). Similarly, in the 

Technical Development Document supporting the Proposed Rule for the Steam Electric NELGs, 

EPA explained that: 

[fJor plants currently treating the FGD wastewater using one-stage chemical 

precipitation, anoxic/anaerobic biological treatment, or vapor-compression 

evaporation systems, EPA did not estimate compliance costs for the specific 

pieces of equipment that are already operating at the plant. For example, ... if a 

plant operates a one-stage chemical precipitation system for the treatment of FGD 

wastewater that includes all the steps included as the basis for the technology 

option other than sulfide precipitation, then EPA would include capital costs for 

the plant to install a reaction tank and sulfide chemical feed system and operating 

and maintenance costs for the amount of sulfide added to the system on a yearly 

basis. The compliance costs for all other pieces of equipment for the system 

would be set to zero. 

2013 TOO, p. 9-11. See also id. at p. 9-26. 

EPA has also followed this approach in other previous CW A rulemakings. For example, in 

assessing the economic achievability ofNELGs for indirect discharges from hazardous waste 

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[f]acilities whose current discharges were not meeting the concentrations 

proposed ... were projected to incur costs as a result of compliance with this 

guideline. A facility which did not have the [proposed] BPT treatment technology 

in-place was costed for installing the [proposed] BPT technology. A facility 

already having [the proposed] BPT treatment technology in-place, but not 

currently meeting the proposed limits, was costed for system upgrades where 

applicable. 

63 Fed. Reg. 6425, 6448 (Feb. 6, 1998) (Proposed Rule) (Effluent Limitations Guidelines, 

Pretreatment Standards, and New Source Performance Standards for the Landfills Point Source 

Category). All of the indirect discharging hazardous waste landfills in EPA's survey of the 

industry were expected to already be in compliance with the baseline treatment standards 

established for indirect dischargers. EPA therefore projected that there would be no costs 

associated with compliance with the proposed regulation. See id. at 644 7 -6448; TOO for Final 

Rule, NELGs for Landfills Point Source Category, p. 9-7.28 See also 77 Fed. Reg. 29,168, 

29,181-29,182 (May 16, 2012) (Final Rule, Effluent Limitations Guidelines and New Source 

Performance Standards for the Airport Deicing Category) (estimated cost for compliance with 

the Rule based on incremental costs to facilities when existing practices would not lead to 

compliance with the regulatory option under consideration); 66 Fed. Reg. 65,266, 65,323 (Dec. 

18, 2001) (Final Rule, National Pollutant Discharge Elimination System: Regulations Addressing 

Cooling Water Intake Structures for New Facilities) (for facilities already planning to install the 

"Best Technology Available" prior to promulgation of the new regulations, the cost of such 

technology installation is not part of the cost of compliance with the new regulations). 

Similarly, in Texas Oil & Gas, 161 F.3d at 929-936, the United States Court of Appeals for the 

Fifth Circuit upheld an EPA economic achievability analysis which supported effluent 

limitations prohibiting certain pollutant discharges and in which EPA determined that the cost of 

compliance with the limitations was minimal because the "reinjection" technology chosen by the 

Agency as the BAT reflected what was already current practice at the vast majority of covered 

facilities. More specifically, EPA found that, due to a combination of factors, the vast majority 

of the coastal oil and gas facilities covered by its rulemaking (and by EPA Region 6's General 

Permit) already used reinjection technology that allowed them to achieve zero discharge of the 

pollutants at issue (e.g., produced water). As a result, EPA found that such already compliant 

facilities would not incur additional compliance costs due to the Agency's BAT-based zero 

pollutant discharge limits. 161 F .3d at 931-932, 934. 

In the present case, Merrimack Station has already installed and is operating the technologies 

that Region I has determined on a site-specific, BP J basis are the BAT for controlling FGD 

wastewater at the Facility. Specifically, as explained in this Fact Sheet, the Region has 
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which can be operated to achieve ZLD) are the BAT. PSNH voluntarily decided to install and 

commence operations of the primary and secondary FGD wastewater treatment systems, 

including the ZLD components. Installing this wastewater treatment system was not required by 

Region 1 at the time. (Doing so did, however, enable Merrimack Station to begin operating its 

FGD scrubbers without needing an NPDES permit, which both accelerated reductions in the 

Facility's air pollutant emissions and maximized its qualification for the state law economic 

incentives that rewarded expedited cuts in the Facility's air emissions of mercury, in particular. 

See RSA 125-0: 11(IV).) By continuing to use this treatment system at Merrimack Station, the 

Facility will be able to comply with the Revised Draft Permit's requirements based on this 

technology. Therefore, PSNH will incur no additional costs to comply with the BAT-based 

requirements in the Revised Draft Permit. (This is, of course, an entirely site-specific 

determination applicable to Men·imack Station and not to other facilities.) In other words, the 

costs of complying with the Revised Draft Permit (including both capital and O&M costs) of 

physical/chemical treatment together with softening and VCE processes are considered zero 

because these technologies are already in operation at Merrimack Station, as described above, 

and were not installed due to this BAT determination. In addition, the Facility would also be 

able to comply with the limitations and conditions in the 2011 Draft Permit, which were based 

on the use of physical/chemical and biological treatment, using its current VCE technology. 

Therefore, the cost of complying with the BAT determination in the 2011 Draft Permit would 

also be considered zero. 

Additional Discussion of Cost 

Although PSNH' s cost to install and operate the primary and secondary wastewater treatment 

systems are not attributable to Region 1 's revised BAT determination for Merrimack Station's 

control of FGD wastewater, the Region analyzed and considered these costs and provides 

additional information regarding them below. 

For the purpose of the 2011 Draft Permit, EPA estimated that the capital cost of installing the 

primary treatment system, together with the VCE system, would be approximately $27,949,000. 

See 2011 Fact Sheet, Attachment E, p. 22. More recently, Region 1 received information stating 

that PSNH had spent approximately $36.4 million to put the secondary wastewater treatment 

system in place ($32.6 million for installing the VCE and crystallizer technology and $3.8 

million for a soda ash softening process that provides pretreatment to the system). Jacobs 

Consultancy, "New Hampshire Clean Air Project Final Report," prepared for NHPUC, 

September 10, 2012, p. 57 ("PSNH elected to install a secondary wastewater treatment system 

for $36.4M."). 29 

29 In order to put these costs into context, the Region notes that it received information that this system is considered 

a component ofPSNH's larger FGD Scr

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Annual O&M costs for the primary and secondary WWTS's include costs associated with 

operating labor, maintenance labor, maintenance materials, chemical purchase, energy 

requirements, compliance monitoring, sludge transportation, sludge disposal, and impoundment 

operation. See 2013 TOO, p. 9-21. See also 78 Fed. Reg. 34481 (Proposed Steam Electric 

NELG's). For the September 2011 Draft Permit, EPA estimated that annual O&M costs for the 

primary system alone (without the EMARS technology) would be approximately $430,000 per 

year. See 20 I1 Fact Sheet, Attachment E, p. 22. With the EMARS technology, the O&M costs 

for the primary system would be somewhat greater. Annual O&M costs estimated for the 

primary treatment system together with VCE would be approximately $1,524,000 per year. 30 !d. 

at p. 28. Based on these figures, a reasonable estimate of the O&M costs for the VCE treatment 

equipment alone would be approximately $1,100,000 ($I ,524,000 - $430.000 =$I ,094,000; 

rounded to $1,1 00,000). 

After learning that PSNH had installed the secondary wastewater treatment system (SWWTS) at 

Merrimack Station, Region I sent PSNH an information t'equest pursuant to CWA § 308(a) 

asking, among other things, "[w]hat was the total operating and maintenance (O&M) cost 

associated with the SWWTS that PSNH incun-ed from September 28, 20 11 through the end of 

20 I2?" February 7, 2013 CWA § 308 Information Request. In response, PSNH did not provide 

the Region with a figure. The company indicated that it does not track S WWTS O&M costs 

separately. March 20 I3 CWA § 308 Response (partially designated as CBI by PSNH). 

Although PSNH did provide a cost per pound for SWWTS salt cake disposal, it did not provide 

figures for other O&M costs. Based on this value, Region 1 estimates that the cost of salt cake 

disposal from the S WWTS is less than $100,000 per year. This value is a small component of 

the estimated total O&M cost of $I, 100,000 per year for the S WWTS. !d. See also AR # 103 7 

and # 1003 (CBI information redacted). In sum, the be~t information that Region I currently has 

about O&M costs for the existing primary and secondary FGD WWTS at Merrimack Station are 

the figures stated above. 

(v) Non-water quality environmental impacts (including energy requirements) 

Finally, Region 1 considered the non-water quality environmental impacts and energy 

for the purpose of the Draft Permit. Jacobs Consultancy, "New Hampshire Clean Air Project Final Report," 

prepared for NHPUC, September I 0, 2012, p. 35-36; 20 1I Fact Sheet, Attachment E, p 28. (In Region I 's February 

7, 2013 CWA § 308 Information Request, we asked PSNH whether it sought, or is currently seeking, recovery of 

SWWTS costs as part of its energy service rate approval application before the NHPUC. PSNH declined to answer, 

however, stating that this information is irrelevant to Region I 's BAT determination. March 20 I3 CW A § 308 

Response (partially designated as CBI by PSNH).) For comparison, if the cost of adding the SWWTS was $36.4 

million, it would represent 8.6% of FGD Scrubber/Clean Air Project's total cost. CLF proposes a different 

comparison

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requirements associated with the primary and secondary FGD wastewater treatment systems at 

Merrimack Station, including solids generation, air emissions, sound emissions, and visual 

effects. To Region 1's current knowledge, there is nothing about either the primary or secondary 

FGD wastewater treatment systems that is likely to generate any significant adverse non-water 

quality environmental effects at Merrimack Station. 

Solids Generation 

At the time of the Draft Permit, EPA estimated that physical/chemical treatment alone at 

Merrimack Station would generate approximately 1,976 tons of solids per year for off-site 

disposal. See 9/16/11 (09:57AM) Email from Ronald Jordan, EPA Headquarters, to Sharon 

DeMeo, Region 1, "Non-water quality environmental impacts for FGD wastewater treatment 

options" (9/16/11 Email from Ron Jordan) (AR #117). Comparatively, EPRI estimated that the 

physical/chemical treatment system at Merrimack Station would generate approximately 5,000 

tons of solids per year. See EPRI, Comments on the Draft Determination of Technology-Based 

Effluent Limits for the Flue Gas Desulfurization Wastewater at Merrimack Station in Bow, New 

Hampshire (EPRI Comments, 2012), February 27,2012, Table 6, p. A-10. Based on more recent 

calculations using a maximum flow of 70 gpm instead of an average flow of 35 gpm, Region 1 

estimates that Merrimack Station could.generate up to 6,100 tons of solids per year. 31 

Region 1 then developed an estimate of the additional amount of solids that would be generated 

from the SWWTS at Merrimack Station. Based on reviewing waste manifests, Region 1 

estimates that Merrimack Station's secondary treatment system generates an average of 4.1 tons 

of salt cake solid waste per day or 1,507 tons per year. March 2013 CW A § 308 Response, 

Attachment 6 (non-hazardous manifests) (not designated as CBI). The Region notes that this 

amount reflects the Facility's relatively low capacity factor during this time period and it would 

likely be higher with greater Facility operations.32 In addition, the PSNH manifests for salt cake 

may not have included the additional solids generated by the added softening step that is used 

prior to the vapor compression evaporator. Using the sludge factors used by EPA in the 2013 

TOO, Region 1 estimated the maximum amount of softening sludge and crystallizer sludge that 

could be generated by Merrimack Station. Using a maximum flow of70 gpm, Merrimack 

Station is estimated to generate 15,768 tons of sludge/year from softening and 5,255 tons of 

sludge/year from the crystallizer.33 See 2013 TOO, p. 12-12. 

31 Assuming a maximum flow of70 gpm, Region 1 determined the annual sludge generation (tons/year) using the 

following equation: sludge generation rate (0.24 tons per day per gallon per minute of FGD wastewater flow) x 

FGD wastewater flow (70 gpm) x 365 days/year. See 2013 TDD, p. 12-12. 

32 While the capacity factors at the few remaining coal-burning power plants in New England may well experience 

short

term fluctuations going forward

Region 1 does not expect significantly greater operations overall in light of 
Merrimack Station Revised Draft Permit 

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Based on the values discussed above, Region 1 estimates that Merrimack Station could generate 

at most approximately 21,000 tons of solids per year from its secondary FGD wastewater 

treatment system. 

Yet, even if the additional solids generated with the use ofthe SWWTS amounts to a maximum 

21,000 tons per year, this would still be a relatively small percentage increase in the amount of 

solids generated at the site overall. With its comments on the 2011 Draft Permit for Merrimack 

Station, CLF submitted a consultant's report which estimates that a total of approximately 

281,000 tons of solids are generated at Merrimack Station each year. See CLF Comments, 2012 

Exhibit 2 (report by John Koon of John H. Koon & Associates). This estimate is based on 

infonnation provided by PSNH to calculate the amount of gypsum and ash generated at the plant. 

The amount of gypsum (187,000 tons/year) was determined using the FGD limestone feed rate at 

design capacity (17.4 tons/hour), extended to an annual basis and applying the Station's 2011 

capacity factor. The amount of ash generated was determined by considering the amount of coal 

burned. 

According to the permit application for the FGD system installation, the station burns 

1,256,896 tons/yr of coal which has an ash content of 7.3 - 7.6%. This calculates to an 

annual ash generation rate of 94,566 tons/yr. (PSNH 2007). 

CLF Comments, 2012, Exhibit 2, p. 13. Region 1 agrees that while this estimate is only an 

approximate value, it nevertheless helps to place the estimated amount of solids generated by the 

SWWTS into some type of larger context. The generation of a maximum 21,000 tons of solids 

per year from the use of Merrimack Station's SWWTS would amount to approximately 7.5% of 

the total amount of solids generated at the plant. 34 

As a result, Merrimack Station is expected to generate up to approximately 21,000 tons of added 

solids per year utilizing VCE and crystallizer technology. In Region 1 's judgment, this is a 

relatively small increase in the total volume generated at the site. 

Based on comments received during the 2011 Draft Permit public comment period, Region 1 

also considered that solid waste generated from some FGD ZLD systems may contain 

hygroscopic salts which could contaminate landfill leachate and increase the cost of disposal. 

The characteristics of the salts formed in the crystallizer depend on the crystallization 

Softening Sludge (tons/year)= Softening Sludge Factor (51.43 lb/hr-gpm) x FGD Wastewater Flow (70 gpm) x 

( l ton/2,000 lb) x 24 hr/day x 365 day/year 

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process picked. With a fully softening process, the salt is mainly composed of sodium 

chloride, which is not hygroscopic. The ZLD's in Italy and China generate this kind of 

salt. 

A partially softened process generates salt with a hygroscopic nature, as it is composed 

mainly of calcium chloride hydrate. A nonsoftened process produces a similar salt that is 

composed mainly of calcium chloride and magnesium chloride hydrate. Both salts tend 

to melt down in a short period of time (minutes to hours). 

Nebrig et. al., 20 11. Roy and Scroggin report that the FGD wastewater at Merrimack Station is 

partially softened and neutralized with lime and soda ash at the end of the facility's primary 

wastewater treatment system. In effect, calcium ions are replaced by sodium ions and the 

resulting solid phase sodium sulfate is removed as settleable solids. Therefore, only the 

remaining liquid-phase sulfates are softened, resulting in the need to dispose of mainly sodium 

chloride. Although the wastewater is "partially" softened, in this case the result is a stable solid 

salt cake that can be disposed of in a commercial landfill. The solid salt cake generated does not 

contain hygroscopic salts that require special processing to reduce absorption of moisture from 

the atmosphere. Personal communication, M. Marlett, Aquatech, and S. DeMeo, Region 1, 

January 8, 2014. 

Energy Requirements 

Generally, multiple effect crystallizers like the one at Men·imack Station conserve energy 

compared to single effect crystallizer. !d. In addition, energy efficiency has been engineered 

into the SWWTS in certain areas. For example, cooled ZLD distillate from both the evaporator 

and crystallizers is used as the cooling water source for the second effect condenser. "Not only 

did this eliminate an additional service water use for the cooling of the crystallizer distillate, the 

warmed distillate enhances wet FGD operation." Roy and Scroggin, 2013. See also Sharon 

DeMeo, Region 1, notes on IWC-13-47 presentation, November 19,2013. Further, the primary 

condenser was removed from service because instead of condensing the first effect vapor, the 

vapor was used as a heating element for the second effect. Therefore, the second effect uses less 

energy. !d. 

For the 2011 Draft Permit, physical/chemical treatment is estimated to require approximately 

339,017 kW-hr/year (339 MW-hr/year) of electricity. See 9/16/11 Email from Ron Jordan. 

Comparatively, EPRI estimates that Merrimack Station's physical/chemical treatment system 

uses 500,000 kW-hrlyear (500 MW-hr/year). See EPRI Comments, 2012, Table 6, p. A-10. 

In response to the Region's request for information regarding the energy demand of the 

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PSNH). Considering the Station is rated at 440 MW (or a maximum 3,854,400 MW-hr/year at 

full load), the contractually guaranteed energy demand value for the SWWTS is a tiny fraction of 

the total energy generated at the Station. CLF' s consultant, John Koon, came to a similar 

conclusion, estimating that the additional energy needed for VCE (17,000 MW -hr/year) amounts 

to 0.8 percent of the total energy generated at the site (based on generation of 2,800,000 MWhr/year). CLF Comments, 2012, Exhibit 2, p. 13. 

Air Emissions 

While some indirect air emissions could potentially be attributed to the energy needed to operate 

the FGD wastewater treatment systems, in Region 1 's judgment any such incremental air 

emissions would be relatively insignificant. Specifically, they will be insignificant relative both 

to Merrimack Station's overall energy production and air emissions as well as to regional energy 

production and air emissions. 

Region 1 estimated that Merrimack Station would generate an average of 4 million tons of C02 

per year if the plant ran at near full capacity. See AR #881 and# 1032 (CBI information redacted 

from AR #1032). Using EPA g.ir market data from 2011-2013 for each Unit, the Region chose 

the highest (most conservative) value oftons of C02 generated per MW-hr (in 2011, Unit 1 

generated 1.09 tons C02/MW-hr) to calculate the amount generated from the SWWTS-dedicated 

boiler. Jd. Considering the contractually guaranteed energy demand value for the SWWTS, the 

total amount of C02 generated by using this system is a tiny fraction of the total amount that the 

Facility generates (<1%). Jd. See also March 2013 CWA § 308 Response (partially designated 

as CBI by PSNH). Likewise, the emission rates for S02 and NOx associated with running the 

SWWTS will. be a similarly small percentage of the overall plant emissions. 

Moreover, it should be understood that any such incremental emissions would not represent an 

increase to the status quo. Rather, they would represent a relatively small reduction in (or offset 

against) the extent to which the FGD scrubber system reduces the Facility's emissions of harmful 

air pollutants. In other words, while the FGD scrubber system substantially reduces Merrimack 

Station's emissions of harmful air pollutants, those reductions might be marginally less because 

of the energy requirements ofthe treatment system needed for the FGD wastewater. The FGD 

wastewater treatment system is needed to avoid a result in which the wet FGD scrubber system 

merely converts air pollution emissions into direct discharges of water pollution. 

Sound Emissions and Visual Effects 

Sound emissions could be a concern if the VCE and crystallizer equipment is located very near 

to sensitive receptors (e.g., residences). Noise comes principally from pump operation, 

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present an unacceptable visual impact, given that Merrimack Station is already a huge industrial 

facility with large buildings, tall smoke stacks and electrical transmission lines on the site. 

As previously discussed, in the absence of applicable effluent limitation guidelines based on the 

best available technology (BAT) standard, a permitting authority must establish BAT effluent 

limits based on its best professional judgment (BP J). During the development of the 2011 Draft 

Permit for Merrimack Station, Region I determined that physical/chemical treatment in 

combination with biological treatment constituted the BAT for controlling Merrimack Station's 

FGD wastewater discharges. Consequently, the Region proposed effluent limits to be applied at 

Outfall 003C consistent with these treatment technologies. 

However, Region 1 subsequently learned, as described in this Fact Sheet, that along with the 

physical/chemical treatment system, PSNH began installation of a secondary, VCE and 

crystallizer system at Merrimack Station in 2011. Region 1 also learned that PSNH has been 

operating the completed systems since at least June 2012.35 As previously described, this 

combined (i.e., primary and secondary) wastewater treatment system is capable of eliminating 

any direct liquid discharge of pollutants to the Merrimack River, though it will generate solid 

waste and distillate/condensate streams. As the system is designed, the solid waste is hauled for 

off-site disposal and the distillate/condensate streams can be used as FGD scrubber make-up 

water. 

In consideration of the appropriate factors, as discussed in detail above, Region 1 has revised its 

site-specific, BP J-based BAT determination. See CWA § 304(b)(2); 40 C.F.R. §§ 125.3(c)(2) 

and 125.3(d)(3); 45 Fed. Reg. 68333. The Region now determines that Merrimack Station's 

existing primary FGD wastewater treatment system (which includes physical/chemical treatment 

components and the EMARS system) combined with its existing secondary FGD wastewater 

treatment (which includes the two-stage evaporation system which can be operated to achieve 

ZLD) are the BAT. 

35 As previously stated, PSNH voluntarily decided to install and commence operations of the primary and secondary 

FGD wastewater treatment systems

including the ZLD components

Installing this wastewater treatment system 
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In this Revised Draft Permit, Region l is proposing to remove Outfall 003C. Presently, 

Merrimack Station has already installed and is operating the technologies (i.e., primary and 

secondary wastewater treatment systems) that Region l has determined on a site-specific, BPI 

basis are the BAT for the controlling FGD wastewater at the Facility. These technologies are 

capable of eliminating the direct discharge of pollutants, as discussed above. Consistent with 

this BAT determination, the permit precludes FGD wastewater discharges to the Merrimack 

River. Removing outfall 003C from the permit would accomplish this result by removing from 

the permit any authorization to discharge FGD wastewater directly to the river. 

While the treatment system could be operated as a ZLD, in practice, Merrimack Station has for 

various business reasons opted at times to collect treated FGD wastewater and ship it off-site for 

indirect discharge through various municipal wastewater treatment plants. The facility has 

collected this wastewater after treatment in the primary (physical/chemical) treatment system, 

after treatment in the primary system and the first stage of the secondary system (i.e., the brine 

concentrator), and more recently "blowdown" from the crystallizer and equipment maintenance 

wash water. Although, the volume and frequency of shipments have declined significantly since 

the system began operating, it is unclear why PSNH would need to continue hauling 

wastewater. 36 Region l notes that the Italian plants with VCE and crystallizer technology, as 

discussed earlier, do not discharge or haul wastewater from their facilities (i.e., they are true 

ZLD systems) and the systems are reported to be working properly. See Personal 

communication, Leonardo AtTighi, ENEL and S. DeMeo, Region l, February 7, 2014. 

36 Within the last seven months, PSNH has hauled a total of344,000 gallons ofFGD wastewater and FGD-related 

wastewater from Merrimack Station for offsite disposal, as shown in Table 4-1 above. In its November 8, 2013 

CWA § 308(a) information request letter, Region 1 asked PSNH to explain the reason(s) for each off-site shipment 

going forward. Instead, PSNH responded with the following general statement applicable to all occurrences: 

[i]n each case, it was a business decision reached after consideration of multiple factors that may have 

included continued optimization of the secondary wastewater treatment system ("SWWTS") or individual 

. components of that system; necessary adjustments based on fuel blends, load changes on either unit, or 

changes in chemistry due to Absorber optimization; operation of individual components or a combination 

of components of the SWWTS; operational constraints (other than the SWWTS); maximizing systemic 

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Region 1 has also reviewed the limited data available for the Facility's off-site shipments of 

FGD wastewater. Based on that review, the Region is concerned about the presence of 

pollutants that present a particular ecological threat due to their tendency to persist in the 

environment and bioaccumulate in organisms. Such pollutants include arsenic, mercury and 

selenium. This data is presented in Table 4-1 above. [t is unclear whether these pollutants 

receive any treatment at the POTW s. These constituents are generally expected to pass through a 

typical municipal sewage treatment plant. 78 Fed. Reg. 34477 (June 7, 2013) (Table VUI-3). 

Ultimately, until EPA promulgates new categorical pretreatment standards, the sewage treatment 

plants accepting this wastewater will have to ensure that any necessary pretreatment 

requirements are in place, which may include local limits, and PSNH will need to comply with 

them. See 33 U.S.C. § 1317(b), (c) and (d); 40 C.F.R. Part 403. See also 78 Fed. Reg. 34438, 

34477-34478,34540-34543 (June 7, 2013) (Effluent Limitations Guidelines and Standards for 

the Steam Electric Power Generating Point Source Category; Proposed Rule) (pretreatment 

standards). 37 

Another potential alternative means by which Merrimack Station could choose to comply with 

the new proposed permit conditions would be to use the wastewater, after treatment in the 

primary and secondary treatment systems, to wet (or ''condition") its fly ash for disposal in a 

landfill. The Region believes that this is a viable option given that PSNH reports that the system 

was designed to do so and that it has disposed of conditioned fly ash at an off-site landfill in the 

past. 38 Roy and Scroggin, 2013. See also Sharon DeMeo, Region 1, notes on IWC-13-47 

presentation, November 19, 20 13. 

Under this approach, the conditioned fly ash would be disposed of at either an on-site or an offsite landfill. Any such landfill disposal would need to comply with any applicable legal 

requirements. Moreover, any discharges of landfill leachate containing_pollutants from the FGD 

wastewater would need to meet any effluent limits applicable to such discharges. For example, 

although PSNH indicated it would not do so, if Merrimack Station proposed collecting and 

discharging such landfill leachate to its onsite settling pond prior to discharge to the Merrimack 

River, then Region 1 would anticipate imposing effluent limits on the leachate discharges at the 

37 EPA's proposed Steam Electric NELGs include categorical pretreatment limitations for new and existing FGD 

wastewater sources discharging to local sewage treatment plants. For existing facilities, EPA proposed that the 

pretreatment limitations found at 40 C.F.R. §§ 423.16 and 423.17 would "apply to pollutants in FGD wastewater 

generated on or after a date determined by the control authority that is as soon as possible beginning July 1, 20 17." 

78 Fed. Reg. 34460-34461, 34541 (June 7, 20 13) (Proposed Rule). Prior to the applicability of the new categorical 

pretreatment standards, FGD wastewater delivered to a municipal sewage treatment plant would be subject to local 

pretreatment program requirements, including any local limits developed to prevent pass through of, and/or 

interference with, the treatment plant. See 40 C.F.R. § 403.5(c); 78 Fed. Reg. 34460,34543. 

38 "The concentrated reject stream from the crystallizer would be stored and used as a wetting agent for the fly ash 
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point of discharge to the settling pond (i.e., prior to the wastewater commingling with other 

wastewaters discharged to the pond). The Region would need to determine appropriate 

technology-based limits either on a BP J basis or by applying any applicable effluent guidelines. 

See 78 Fed. Reg. 34,457-34,463 (June 7, 2013) (Proposed Rule). In addition, water qualitybased limits for the slag settling pond (outfall 003A) may also be necessary based on an 

antidegradation review. Region 1 welcomes public comments recommending what limits should 

be applied to any such leachate discharges containing pollutants from the treated FGD 

wastewater. 

In the future, Merrimack Station could potentially use this multi-faceted approach to comply 

with the proposed NPDES permit conditions precluding the Facility from directly discharging its 

FGD wastewater to the Merrimack River. Under all of the three scenarios- (l) operating the 

SWWTS as a true ZLD system that eliminates wastewater discharges by enabling reuse of the 

distillate in the FGD scrubbers, (2) hauling wastewater for disposal at municipal wastewater 

treatment plants, 39 or (3) using treated FGD wastewater for ash conditioning prior to landfillingMerrimack Station would have no direct discharges ofFGD wastewater to the Merrimack River. 

In the latter two cases, there could be indirect contributions of the treated wastewater to the river 

subject to applicable requirements for pretreatment or landfill disposal and leachate discharge, as 

the case may be. In light of these three viable approaches to managing FGD wastewater without 

directly discharging it to the Merrimack River, Region i is proposing to remove Outfall 003C 

fron'l the Facility's NPDES Permit. This change is reflected in the Revised Draft Permit. 

The Region also considered assigning discharge permit limits for the distillate and condensate 

streams of the SWWTS. Under this approach, the distillate/condensate streams could be 

discharged to the Merrimack River, subject to applicable effluent limits. Region 1 ultimately 

determined, however, that this approach was not consistent with the BAT standard because the 

existing FGD WWTS is capable of achieving zero liquid discharge (e.g., reusing these streams as 

FGD scrubber water). 

For this approach, however, Region 1 considered the idea of permit limits for specific pollutants 

based on the levels of these pollutants found in the distillate/condensate from the power plant 

located in Brindisi, Italy, and put forward in the proposed Steam Electric NELG. The Agency 

explained that: 

[i]n April2011, EPA conducted a three-day sampling episode at Enel's Federico II 

Power PLant (Brindisi), located in Brindisi, Italy. The purpose was to characterize 

untreated FGD scrubber purge and treated FGD wastewater from an FGD wastewater 

treatment system consisting of chemical precipitation followed by mechanical vaporcompression evaporation. 
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The mechanical vapor-compression evaporation system used a falling-film brine 

concentrator to produce a concentrated wastewater stream and a reusable distillate 

stream. The concentrated wastewater stream was further processed in a forced-circulation 

crystallizer, in which a solid product was generated along with a reusable condensate 

stream. 

2013 TDD, p. 3-12. Although the Brindisi FGD treatment plant is operated as a ZLD system, 

EPA determined that "[t]he plant could choose to discharge both the brine concentrator and the 

crystallizer condensate streams, together or separately." 2013 TOO, p. 10-14 n. 93. On this 

basis, the Agency included possible VCE-based effluent limits for distillate and condensate in 

the proposed Steam Electric NELGs. These proposed limits were determined based on averages 

of three days of data for the distillate and condensate streams from the Brindisi plant. See Table 

5-1 below. 

The Region has determined, however, that it would not be appropriate to use the Brindisi data 

documented in the proposed Steam Electric NELG as the basis for limits for Merrimack Station 

because the latter facility is capable of operating without any discharge and, therefore, the BAT 

standard calls for permit requirements requiring "zero discharge." Futihermore, using the 

Brindisi facility data to set specific effluent limits for Merrimack Station distillate/condensate 

would be inappropriate because the former does not have Merrimack's EMARS technology for 

removing mercury from the treated FGD wastewater. Specifically, in PSNH's December 3, 2010 

Report, submitted to Region 1 in response to an information request under CW A § 308(a), PSNH 

identified the concentration of mercury that it predicted would be present in the discharge from 

Merrimack Station's primary FGD wastewater treatment system, including the EiviARS step. 

PSNH predicted that the proposed treatment system could achieve a mercury limit of 14 ng/L, 

which would ultimately result in a BPJ-based limit lower than the proposed limit based on the 

data from the Brindisi facility. Thus, Merrimack Station is capable of achieving lower pollutant 

levels in its condensate and distillate streams than the Brindisi facility and any permit effluent 

limits would need to reflect that. In any event, both facilities are capable of operating as ZLD 

systems and Region 1 is proposing to eliminate authorization of FGD wastewater discharges 

from Outfall 003C in Merrimack Station's permit based on its determination of the BAT for the 

Facility. This will, of course, obviate the need for setting permit effluent limits for such 

discharges. 

In addition to the Brindisi data, Region 1 also considered information presented by the Permittee. 

Specifically, PSNH submitted four sets of data from sampling the secondary treatment system's 

distillate stream. The following table shows the difference between the effluent limitations for 

the VCE and crystallizer distillate streams from the proposed Steam Electric NELGs and the 

Merrimack Station distillate samples. See 78 Fed.Reg. 34,490 and 34,534 (June 7, 20 13). 
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Table 5-l 

Pollutant 

Arsenic 

Mercury 

Selenium 

Effluent Limitations for FGD after VCE from Proposed Steam 

Electric NELGs Compared to Merrimack Station Distillate Samples 

Proposed Limits 

after Chemical Merrimack Station 

Precipitation and Distillate Sampling Results 

VCE/Crystallizer 

Units Daily Monthly 3/4/I2 8/I6/I2 9/6/12 I 0118112 Max Ave 

flg/L 4=DL * <O.I5 6 6 <I 

ng/L 39 24 <0.50 <200 <200 <200 

flg/L 5 =DL * 0.7I 22 20 2 * monthly average hmttatJOn ts not establtshed when the dat!y maxtmum hmttatwn is based 

on the detection limit. 

The current Merrimack Station Draft Permit limit for mercury is I4 ng/L. This limit was based 

on the level of treatment that PSNH projected would be provided by Merrimack Station's 

physical/chemical treatment with the added EMARS step. Region 1 determined that this was 

also a valid limit to use after biological treatment, which was the BAT proposed for the 20 II 

Draft Permit. With regard to the data submitted by PSNH, the Region does not consider four 

days of data sufficient to determine the permit limits for Merrimack Station's 

distillate/condensate streams. Furthermore, the <200 ug/L value repotied for mercury is too high 

to be useful for permit limit determination. 

In any event, Region 1 is not proposing an option that would include discharge limits for the 

distillate/condensate streams. This wastewater is relatively clean and can be recycled back to the 

FGD scrubber without difficulty. PSNH has been doing so since September 2012 (PSNH reports 

hauling distillate on only two occasions (August and September, 20 12) since the SWWTS has 

been operational). If the Permittee decides to use the distillate/condensate as a water source for 

another process(es) other than the FGD scrubber (e.g., boiler make-up), the Region would need 

to consider if pollutants in the distillate/condensate would be detected in any discharges from 

that process(es)(e.g., boiler blowdown) and potentially develop appropriate NPDES discharge 

limits. 

Outfall 003A is the sampling location for the slag settling pond. The slag settling pond currently 

receives bottom ash transport wastewater, storm water, boiler blow-down, treated chemical metal 

cleaning effluent, and other miscellaneous and low volume wastes. PSNH initially indicated that 
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informed by the 2010 NH DES antidegradation analysis, which accounted for the addition of 

FGD wastewater into the slag settling pond. 

PSNH subsequently changed its approach to managing the FGD wastewater with the installation 

of the secondary FGD wastewater treatment system and Merrimack Station is presently operating 

its wet FGD scrubber system without any discharges ofFGD wastewater to the pond. Based on 

the Region's revised BAT determination, PSNH is expected to continue operating in this 

manner. Therefore, Region 1 re-evaluated the basis of the water quality-based limits for Outfall 

003A mentioned above and found that there is no reasonable potential to violate water quality 

standards for these pollutants. See AR #1086 (data and calculations). Based on this evaluation, 

Region 1 is removing these permit requirements from the Revised Draft Permit. This means that 

discharges of FGD wastewater to the Merrimack River via the slag settling pond will not be 

authorized under the new permit. Region l welcomes comments regarding this revision. 

In addition, Region I re-evaluated the basis of the water quality-based copper limits for Outfall 

003A and found that there is no reasonable potential to violate water quality standards for 

copper. !d. Region 1, therefore, proposes removing the copper discharge limitations from 

Outfall 003A 40 of the Revised Draft Permit. The anti-backsliding regulations at 40 C.P.R. § 

122.44(1)(1) allow for this change when "circumstances on which the previous permit was based 

have materially and substantially changed since the time the permit was issued and would constitute 

cause for permit modification or revocation and resissuance under§ 122.62." See 40 CFR 

122.62(a)(2). The "circumstances" that have changed include: 1) the Region has a performed a more 

robust statistical reasonable potential analysis (AR # 1 086); and 2) the 2011 Draft Permit includes 

technology-based copper limits for metal cleaning wasteat Outfall 003B, upstream of the slag 

settling pond. 

Region 1 is not altering the remaining requirements for Outfall 003A for purposes of the Revised 

Draft Permit. The Region has not, however, made decisions about these permit conditions for 

purposes of the Final Permit. Region 1 will consider public comments already submitted 

concerning these Draft Permit requirements as it makes its decisions about the Final Permit's 

conditions. The Draft Permit's technology-based draft permit limits for TSS and O&G petiain to 

the low volume and ash transport waste streams entering the slag settling pond. See 2011 Fact 

Sheet. Despite the fact that the FGD wastewater will not be discharged to the settling pond, 

Region l is not revising the Draft Permit's flow limits for Outfall 003A because 1) the volume 

removed from the pond for scrubber make-up water has been reduced41 and 2) the proposed 

contribution of FGD wastewater (0.07 MGD average and 0.10 MGD maximum) to the pond is 

eliminated. Therefore, there should be little chahge in the expected flow from the slag settling 

pond compared to the permitted limit (5.3 MGD average monthly limit, 13 MGD maximum 
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daily limit). In addition, the water quality-based requirement to monitor and report pH is 

continued from the existing permit. 

6.0 Endangered Species Act (ESA) 

Section 7(a) of the Endangered Species Act of 1973, as amended, grants authority to, and 

imposes requirements upon, federal agencies regarding the potential effects of their actions on 

endangered or threatened species of fish, wildlife, or plants ("listed species") and any habitat of 

such species that has been designated as critical (a "critical habitat"). The ESA requires every 

federal agency, in consultation with and with the assistance of the Secretary oflnterior or 

Commerce, to insure that any action it authorizes, funds, or carries out, in the United States or 

upon the high seas, is not likely to jeopardize the continued existence of any listed species or 

result in the destruction or adverse modification of critical habitat. The U.S. Fish and Wildlife 

Service (USFWS) typically administers Section 7 consultations for fresh water species, while the 

National Marine Fisheries Service (NMFS) administers consultations for marine species and 

anadromous fish. 

At the time it issued the Draft Permit, Region 1 concluded that the proposed permitting action 

would have no effect on either any listed species or the critical habitat of any listed species. This 

conclusion was based on the Region's review of culTent protected species information provided 

by NMFS and USFWS (collectively referred to as "the Services") to assess the possible presence 

of listed species in the Hooksett Pool area of the Merrimack River, the section of the river that 

would be affected by the permitting action. From this review, Region 1 concluded that there are 

no federally-listed endangered or threatened species present in that area of the river. As Region 

I indicated in the 2011 Fact Sheet (p. 57), it will seek the Services' concurrence with its 

conclusions under the ESA. Region l is not altering its conclusions in light of the proposed 

changes to the Draft Permit that are reflected in the Revised Draft Permit because the Revised 

Draft Permit conditions will not result in any effect on any listed species or the critical habitat of 

any listed species, because, as stated above, there are no federally-listed endangered or 

threatened species present in that area of the river. As stated previously, Region l will seek the 

Services' concurrence with its conclusion on these issues prior to issuing a Final Permit. 

7.0 Essential Fish Habitat (EFH) 

Under the 1996 Amendments (PL 104-267) to the Magnuson-Stevens Fishery Conservation and 

Management Act (16 U.S.C. §§ 1801 et seq. (1998)), EPA is required to consult with NOAA 

Fisheries if actions that EPA funds, permits, or undertakes may adversely impact any essential 

fish habitat such as

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In the 20 ll Fact Sheet (p. 57), Region 1 concluded that the Draft Permit's conditions and 

limitations will adequately protect all aquatic life, including Atlantic salmon, the only species in 

this segment of the Merrimack River with an EFH designation. The Region further concluded 

that the Draft Permit's conditions will minimize impacts from the Facility to the EFH species, its 

habitat and forage, to the extent that no significant adverse impacts are expected and no further 

impact mitigation is warranted. Region 1 has also considered the new conditions proposed in the 

Revised Draft Permit and believes that its earlier conclusions, as stated above, still hold true. 

Should adverse impacts to EFH be detected as a result of this permit action, or if new 

information is received that changes the basis for Region 1 's conclusions, the Region will 

contact NMFS and the EFH consultation will be re-initiated. 

8.0 Monitoring and Reporting 

As discussed above, Outfall 003C was a discharge point in the 2011 Draft Permit from which 

FGD wastewater was to enter the slag settling pond. Because the Revised Draft Permit proposes 

to eliminate Outfall 003C, it also proposes to eliminate any reporting and monitoring 

requirements associated with that outfall. 

In addition, Outfall 003A is associated with the discharge of wastewater from the slag settling 

pond to the Merrimack River via the Station's discharge canal. Because the Revised Draft 

Permit would eliminate FGD wastewater discharges to the slag settling pond, the Region is 

proposing to remove the monitoring and repotiing requirements related to FGD wastewater from 

Outfall 003A. These permit conditions included reporting requirements for chloride as well as 

reporting requirements and effluent limits for aluminum, arsenic, copper, mercury and selenium. 

9.0 State Certification Requirements 

EPA may not issue a permit unless the state water pollution control agency with jurisdiction over 

the receiving water(s) either certifies that the effluent limitations and/or conditions contained in 

the permit are stringent enough to assure, among other things, that the discharge will not cause 

the receiving water to violate state's surface water quality regulations or waives its right to cetiify 

as set forth in 40 C.F.R. §124.53. See also 33 U.S.C. § 134l(a)(l). 

In the 2011 Fact Sheet, Region 1 explained that it had requested a CWA § 40l(a)(l) certification 

by the state pursuant to 40 C.F.R. §§ 124.53 and 124.55, and expected that the state would 

cetiify the Draft Permit conditions. The state will be deemed to have waived its right to certify 

unless certification is received within 60 days of receipt of this request unless the Regional 
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requested a CW A § 401 (a)( 1) certification from the state, and again the Region expects that the 

state will certify the conditions of the Revised Draft Permit. 

Reviews and appeals of limitations and conditions attributable to State certification shall be 

made through the applicable procedures of the State and may not be made through the applicable 

procedures of 40 C.F .R. Pati 124. 

10.0 Comment Period, Public Hearing, and Procedures for Final Decisions 

All persons, including applicants, who believe that any provision of these draft permit conditions 

is inappropriate must raise all issues and submit all available arguments and all supporting 

material for their arguments in full by the close of the public comment period, to the U.S. EPA, 

Office of Ecosystem Protection, Industrial Permits Branch, 5 Post Office Square, Suite 100, 

Boston, Massachusetts 02109-3912. As explained fatiher above, there will be a two stage 

comment period for the Revised Draft Permit. In the first stage, interested persons may 

comment on the revised permit conditions and the analysis suppotiing them. In the second stage, 

interested persons may respond to submissions of other commenters. In reaching a final decision 

on the Revised Draft Permit conditions, the Region 1 will respond to all significant comments 

and make these responses available to the public at Region 1 's Boston office. 

Following the close of the comment period, and after the public hearing if one is held, Region 1 

will issue a final permit decision and forward a copy of the final decision to the applicant and 

each person who has submitted written comments or requested notice. Within 30 days of Region 

1 's serving notice of the final permit decision, any interested person may submit a petition for 

review of the permit to EPA's Environmental Appeals Board to review any condition of the 

permit decision. See 40 C.F.R. § 124.19(a)(3). 
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11.0 Region 1 Contact Information 

NH0001465 

Additional information concerning these Revised Draft Permit conditions may be obtained 

between the hours of9:00 A.M. and 5:00P.M., Monday through Friday (excluding holidays) 

from the Region 1 contact below: 

Ms. Sharon DeMeo, Environmental Engineer 

U.S. Environmental Protection Agency- Region 1 

Office of Ecosystem Protection 

5 Post Office Square, Suite 100 (CIP) 

Boston, Massachusetts 02109-3912 

Telephone: (617) 918-1995 I FAX: (617) 918-0995 

Email: demeo.sharon@epa.gov 

_...;A:;..::.t;:p..:..r:.:.il-=2'-"'0..:.1...:..4 ___ Ken Moraff, Director 

Date: Office of Ecosystem Protection 

U.S. Environmental Protection Agency 
NEW HAMPSHIRE DEPARTMENT OF 

ENVIRONMENTAL SERVICES 

WATER DIVISION 

P.O. BOX 95 

CONCORD, NEW HAMPSHIRE 03302-0095 

U.S. ENVIRONMENTAL PROTECTION 

AGENCY-REGION 1 

OFFICE OF ECOSYSTEM PROTECTION 

5 POST OFFICE SQUARE 

BOSTON, MASSACHUSETTS 02109-3912 

JOINT PUBLIC NOTICE OF A REVISED DRAFT NATIONAL POLLUTANT DISCHARGE 

ELIMINATION SYSTEM (NPDES) PERMIT TO DISCHARGE INTO THEW A TERS OF THE UNITED 

STATES UNDER SECTIONS 301 AND 402 OF THE CLEAN WATER ACT (THE "ACT"), AS AMENDED, 

AND REQUEST FOR STATE CERTIFICATION UNDER SECTION 401 OF THE ACT, AND ISSUANCE 

OF A STATE SURFACE WATER PERMIT UNDER NH RSA 485-A:13, I(a). 

DATE OF NOTICE: April18, 2014 

PERMIT NUMBER: NH0001465 

PUBLIC NOTICE NUMBER: NH-002-14 

NAME AND MAILING ADDRESS OF APPLICANT: 

Public Service ofNew Hampshire (PSNH) 

P.O. Box 330 

Manchester, New Hampshire 03105-0330 

NAME AND LOCATION OF FACILITY WHERE DISCHARGE OCCURS: 

Merrimack Station 

97 River Road 

Bow, New Hampshire 03301 

RECEIVING W A TER(S): Merrimack River, Class B 

PREPARATION OF THE DRAFT PERMIT: 

The U.S. Environmental Protection Agency (EPA) and the New Hampshire Department of Environmental 

Services, Water Division (NHDES-WD) have cooperated in the development of a Revised Draft Permit for 

Merrimack Station, which discharges industrial wastewater. The effluent limits and permit conditions imposed 

have been drafted to assure compliance with the Clean Water Act, 33 U.S.C. sections 1251 et seq., Chapter 485-

A of the New Hampshire Statutes: Water Pollution and Waste Disposal, and the New Hampshire Surface Water 

Quality Regulations, Env-Wq 1700 et ~· EPA has formally requested that the State certify the Revised Draft 

Permit pursuant to Section 401 of the Clean Water Act and expects that the Revised Draft Permit will be 

certified. 
information in response to those comments. After considering all this material in connection with an evaluation 

of the Best Available Technology (BAT) factors specified in the statute and regulations, see 33 U.S.C. § 

1314(b)(2)(B) and 40 C.F.R. §§ 125.3(c)(2) and (d)(3), Region 1 has concluded, based on its Best Professional 

Judgment (BPJ), that the combined primary and secondary FGD WWTS currently operating at the Facility is 

the BAT for treating the FGD wastewater generated at Merrimack Station. 

The particular provisions of the September 2011 Draft Permit now being reconsidered and revised are 

the effluent limits and reporting requirements for Outfall 003C at Part I.A.4 and for Outfall 003A at Part 

I.A.2. Region 1 has prepared a Revised Draft Permit and Fact Sheet that includes certain changes to these 

provisions from the September 30, 2011, Draft Permit. The Revised Draft Permit and explanatory Fact Sheet 

may be obtained at no cost at http://www.epa.gov/region 1/npdes/draft permits listing nh.html or by 

contacting: 

Sharon DeMeo 

U.S. Environmental Protection Agency- Region 1 

5 Post Office Square, Suite 100 (OEP06-l) 

Boston, MA 02109-3912 

Telephone: ( 617) 918-1995 

The administrative record containing all documents relating to this Revised Draft Permit including all data 

submitted by the applicant may be reviewed at Region l's offices in Boston, upon request or at 

http://-vvww.epa.gov/region1/npdes/merrimackstation/index.html. 

PUBLIC COMMENT AND REQUEST FOR PUBLIC HEARING: 

All persons, including applicants, who believe any condition of the Revised Draft Permit is inappropriate, must 

raise all issues and submit all available arguments and all supporting material for their arguments in full by 

June 17, 2014, to the address listed above. Any person, prior to such date, may submit a request in writing to 

EPA and NHDES for a public hearing to consider this Revised Draft Permit. Such requests shall state the 

nature of the issues proposed to be raised in the hearing. A public hearing may be held after at least thirty days 

public notice whenever the Regional Administrator finds that response to this notice indicates significant public 

interest. Region 1 will provide an additiona135-day comment period extending from June 17, 2014 to 

July 22, 2014 during which any interested person may file a written response to the material filed by any 

other person. Public comments will be added to the Administrative Record in a timely manner to allow for 

review and response during the additional35-day period. In reaching a final decision on the Revised Draft 

Permit, the Regional Administrator will respond to all significant comments and make these responses available 

to the public at EPA's Boston office. 

FINAL PERMIT DECISION: 

Following the close of the comment period, and after a public hearing, if such hearing is held, the Regional 

Administrator will issue a final permit decision and forward a copy ofthe final decision to the applicant and