Groundwater Discharge Permit Falmouth Wastewater Treatment Facility. Response to Comments

Transcription

1 Groundwater Discharge Permit Falmouth Wastewater Treatment Facility Response to Comments MassDEP issued a draft groundwater discharge permit (4-168) to the Town of Falmouth for the Falmouth Wastewater Treatment Facility (the Facility ) on December 15, A public notice was published in the Falmouth Enterprise on January 7, 2011 and in the Environmental Monitor on July 20, MassDEP received comments on the draft permit from the Town of Falmouth ( the Town ), the Coalition for Buzzards Bay ( CBB ), the United States Environmental Protection Agency ( USEPA ) and Mr. Ronald Zweig. 1 This document provides background on the permit and addresses the specific comments received. The draft permit has been revised to reflect the following changes in response to the comments received: The Town is required to submit a Draft Comprehensive Wastewater Management Plan (CWMP) by February 28, 2012 which shall include a compliance schedule to meet the Total Maximum Daily Load (TMDL) for West Falmouth Harbor (Report # 95-TMDL-1 Control #243.0). Upon review of the CWMP, MassDEP will determine if additional compliance milestones are needed in order to meet the TMDL. Compliance with the TMDL for West Falmouth Harbor will be a phased approach, which will achieve quantifiable nitrogen reductions after each phase and ultimately will result in full compliance with the TMDL. Implementation of the first phase was the construction of an upgraded wastewater treatment facility in 2005 which is the subject of this permit. This permit reflects completion of this first phase as an initial step towards full 1 In response to an inquiry from CBB, MassDEP mistakenly provided CBB with a copy of an unreleased, internal draft final permit on July 19, (MassDEP personnel contacted by CBB acted under the incorrect assumption that this internal draft had been previously issued as the final permit in this matter.) On July 21, 2011, MassDEP notified CBB that, in fact, the final permit had not been issued and that the internal draft had been provided to CBB in error. This information is available in alternate format. Call Michelle Waters-Ekanem, Diversity Director, at TDD# or MassDEP Website: Printed on Recycled Paper

2 2 compliance with the TMDL by limiting nitrogen at the point of discharge to an annual average of 3 mg/l and a daily maximum of 10 mg/l from its current limit of 50 mg/l. The CWMP, while addressing compliance with the TMDL for West Falmouth Harbor will also address implementation strategies for several other TMDL s within Falmouth. The permit explicitly sets an annual average 3 mg/l Nitrate-Nitrogen and Total Nitrogen limit. The permit requires more stringent oversight for future connections. The permit has a maximum flow limit of 1,000,000 gpd allocated as follows: o 470,000 for existing flow, o 90,000 gpd for infill within the existing service area, o 10,000 gpd for the high school (which is already connected), o a maximum allocation of 200,000 gpd for the Scranton Avenue/North Davis Straits (SANDS) service area, and o 230,000 gpd specifically reserved for the potential sewering of the West Falmouth Harbor watershed. However, the permit also requires MassDEP s written approval for any new sewer extensions or connections, except for infill within the existing service area. In essence, this limits flow to existing conditions and identified infill without sewering the West Falmouth Harbor watershed or implementing alternative strategies for TMDL compliance unless the Town obtains specific written approval from MassDEP for any such additional sewer connections or extensions beyond the infill. Nitrogen monitoring has been increased from monthly to weekly. The Town is required to submit quarterly reports identifying new connections, flow estimates for those connections and the service area in which those connections were made. The Town is required to monitor water quality at the Snug Harbor sentinel station in the summer of 2014 to see if there are indications of water quality improvement. The permit will be modified (in accordance with applicable regulations) once the Department has approved the CWMP to incorporate the timelines for implementation of measures to meet TMDL compliance as a permit condition. INTRODUCTION: The Town of Falmouth has operated a wastewater treatment facility located at Blacksmith Shop Road in the West Falmouth Harbor (WFH) watershed for approximately 25 years. A groundwater discharge permit for the Facility was originally issued under the then existing groundwater discharge permit regulations, and the Facility became operational in October In accordance with those regulations, the discharge was designated as a Class III 2 2 The regulations in effect at the time of the original permit (314 CMR 5.00 Groundwater Discharge Permit Program and 314 CMR 6.00 Groundwater Quality Standards ) allowed for Class I, Class II, or Class III groundwater designations. Fresh groundwaters designated as a source of potable water supply were defined as Class I. Saline

3 3 discharge and allowed a total nitrogen (TN) effluent limit of 50 mg/l at an annual average flow limit of 810,000 gallons per day (gpd) with a maximum day flow of 2.9 million gallons per day (MGD). At the average annual flow, this would result in annual discharge of 123,286 lb/yr of total nitrogen. From September 1994 to September 2005, operating data shows that the actual annual average discharge was 410,000 gpd at 23.6 mg/l TN (29,455 lb/yr). The Facility is located off of Blacksmith Shop Road in West Falmouth and the discharge beds are approximately 0.6 miles from Mashapaquit Creek which leads into WFH. When the permit was issued, groundwater modeling predicted that the effluent plume would reach West Falmouth Harbor (WFH) in approximately seven (7) years, or By 1995 there was evidence of significant eelgrass loss which was attributed to the wastewater plume from the facility as that was the only significant change in nitrogen loading during this time period. Starting in 1999, the Town initiated a Comprehensive Wastewater Management Plan (CWMP) to address eutrophication in West Falmouth Harbor. The CWMP included a nutrient load analysis, performed by the University of Massachusetts-Dartmouth s School of Marine Science and Technology (SMAST), which determined that a water column threshold concentration of 0.35 to 0.37 mg/l TN would restore eelgrass to pre-discharge conditions. The Town completed the plan in 2001 and the recommended strategy encompassed two phases. The first was to replace the existing Class III Facility with a new 1.2 MGD Facility capable of achieving a 3 mg/l TN discharge with 1 MGD of flow (for a total of 9,132 lb/yr TN) discharged at new and existing beds in the watershed and the remainder (0.2 MGD) to areas outside the watershed. This level of discharge represents a reduction of 69% of the actual nitrogen load from the Class III effluent discharged prior to the upgrade of the Facility. The upgraded Facility went on-line in The second phase of the CWMP provided that the watershed area west of Route 28 would be sewered. The 1 MGD flow to the Facility was allocated from the existing and proposed service areas as follows: 470,000 gpd for existing flow 90,000 gpd for infill 10,000 gpd for the Falmouth High School 200,000 gpd for Scranton Avenue/North Davis Straits (SANDS) (proposed for potential groundwaters designated as a source of potable mineral waters, for conversion to fresh potable waters, or as a raw material for the manufacture of sodium chloride or its derivatives or similar products were defined as Class II. Groundwaters, fresh or saline, designated for uses other than potable water supply were defined as Class III. Class III designations required a specific regulatory assignment of which there were only four in the Commonwealth (Falmouth, two in Nantucket and Orleans). In all four instances nitrate nitrogen and total nitrogen effluent limits were set at 50 mg/l. In 2009, 314 CMR 5.00 was revised and effectively designated all groundwaters of the Commonwealth as a source of potable water supply thus eliminating the prior classification system. The exceptions allowed were for Class III waters classified prior to March 20, 2009 and which were designated for uses other than a source of potable water supply. Parallel to this revision, 314 CMR 6.00 was eliminated and its standards incorporated in 314 CMR 5.00.

4 4 sewering) 230,000 gpd for West Falmouth Harbor (proposed for potential sewering). In February 2011, the Town applied for a Notice of Project Change (NPC) through the MEPA office to expand the SANDS service area to allow a small affordable housing development. The NPC indicates that the 200,000 gpd projection allocated for the area was conservative and recent projections for flow, including growth and infiltration/inflow (I/I) is 65,000 gpd. As can be seen, the maximum discharge allowed by both the permit and the CWMP without sewering West Falmouth Harbor is 770,000 gpd resulting in a TN load of 7,032 lb/yr. However, all new sewer extensions and connections, except for infill of the existing service area, must receive MassDEP s prior written approval. This provision will allow MassDEP to maintain appropriate oversight of discharge within the WFH watershed and balancing the Town s need to address the restoration of other impaired embayments while still focusing on restoration of WFH. The upgraded facility went online in the autumn of From October 2005 to December 2009 the average annual discharge was 362,000 gpd at 5.5 mg/l TN (6,061 lb/yr). This represents a 79% reduction in nitrogen load from the older wastewater treatment facility which the new facility replaced. These four years of operating data indicated that the facility did not, on average, met the 3 mg/l TN limit; however, there were some contractual disputes regarding process equipment which may have affected performance and that have been recently rectified. From January 2010 to 2011 flows averaged about 350,000 gpd and from July 2010 to June 2011 nitrogen removal performance improved and averaged 3.4 mg/l TN (3,622 lbs/yr). MassDEP anticipates that performance will continue to improve in the future. The Massachusetts Estuaries Project (MEP) completed a nitrogen evaluation of the West Falmouth Harbor watershed in a 2006 report titled Linked Watershed-Embayment Model to Determine Critical Nitrogen Loading Thresholds for West Falmouth Harbor, Falmouth, Massachusetts (the MEP Report ) and refined the findings of the original evaluation by setting a target threshold of 0.35 mg/l TN. This targeted MEP study was also completed by SMAST as a more sophisticated outgrowth of the original evaluation performed for the 2001 CWMP. The modeling showed that the original two phased approach of the CWMP would achieve the target threshold. A Total Maximum Daily Load (TMDL) was developed in 2007 based primarily on the findings of the MEP study. The Town of Falmouth has also embarked on a new CWMP to address nitrogen enrichment in the south coastal embayments of town, many of which exhibit more severe impairment than West Falmouth Harbor. Recognizing this fact, this permit has been structured

5 5 to reduce significantly the amount of nitrogen discharged to the WFH watershed from the WWTF compared to the previous Class III allowance while at the same time providing some capacity and flexibility for the Town to address nitrogen reductions both in other impacted areas of town and in WFH. MassDEP considers this permit consistent with the WFH TMDL because it outlines a phased approach that (1) limits the nitrogen load discharged from the Facility commensurate with a level that achieves the identified restoration goals for the WFH system; (2) requires the Town to develop a CWMP by February 28, 2012 which addresses and identifies appropriate strategies and a schedule to achieve the target thresholds in the WFH watershed to complement the reduced nitrogen load from the Facility and be consistent with the implementation plan required under the TMDL; and (3) will be modified to incorporate the compliance schedule developed by the CWMP and approved by MassDEP. RESPONSE TO SPECIFIC COMMENTS: 3 The Coalition for Buzzards Bay 1. The Permit must comply with Federal Total Maximum Daily Load (letter dated February 3, 2011); Limit the Discharge of effluent from the Wastewater Treatment Facility to West Falmouth Harbor to 500,000 gallons per day (letter dated August 19, 2011) The Permit must explicitly require the sewering of existing septic systems in the West Falmouth Harbor watershed prior to any new connections to the wastewater treatment facility from outside the watershed (letter dated August 19, 2011) The permit requires the town to develop a CWMP which will comply with the TMDL through a phased approach. This is consistent with other implementation plans which achieve compliance through adaptive management practices. As mentioned above, this permit supports the first phase of the restoration strategy for WFH. Under the 2001 CWMP, the second phase involved sewering appropriate areas of the WFH watershed. Due to the high costs associated with both phases, the Department did not expect that these two phases would be completed at the same time. Past practice has recognized the phasing of TMDL implementation as part of an adaptive management strategy and this 3 In CBB s August 19, 2011 comment letter, to the extent that CBB asserts that MassDEP fails to adequately address issues CBB raised in its February 3, 2011 comment letter, MassDEP notes that these assertions (i.e., responses to MassDEP s internal draft response to comments), themselves, appear merely to reiterate issues CBB previously raised.

6 6 permit is being issued in recognition of that fact. Accordingly, since the discharge represents a very significant reduction in nitrogen load (69%) while allowing the town some flexibility in addressing sewer needs in other parts of town and requiring sewering of the WFH watershed (in order to utilize the 230,000 gpd allocation assigned to that service area), subject to MassDEP approval (except for infill), MassDEP believes that by recognizing the construction of the new wastewater treatment facility, and establishing more stringent treatment limits, this permit represents completion of the first phase of an implementation strategy designed to comply with the TMDL. Additionally, in response to CBB s concerns, the language has been modified in Section C. (Supplemental Conditions), Condition 7 to read, By February 28, 2012, the Town of Falmouth shall submit to the Department a Comprehensive Wastewater Management Plan (CWMP) which shall include a compliance schedule to meet the thresholds established in the Total Maximum Daily Load (TMDL) for West Falmouth Harbor (Report # 95-TMDL-1 Control #243.0) which further clarifies the need to provide a schedule to comply with the TMDL. Once the Department approves the CWMP, the permit will be modified to incorporate the compliance schedule as a permit condition. CBB states that the nitrogen discharge from the Facility at 9,132 lb/yr is in excess of the threshold equivalent annual load to Snug Harbor of 2,993 lb/yr. What may not be apparent is that the 9,132 lb/yr discharged from the Facility represents the end-of-pipe discharge and does not account for attenuation through Mashapaquit Creek prior to any impact at Snug Harbor. It should be recognized that the MEP Report evaluated the discharge at the virtually the same permitted load (9,119 lb/yr in the report as opposed to 9,132 lb/yr in the permit). The 13 lb/yr (0.1%) difference is attributable to rounding of numbers in two different sets of calculations. With appropriate sewering in WFH, the MEP analysis determined that the threshold would be met in Snug Harbor. CBB also references a 2007 Technical Memorandum ( Tech Memo ) prepared by SMAST, at the request of CBB, describing three model runs of different scenarios for WFH. It should be noted that this Tech Memo was not commissioned by the Town or MassDEP and therefore neither party had any control over its contents nor have access to all assumptions made in the development of the model runs. Nonetheless, the Tech Memo asserts that a limit of 0.5 MGD at 3 mg/l TN (4,566 lb/yr TN) is the Facility discharge limit which would maintain the nitrogen threshold with no additional sewering. CBB further quotes the Tech Memo as saying [b]ut increases to 0.7 and 1.0 MGD result in large exceedances of the threshold. However, the MEP Report evaluated a scenario with a discharge of 1 MGD at 3 mg/l and no sewering in WFH which resulted in a watercolumn concentration of mg/l TN, an 18.6% decrease from the mg/l TN watercolumn concentration under the then current conditions from discharge of the old Facility. Furthermore, the mg/l TN watercolumn concentration represents an 8% exceedance over the 0.35 mg/l TN threshold concentration identified in both the MEP Report and the TMDL as opposed to a 32% exceedance under the old discharge conditions. The

7 7 first phase of TMDL compliance represented in this permit results in significant progress in achieving the necessary nitrogen reductions to meet the ultimate TMDL requirements. Again, it must be emphasized that the maximum flow authorized by this permit without sewering WFH is 770,000 gpd and that the permit further limits total flow to existing flow and infill without written approval by MassDEP. The revised permit includes a monitoring program to commence in 2014 to begin to document if any changes in water quality have occurred. Monitoring will be conducted at the Snug Harbor sentinel station. By 2014 it is anticipated that the plume from the old Facility will have flushed out of WFH and that water quality improvements resulting from the discharge from the upgraded Facility should be observed. 2. The Permit must comply with State Groundwater Discharge Permit Regulations (letter dated February 3, 2011) CBB quotes 314 CMR 5.06(1) of the Groundwater Discharge Permit Program regulations: The Department shall not issue a permit pursuant to 314 CMR 5.00 when the discharge will cause or contribute to a violation of 314 CMR 4.00: Massachusetts Surface Water Quality Standards. As demonstrated above, this permit recognizes the improvement in water quality resulting from the significant reduction in nitrogen discharge as a result of Facility upgrades and this permit s sewering and ultimate requirement for the Town to develop a CWMP which includes a schedule for TMDL compliance. Again, this is a phased program that recognizes ultimate TMDL compliance must be achieved while still providing some flexibility to allow the Town to address its sewering needs as identified in the 2001 CWMP and the draft CWMP currently in progress. Given the reduction in nitrogen load to the WFH watershed under this permit as compared to the previous Class III discharge coupled with a requirement for a plan and schedule for TMDL compliance, MassDEP determines that the permit meets the requisite standards in 314 CMR The Permit must comply with M.G.L. c. 30, 61 and 310 CMR (letter dated February 3, 2011) For the reasons outlined above in the response to CBB s Question 2, MassDEP has determined this permit assures compliance with M.G.L. c. 30, 61 and 310 CMR Public Access to the Massachusetts Estuaries Project Model (letter dated August 19,

8 8 2011) MassDEP supports transparency in the MEP methodology and is working with SMAST to develop appropriate protocols for public access. United States Environmental Protection Agency (USEPA) 1. Consistency with Groundwater Discharge Permitting Regulations and Surface Water Quality Standards. The substance of these comments have been addressed in the responses to the CBB. 2. Discharge Effluent Limitations and Monitoring Requirements USEPA has commented that new flows should be the same as those anticipated in the MEP Report. MassDEP is using the 2001 CWMP as a benchmark for allocating new flows to the Facility. The Draft permit has been revised to require a quarterly report that identifies any new connections and tabulates the total flow in all service areas. USEPA has also suggested that a rolling monthly average for nitrogen load should be used in lieu of the proposed calendar year calculation in the present draft. This comment reflects concern that an annual evaluation is insufficient. MassDEP disagrees with USEPA s proposed approach and feels that a calendar year calculation is more appropriate in that it provides a consistent year over year basis for determining compliance. With respect to USEPA s concern that the load is only evaluated once a year, it must be noted that the permit requires monthly reporting and that loads are evaluated on a monthly basis as the reports are submitted. Furthermore, assessing the load on a calendar year basis is consistent with MEP methodology which evaluates annual loads to the watershed. The 3 mg/l TN average annual effluent concentration is implicit in the 9,132 lb/yr limit; however, the draft permit has been revised to state explicitly that a 3 mg/l TN average annual concentration is required while maintaining the 10 mg/l TN maximum day limit. USEPA has suggested that nitrogen species be sampled and analyzed three times per week. MassDEP considers this to be excessive; however, the draft permit has increased the effluent sampling frequency for nitrogen species from monthly to weekly.

9 9 3. General Comments on Future Flow Allocations The significance of the flow allocation table in Part I.A., Footnote 1 is to assure that the threshold target nitrogen levels in WFH can be achieved in accordance with the 2001 CWMP. As stated above, compliance with the TMDL is a two phased process. The draft permit has been revised to require both reporting on new connections and tabulation of all flows in the respective service areas as well as requiring submission of a new CWMP (currently in process) by February 28, 2012 that specifies an implementation schedule for ultimate TMDL compliance. Town of Falmouth 1. Page 6, Supplemental Condition No. 7 The Town requested that this condition be removed. MassDEP has revised the condition to require the Town to submit a CWMP to MassDEP by February 28, 2012 that provides a schedule for compliance with the TMDL. 2. Page 4, Special Condition B.(3) The Town requested reduction of the monitoring frequency for ph, water table elevation and specific conductivity in the monitoring wells to be reduced from monthly to quarterly. The monitoring frequencies listed in the draft permit are consistent with current MassDEP monitoring protocols and no change has been made. Mr. Ronald Zweig Mr. Zweig s comments regarding Facility performance and loading and flow limits have been addressed in previous responses. He does raise an issue regarding the Town s current CWMP process by referencing a Technical Memorandum No. 7 (October 20, 2010) prepared for Falmouth by Stearns and Wheler. Mr. Zweig states that this memorandum was endorsed by Falmouth s Comprehensive Wastewater Management Committee in the Committee s October 26, 2010 recommendations and accepted by the Falmouth Board of Selectmen on January 24, 2011 and does not include sewering of WFH. The Town has not formally submitted a CWMP (and, as noted previously is required to do so in this revised permit). In its review of the CWMP, MassDEP will require that appropriate strategies and schedules are identified to meet ultimate TMDL compliance in the WFH watershed.

10 10 CONCLUSION: MassDEP has given careful consideration to all comments received and made changes to the permit as has been determined to be appropriate. The Town has already taken a positive step by upgrading the Facility designed with best available control technology to meet a limit of 3 mg/l total nitrogen. The Town is also developing a CWMP to address nutrient impairment in a number of additional estuaries and evaluating appropriate measures to meet the WFH TMDL. MassDEP considers that the revised permit adequately protects the resources of WFH by recognizing the first phase of TMDL compliance which reduces the nitrogen load to the resource by 69% and requires submission of a CWMP that sets a schedule for implementation of the second phase to achieve the threshold limits identified in both the MEP Report and the TMDL. Additionally, once MassDEP approves the CWMP, the permit will be modified to incorporate the implementation schedule identified in that document. This represents a pragmatic approach which recognizes the advances the Town has already made in upgrading the Facility while allowing limited flexibility to address the sewering needs of other identified service areas.