Prince William Conservation Alliance

Vint Hill Farms Wastewater Treatment Plant


The State Water Control Board agenda for October 28 included the following item:
Reissuance of VPDES Permit VA0020460, Vint Hill Farms Station Waste Water Treatment Plant, Fauquier County:
On November 15, 2002, DEQ received a VPDES Permit Application from Fauquier County Water and Sanitation Authority for the reissuance of the permit for Vint Hill Farms Station Waste Water Treatment Plant. The treatment plant is located on the closed Vint Hill Farm Station army base and currently discharges to South Run, a tributary to Lake Manassas, the drinking water source for Manassas, Manassas Park, and parts of Prince William County. The current discharge point is less than 5 miles from Lake Manassas. The proposed flow increases will discharge to Kettle Run, which is not a tributary to Lake Manassas. Moving the discharge point to Kettle Run will result in the new discharge point being approximately 37 river miles from the Fairfax County Water Authority’s intake in the Occoquan Reservoir. The Vint Hill treatment plant is located in the Occoquan River Watershed near Warrenton, which makes this facility subject to the Occoquan Policy, 9 VAC 25-410. The interpretation and implementation of the Occoquan Policy is the main issue in this reissuance.

The State Water Control Board approved the request of the Fauquier County Water and Sanitation Authority to increase the capacity of the Vint Hill Farms Station Wastewater Treatment Plant from 246,000 gallons per day to 600,000 gallons per day. The plant is projected to grow to 950,000 gallons per day.

The treated sewage from that plant will flow downstream into Lake Jackson and the Occoquan Reservoir. The Upper Occoquan Sewage Authority (UOSA) plant on Bull Run, between Centreville and Manassas, also flows into the Occoquan Reservoir - from which nearly 1 million people get their drinking water. The UOSA facility replaced 11 inadequate wastewater treatment plants upstream from the reservoir. That plant complies with state requirements for unusually high levels of wastewater treatment, as established in the State Water Control Board's Occoquan Policy for waste treatment and water quality management in the Occoquan watershed (Virginia Administrative Code - 9VAC25-410-30. Expansion of existing plants in the Occoquan watershed).

The expansion of the Vint Hill Farms Station Wastewater Treatment Plant appears designed to fall below the threshold of 1,000,000 gallons per day (1 million gallons per day, also written as 1 MGD) that would require the Fauquier County Water and Sanitation Authority to build a plant with high performance comparable to UOSA, which naturally would involve higher-than-average costs. State law calls for a second high-quality regional wastewater treatment plant in Warrenton/Fauquier (Virginia Administrative Code - 9VAC25-410-20. Long-range policy), but the Fauquier County Water and Sanitation Authority has not proposed upgrading the Vint Hill Farms Station Wastewater Treatment Plant to serve that function.

The Fairfax County Board of Supervisors asked the state to require the Fauquier County Water and Sanitation Authority to fund new water quality monitoring stations, to ensure that the phosphorous levels in the wastewater will not degrade the quality of the Occoquan Reservoir. A common assumption in Northern Virginia is that population and development will continue to grow, and the Vint Hill Farms Station Wastewater Treatment Plant inevitably will have to expand further. A worst-case scenario is that the facility will exceed 1 MGD before the high levels of wastewater treatment are operational.

topographic map of Vint Hill area
topographic map of Vint Hill area
Source: Terraserver

The expansion of the sewage plant will also involve shifting the discharge point. The 246,000 gallons per day flowed into South Run, then to Lake Manassas - the source of the drinking water for Manassas and some of western Prince William. From Lake Manassas, it flowed down Broad Run to Lake Jackson and then the Occoquan Reservoir. The 600,000 gallons per day will discharge to Kettle Run, bypassing Lake Manassas and flowing into Cedar Run before reaching Lake Jackson and then flowing into the Occoquan Reservoir.

The staff report for the State Water Control Board meeting on July 17, 2003 addressed the request from Fairfax, plus comments from others:

VPDES Permit VA0020460
Vint Hill Farms WWTP
Public Hearing
July 17, 2003
Warrenton Community Center

On November 15, 2002, DEQ received a VPDES Permit Application from Fauquier County Water and Sanitation Authority for the reissuance of the permit for Vint Hill Farms Station Waste Water Treatment Plant. The treatment plant is located on the closed Vint Hill Farm Station army base and currently discharges to South Run, a tributary to Lake Manassas, the drinking water source for Manassas, Manassas Park, and parts of Prince William County. The current design flow for this facility is 0.246 mgd. In this reissuance, the Sanitation Authority requested two flow increases to 0.6 mgd and 0.95 mgd.

The current discharge point is less than 5 miles from Lake Manassas and the proposed flow increases will discharge to Kettle Run, which is not a tributary to Lake Manassas. This would result in the new discharge point beginning approximately 37 miles up river from the Fairfax County Water Authority’s intake in the Occoquan Reservoir.

The Vint Hill treatment plant is located in the Occoquan River Watershed near Warrenton, which makes this facility subject to the Occoquan Policy, 9 VAC 25-410. The interpretation and implementation of the Occoquan Policy is the main issue in this reissuance. This facility is subject to two different parts of the Occoquan Policy:

- Part 20 states that there shall be preferably two but no more than three regional sewage treatment plants in the Occoquan Watershed and one of the plants shall be in Fauquier County near Warrenton.

- Part 30 states that existing sewage treatment plants may expand, provided that it is not feasible to connect to a regional plant, and that their loadings not increase.

There is no regulatory definition of the term regional. In this permitting process staff has likened regional to major and made the following interpretation and implementation of the policy:

1. The Vint Hill treatment plant is subject to Part 30 until it becomes a major STP, that is, a design flow of 1.0 mgd or greater. At that time the treatment plant will be subject to the requirements for a regional plant under Part 20.

2. The above implementation is premised on Vint Hill treatment plant eventually becoming the regional plant specified by Part 20. That is, DEQ will recommend to the SWCB denial of any application for another STP becoming the regional plant in the Warrenton area.

Staff recognizes that the above is an interpretation and that there is no definitive right answer. We believe this interpretation achieves a balanced compromise with regard to regulatory parity, allows for future sewage planning, and most important, does not compromise existing water quality and provides opportunity for improved water quality.

Notice of the proposed permit reissuance and public hearing information were published in the Fauquier Citizen newspaper on June 12 and June 19, 2003.

DEQ has received written comments from Fairfax County, City of Manassas, City of Manassas Park, Upper Occoquan Sewage Authority (UOSA), Fairfax County Water Authority, Prince William County Service Authority, and State Senator Charles Colgan. These comments were submitted before the public comment period and staff has entered them into the record. All of the aforementioned commenters have objected to the above interpretation.

The following is a summary of the six comments staff have received to date and with staff’s responses.

Comment 1

Declaration of Regional Plant - The Fauquier County Water and Sanitation Authority stated that staff should not predetermine the Vint Hill treatment plant as the regional plant through this permitting process and that it should be sufficient for DEQ to note that the expansion is in full compliance with Part 30 of the Policy.

Staff Response: It is DEQ’s job to interpret and implement regulations and provide explanation there of. The destiny of this plant as the regional plant is part of the interpretation. Such a declaration is necessary to notify the permittee and everyone that the interpretation of regional meaning major is in part based on the presumption that there will be no other STPs in this area. We do not believe it would be acceptable to allow the Vint Hill treatment plant to expand to 0.95 mgd and allow another plant to be constructed and discharge under Part 20 of the policy.

Comment 2

Regulatory Equity - Most of the commenters stated that it would be neither prudent nor equitable to allow a neighboring jurisdiction within the Occoquan Watershed to digress from the intent of the Occoquan Policy, which mandates stringent wastewater treatment standards and consistently high reliable performance; that upon any expansion, the Vint Hill treatment plant should be declared a regional plant and be required to meet the criteria of Part 20 of the policy.

Staff Response: Staff believes the draft permit is consistent with the Occoquan Policy; part 30 which allows expansions of existing plants. Further, staff believes the no net increase in effluent loadings in the draft permit is in keeping with the Policy. The following are the effluent limits for the 0.95 design flow in the draft permit:
- BOD 4 mg/l
- TSS 5.2 mg/l
- Total Phosphorus 0.6 mg/l
- Ammonia as Nitrogen 2.3 mg/l
Staff believes these are very stringent effluent limits and are protective of water quality and all designated uses.

Comment 3

Feasibility to connect to a regional plant – The Occoquan Policy requires that before a plant in the Occoquan watershed may be expanded, the applicant must show that it is not feasible for the flow to be directed to a regional plant and that the quantities of pollutant loadings discharged from the expanded plant must not increase loads to the receiving streams and that no such determination has been made.

Staff Response: In 1997, FCWSA conducted an evaluation of five wastewater handling alternatives for the Vint Hill area. The alternatives included connection to UOSA and expansion of the Vint Hill treatment plant. The final recommendation, based largely on costs, was expansion of the Vint Hill treatment plant. The estimated 20-year Capital and Operation costs for the connection to UOSA were $39.27M. The 20-year Capital and Operation costs for the expansion of the Vint Hill treatment plant were $32.4M. Further, Fauquier believes the expansion option provides them greater flexibility since they would not be subject to agreements with other jurisdictions.

Staff did not require any further analysis of feasibility for the following reasons:

1. The only existing regional plant is UOSA and Fauquier County is not a member jurisdiction to UOSA.

2. The Occoquan Policy recognizes the need for a plant in the Warrenton area and the Fauquier Water and Sanitation Authority has determined expansion is most feasible for them.

3. Staff's acceptance of general information for a feasibility analysis is consistent with the precedent set in a previous expansion request. In 1990, Prince William County Service Authority requested permission to expand the Nokesville STP, another pre-existing STP in the watershed. Staff accepted the Authority's determination that expanding the plant was the most feasible and the preferred approach to dealing with flows in that area of the watershed without any detailed analysis.

Comment 4

One-time Improvement of an existing Wastewater facility – The Fairfax County Water Authority interprets Part 30 of the Occoquan Policy to relate to a single one-time improvement of an existing waste treatment facility and not for the replacement of said facility which the FCWSA is proposing to do.

Staff Response: The Occoquan Policy does not state that there shall only be one expansion. Further, it is common practice for permittees to request permits for the maximum flow needed to address long range plans. Staff considers the maximum flow requested as the expansion request and any smaller flows as intermediate flows. Staff believes the two expanded flow tiers are allowable under the Policy.

Comment 5

Upstream drinking water supply (Lake Manassas) - The City of Manassas expressed concerns with the discharge and its proximity to the down stream drinking water supply in Lake Manassas.

Staff Response: These comments were received before Sanitation Authority modified their application for the discharges to go to Kettle Run. Kettle Run is not in the Lake Manassas watershed and the expanded flows will have no impact on Lake Manassas.

Comment 6

New Loadings to Kettle Run - Fairfax County commented that the proposed discharge to Kettle Run violates the Occoquan Policy, unless the plant is required to meet the regional plant criteria, because these pollutant loadings would be new to Kettle Run.

Staff Response: The Occoquan Policy does not prohibit new loadings to streams within the watershed; part 20.G allows new discharges to be permitted. With specific regard to STPs, staff believes the intent of the Policy is to protect drinking water intakes from STP discharges. By moving the discharge to Kettle Run, the discharge is no longer above Lake Manassas thereby providing maximum protection for that drinking water source. And, since the loadings are not increasing, there is no net effect on the Occoquan Reservoir and Fairfax County Water Authority's intake.

This concludes the staff presentation.

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Occoquan Reservoir
Prince William Conservation Alliance