Thursday, October 21, 2010

Implications of Complying with the TMDL for Virginia

The Chesapeake Bay Commission was created in 1980 to coordinate Bay-related policy across state lines and to develop shared solutions. The six Bay watershed states are Virginia, Maryland, Pennsylvania, West Virginia, New York, and Delaware and the District of Columbia and are all parties to the Chesapeake Bay Agreement. Back in May 2010 the EPA announced that it will mandate that the six states and the District of Columbia who are parties to the Chesapeake Bay Agreement limit their nitrogen, phosphorus and sediment flow into the bay in compliance with an overall daily maximum, TMDL, allocated by the EPA. The six Bay watershed states (Virginia, Maryland, Pennsylvania, West Virginia, New York, and Delaware) and the District of Columbia have all developed Watershed Implementation Plans, WIPs, to meet these targets.

The EPA found that none of the states met the reasonable assurance standard they set, but that Virginia’s WIP had a “moderate need” for federal backstops (the WIPs from Maryland and Washington, DC were found to need only minor backstops). Virginia’s WIP was found to have serious deficiencies. It did not meet allocations for nitrogen (6 percent over) and phosphorus (7 percent over), but did meet allocations for sediment (12 percent under). EPA will invoke federal authority where they can to ensure the mandated reduction in nutrient pollution to the Chesapeake Bay. Though EPA states that they prefer the individual states develop their own approach to develop a final WIP with an acceptable level of assurance, so that EPA will not have to invoke federal actions. The states have more flexibility and can achieve reductions from a wider range of sources than EPA can. Dozens of small measures will allow the state to achieve the TMDL goals. The problem is creating the regulatory network to control the non-point source nutrient and sediment contamination.

If the states’ WIPs do not meet the EPA standard of reasonable assurance, the EPA’s only possible response is to further control the point source contamination it can regulate. This means that more stringent waste load allocations will be applied to waste water treatment plants (regulated via federal programs). The waste stream from wastewater treatment plants was assigned to be 4 mg/L total nitrogen and 0.3 mg/L total phosphorus. For municipal separate storm sewer systems, MS4s, the federal government has imposed the requirement that 50% of urban MS4 lands meet aggressive performance standard through retrofit/ redevelopment; 50% of unregulated land will be treated as regulated, so that 25% of unregulated land meets aggressive performance standard.

At the public hearing held in Annandale, Virginia, Anthony Moore, Assistant Secretary for Chesapeake Bay Restoration in Virginia stated that the reduced levels of discharge of total nitrogen would not be set so low as to cause algae blooms in the Occoquan Reservoir. This statement left me confused since it is the nitrogen and phosphorus contamination which cases the algae blooms. I went down to the HL Mooney Waste Water Treatment Plant in Woodbridge, VA to talk about the TMDL and algae blooms with Glenn B. Harvey, the plant Process Engineer. He provided me with additional insight into the very complicated balancing act necessary to restore the Chesapeake Bay.

HL Mooney is an AWWTP operating at around 13 million gallons of waste water a day. The plant was built originally in 1979, expanded in the 1990’s and is being expanded to 23 million gallons a day today. HL Mooney serves around 130,000-150,000 people a day which represents about 40% of the population of Prince William County. Mr. Harvey explained to me that the sediment of the Occoquan contains amongst other contaminants nitrogen and phosphorus. He stated that when the nitrogen in the Occoquan waters falls too low, anaerobic nutrients are released from the sediment. According to Mr. Harvey, the nitrogen keeps it anoxic and not anaerobic. Unless, the entire Occoquan were dredged, which would make the water undrinkable for an extended period of time, release of nutrients from the sediment would have to be considered in any point sourc reduction.

HL Mooney is only a fraction (about 7%) of the size of Blue Plaines AWTTP. The monthly discharge averages are less than 0.1 for phosphorus, TSS 1 mg/l, BOD non- detect and nitrogen is currently 5 mg/l but according to Mr. Harvey will be 3 mg/l when the expansion is completed. He pointed out that the average monthly TMDL is about 50% more lenient a measure than the weekly measure that EPA is mandating. Mr. Harvey worried that the cost of the technology to achieve the weekly TMDL limit might be prohibitive. The more I examine the issure the more complicated it becomes. Weighing raising sewage and water rates on public systems to pay for the technology to meet the TMDL goal for the state and implementation and enforcement costs to have the Commonwealth regulate the non-point sources of contamination.

No comments:

Post a Comment