The following is an update concerning what framework the PA Department of Environmental Protection (PADEP) will propose in a revised TDS regulatory approach. PADEP had proposed a uniform 500 mg/l TDS effluent limit on all new or increased “High-TDS” dischargers. In response to a request for public comments, PADEP received the message that the 500 mg/l end of pipe discharge standard was burdensome and unworkable to existing industries outside of Oil & Gas.
DEP is developing a revised Chapter 95 proposal that has three basic elements:
A “watershed-based” approach to regulating TDS for most sectors
- Some form of mandatory or incentive-based recycling and reuse program for the Marcellus Shale gas industry
- A sector-based approach for high-TDS dischargers (Oil & Gas).
Watershed Based Approach
DEP is proposing what it describes as a watershed based approach, which was characterized as a “pre-TMDL” program under which DEP would identify watersheds which are approaching and threaten to exceed some percentage of their assimilative capacity as measured at the applicable downstream public water supply intakes.
DEP’s watershed approach does not include allowance for real time discharge management based on flows. DEP understands that a number of commenter’s suggested this approach. The question posed was whether this could be done within existing regulations, and whether any necessary changes to existing state regulations would be acceptable to EPA (which DEP contends would need to approve those changes as part of the state’s administration of the NPDES program). DEP takes the position that the water quality standards include an “anti-degradation” approach for all streams, in that existing uses that are currently being achieved must be protected.
Discharge Standard for Significant New or Expanded High-TDS Load Discharges
Under the new proposal, DEP would impose a discharge limit on significant new or expanded High-TDS loads as follows:
- Subject to several exclusions, new or expanded TDS-loads of greater than 5,000 pounds per day, and involving concentrations > 2000 mg/l would be subject to a discharge limit. This discharge limit would apply only to the new or expanded load. Any pre-existing TDS discharge loads, regardless of mass or concentration would not be subject to this limit.
- Such significant new or expanded TDS-loads would be subject to an effluent limit of 2000 mg/l, but with a provision allowing a “variance.” The variance procedure would allow DEP to set a higher effluent limit if the watershed wasteload analysis indicated that such a limitation was not needed to meet downstream TDS limits at the nearest water supply intake or near field protection of instream uses.
- DEP will conduct an annual analysis of all affected watersheds, based on information from the water quality monitoring network. DEP understands that the water quality network will need to be upgraded, with real-time conductance monitors installed in additional watersheds. Currently it appears that there are 36 water supply intakes in watersheds of potential concern. If it appears that TDS trends are increasing, and assimilative capacity is threatened, DEP would then consider imposing more stringent TDS limits on major TDS load dischargers following a wasteload allocation approach. For purposes of this rule, DEP defines “watershed” based on surface water and GUDI water supply intake locations (current existing point of Ch. 93 compliance for TDS) and the contributing watershed areas upstream of each applicable water supply intake.
Marcellus Shale Natural Gas Wastewater
- DEP will be proposing recycling/reuse requirements, the details of which will be released soon.
Oil and Gas Sector Limit
- DEP will propose that all new or expanded TDS loads from the Oil & Gas sector be subject to a 500 mg/l discharge limit. This would apply to new or expanded TDS loads from both conventional and Marcellus Shale development.
What’s Next: DEP plans to present this revised package to the WRAC (Water Resources Advisory Committee) on April 14 and intends to present the revised package to the EQB “this spring”. Industry is urged to formulate and provide comments and concerns to DEP as soon as possible.
For more information on this topic, or for help with identifying and implementing a strategy to meet the rules proposed above, please contact Travis Buggey, Venture Engineering & Construction, at 412-231-5890, ext. 325.