March 16, 2009
Vol. 39, No. 93

Contacts:  Richard Greene, Division of Water Resources, 302-739-9939; or Melanie Rapp, Public Affairs, 302-739-9902.

DNREC Issues Secretary’s Order Approving Final Regulation Amending Total Maximum Daily Load
for Zinc in Red Clay Creek

Department of Natural Resources and Environmental Control Acting Secretary David S. Small has issued a Secretary’s Order for approval of the final regulation amending the total maximum daily load for zinc in the Red Clay Creek in northern New Castle County.

The final regulation amends the total maximum daily load (TMDL) for zinc to 55.93 pounds per day based upon using scientific modeling – lognormal probability modeling – which provides an improved match between the strength, location and timing of zinc mass loading to the Red Clay Creek with the inherent ability of the creek to assimilate the loading without adverse impact.

DNREC’s scientific results show that the water quality standards for zinc will be met with the TMDL derived from the lognormal method.

DNREC first established the TMDL for zinc in the Red Clay Creek in November 1999. TMDL is the maximum allowable mass loading of a pollutant (pounds per day) that can enter a waterbody and still assure that applicable water quality standards are met.

National Vulcanized Fiber Company (NVF), which owns and operates a manufacturing company along the banks of the Red Clay Creek, appealed the 1999 TMDL regulation to the State Environmental Appeals Board and the State Superior Court.  In February 2007 DNREC entered into a Settlement Agreement with NVF that required DNREC to amend the TMDL for zinc based upon a lognormal probability modeling approach.  In addition, the settlement required NVF to implement a Pollution Control Strategy to significantly reduce the release of zinc into the Red Clay Creek from their property.

A public hearing on the proposed amendments to the regulation was held in October 2008. The Secretary’s Order, along with oral and written public comments and DNREC responses, can be accessed online, http://www.dnrec.delaware.gov/Info/Pages/SecOrders.aspx.