NPDES Permit for Dan River
Facilities that discharge wastewater to streams, lakes and other state waters are regulated through National Pollutant Discharge Elimination System – or NPDES – permits. The permits include federal and state regulatory requirements for the protection of human health and aquatic life. In North Carolina, electrical generating facilities that have coal ash ponds are also required to monitor groundwater in accordance with the state's regulatory program. This document contains groundwater monitoring data for the Dan River facility from Jan. 2010 - Feb. 2014.
DENR's Division of Water Resources has more information about coal ash regulation.
What is in coal ash and the wastewater discharge?
During the last five years the following parameters have been monitored by the Dan River facility in association with their federal discharge permit: Arsenic, Selenium, Copper, Iron, Sulfate, temperature, pH, Total Suspended Solids, oil and grease and nutrients including nitrogen and phosphorus. They have also been required to perform Whole Effluent Toxicity testing – a test that uses the entire waste stream at different concentrations to evaluate its effect on aquatic life.
The wastewater is analyzed, in accordance with EPA guidance, for its potential to be noncompliant with state water quality standards. The analysis of data indicates that the concentration of the compounds monitored at the Dan River facility is significantly lower than what is allowed by EPA. The Dan River facility has also consistently passed all quarterly Whole Effluent Toxicity tests.
Ash has a large variety of constituents, it is mostly consists of silicon oxide, iron oxide, and aluminum oxide. But it also has trace amounts of arsenic, selenium, mercury, boron, thallium, cadmium, chlorides, bromine, magnesium, chromium, copper nickel, and other metals.
The ash composition varies widely depending on the coal type and origin, burning regime, air pollution control equipment, etc.