Thursday, April 21, 2011

Determining Benchmark Concentrations For Metals Under Draft Ohio MSGP

The Ohio Environmental Protection Agency (OEPA) has released its draft Multi-sector General Permit (MSGP) which, once finalized, will replace the existing industrial stormwater discharge general permit, which will expire on May 31, 2011. The draft MSGP is modeled after the US EPA MSGP, released in 2008, and is significantly different compared to the existing Ohio permit.

One of the key changes is the requirement for most permitted facilities to conduct benchmark monitoring of their industrial storm water discharge. Results are compared to a list of sector-specific benchmark concentrations to determine if improvements to the stormwater pollution prevention program are needed, and whether or not further benchmark monitoring is needed.

The benchmark concentrations for each sector are listed in the permit, with several important exceptions. These are benchmarks for seven metals:

  • Beryllium

  • Cadmium

  • Copper

  • Lead

  • Nickel

  • Silver

  • Zinc

The benchmarks for these chemicals must be calculated for each individual facility based on the hardness of the receiving water, which each facility must determine. This will require individual facilities or groups of facilities to collect additional samples and do additional testing prior to starting their benchmark monitoring program.

The necessity to determine site-specific stormwater benchmarks only affects certain Ohio discharges, includes some or all facilities in fall into ten of the industrial sectors:

Sector A – Timber Products
Sector C – Chemical and Allied Products Manufacturing, and Refining
Sector F – Primary Metals
Sector G – Metal Mining
Sector K – Hazardous Waste Treatment, Storage, or Disposal Facilities
Sector M – Automobile Salvage Yards
Sector N – Scrap Recycling and Waste Recycling Facilities
Sector Q – Water Transportation Facilities
Sector Y – Rubber, Miscellaneous Plastic Products, and Miscellaneous Manufacturing Industries
Sector AA – Fabricated Metal Products

Caltha LLP provides expert consulting services to public and private sector clients in Ohio and nationwide to address stormwater permitting & regulatory support, including determination of stormwater benchmarks for water hardness dependant metals, development of Stormwater Pollution Prevention Plans (SWPPP) using a SWPPP template prepared to meet the new permit requirements, stormwater monitoring and stormwater training.

For further information contact Caltha LLP at or Caltha LLP Website

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