Louisiana Department of Environmental Quality Reissues Storm Water General Permit for Large Construction Activities

The Louisiana Department of Environmental Quality (LDEQ) has reissued its Storm Water General Permit for Large Construction Activities LAR100000, which became effective on October 1. This General Permit applies to discharges of storm water from construction activities of five acres or more such as large industrial buildings, chemical plants or solar farms.

Permittees that were operating under the previous version of the General Permit, which expired on September 30, are automatically reauthorized under the terms and conditions of the new General Permit for 180 days, until March 28, 2025. If construction activities, including final stabilization, are anticipated to continue beyond March 28, 2025, permittees must submit a Notice of Extension by March 1, 2025, to avoid a lapse in coverage. LDEQ intends to notify current permittees of the requirements for continued coverage in the first few weeks of October.

The new General Permit retains many of the same terms and conditions of the previous version; however, notable changes include the following:

• • An LPDES permit is expressly required if a discharge of sediment from oil and gas construction activities will contribute to a water quality standard violation or exceed the reportable quantity discharge limits under 40 CFR 122.26(c)(1)(iii)(A) and (B).
  • Adoption of technology-based effluent limitations.
  • Adoption of water quality-based effluent limitations.
  • The permittee’s Storm Water Pollution Prevention Plan (SWPPP) must address off-site material storage areas.
  • The 100-foot natural buffer zone required to protect waters designated as Outstanding Natural Resource Waters must be a vegetated riparian buffer zone.
  • Pollution prevention measures must minimize exposure of building materials and products, construction wastes, trash, landscape materials, fertilizers, pesticides, herbicides, detergents, sanitary waste, and other materials at the site, which may be exposed to storm water and precipitation.
  • Pollution prevention measures must minimize any discharges from support activity areas both on and off the construction site, to the maximum extent practicable.

All permittees that have coverage under LPDES Permit LAR100000 or that may need coverage for future operations should review the changes to ensure compliance.

Please contact Blake Donewar, Sophie D. Gray, David Topping or any member of Phelps’ Environmental team if you have questions about the proposed changes and their impact.