Storm Water Pollution Prevention

Posted on Jun 24, 2019 in Main

Storm Water Runoff and the NPDES Storm Water Program

What is storm water runoff?

Storm water runoff is rain that does not infiltrate into the ground. Instead, it flows over land or impervious surfaces, such as streets, parking lots, building rooftops, and other paved surfaces.

As storm water runoff flows across these hard surfaces it picks up pollutants such as oil and grease, metals, sediment, nitrogen, phosphorus, bacteria and other toxic substances before discharging into our streams, harbors, and ocean.

These pollutants come from many sources including vehicles, construction sites, lawn fertilization, pesticide application, illegal dumping and spills, and pet waste. 

NPDES Storm Water Program

Under the Clean Water Act, the National Pollutant Discharge Elimination System (NPDES) permit program aims to prevent and reduce water pollution by regulating point sources that discharge pollutants into bodies of water. A point source is generally considered any confined and discrete conveyance such as a pipe, ditch, channel, or conduit.

Municipal separate storm sewer systems (MS4s), construction activities, and industrial activities are required to obtain a NPDES permit prior to discharging storm water. A MS4 is a conveyance or system of conveyances that is:

  • Owned by a state, city, town, village, or other entity that discharges to U.S. waters,
  • Designed or used to collect or convey storm water (e.g., storm drains, pipes, ditches),
  • Not a combined sewer, and
  • Not part of a sewage treatment plant, or publicly owned treatment works (POTW).

In Kaka’ako

HCDA owns a portion of the storm drain system in Kaka’ako and at the Kewalo Basin Harbor and has coverage under the NPDES General Permit for Small MS4s. Under the NPDES Permit, HCDA is required to develop and implement a storm water management plan (SWMP).

The SWMP describes the efforts HCDA will take to reduce the discharge of pollutants from its MS4 using the six program elements outlined below, as described in the EPA’s Stormwater Phase II Final Rule: Small MS4 Stormwater Program Overview.  HCDA’s SWMP can be viewed here: Storm Water Management Program.

The SWAP includes:

Distribute educational materials and perform outreach to inform residents about the impacts to water quality due to polluted stormwater runoff discharges.

Provide opportunities for residents to participate in program development and implementation, including effectively publicizing public hearings and/or encouraging resident representatives on a storm water management panel.

Develop and implement a plan to detect and eliminate illicit discharges to the storm sewer system (includes developing a system map and informing the community about hazards associated with illegal discharges and improper disposal of waste).

Develop, implement, and enforce an erosion and sediment control program for construction activities that disturb 1 or more acres of land (controls could include catch basin inlet protection, silt fences, and temporary detention ponds).

Develop, implement, and enforce a program to address discharges of post-construction storm water runoff from new development and redevelopment areas. Applicable controls could include preventative actions such as protecting sensitive areas (e.g., wetlands) or the use of structural BMPs such as dry wells, downspout disconnection, or porous pavement.

Develop and implement a program with the goal of preventing or reducing pollutant runoff from municipal operations. The program must include municipal staff training on pollution prevention measures and techniques (e.g., regular street sweeping, spill response, reduction in the use of pesticides, and proper storage/disposal of waste materials).

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