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Stormwater Management in Oahu, Hawaii

Stormwater Management Services

What is Stormwater Management?

As Hawaii’s land is being converted via construction for housing and commercial development the increase in paved areas and shifting of underlying soil also changes how water flows during and after rainstorms.

As rainwater runs off impervious areas it increases the amount of water and pollutants that enter our drinking and recreational waterways. Additional care must be taken in addressing the problem of dirt and other pollutants on roads before they reach storm drains.

The result? Over time, water quality is degraded. The Clean Water Act (1972) set up regulations for addressing sewage, industrial waste, and stormwater discharge.

Using BMPs Strategically

The purpose of identifying and using Best Management Practices (BMPs) for areas undergoing construction activities is to prevent or reduce pollutants from entering the State of Hawaii municipal separate storm sewer system (MS4) thereby protecting State waters from pollutant discharges.

Ideally, stormwater can be absorbed into the soil and filter down to aquifers or it flows directly into streams and rivers. However, with construction-based soil disturbances, during rainstorms, all excess water runs across road surfaces and into ditches and storm sewers. When the roads are dirty, the rainwater water picks up bacteria, chemicals, debris, and other pollutants on its way and dumps them into water sources.

Kleen Sweeps Can Help You Comply With EPA Standards

The Environmental Protection Agency (EPA) oversees stormwater management nationally. In turn, the EPA works with the state of Hawaii to improve both air and water quality overall.

To comply with Stormwater Pollution Prevention Plans (SWPPP) your construction company needs to pay attention to water runoff at and immediately around the site. BMPs that control potential pollutants from site activities or materials and waste handling control are established practices and procedures to control potential pollutants at their source.

The BMPs advised by the City and County of Honolulu focus on the areas of erosion control, sediment control, tracking control to reduce dirt and other debris from tracking off-site and entering the airstream or waterways.

Sediment control BMPs include devices installed or constructed by the contractor on disturbed soil to protect the ground surface from erosion due to wind, rain, or runoff. Tracking control BMPs are devices or procedures that minimize the amount of sediment and debris that is tracked offsite by vehicles and equipment.

For instance, you can reduce the amount of sediment tracked offsite by stabilizing the entry / exit points to the construction site. Steel grating, rumble strips or even a gravel-based apron removes soil, rock and mud from vehicles leaving the work zone and entering offsite areas such as public roadways. This greatly reduces safety hazards on the public roadway and sediment pollution in waterways.

Vehicle track-out reducing BMPs limit the amount of pollutants leaving the construction site. The effectiveness of a stabilized construction entrance/exit is greatly increased if a wash rack is included for removing caked on sediment from vehicles and equipment before they leave the site.

Once track-out dirt and sediment reach a paved road, Kleen Sweeps street sweeping BMP comes into play. In Honolulu, in addition to controlling sediment from entering the sewer system, dirt tracked off a construction site must be removed immediately subject to air quality control measures. Ideally, you should contact your local air and water quality management agency for details and help on developing a SWPPP plan before construction begins.

Post-Construction Stormwater Management

Post-construction stormwater management is designed to manage stormwater runoff in new developments and redevelopment areas. The program is required to provide long-term operation and maintenance using best practices to ensure minimal water quality impacts. 

Kleen Sweeps can help your company with construction site-based stormwater management and suggest ways to improve track-out dirt problems so stormwater will flow with fewer pollutants.

Call Kleen Sweeps today.