Lessons Learned: BMP Strategies For Achieving a NONA Exemption from the IGP

Date / Time:
Tuesday, Oct 20 2:05pm to 2:35pm
Big Sur
Track / Session:
Industrial Stormwater Management / Source Identification and BMP Implementation

Compliance with the recently authorized Industrial General Permit (IGP) will be time consuming and expensive for most industrial facilities. However, certain facilities may be able to opt out of permit coverage by filing a Notice of Non-Applicability (NONA). NONA filing includes submittal of a No Discharge Technical Report demonstrating that the facility is engineered and constructed to retain all runoff even under historic rainfall conditions or, alternately, that the facility is not hydrologically connected to waters of the United States. This talk presents lessons learned while assisting clients with obtaining both types of NONA exemption.

BMPs designed for “no discharge” NONA compliance generally utilize infiltration, on-site storage for later consumptive use, or a combination of these strategies. The NONA Technical Report includes a continuous simulation modeling demonstration that BMPs are of sufficient size to retain all runoff on-site based on historical rainfall patterns. Depending on location, this standard requires that sites are engineered to manage maximum daily runoff of 70,000 gallons per acre to more than 200,000 gallons per acre.

At most sites, we were asked to assess whether existing BMPs are NONA-compliant. It seems that many dischargers are choosing to wait to install new NONA-compliant BMPs pending the significance of initial monitoring results. At most sites with sufficiently large BMPs, addition improvements (such as berms, curbs, or trench drains) were required to prevent incidental runoff from all portions of the site. In most cases, topographic surveys and infiltration testing were necessary to convincingly demonstrate that sites were engineered to retain runoff under all forseeable circumstances.

The EPA’s new rule for defining which surface waters are Waters of the United States (WOTUS) is scheduled to become final in July 2015, and has a significant impact on certain facilities seeking a NONA exemption. Our experience is that, despite the new EPA rule, facilities in many regions of California can achieve NONA by demonstrating that they are not hydrologically connected to WOTUS. In some cases the lack of connectivity is due to geographic isolation (i.e. the facility is located in a topographic basin that does not contain WOTUS). In other instances disconnection is due to the presence of an off-site basin of sufficient size to capture and infiltrate all runoff from the site (and usually the surrounding area) and prevent any runoff from reaching surface water.

Primary Speaker:
Marty Spongberg, AMEC Foster Wheeler
Marty Spongberg, PhD, PE, PG, is a Senior Associate Engineer with AMEC with more than 30 years of professional experience, primarily in the fields of hydrology, stormwater engineering, and hydrogeology. Dr. Spongberg holds geophysics and civil engineering degrees from Colorado School of Mines and Texas A&M University, respectively, and is California-registered in civil engineering and geology. He has published stormwater, groundwater modeling, and statistical hydrology literature; and taught water resources engineering, statistics, and geology courses at the university level. For the last 14 years, Dr. Spongberg’s practice has consisted primarily of design, implementation, and effectiveness monitoring of storm water BMPs, with a focus on infiltration BMPs.