Taking stormwater compliance to a whole new level
Big problems require big solutions
From the early 1950s a major aerospace manufacturer conducted rocket engine testing at a large site, which spans approximately 3,000 acres (5 square miles). The nature of the legacy activities and site impacts led regulators to issue a site-specific stormwater National Pollutant Discharge Elimination System (NPDES) permit that has driven one of the most ambitious industrial stormwater management and treatment programs in the United States.
The site is located at the headwaters of multiple watersheds such that stormwater historically drained in different directions through multiple outfalls. The NPDES permit for this site includes stringent effluent limitations for a variety of constituents, which vary by outfall. As a condition of the permit, the facility is required to sample flows from every outfall, for every storm event.
Outfalls are equipped with programmable ISCO auto samplers and flow meters, which enable collection of flow-weighted composite stormwater samples. The site also has a weather station and several rain gauges to record differences in rainfall across the large area of the site. Runoff from most of the outfalls is diverted through a series of pumps and conveyance structures that move the water toward the center of the site where it is stored in ponds and storage tanks pending treatment, prior to offsite discharge.
There are two sophisticated engineered stormwater treatment systems onsite that may be operated to treat the runoff using an ACTIFLO system and associated chemical and physical treatment processes (e.g., flocculation, coagulation, sand filters). In addition the site also has flow-through media filters, an advanced – and in fact, award winning – biofilter, a bioswale, culvert modifications, and extensive site-wide erosion and sediment controls.
Compliance takes more than technology
But while an extraordinary technology foundation is essential to enabling compliance, actually achieving it comes down to human performance. And to reliably execute the compliance program, the client needed a partner with stormwater management capabilities that were exceptionally broad and deep.
Haley & Aldrich was chosen to manage the property’s stormwater compliance program at the site on a year-round basis, including overseeing stormwater, sediment, and receiving water quality monitoring; bioassessment monitoring; best management practices (BMP) inspections and maintenance; data analysis and management; quarterly and annual reporting; Stormwater Pollution Prevention Plan (SWPPP) preparation and training, Quality Assurance Project Plan (QAPP), and Sampling and Analysis Plan (SAP) updating; NPDES permit renewal support; flow modeling support and review; Reasonable Potential Analysis; community outreach support; and general stormwater training.
Haley & Aldrich is also responsible for overseeing the operation and maintenance of the stormwater treatment systems, including optimizing real-time chemical dosing rates during storm operation. We also oversee the inspection, operation and maintenance of all BMPs, and manage the Construction Stormwater General Permits required for construction of new BMPs, and demolition of buildings and other facilities.
On the path to closure
The long-term objective for this site is to eventually terminate the individual NPDES stormwater permit, as the site is undergoing extensive demolition and restoration activities aimed at turning the site back into natural, open space that will serve as a park and wildlife corridor. While working toward that goal, the owner has received significant value thanks to engaging Haley & Aldrich on the project. The client has peace of mind: the property has been managed to full compliance, and liability for exceedances has been reduced. Because of its vast size and complexity, the manpower cost of operating the system is huge. Haley & Aldrich’s expertise in efficient operations continues to generate significant operating cost savings through optimizing system operation, without compromising system performance.
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