Compressor Station Stormwater Management Design

Challenges

Compressor stations are active facilities and highly regulated industrial sites that face stringent stormwater management requirements during major system upgrade required by regulatory agencies. Stormwater runoff from facility discharges in New Jersey are classified by the New Jersey Department of Environmental Protection (NJDEP) Surface Water Quality Rules as a FW2-NTCategory 1 Water. NJDEP Stormwater Management Rules require runoff discharging to Category 1 waters receive water quality treatment for 95% total suspended solids (TSS) removal prior to discharge. This is more stringent than the standard requirement of 80% TSS removal. Category 1 waters also require a 300-foot riparian buffer on each side, measured from top of bank. Intermediate resource value wetlands were also present on the site, requiring 50-foot buffers. These regulated riparian and wetland areas and their associated buffers required additional attention to detail in terms of limiting disturbance.

Due to the NJDEP regulations cited above, a proposed site development for a facility had limited available space. This created challenges in finding available space for the required facility upgrade, which included an effective stormwater management system to address regulatory constraints and discharge requirements.

Solutions

In order to overcome these challenges, TRC proposed use of a surface collection system consisting of inlets and piping to direct regulated runoff to NJDEP approved best management practices (BMPs). Selected BMPs consisted of a treatment train approach. The upstream BMP of each treatment train consisted of hydrodynamic separators rated for 50% TSS removal discharging to bioretention basins designed for 90% TSS removal. This treatment train approach provided a combined total of 95% TSS removal. Two separate hydrodynamic separator/bioretention basin systems were used due to the size and layout of the site.

HydroCAD® stormwater management software was used to model the potential worst-case 2, 10 and 100-year storm events. Each bioretention basin was designed with a controlled outlet structure to meet quantity reduction requirements. NJDEP approved soil layering and plantings were used to meet water quality treatment requirements. No groundwater recharge was required due to the presence of potentially contaminated soils on the site.

Results

The client was extremely satisfied with how TRC obtained permit approvals due to the many constraints and challenges for the facility. TRC was able to support the client with design, permitting and oversight services which provided a smooth workflow and proper installation of the management system.