Commercial Wastewater Treatment System Design & Permitting

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Project Description

A planned facility expansion at the subject property necessitated redesign of this industrial site’s existing sewage disposal system (which was sized to receive 5,000 gallons of sewage per day from a manufacturing facility with 333 on-site employees). The proposed expansion increased the facility to 600,000 square feet and doubled the total number of on-site employees. Whitestone was retained to design and permit a new sanitary wastewater treatment system to accommodate the increased sewage discharge flow resulting from facility expansion.

Whitestone collected and prepared the required technical data for a New Jersey Pollution Discharge Elimination System (NJPDES) Discharge to Groundwater (DGW) Individual Permit Application. Test pits, soil borings, and monitoring wells were installed to depths of 70 feet in the proposed on-site disposal area to:

  • determine depth to bedrock;
  • characterize site soils;
  • identify restrictive horizons;
  • collect soil samples for grain-size analyses in Whitestone’s geotechnical laboratory;
  • confirm depth to groundwater and seasonal high groundwater levels;
  • determine the permeability and hydraulic conductivity of the area’s substrata;
  • identify the direction of groundwater flow; and
  • characterize ambient groundwater quality.

Parameters calculated from the obtained data included transmissivity, hydraulic gradient, Long Term Acceptance Rate (LTAR), and a groundwater mounding analysis. Whitestone’s engineers used these data to design the new wastewater treatment system and prepare the NJPDES-DGW and Treatment Works Approval (TWA) permit applications. Whitestone also prepared and obtained a Watershed Quality Manage-ment Plan amendment from Roxbury Township for the increased discharge volume.

The expanded wastewater treatment system more than doubled the site’s daily sewage treatment capacity and included the addition of four additional disposal beds for a total disposal area of 28,000 square feet. The new system consisted of:

  • a series of septic tanks to provide primary treatment;
  • an aerobic treatment tank;
  • denitrification process equipment;
  • an equalization tank;
  • a pump tank and delivery pump; and
  • discharge to groundwater through alternating dosing disposal beds.

Upon securing the required permits and approvals, Whitestone supervised construction of the new 11,565 gpd sanitary wastewater treatment system. The system is operating as designed in compliance with the NJPDES-DGW permit.