Dewatering Project
An environmental services company was contracted to treat dewatering water generated during excavation activities. Analytical sampling identified elevated concentrations of oil and phosphate that exceeded discharge criteria. A treatment system was designed to operate at a continuous flow rate of 250 gallons per minute (gpm) and successfully achieve compliance prior to discharge.
The treatment train used a multi-stage approach that included:
- Chemical Treatment
- Settling Tank
- Sand Filter
- Bag Filter
- HS-200 – 40,000 lbs
- HS-300 – 10,000 lbs
The table below is the theoretical calculations for HS-200 and HS-300 Hydrosil medias when running the medias in series. The concentrations used for oil and phosphate were the average concentrations found over the 3 samples of data given.
The system operated continuously for approximately three weeks and successfully treated nearly 6,000,000 gallons of dewatering water.
Final effluent sampling conducted on the last day of operation indicated:
- Oil: 0.1 ppm
- Phosphate: 0.05ppm
These results confirmed:
- Sustained adsorption performance
- No observable breakthrough at shutdown
- Effective integration of chemical and adsorption treatment stages
- Compliance with discharge requirements
