What do you do when an NJDEP-issued CAFRA permit specifies that 22 million gallons of highly acidic water must be neutralized and drained from a pond before the surrounding property can be developed?  This situation was successfully resolved by Najarian Associates’ staff during the construction of a large-scale, planned residential development in East Brunswick, New Jersey.

The subject waters were contained within the drainage pit of an old sand and gravel quarry.  Over the years, mine drainage through exposed, acid-producing deposits had lowered the pH of these waters to almost 2 -- a level that renders the pit’s waters biologically inert.  Others had unsuccessfully attempted to neutralize this pond through in-situ applications of crushed limestone.  Najarian Associates adopted a more technical approach to investigate the problem.  A series of laboratory tests were conducted on these waters to determine the extent of their buffering capacity and the appropriate agent for their neutralization.  These titration tests indicated that hydrated lime (CaO) would best serve this desired objective.

Within a mobile, 22,000-gallon mixing hopper, a 2% mixture of hydrated lime was prepared for injection into this same inlet.  A metered dosage of 50 gallons per minute was found to be sufficient for the neutralization of these flows. 

The waters of the mine pit were completely neutralized and drained without any contravention of the CAFRA permit conditions.  In spite of torrential rains which contributed an additional 3.0 million gallons of water to the pond during the course of this operation, our assignment was successfully completed within a period of 12 days.  The expeditious resolution of this problem enabled the project to proceed on schedule.