Stormwater Pond Outlet Structure Grouting

Washington TWP, NJ


The stormwater pond in a neighborhood was not holding water. Geotechnical investigations of the lining material showed that it was adequate. The developer determined that outlet structure grouting may be required to address water loss around the buried structures.

Due to a very tight site, the pond was designed to release water through two structures feeding manifolds. While the pond was equipped with a well and pump to make up for water loss, the pond would still not stay at the level. The inlet and two outlet structures were identified as potential flow paths for water exiting the pond, causing the level to drop.

The township engineer told the developer that if they could not get the pond to hold water, they were going to have to install a liner system, which was very expensive.


The repair had to be done without impacting water quality, well operations, or creating large disruptions to the residents. Because the exact pathway of water flow around the structures could not be determined, the repair had to address water flows through various seepage paths around the structures.


CJGeo successfully performed chemical grouting to stop water migration through the stone beds on two outlet structures and an inlet structure. The work was completed in a day.