STORM WATER DETENTION and management is becoming a routine component in land development projects, particularly along riparian corridors where rain run off surge and silt are degrading water quality and the ecology.

Grading and paving disrupts the historical stormwater flow path and the natural soil absorption process. The resulting soil erosion and transportation of oils and trash into the surface drainage patterns must be remediated. The surface water speed and volume is reduced by "detaining" the rain surge water in ponds or tank systems and then releasing it more slowly over a period of hours or days to meet acceptable natural or historic run off rates.

Ponds detain the water but do little to remove floating trash and oil. In addition to being high maintenance, ponds are often an attractive nuisance as well as a breeding area for mosquitoes, if not properly managed.

Shallow ponds generally take up more space or real estate than an underground storage tank system. Darco manufactures underground storage tanks that can be used for storm water detention and management. Underground tank systems can be designed to intercept silt, floating trash, and oils as well as store and release the clarified water at acceptable historic rates.

There is definitely a maintenance factor with tanks as well. Sand, oil, and floating trash accumulation must be monitored and removed as necessary. Fine suspended solids and silt may pass through a sand interceptor but generally fall out while water is held in the quiescent storage tank system. Silt accumulating in the bottom must be occasionally removed by vacuum truck in slurry form and then dewatered for reclamation as top soil.