In June of 2020, the Colorado Department of Public Health and Environment (CDPHE) revised their rules for construction dewatering and also for long-term dewatering for non-residential facilities. Every non-residential facility in the state that has a sump pump or drains to control groundwater seepage and discharges the produced water to gutters or stormwater drains must now have a dewatering permit, regardless of the amount of water produced or the water’s chemical makeup. Depending on Site conditions, there may be alternatives to these permits.
The water’s clear, what’s the deal?
In some areas, fuel or chemical spills may contaminate groundwater that seeps into buildings and CDPHE wants to prevent these contaminants from entering streams. More commonly, however, as groundwater flows through the subsurface, minerals in the aquifer can dissolve and leach metals such as selenium or arsenic, salts, or radioactive elements such as uranium, into the groundwater. Normally these mineral constituents would slowly seep into streams and become diluted to concentrations that are harmless to downstream water users, and the fish and wildlife.
With the Front Range’s many unlined irrigation canals, and irrigated lawns where there were once arid grasslands, the natural groundwater system has changed and the water table has risen to near-surface conditions in many places. To prevent basement flooding or foundation damage, buildings may need dewatering pumps that may produce a few gallons here and there, or may pump thousands of gallons daily. When all of these discharges across the Metro Area add up, large quantities of groundwater are being discharged to storm sewers that drain to streams. In order to decrease the drinking water treatment burden for downstream communities, help prevent salt buildup in farmland soils, and protect fish and other aquatic life in creeks and rivers, CDPHE has created a permitting system to limit the amount of potentially toxic constituents flowing into local rivers and creeks.
Depending on the groundwater quality, one of two discharge permitting tracks will be followed if the discharged water will flow back to streams. These are referred to as either the “easy permit” or “hard permit.” If the water is relatively free of impurities, then the “easy permit” only requires limited sampling, a permit application, and a year of 
minimal monthly monitoring. If the groundwater contains higher concentrations of metals or other constituents, the “hard permit” is needed and sampling is much more involved and expensive, regular monitoring and reporting are required, and a treatment system may be needed for the discharged water.
Fortunately, depending on the geologic conditions, water quality, and volume discharged, there may be alternatives to either of these permits and commercial facility owners may be able to circumvent the CDPHE permitting requirements. Westwater Hydrology LLC will be glad to provide a confidential assessment of your dewatering system and work to find the most cost-effective way to handle building dewatering discharges.