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.
toxicity levels. Additionally, CDPHE translated the narrative standards using results from federally-derived consensus findings on the toxicity of the compounds PFOA, PFOS, PFNA, PFHxS, and PFBS to develop the Colorado Standard. CDPHE is also taking the novel approach of including four polyfluorinated compounds that are “oxidizable precursors” or “parent compounds” to the five compounds. While there may be many more parent compounds, CDPHE is only considering those that are included on the analytical list for EPA’s proposed draft laboratory method, EPA SW-846 Method 8327* (Method 8327).
PFOA; PFNA has been added to this pair based on the ATSDR’s 2018 report showing a similar minimal risk levels (MRLs) for developmental toxicity as PFOS and PFOA. CDPHE is following EPA’s lead setting the Standard at 70 ppt level for the sum of these three compounds. Additionally, parent compounds reported in the Method 8327 list are NEtFOSAA, NMeFOSAA, PFOSA/FOSA which can be oxidized in the environment to PFOS, and the parent compound 8:2 FTS which can be oxidized to PFOA. The Standard conservatively assumes all of the parent compound mass will be oxidized and uses a formula based on concentration and molecular weights.
with industrial pre-treatment programs, other POTWs with significant sources of PFAS, and some dewatering permits. Industrial sources, wastewater treatment plants and some dewatering activities will require initial monitoring. Continued monitoring and source investigation may be required if PFAS is present, and based on proximity to drinking water sources. Effluent limits will apply to only to PFOA, PFOS, PFNA, PFHxS, and PFBS. The standard also makes provision for applicability to Colorado’s list of impaired waters.
many commercially-available modified 537 methods. The DoD’s Environmental Data Quality Workgroup considers Method 8327 only useful as a screening-level analytical method “
I’m no longer so sure of myself. I thought the public water supply was safe, that we’d dealt with toxic chemicals in public distribution systems years ago. Environmental remediation of groundwater was my profession but I seldom worked on sites with contaminants directly entering public water supplies. I thought situations such as the case of Woburn Massachusetts, portrayed in the 1998 movie