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COLORADO DEPARTMENT OF PUBLIC HEALTH AND ENVIRONMENT, Water Quality Control Division <br />Rationale - Page 5. Permit No. COR- 030000 <br />II. CHANGES IN THIS GENERAL PERMIT (cont.) <br />Where adequate management practices are not followed to protect groundwater quality, the <br />Department may require discharges to unlined pits to cease, or require the entity to obtain <br />alternate regulatory approval through notice from either the Water Quality Control Division <br />or the Hazardous Materials and Waste Management Division. <br />In addition, Part I.D.1(b) of the permit has been revised to clearly state that the permit does <br />not authorize on -site permanent disposal of concrete washout waste, only temporarX <br />containment of concrete washout water from washing of tools and concrete mixer chutes. <br />Upon termination of use of the washout site, accumulated solid waste, including concrete <br />waste and any contaminated soils, must be removed from the site to prevent on -site disposal <br />of solid waste. <br />v) Construction Dewatering. Part I.D.3(d) of the permit has been revised to conditionally <br />authorize discharges to the ground of water from construction dewatering activities when <br />appropriate BMPs are implemented. The permit does not authorize the discharge of <br />groundwater from construction dewatering to surface waters or to storm sewer systems. Part <br />I.C.3(c)(8) of the permit requires that BMPs be in place to prevent surface discharges. The <br />permittee may apply for coverage under a separate CDPS discharge permit, such as the <br />Construction Dewatering general permit, if there is a potential for discharges to surface <br />waters. <br />The Division has determined that potential pollutant sources introduced into groundwater <br />from construction dewatering operations do not have a reasonable potential to result in <br />exceedance of groundwater standards when the discharge is to the ground. The primary <br />pollutant of concern in uncontaminated groundwater is sediment. Although technology -based <br />standards for sediment do exist in 5 CCR 1002 -41, the discharge of sediment to the ground as <br />part of construction dewatering does not have the reasonable potential to result in transport <br />of sediment to the groundwater table so as to result in an exceedance of those standards. <br />For a discharge of water contaminated with other pollutants that are present in <br />concentrations that may cause an exceedance of groundwater standards, separate CDPS <br />discharge permit coverage is required. Contaminated groundwater may include that <br />contaminated with pollutants from a landfill, mining activity, industrial pollutant plume, <br />underground storage tank, or other source of human - induced groundwater pollution and <br />exceeding the State groundwater standards in Regulations S CCR 1002 -41 and 42. <br />J. Terms and Conditions, General Limitations and Design Standards <br />This section reiterates the requirement that facilities select, install, implement, and maintain appropriate <br />BMPs, following good engineering, hydrologic and pollution control practices. In addition, requirements for <br />protection of water quality standards (see Part I. D.1. (a) of the permit) and requirements to adequately design <br />BMPs to prevent pollution or degradation of State waters (see Part I. D.2 of the permit) have been revised and <br />are fully discussed in Part III.B of the rationale, below. Additional language was also added to Section III.B <br />of the rationale further clarifying the expectations for compliance with this permit. <br />Management of Site Waste <br />This section has been modified to clarify that on -site waste must be properly managed to prevent <br />potential pollution of State waters, and that this permit does not authorize on -site waste disposal. Solid <br />waste disposal is regulated by the Hazardous Materials and Waste Management Division. <br />