Conifer Metro District (CMD), at Safeway, started operations about 2005.
Total dissolved solids (TDS) are dissolved ions, including salts, minerals and metals, that can be found in all non-pure water sources.
From the EPA Guidance:
EPA has established National Primary Drinking Water Regulations (NPDWRs) that set mandatory water quality standards for drinking water contaminants. These are enforceable standards called “maximum contaminant levels” (MCLs) which are established to protect the public against consumption of drinking water contaminants that present a risk to human health.
EPA has also established National Secondary Drinking Water Regulations (NSDWRs) that set non-mandatory water quality standards for 15 contaminants. EPA does not enforce these “secondary maximum contaminant levels” (SMCLs). They are established as guidelines to assist public water systems in managing their drinking water for aesthetic considerations, such as taste, color, and odor. These contaminants are not considered to present a risk to human health at the SMCL.
The TDS 400 mg/L SMCL established May 13, 2014. CMD has been exceeding the limit since it was imposed. If an SMCL is exceeded (such as TDS), further investigation may be required.
Conifer is a well-based community, so recharge of the fractured-rock aquifer is crucial to sustainability. Reverse Osmosis (RO) systems are used by several CMD users (Safeway, etc.) to reduce TDS levels for customers. The brine removed from the water, however, is returned to the collection system and recharged into the aquifer.
To address the TDS exceedance, last year CMD considered a surface discharge of the processed effluent. Quoting from the application for variance by the AquaWorks, CMD consultants:
To achieve compliance with the CDPHE Discharge Permit, CMD is requesting a change in limits.
When CDPHE opens the issue for public comment, the CAC Water Team will suggest that TDS levels above the SMCL require periodic analysis of the TDS composition as opposed to a violation and cease and desist.
The CAC Water Team has started to monitor TDS at various points in Conifer. Three are tap water readings (Staples, Safeway, King Soopers). All other readings are culverts or Church spigot.