The 10-year-long disagreement between the Colorado Department of Health and Environment and Cherokee Metropolitan District over Cherokee’s wastewater treatment plant could finally be settled, with a plant upgrade.The problem has been the total dissolved solids. TDS are mostly salts found naturally occurring in ground and surface water and also added through household and commercial uses. In 2008, when the plant was designed, the state imposed no limit on TDS in treated wastewater discharged into groundwater.The Cherokee wastewater treatment plant was ìbuilt exactly as designed and permitted by the state,î said Amy Lathen, general manager of Cherokee. Lathen was responding to the claim by Meridian Metropolitan Service District that the current non-compliance of the plant was caused by design and construction defects that Cherokee caused or allowed to happen.ìWe have met every order for compliance,î Lathen said.In March 2010, the state issued a draft discharge permit for the plant that for the first time included a limit for TDS of 400 parts-per-million discharged into groundwater. In April 2010, Cherokee requested a revision to the TDS limit. The request was denied and a final discharge permit of 400 parts-per-million became effective June 12, 2010. Because the plant became operational about that time, Cherokee officials felt they had no choice but to begin receiving wastewater flows as designed and contracted. Since that time, Cherokee officials have unsuccessfully tried several times for a variance on the 400 parts-per-million.The U.S. Environmental Protection Agency states that TDS in drinking water are not health threatening. However, according to the EPA, a TDS level of 500 could cause water to appear cloudy or colored or smell or taste bad.According to the World Health Organization, a TDS level of less than 300 is excellent. A TDS level of between 300 and 600 is good, between 600 and 900 is fair, between 900 and 1200 is poor and over 1200 is unacceptable.Lathen said the Cherokee plant averages 550 parts-per-million for TDS.It is Cherokee’s position that since the plant became operational in mid 2010, it has functioned as originally designed and permitted. Between 2010 and 2014, Cherokee engaged in investigative and legal actions related to the construction of the rapid infiltration (discharge) basins, but those construction issues were unrelated to the stateís imposition of TDS standards.After extensive negotiations, on May 14, 2014, the state issued a Compliance Order on Consent that required actions and timelines leading to compliance of all permit restrictions.In March 2017, Cherokee began moving forward with plans to upgrade the plant with a reverse osmosis treatment system. This is a high-density membrane filtration system designed to remove TDS from the treated wastewater before being discharged into groundwater. In February 2019, Cherokee submitted preliminary designs as required by the compliance order timeline, which were subsequently approved by the state.In August 2019, the Cherokee board of directors approved a design-build engineering firm for final design of the upgrade to reverse osmosis. Construction is scheduled to begin this year, with completion scheduled for 2022. Throughout this entire process, Cherokee officials have stated they have remained on schedule with all mandated requirements. To pay the estimated $40 million to upgrade the system to come into compliance with TDS limitations, Cherokee has instituted a surcharge of $5.07 per month, separate from water and wastewater rates, on all residential users of the system. At the present time, users in Meridian Ranch do not pay this surcharge because of ongoing arbitration. That surcharge will be used exclusively for costs relating to the plant upgrade and meeting TDS limitations. Editor’s note: In the preparation of last month’s article on wastewater treatment, through communication errors, The New Falcon Herald was not able to contact Cherokee officials. We acted in good faith to contact someone from Cherokee. The telephone messages that were left apparently did not get to the right person, and we had an incorrect email address. Since that time, The New Falcon Herald has been in contact with Amy Lathen, general manager, who has been cooperative and transparent in answering questions. She has also furnished written documentation.
