2023-08-22 - Permit Narratives Form - Lagoon Seepage Analysis No. 1.pdf

The document is a Permit Narrative Conditions Report Form submitted by the Town of Hot Sulphur Springs to the Colorado Water Quality Control Division, specifically related to a Wastewater Treatment Plant (WWTP) lagoon seepage evaluation. The report, prepared by Element Engineering LLC on August 22, 2023, details a preliminary analysis of the town's wastewater treatment facility's lagoon seepage, comparing pan evaporation data, influent and effluent flow data, and rainfall data. The study was conducted to assess the lagoon's compliance with Colorado Department of Public Health and Environment (CDPHE) regulations regarding seepage rates.

The engineering analysis revealed that the lagoon ponds are seeping at a rate of 1.54x10^-6 cm/sec, which exceeds the allowable limit of 10^-6 cm/sec set by CDPHE regulations. Element Engineering identified potential inaccuracies in flow measurements due to a degrading weir and recommended that the town replace the existing 90-degree V-notch weir with a 45-degree weir to improve measurement accuracy. The report suggests that the pond liners are not acceptable and are leaking at a rate greater than permitted, which may require further investigation or remediation of the wastewater treatment facility's infrastructure.