Car wash flow data shows high sewer discharge; commission may require extra ERUs and backup data

Staff presented a spreadsheet the car wash owner submitted that afternoon showing an 18–19 day sample in which roughly 88% of incoming water was recorded as sewer discharge. Using fiscal‑year meter readings, staff estimated the car wash's annual discharge could require about 36 additional ERUs to cover actual use.

"Based on the numbers, 88% of their water intake is going into the system," staff said, summarizing the owner's flow‑assessment chart. Staff also noted they had not yet been able to independently log into the water district's system to verify the owner's exported data and has requested the water district logs and Flow Assessment backup documentation.

Board members raised technical questions about reclaim systems at the car wash, sand and solids removal, and whether periodic cleanouts or reclaimed water storage could explain days when recorded sewer discharge exceeded water intake. Commissioners directed staff to invite the owner and Flow Assessment (or the water district) to the board's next meeting with full backup so the commission can decide whether to adjust usage billing or require purchase of additional ERUs for capacity.