Chesapeake Beach investigates intermittent high effluent readings as council approves $214,107 PLC upgrade

Chesapeake Beach wastewater staff told the Town Council on Sept. 18 that they have seen intermittent spikes in effluent readings and are conducting emergency measures while investigators work to identify the source.

The town's wastewater operator, Josh, told the council the plant completed a scheduled cleaning of filter No. 1 that produced performance gains — "the filter seems to be operating much better than it was before" — but that staff have seen unexplained, short-lived high readings in effluent tests after disinfection. Josh said the plant has run parallel samples and temporarily redirected flow to a shellfish tank and performed a full super‑chlorination of the effluent tank and piping "to try and eliminate whatever source that is." He said outside process‑control contractors are "perplexed" and staff are documenting all steps to avoid violating permit limits.

Council members and staff discussed possible causes. Josh said the town's test detects enzyme byproducts and may show a false positive; he mentioned Vibrio as one possible organism that could affect readings but said the test does not directly measure fecal coliform. Council members also asked about temperature and sampling cadence; Josh said the plant takes three samples a day per its permit and that temperatures rose during the recent hot weather but were decreasing.

The plant also reported several maintenance and procurement issues: an RFP for flow meters returned a single bid that exceeded the budget and will be reassessed; annual service and calibration were completed on the plant's Chemscan chemical analyzer; semiannual service on the emergency generator recommended battery replacement (batteries were last changed in February 2021); and the recent filter cleaning delivered about a 17% better cleaning effectiveness than expected based on microscopic and media‑weight analysis.

Separately, the council approved a $214,107.47 contract with IMAX to upgrade the plant's legacy Siemens PLC controls to Allen‑Bradley to restore reliable communications between older headworks equipment and the plant's newer SCADA systems. Town staff said the existing Siemens controllers are roughly 20 years old, parts are aging, and communications with off‑site SCADA were degraded; the upgrade aims to eliminate compatibility gaps and reduce operations risk. A motion to approve the contract passed (vote recorded as the ayes have it).

Town engineers also reported related work at the Seagate pump station: staff are coordinating a site meeting with the Maryland Department of the Environment, the U.S. Army Corps of Engineers and the Department of Natural Resources to explore whether the town can pump water to the bay, and attendees expect pretreatment requirements before any direct discharge would be permitted.

What happens next: staff will continue sampling and documentation and pursue further diagnostic work with contractors. If the super‑chlorination and sampling do not resolve the spikes, the town warned it could face required remediation by MDE and potential fines if permit limits are exceeded. The PLC upgrade contract is expected to proceed as approved and to reduce remote‑monitoring gaps once installed.