Thinking Outside The Box
4Pages

Dallas When the third set of results came back from the lab, sanitarians in three Iowa county health departments knew they had a problem. Effluent samples from the box-like sand filters were significantly out of compliance. The standard approach was to replace the failed sand filter with a new one, even though it was obvious the same problem would occur in a few years. To find a permanent solution, it was apparent to everyone involved that they must find a new approach. Background Information Dallas, Polk and Warren Counties encompass a large portion of Iowa’s farming community. The majority of this rural farmland falls outside the reaches of municipal sewers, so local residents must rely on innovative and alternative technologies for sewage treatment and disposal. For generations, much of the area’s livelihood has been dependent upon land use and conservation. To preserve this valuable resource and protect public health, the Iowa Department of Natural Resources instituted a general permit program. All onsite treatment systems installed under the requirements of Iowa’s statewide general permit must be maintained by a county authorized service provider. In addition, the effluent from each system must be routinely sampled and analyzed by a state approved laboratory to establish permit compliance. In the early Spring of 2000, Kathy Witkovski, an Environmental Health Specialist with Dallas County Environmental Health, began receiving unacceptable performance data from a number of onsite wastewater treatment systems. Dallas County and the Iowa Department of Natural Resources conducted a study to pinpoint the cause of the problem. Their study included a complete review of maintenance and service records and visual inspections. Approximately forty percent of the systems surveyed were failing. Sanitarians observed wastewater seeping out of the top of several single-pass sand filters and ponding on the surface of the ground. The sand filters, originally designed to polish effluent, were being overloaded organically and hydraulically. This condition caused the filters to overflow and bypass. Once Ms. Witkovski consulted sanitarians from nearby Polk and Warren Counties, it became obvious that the problem wasn’t limited to Dallas County. Polk and Warren County sanitarians were experiencing a similar situation. Hundreds of sand filters were malfunctioning and they knew something had to be done to protect the area’s water quality. “Many existing management programs are inadequate or too narrow in focus, allowing premature system failures to occur.” (USEPA Voluntary National Guidelines for Management of Decentralized Wastewater Treatment Systems) Polk Warren Thinking Outside The Box

- 2 - Iowa’s Requirements Under Iowa’s state code, Chapter 69, any wastewater discharge from onsite wastewater treatment and disposal systems is prohibited except under an NPDES general permit. Individual systems discharging effluent to the surface of the ground, into surface waters or into an underground drainage tile must adhere to the requirements of NPDES General Permit No. 4. This permit requires continuous monitoring of each system’s performance, including parameters for CBOD5 and TSS effluent concentrations. Neither result can exceed 25 mg/L. Sampling must be conducted by a...

removal during routine service. Unlike sand filters, the BK 2000 cannot be bypassed. If the filter is not serviced regularly, the homeowner will begin experiencing sluggish drainage from sinks and toilets, indicating service is necessary. A complete lack of service would eventually cause flow to backup into the facility and not allow overflow onto the ground surface. During service, solids are automatically returned to the primary treatment system. Off site disposal of contaminated filter media is eliminated. Treatment Efficiency The agencies issued county level variances allowing Capital...

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