Care & Feeding

A higher level treatment (HLT) system is a type of onsite wastewater treatment system (OWTS) that uses mechanical components to provide improved wastewater quality. These systems are typically required when minimum setbacks to wells cannot be met, on smaller lots and to prevent further groundwater degradation in acres of known contamination, such as Indian Hills. While a few older HLT consist of recirculating sand filter beds, most are manufactured units which have passed a rigorous national certification requirement known as NSF 245. Trade names for these systems include aeration systems such as HOOT® and MicroFAST®, as well as Trickling Media Filters such as Advantex®. Although most of the treatment is provided within the HLT unit itself, final disposal will take place in a regular absorption bed or leaching field, where the soil will provide additional treatment before the wastewater re-enters the ground water cycle.

How They Work

Aeration Type Systems

Septic tank with a blower.Aeration type systems consist of a specialized septic tank with a blower or impeller that introduces air into the wastewater through agitation. This process encourages bacterial growth and provides improved treatment. Usually, the blower will be placed at or near the tank in a small box on the ground surface. Most blowers will run continually and should be kept free of snow and ice that could impede airflow. Blowers operate quietly but if you cannot hear it working, you should call your service provider for assistance.

Trickling Media Filter Systems

A typical trickling filter pod outside.Trickling media filter systems operate by spraying wastewater across a series of hanging fabric sheets within a treatment pod. It then trickles down the fabric where air interacts with the water in a way that also encourages bacterial growth and improved treatment. Typically, these systems do not have blowers or aerators, although a pump is needed to circulate the wastewater through the filters. As with other HLT systems, once the wastewater is treated it is conveyed to an absorption bed or leaching field for final disposal.

Control Boxes

A control Box with alarm mounted on wall.All HLT will have a control box of some kind to regulate the electrical and mechanical operation of the system. These boxes may be located on a post next to the tank or more commonly, on the structure it serves. Often these boxes will have a visual and audible alarm to indicate if there is a problem with the system. Should you see or hear an alarm it is important to contact your service provider to diagnose and fix the problem. Failure to do so may cause significant (and expensive) damage to the system.

Operation & Maintenance Service Providers

Since proper operation and maintenance of HLT systems is beyond the ability of the average homeowner, the Department requires that routine service be performed by a service provider who has taken the necessary nationally-recognized training to do so. 

Service Contracts

To provide the required maintenance, most service providers will enter into a contract with the homeowner. This contract should be for a specific time period and provide for routine service inspections every 6 months in accordance with department requirements. Responding to alarms or other emergencies is typically billed as a separate item. Multi-year contracts are usually paid on an annual basis. Be sure to obtain a detailed list of services to be provided and the associated costs. The service providers are required to notify the Department if a contract is terminated.

Operating Permits

Due to the complexity of HLT systems and the need for ongoing routine maintenance, these systems are required to have an operating permit effective January 1, 2015. These permits will be issued when the current service contract is renewed and will run for the length of the new service contract. The permit will require service and maintenance inspections, typically every six months, along with specific reporting requirements to verify that the work was completed.

The Department will issue the initial operating permit at no charge; renewals will be assessed a nominal fee. These fees are in addition to the actual cost of the contract itself with the service provider.

The service provider will report all inspection visits to the Department as they are completed. Upon review, we will also notify the homeowner of what was done and whether any problems were noted and corrected. Since proper maintenance is critical to HLT operation, the Department has the right to initiate legal action for failure to maintain an Operating Permit or failure to perform and report the required service visits.