On Thursday, July 30, 2009 the third meeting of the Virginia Department of Health “Alternative Onsite Sewage Systems Emergency Regulations Ad Hoc Committee” took place. I am a participant in the process representing the homeowner’s point of view. Legislation approved in 2009 (HB 2551, Acts of Assembly, 2009, Ch 220) requires the Board of Health to promulgate emergency regulations to establish performance requirements and horizontal setbacks necessary to protect public health and the environment for alternative on-site sewage systems. The regulations must go into effect no later than April 6, 2010 and must also contain Operation and Maintenance requirements for alternative on-site sewage systems.
Truthfully, the most stimulating (and thought provoking) discussion was a brief end of the day conversation between Bob Lee from the Loudon County Department of Health, Anish Jantrania of NW Cascade and an attorney (whose permission to use his name I failed to get). At the end of the meeting the meeting facilitator, Bruce Dotson, and Allen Knapp of the VDH assigned homework to Anish Jantrania to address the list of discussion topics to clustered alternative systems. Anish quickly assembled a small group to discuss how to best accomplish this goal and I eased dropped on their general discussion.
First a little background. Cluster systems are merely a large on-site waste disposal system designed to serve groups of homes using a single type of system or a combination of collection and treatment methods. I had always had an uneasy feeling about these systems because of human nature; I felt that if enough homes were clustered together, then individuals would take advantage of the anonymity to abuse the systems, excessive use of garbage disposal, household load and household chemicals. Without having to face the direct consequences of their actions or feeling that they were forced to face the consequences of other’s actions, people would not be “good” users of the systems. However, the use of cluster systems has a number of benefits and can be appropriate in small communities with small home lot size and a variety of site conditions. Decentralized clustered systems may be more desirable for ecologically sensitive areas because of the professional management and monitoring (i.e., where advanced treatment such as nutrient removal or disinfection is necessary such as beach and lake locations) and can also achieve cost savings while also recharging local aquifers. In addition, the professional management of the system may more than compensate for the anonymity factor. This may be a preferred solution for the tidally influenced areas of the Tidewater.
Cluster on-site waste systems typically serve fewer than a hundred homes, but they can serve more. Under this approach, septic tank effluent from each home is collected and routed to another site for further treatment and soil discharge. In some designs waste is pumped directly to the treatment site and primary treatment occurs at the treatment site instead of in individual home septic tanks. Collection and movement of raw or settled wastewater to the final treatment site can be accomplished by gravity, pressure, pump or vacuum systems.
As Anish and Bob Lee made clear, the advantages of these alternative collection systems include significantly lower capital cost, less opportunity for infiltration and inflow, and increased construction and location flexibility. This can be used to solve a wide variety of site challenges in an optimal fashion while allowing the development of the site. The off-site treatment facility is still close to the wastewater sources, and may or may not have some features that resemble a traditional small sewage treatment plant. The primary goals of such a facility are to either prepare the wastewater for dispersal back to ground water or provide reuse of the treated wastewater, usually for landscape irrigation. Regardless of the particular cluster system treatment technology selected, third-party sustainable management by an entity with the technical, financial, and managerial capacity to assure proper operation is required to ensure long-term service. Professional management and operation ensures consistent operation.
Treatment facilities range from sedimentation tanks and soil dispersal facilities to advanced treatment systems with distribution to drip irrigation fields or other reuse sites. Although some facilities use technologies similar to centralized treatment plants (such as trickling filters, aerobic tanks or lagoons, constructed wetlands, etc), most designers employ low-maintenance, upset-resistant alternatives that simplify and reduce operation and maintenance requirements. Final dispersal of treated effluent is usually to the soil, due to greater treatment advantages and avoidance of NPDES permitting, monitoring, reporting, and other requirements. However, cluster systems can be designed and permitted to discharge to surface waters, if necessary. What needs to be accomplished is to make the process and time frame of permitting a clustered system equivalent to the time frame and process of permitting the dozens of individual systems. Right now, it is much simplier and quicker for a developer to permit a single use system for each home rather than to design a superior system for the development as a whole.
There are numerous alternative treatment and/or dispersal system alternatives that can be used in areas where conventional septic systems cannot provide adequate treatment of wastewater effluent. These include mound systems, fixed-film contact units, constructed wetlands, low-pressure and drip dispersal, and advanced treatment systems. These systems, can be used in areas near sensitive surface waters or to protect sensitive groundwater resources. Alternative on-site systems are designed to promote degradation and/or treatment of wastes through biological processes, oxidation/reduction reactions, filtration, evapotranspiration, and enhanced soil application processes. Cluster systems often use suspended growth and attached growth facilities to effect better effluent steams without traditional leech fields. The cost of collecting and treatment wastewater from multiple facilities at a common treatment and dispersal/reuse site offers economies of scale that lower capital and operation/maintenance costs. Cluster systems are often designed to incorporate individual septic tanks for each property served to provide primary treatment and minimize fat, oil, grease, and solids loadings to the collection system and/or secondary treatment units.
(Note: Cluster systems that serve 20 or more people are regulated as Class V facilities under the federal Underground Injection Control Program. Thanks to the CA SWRCB for all their information and input.