In a condominium, trustees, owners, managers, and developers are confronted each and every day with myriad infrastructure issues, each of which significantly affects the financial considerations of the development. Although not often a topic of polite conversation at social functions or even industry roundtables, waste- water management is typically a significant consideration for condominiums that are located in unsewered areas, where the condominium development must provide and manage its own wastewater collection, treatment, and dispersal system.

Effective System Design

Every home, regardless of whether it is a single family or a condominium, connected to a sewer line or to a septic tank, has to deal with the household's generated waste-water, typically 60 gallons per day (gpd) / person. Sewer system designers use the criteria of 200—250 gpd/residential unit. Houses connected to municipal sewers transfer the responsibility for treating and dispersing the treated effluent to the municipality in exchange for an annual fee, Homeowners with septic systems are managing their own wastewater treatment and dispersal system. Many condominiums in unsewered areas provide a community wastewater system comparable in purpose to a municipal system.

Wastewater management consists of three steps:

· Collection

· Treatment

· Dispersal/Reuse

Compared to minimum 8-inch gravity sewers with pump stations, alternative wastewater collection systems can provide significant cost savings for new developments. The alternatives collection systems are:

· Septic Tank Effluent (STE)

gravity and/or pressure

· Grinder pumps

· Vacuum sewers

Collection systems can represent 50—70 percent of the costs of a wastewater system.

Treatment requirements are dictated by both minimum standards and site-specific conditions. When designing a wastewater management system, the dispersal/reuse part of the system should be addressed first, before the treatment system is specified, because the dispersal/reuse application will dictate treatment requirements. One dispersal/reuse option worth considering is subsurface drip irrigation. This approach reduces water demands for irrigation and, therefore, provides not only significant economic returns, but also environmental benefits. Although irrigation systems may be the exception rather than the rule in condominiums, their use for treated wastewater reuse/dispersal can create an attractive amenity associated with the functional aspects of wastewater dispersal. Condominiums that are located in unsewered areas are often large enough to require state groundwater discharge permits, which are issued in Massachusetts, Connecticut, and Maine by the Department of Environmental Protection. In Rhode Island, the permitting agency is the Department of Environmental Management; in New Hampshire, the Department of Environmental Ser- vices; and in Vermont, the Department of Environmental Conservation.

The required treatment performance of a wastewater system is dictated not only by minimum standards, but also by requirements that are driven by the environmental sensitivity of the area in which the treated wastewater is being dispersed. For example, in water supply aquifers and coastal areas, minimum nitrogen removal requirements for dispersal areas will be higher than other areas. Nitrogen is a persistent problem in water supply, and high levels in drinking water are known to cause blue-baby syndrome in infants. Nitrogen is a fertilizer, and its presence in coastal waters causes exces- ssive algae growth and consequent ecological decline. Recent examples of this growth and decline have occurred in Long Island Sound, Cape Cod, and other New England coastal waters. Acceptable levels of nitrate nitrogen in drinking are determined by the U.S. Environmental Protection Agency, which has set a standard of 10 mg per liter. By contrast, in coastal waters, nitrogen levels above 0.3 mg per liter will cause severe water quality degradation and ecological decline, including the loss of sea grasses and shellfish.

Wastewater Treatment Considerations

Wastewater treatment is a complex science that requires the integration of physical, chemical, and biological mechanisms to remove both human-introduced and natural-occurring chemicals that affect aquatic life and human water uses.

The primary issues associated with wastewater treatment are:

· Organic material degradation, which is measured as Biological Oxygen Demand (BOD) and Total Suspended Solids (TSS)

· Pathogen Removal, which is measured as the concentration of fecal coliform or E. coli

· Nutrients, a measure of the quantity of nitrogen and phosphorus

Limitations of the amount of phosphorus in wastewater are generally required only in freshwater areas where phosphorus is the nutrient that controls algae growth, which, in turn, affects water quality. Phosphorus concentrations above 0.03—0.05 mg per liter in freshwater bodies, including lakes and rivers, will cause excessive algal growth and create highly undesirable, sometimes toxic, conditions. For reference purposes, nitrogen and phosphorus concentrations in wastewater are typically 60 mg per liter and 6—10 mg per liter, respectively.

In condominium wastewater treatment systems, the typical requirements for wastewater are defined in Figure 1.

For existing condominium wastewater treatment systems in environ- mentally sensitive areas, treatment requirements may become more stringent when permits are renewed, particularly for nitrogen and phosphorus removal, as the need for and ability to achieve stricter standards are recognized.

Operation and maintenance of condominium wastewater systems can be both expensive and a management headache. The good news is that new passive wastewater systems require less operational and maintenance attention and are highly reliable. The most sophisticated piece of equipment in these systems can be a small pump. Using low-cost telemetry and Web-based electronics, a manager or engineer can monitor a system without being on-site. This is important to a condominium's bottom line because, with regulatory approval, these techniques can reduce a significant (up to 40—50 percent) portion of the condo's annual operating and maintenance costs.

A Case Study

Stringent nitrogen removal requirements are a real life issue for condominiums located in the coastal areas of New England. Hundreds of millions of dollars have been spent to remove wastewater nitrogen in the efforts to restore Long Island Sound, and more funds will be required to restore the other New England coastal waters, especially along the Rhode Island and Cape Cod coastlines.

By way of example, consider the Main Street Village in Mashpee, Massachusetts, a mixed-use residential and commercial community with the atmosphere of a small New England village. The development broke ground in early fall of 2004 and was fully occupied and operational in early 2006. The development is owned by Southside Realty Trust and consists of individually owned units and condo units both of which are managed by a homeowners association. The development was developed by McShane Construction, and Horsley & Witten, Inc., served as the project's wastewater collection and dispersal engineer. My own company, Lombardo Associates, Inc., served as the wastewater treatment design-build-operate engineer.

The development has 24 residential units of mixed housing styles and 9,800 square feet of attractive commercial space. Housing prices ranged from the low $300's to mid-$400's, and condominiums were in the $200,000 price bracket.

The community's wastewater system is located in an area defined by the Massachusetts Department of Environmental Protection as a Zone II of a public water supply well. Zone II areas contribute to a water supply well and are, therefore, nitrogen-sensitive. Additionally the area drains to the nitrogen-sensitive coastal waters of Mashpee, Massachusetts. The required capacity of the wastewater system is 5,226 gallons per day (gpd).

To solve the wastewater challenge, McShane elected to install a wastewater management system that included a nitrogen filtration component. The drainfield area was 7,062 square feet.

The development is served with town water. The wastewater treatment system consists of a septic tank, a biofilter, and a nitrogen-specific filter to reduce effluent total nitrogen prior to treated wastewater being discharged to the drainfield.

The wastewater system's process flow diagram is illustrated in Figure 2.

After the start-up period, wastewater effluent total nitrogen levels have been < 3—5 mg/l as follows, comparable in performance to the most sophisticated centralized wastewater treatment plant. Effluent BOD and TSS are < 20 mg/l and < 10 mg/l, respectively.

Operations and maintenance requirements for the system are limited to monthly visits for routine maintenance and sampling to document treatment system performance. Daily electrical consumption is approximately 5 KWH, or $0.75/day with electric unit costs of $0.15/KWH. Remote monitoring of flow and notification of alarm conditions are conducted via remote phone connections. No chemicals and no other utilities are required.

The results in the Mashpee case study are similar to results achieved in installations in Cape Cod, Oregon, Montana, and Canada, all of which demonstrate that high levels of nitrogen removal can be achieved with small, passive systems.

The expected life of the nitrogen filter is more than 20 years, and the technology demonstrates that decentralized wastewater systems can offer performance similar to that of centralized facilities. Decentralized systems can achieve acceptable levels of total nitrogen (< 3—5 mg/l) and are another tool for condominium owners who live in nitrogen-sensitive areas.

This case study illustrates that condominiums can achieve the highest level of wastewater treatment with passive systems that require low levels of maintenance and provide environmental protection at an affordable cost with minimal management requirements.