Cluster Wastewater Systems Planning Handbook群污水系统规划手册.pdf

Cluster Wastewater Systems A cluster wastewater system is one which serves more than one property, with sizes ranging from a few homes up to several hundred homes and/or businesses. Conceptual illustrations of clustered wastewater collection and treatment systems are shown on the following pages. An appropriate method of treatment is provided prior to final effluent distribution/disposition using a suitable subsurface or surface effluent dispersal method. The method of treatment and final dispersal of effluent are based on local conditions and treatment needs, and applicable regulatory requirements. Homes and businesses served by cluster systems may be at varying distances from each other. Primary treatment of wastewater for cluster systems served by small diameter effluent collection systems (gravity or pumped) is provided at the home or business with a properly designed and sized septic tank. Effluent filters or screens are used at the outlets of the septic tank or pump tank to prevent larger solids (greater than 1/8”) from entering the shared portions of the system. Shut-off, or isolation valves are installed at each property served, and other appropriate valving is used to isolate and service portions of the system as needed. The use of cluster systems for wastewater service can offer a number of economic and environmental benefits. Those include: • Site disruption, including erosion and sedimentation impacts, can be substantially reduced on each property if only a septic tank and possibly a pump tank is needed, rather than an entire treatment and disposal system constructed for each individual site. • One treatment and final dispersal system serving multiple properties can offer savings through economies of scale to those served. This is due to reduced initial capital costs per property, as well as lower long term operation and maintenance costs (costs