Water Resources Professional Project Reports

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On-site wastewater treatment systems (OWTS) have been utilized to provide treatment and disposal for the Chical Area of the Pueblo of Isleta for over 30 years. The OWTS technology used here primarily consists of septic tanks and absorption fields. The groundwater below the Chical Area is a highly valued resource by the Isleta Pueblo, but the hydrogeology makes it vulnerable to contamination from OWTS. Most of these systems have been installed with the assistance from the Indian Health Service. However, Isleta has not developed a plan or management program to ensure that these OWTS are properly sited, constructed, operated or maintained. Over this time, the number of septic systems has increased and the trend continues due to unregulated housing development on the irrigated lands in the Chical Area. The Environmental Protection Agency (EPA) reports nationally that septic systems are utilized by 25% of existing homes and 33% of new homes. The more alarming statistics are that up to 30% fail annually and over 50% are over 30 years old (EPA, 2003). All homes in the Chical Area utilize septic systems and many existing systems are over 30 years old. In 2003, the EPA published its Voluntary National Guidelines for Management of Onsite and Clustered (Decentralized) Wastewater Treatment Systems (Management Guidelines). The intent of these guidelines is, "to improve the performance of decentralized wastewater systems through better management." This guidance is applicable to tribal government and their communities to improve OWTS management programs. Implementation of these guidelines will help insure that individual wastewater treatment systems function properly to protect public health, the environment, and water resources. The objective of this professional project report was to identify and recommend an OWTS management plan for the Chical Area and the Pueblo of Isleta. Five Conceptual Models from the EPA. Management Guidelines were reviewed and those management components found applicable were integrated to form the Chical Area OWTS Management Plan. Recommended management components include: 1) inventorying and evaluating OWTS performance and creating a data base; 2) OWTS are properly sited, designed, and constructed; 3) OWTS are periodically inspected and repaired when necessary; 4) professionally trained personnel perform system operation and maintenance service; and 5)the design of the OWTS is determined by performance criteria. The management components are to be implemented through a Tribal OWTS Management Program that assesses a fee for the O&M service to be provided.

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on-site wastewater treatment systems (OWTS), Indian Health Service, septic systems, non-point source pollution, primary treatment, biodegradation, EPA Management Models, performance criteria based management


A Professional Project Report Submitted in Partial Fulfillment of the Requirements for the Degree of Master of Water Resources, Policy Management Concentration, Water Resources Program, The University of New Mexico, Albuquerque, New Mexico,December 2005