New Territory Reclaimed Water Use for Subsidence Credits

Ft. Bend County, Texas, south of Houston, Texas, is experiencing ground subsidence due to over pumping of the groundwater aquifer for domestic and agricultural use. A Subsidence District was created by the State and Regulations have been issued requiring all Public Water suppliers to decrease their groundwater withdrawal by 30 percent by 2013 and 60 percent by 2025. Each user must identify their method of meeting this goal to avoid paying a Disincentive Fee. Some users are uniting to consider conversion to new surface water sources with water potentially available from the Brazos River Authority. Conservation and use of Reclaimed Water can also be considered. Each Water Utility must decide the combination of alternatives that best meets their rate payer's interest.New Territory is an upscale neighborhood in Ft. Bend County, Texas on the west City Limits of Sugar Land, Texas, just south of Houston. Ft. Bend Subsidence District has enacted water use regulations that require all significant groundwater users in the County to develop plans to reduce ground water use by 30 percent in 2013 and by 60 percent in 2025. This requirement is driven by a rapidly increasing population creating increased demand on groundwater resources, with attendant subsidence in the areas with withdrawals exceeding recharge. New Territory Residential Community Association, Inc. entered into contract with Kimley-Horn for a Water Reuse Feasibility Study. The goal of the Water Reuse Feasibility Study reported in this paper is to define the options for Reclaimed Water use as alternative water under the Subsidence District regulations for the New Territory Development in Ft. Bend County. Capital Cost and relative operating cost are identified in order to compare the cost and benefits of Reclaimed Water conversion with that of converting to use of surface water.New Territory, with 4600 homes, three schools, and several businesses, is served by five Municipal Utility Districts that jointly fund the operation of one wastewater treatment plant rated at 2.5 million gallons per day (MGD). The Permit Limits are 10 mg/l CBOD, 15 mg/l TSS, and 3 mg/l ammonia nitrogen. New Territory has significant landscape and lake amenities that currently use over 200 MG per year of potable water for irrigation and groundwater for lake maintenance. The Feasibility Study identified options within New Territory and adjoining developments to use the reclaimed water. The Study reports options for improvements within the wastewater treatment plant to upgrade the treatment to Type I reclaimed water for that component that can be effectively utilized. Customers are identified beyond the landscape and lake amenity use, pipeline routing options discussed, and impacts on installing a dual water system within an existing community are evaluated.The Study presents capital cost, phasing options, and the cost benefits to the New Territory residents by choosing to use reclaimed water as an alternative water source. The cost benefit is partially driven by the Subsidence District Disincentive Fee (3.25/1000 gallons) for all groundwater use that exceeds the cap established for each Permit. The incentive for conversion to Reclaimed Water is a 150 % credit for each gallon of reclaimed water use as alternative water. In addition, by reducing groundwater use, the annual pumping fee charged by the District is reduced. If New Territories is able to implement their use of Reclaimed Water prior to the 2013 deadline, they can “bank” Over-Conversion credits that could off-set future Disincentive Fees and/or extend the schedule for future capital expenditures to meet the 2025 requirements.The Study also identifies the advantages to New Territory to continue to participate within another group of Utilities in a jointly funded surface water plant. The construction schedule for the reclaimed water system allows it to come on line in advance of the proposed surface water facility, thus allowing New Territory to bank credits and reduce the amount of investment in the new surface water plant.