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engineering planning environmental construction 701 Xenia Avenue South Suite 300 Minneapolis, MN 55416 Tel: 763-541-4800 Fax: 763-541-1700 Equal Opportunity Employer wsbeng.com January 21, 2016 Mr. Mike Grochala, AICP Community Development Director City of Lino Lakes 600 Town Center Pkwy Lino Lakes, MN 55015 Re: Mattamy Homes Water Reuse – Water Balance Technical Memorandum WSB Project Number 02988-01 Dear Mr. Grochala: We are providing you this technical memorandum to summarize the results of the water balance model for the water reuse feasibility study in the Mattamy Homes development. This document describes the methodology used to calculate the quantity of stormwater available and the amount used for irrigation purposes. Project Background The City of Lino Lakes wishes to implement a water reuse program using water from the lake in the Mattamy Homes development to irrigate portions of the development. There are three potential scales with respect to water reuse that were evaluated. The first is using water in the lake to irrigate the development’s park and the berms on the eastern edge of the development. The second is to irrigate the park and the berms as well as the townhomes in the southeastern corner of the development. Finally, the water balance modeled the feasibility of irrigating the entire development, including single-family homes, with water from the lake. Water Balance Theory The water balance presented in this document evaluates the amount of water provided to the pond via stormwater runoff, the amount that will be withdrawn for irrigation, and the resulting lake levels. The estimate takes into consideration precipitation, runoff, evaporation, irrigation demand, and pond overflow. While water balances rely on historic data and do not predict future climate patterns, they are a helpful tool when determining if stormwater irrigation is feasible, and if so, whether or not potable water augmentation will be required. Calculating Drainage Area To determine the amount of water available for irrigation, the drainage area to the lake was taken from the current Lino Lakes Northeast Study being conducted by WSB & Associates for the City. In addition, drainage information was obtained from the the developer to estimate the area in the future development that will drain to the lake.