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I I I I I I I I I I I I I I I I I I I Service Area and Future Urban Landscape Water B!guirements Service Area and Irriaated Area The conceptualized pressurized pipe system will serve an area of approximately 14,583 acres. This area was determined from the following assumption, as directed by the Highland Ditch Company Board of Directors. Approximately 5/6th of the total company service area (35,000 acres) is in Weld County, The other 1/6th is in Boulder County and development is not anticipated. Of the 5/6th service area within Weld County, the BOD estimated that 50% would become multi-use developments, including residential and commercial sites that could benefit from a dual water system for landscape irrigation. Therefore, 14,583 acres [(5/6)*(35,000)*(50%)] are considered to be the potential service area for secondary supply. Several assumptions were made to determine the water use requirements and overall sizing of the pump stations and pipelines. The first assumption is the actual future irrigated area to be served by the system. The irrigated area is the fraction of total service area to be irrigated with landscape irrigation systems. These areas include parks, open spaces, rights-of-way, golf courses, streetscapes, commercial lots, schools and public spaces, multi-family housing areas, and individual residential lots. For the water requirement elements of the study, it was assumed that the actual irrigated area was 30% of the service area, or about 4,375 acres, Experience has shown that irrigated area can range from 20% to 40% of a development site, which is a function of the type of construction and local development and landscape requirements. For instance, a commercial development may only have 20% of the area irrigated while an "estate" type residential development may have 40% of the area irrigated or a golf course or park site may have 90% to 100% of the area irrigated. Considering a mixed land use development (including parks and subdivision residential lots), the assumption of 30% of the total area irrigated is reasonable for this study. Water Reauirements The peak season daily water use was calculated for 4,375 acres. It was assumed that irrigation will occur over an average 12-hour watering window, seven days per week. Water requirements were calculated based on historical averages, turf water requirements, and assumptions made during this modernization feasibility study. Peak season daily application rate in the Longmont area is estimated to be 0.29 inches for bluegrass turf. The crop coefficient used for turf is 80%. The crop coefficient is a parameter used to scale potential evaporation and transpiration (evapotranspiration) to the actual levels for the particular crop, which was assumed to be entirely bluegrass turf for simplifying this analysis. Bluegrass is more of a water consumer than other common grass varieties and the seasonal water requirement for bluegrass also compares favorably with most mature shrub bed plantings. Therefore, a bluegrass assumption, for purposes of this analysis, is somewhat conservative, Aqua Engineering, Inc. November 8, 2004 Canal Modernization Feasibility Study - 8 -