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MWMC WASTEWATER FACILITIES PLAN AND SYSTEM DEVELOPMENT CHARGE UPDATE - RESPONSE TO APRIL 2, 2004, QUESTIONS FROM EUGENE CHAMBER OF COMMERCE Dry Season Maximum Month Flow Historical and Projected o30~E40gs0~ ~ 20 [~ 2004 Facilities Plan-*-DEQ Methodology 10 1997 Master Plan -x-Historical Data 0 ' ' ' ' I .... I .... I 1990 2000 2010 2020 Year Also shown in this graph are the projections from a previous study (1997 Eugene- Springfield Water Pollution Control Facility Master Plan) and projections calculated using guidelines provided by the Oregon Department of Environmental Quality (DEQ). The 1997 study projected higher flows relative to the 2004 Facilities Plan projections because it considered a smaller historical data set that happened to be collected during a period of higher-than-average rainfall. Projections based on the DEQ guidelines, which result from historical rainfall data, are also higher than the 2004 Facilities Plan projections, which are based on historical WPCF flow data. MWMC is working with DEQ staff to determine whether the MWMC methodology results in an adequate dry weather flow projection, will provide adequate reliability in treating peak wet weather flows, and whether the historical methodology used by MWMC can be accepted as an alternative to the DEQ guidelines. 3. Comment: The 40% growth projection is inconsistent with the growth rate used in other planning activities (e.g., transportation, water, and power supply). The growth projection used for 2004 is about 36.7% at 2025. Typically, wastewater planning uses population projections deeeloped by the local planning jurisdiction(s). In this case, the Eugene-Springfield Metropolitan Area General Plan (Metro Plan) and its adopted functional plans have provided the basis for projecting population growth and land usage through the year 2015. Because the MWMC Facilities Plan is intended to serve the two cities plus the population in the River Road/Santa Clara area that is provided with sanitary sewerage through the year 2025, a population projection beyond the timeframe of the Metro Plan projection is necessary and required by DEQ for a 20-year plan. Population projections used in the 2004 Facilities Plan were determined assuming a 1.59% annual growth rate applied to the year 2002 population. This growth rate is based on historical growth rates for the community since 1990 (see graph). The graph also shows population as far back as 1970 for historical perspective. This is a downward revision of the CHAMBER OF COMMERCE RESPONSES FINAL.DOC PAGE 3 OF 8