Item A - PH on MWMC/Metro Plan - Laserfiche WebLink

Home Browse Search

ATTACHMENT 4 To 05-06-04 Draft MWMC Minutes calculated. Every year since the mid ~)r late 80s, because of water conservation efforts, our per capita consumption of water has declined. We flush our toilets with less water and use more efficient shower heads. Because of past drought years, we mm off the water while brushing our teeth rather than leaving the tap running, as was customary in the 70s. The Register Guard recently ran an article reporting that while the state population had grown by 17% (I believe since 1990), water consumption had increased by only 2% in the same period. Some of the water conservation results in water savings that do not impact our wastewater flows, better means of watering our lawns, for example; however, much of the conservation has occurred inside homes and businesses. The result is that the MWMC facility can actually serve a larger population than the 277,100 persons originally projected in the rrdd-7Os.[Under the same conditions and treatment levels established in 1977, there may be a small impact and a slight increase in population served. However, reduced water usage in homes does not translate to reduced organic loadings at treatment plants, which define capacity of some unit processes. Under required treatment levels established now and anticipated for 2025, this statement is absolutely incorrect. Seasonal variations in climate and I/I into the system have a much more significant impact on wastewater flows than do water conservation practices. There are three sources that we can use to determine how much facility capacity, still exists: The 1997 MWMC Master Plan prepared by CH2MI-Iill;['l'his plan is not based on the current NPDES permit and cannot be used to assess current capacity] the 2004 Draft MWMC Facilities Plan prepared by CH2MHill; and the 2002 'Fact Sheet and NPDES Wastewater Discharge Permit Evaluation prepared by the Department of Environmental Quality (DEQ).[This fact sheet was developed from information MWMC staff provided DEO in ~96 while applying for a permit .renewal The information was taken from the ~7 Master Plan. DEO took 5 years to respond to the permit renewal request and turned the application for permit renewal into a fact sheet in 2002 without updating the information.] The facility has many components but reference is frequently made to four more generic categories of capacity: (1) Liquid effluent dry weather flow, (2) liquid effluent wet weather flow, (3) BOD and TSS dry weather capacity, and (4) biosolids processing. It is important to look at each of the larger category's capacity individually. Liquid Effluent Dry Weather Capacity.: DEQ defines the dry season as May 1 through October 31, although the 2002 permit appears to extend the emergency overflow criteria for a storm event greater than the one- in-five-year, 24-hour duration storm through May 21 rather than May 1, and allows that same criteria to extend to June 1 if there is no increase in risk to beneficial uses. The facility has two important effluent dry weather design capacities. The average monthly dry weather flow capacity is 49 million gallons per day (mgds). The average monthly capacity most closely reflects the base flow from residences, businesses, and industrial Attachment 4 Page 6 of 17 4-9