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ATTACHMENT 4 To 05-06-04 Draft MWMC Minutes To summarize flue availability of dry weather effluent capacity, seven years ago, the MWMC Master Plan estimated that we were using 53% of our dry weather capacity. Five years later, in 2002, DEQ dismissed the importance of even discussing the liquid effluent dry weather capacity and noted that thereal issue was the amount of capacity for treatment of organic loads (such as BOD and TSS) [This is incorrect. With the new NPDES permit, nitrification and secondary clarification control secondary treatment capacity.] and estimated that capacity at approximately 60%. Two years [This was actually 7.5 years later, as the fact sheet was based on information supplied in 1996, as the date of the fact sheet implies] later, using the numbers provided by CH2MHill in the draft facilities plan, the estimated the dry weather average month capacity would be just over 60% and the dry season maximum month at just under 70%. However, CH2MHill is also estimating that UI will be reduced by approximately 17% during the planning period, which would make more dry season maximum capacity available [This is incorrect, the reduction of wet season I/I will not make more capacity available for dry season] (Draft System Development Charge Methodology (page C-2). All three of the sources indicate that we have substantial dry weather capacity remaining in the facility, which is what we would expect, given the reduced population projections and the effect of water conservation efforts on plant flows. [As stated earlier, the sources obtained there information from the same source - a capacity assessment done over 7 years ago done under a different NPDES permit (i.e. no ammonia limit). Also, Water conservation efforts do not reduce organic loading.] However, CH2MHill does contend in the proposed System Development Charge Methodology that the available dry weather capacity is substantially less than that provided by the other sources. In that document, CH2MHill claims that we are Currently using 89% of our liquid effluent dry weather capacity. CH2MHill arrives at that conclusion by calculating the available capacity differently than they did in the Master Plan or than DEQ does in its evaluation of the plant capacity. [As stated earlier, DEQ never did any evaluation. They took what was given to them in ~9~}6 and included it in the 2002 permit fact sheet. DEQ is currently requiring MWMC /CH2M HILL to use maximum month when assessing capacity.] In the Master Plan CH2MHill arrived at the dry weather capacity by comparing the dry season maximum month design capacity of 66 mgds with the dry season maximum month flows (apples to apples). DEQ compared the dry season average month design capacity of 49 mgds with the dry season average flows (apples to apples). [DEO has requested that this be the apprOach taken.] In the system development charge methodology, CH2MHill compares the dry season average flow design (49 mgds) with the dry season maximum monthly flow (apples to oranges). The design capacity used does not include any significant I/I, but the maximum monthly flow does. Needless to say, the available capacity evaporates immediately, and we go from having 40% of the dry season capacity available to meet future needs to having only 11% of the dry season capacity available. That is an incredible difference. While I haven't seen any place in the facility plan where Attachment 4 Page 9 of 17 4-12