Questions are being asked about the OSCC law suit and what really is the impact of plant discharges. The following is offered to help explain how a few days of discharge of partially treated effluent can be called “1274 violations” by the plaintiff.

The suit lists 32 days, between October 27, 1994 and March 24, 1998, when plant discharges were in excess of permit limits, totaling 184 violations. The plaintiff then extends these figures to their calculation of 1274 “violation days”.

To get to these figures one must understand the structure of the National Pollutant Discharge Elimination System (NPDES) permit. Under the permit three components of effluent are measured: Biochemical Oxygen Demand (BOD), Total Suspended Solids (TSS) and Fecal (FC). Further, BOD and TSS have monthly and weekly average concentration limits, monthly, weekly and daily mass load limits (expressed in pounds), and monthly removal efficiency requirement of 85%. Fecal is controlled by colonies per 100 milliliter of effluent, weekly and monthly.

The result of all this is that during heavy rains and high ground water conditions, which overload the plant hydraulically causing discharge of effluent which does not meet permit requirements, 2 or 3 days of such discharge condition could mean the plant would not meet BOD and TSS weekly and/or monthly requirements for Concentration, Mass Load Limits, and Daily Removal requirements, plus weekly and monthly Fecal Concentration limits for potentially as many as 18 violations for 3 days discharge. This gets us to the 184 violations for 32 days discharge of partially treated effluent. The plaintiff then claims that if a bypass event causes the weekly or monthly average for any permit parameter to exceed the permit, then all the days in that week or month would also count as “violation days” even though no actual permit parameter may be exceeded on most of those days. This “multiplier” is how they come up with 1274 “violation days” - all from 32 days, primarily mid-winter, spread over 3 1/2 years.

I have stressed “partially treated effluent” in the above discussion because it should be understood what is being discharged when the plant bypasses. The term bypass means that one or more processes in the plant do not complete their phase of treatment, such as aeration, clarification, chlorine contact, etc. Because all wastewater entering the plant first goes through pumping, then fine screening (0.060” opening vertical screens), the wastewater entering the treatment process train looks like muddy water. When the plant is overloaded the aeration basin may discharge to chlorine contact, then the outfall; or the clarifiers may “bulk”, that is, some of the suspended solids which should be settling in the bottom of the clarifier for pumping to the digester flow out of the top discharge of the clarifier, to chlorine contact and the outfall. When the plant is not meeting permit effluent requirements the discharge to the river would appear as cloudy or brown colored water.

The City has recognized that the plant needs improving; we are now midway through the design of the plant, with construction slated for next year, completion fall of 2000. This schedule, and the level of improvements required, is a part of the requirements laid upon the City under the Mutual Agreement and Order signed with Department of Environmental Quality. In addition, other improvements, or provision for improvements, have been accomplished:
 

Fiscal Year	Project	Cost $	Funds
FY 90	Capacity study of existing collection system and preliminary feasibility of north interceptor	23,000	SDC
FY 91	Add 3rd headworks screen Acquire abutting property	60,000 60,000	SDC SDC
FY 93	Acquire abutting property	40,000	SDC
FY 94	Acquire abutting property Add solids thinckening facility	40,000 680,000	SDC SDC
FY 97	Wastewater Facilities Plan Main replacement project	200,000 216,000	SDC/user* user
FY 98	Ivy Street pump station improvements Treatment Plant design, start construction	145,000 3,900,000	SDC/user SDC/user*
FY 99/00	Complete plant improvements	9,000,000**	SDC/user*
	* 20 year bonding through DEQ State Revolving Fund ** approx.

Ongoing will be the effort to reduce infiltration and inflow in the collection system, including replacing or repairing leaking mains; working with property owners to repair faulty laterals, sealing the tops of manholes, etc. This work will require an increased effort in line cleaning and TV’ing of all older mains and suspect lines and laterals. Though difficult to quantify costs until the TV work (estimated at $50,000) is done, the total effort could exceed $500,000.