Chapter 13.24
CLASSIFICATION OF HIGH‑STRENGTH WASTEWATER, CHARGES ASSOCIATED WITH SUCH DISCHARGES, AND PRETREATMENT REQUIREMENTS
Sections:
13.24.030 Standard Industry Code classifications.
13.24.050 Alternate approach to determination of rates.
13.24.010 Purpose.
The purpose of this chapter is to classify high-strength wastewater and establish special wastewater rates for users of the city’s sewer system which generate certain high‑strength wastes or have high variability in waste loadings and identify pretreatment requirements. It is intended that such special rates will provide a system of charges which equitably reflect the costs to the city of treating such wastes. (Ord. 2579 § 1, 1997; Ord. 2343 § 1, 1993).
13.24.020 Permission to discharge high-strength waste – Pretreatment requirements – Grease traps required.
A. Any person or business proposing to discharge high-strength wastes to the city’s sewer system shall apply to the public works director for approval to discharge. The public works director may establish conditions for discharge and monitoring requirements as further established in this chapter.
B. Whenever preliminary treatment is necessary to reduce the strength of the waste to within the maximum limits prescribed by Chapter 13.21 PTMC, such preliminary treatment shall be at the sole expense of the owner of the premises and shall be installed when the director determines that the same is necessary to comply with the standards prescribed. In such cases, all plans, specifications and other pertinent information relating to such proposed preliminary treatment facilities shall be submitted to the director prior to commencement of construction and no construction thereof shall be commenced until the director’s approval is noted on the plan. In the event of such installations, they shall be maintained continuously in efficient operation by the owner at his or her own expense.
C. Grease traps will be required on all restaurants or other establishments as determined necessary by the public works director. All costs associated with design, installation and maintenance to insure a working, reliable grease trap system will be the responsibility of the owner. (Ord. 2579 § 1, 1997).
13.24.030 Standard Industry Code classifications.
A. The following types of business activities shall be assigned Standard Industry Code (“SIC”) classifications as indicated below:
|
Business Activity |
Classification |
|
Brewery |
SIC #4 |
|
Restaurants/taverns full‑service |
SIC #3 |
|
Fast food |
SIC #3 |
|
Prepackaged servers |
SIC #1 |
|
Supermarkets: |
|
|
with deli, bakery, etc. |
SIC #3 |
|
without deli, bakery, etc. |
SIC #1 |
|
Convenience stores |
SIC #1 |
|
Canneries (food processors) |
SIC #4 |
|
Convalescent homes |
SIC #3 |
|
Marinas |
SIC #3 |
|
Washington State Ferries |
SIC #4 |
B. Each commercial and industrial account shall be assigned to a SIC by the director of public works based on a review of the wastewater discharges from each account. (Ord. 2579 § 1, 1997; Ord. 2343 § 1, 1993).
13.24.040 Commodity charge.
A. A commodity charge shall be based on water use and wastewater strength. Charges shall be on a block rate, with the block rate increasing based on strength of the waste, as follows:
|
Classification |
Surcharge above commodity charge as identified in Chapter 13.05 PTMC |
|
SIC #1 |
|
|
< 300 mg/l BOD or TSS |
$0.00/1,000 gallons |
|
SIC #2 |
|
|
301 – 500 mg/l BOD or TSS |
$0.00/1,000 gallons |
|
SIC #3 |
|
|
501 – 700 mg/l BOD or TSS |
$0.00/1,000 gallons |
|
SIC #4 |
|
|
>700 mg/l BOD or TSS or |
$0.88/1,000 gallons |
|
variability in loadings * |
plus $0.98/lb BOD |
|
|
plus $0.62/lb TSS |
*Such as Washington State Ferries or other users with instantaneous discharges or other use that causes wide swings in either wastewater quantity or strength that may cause collection or interceptor sewer concerns or potential adverse impacts on the wastewater treatment plant process. The city has the option to monitor and/or test the quality of these wastes or assume that the strength is 700 mg/l for BOD and/or TSS.
B. Water use may be measured at the customer’s water meter, or by installation of a wastewater meter per PTMC 13.24.050. (Ord. 2579 § 1, 1997; Ord. 2343 § 1, 1993).
13.24.050 Alternate approach to determination of rates.
When the director deems necessary, or when any sewer customer believes they have been assigned a Standard Industrial Code classification which is not appropriate, the sewer rate may be determined as follows and the customer shall pay the city a monthly fee based upon the actual use of the city wastewater treatment facility as measured by parameters which shall be determined in accordance with the following procedures:
A. Metering. The wastewater flow into the sewerage system will be metered at the point where the facility discharges wastewater into the city system. The cost of installation and maintenance of the meter shall be paid by the customer. The flow metering installation at the facility shall be calibrated quarterly and equipped with a totalizer. Daily maintenance by the facility shall include at least a check of the primary element of the flow meter for obstructions and a visual check of all other elements of the installation for normal operation. A daily log shall be kept by the facility in which all maintenance operations performed and any abnormalities observed shall be noted. The totalizer reading shall also be recorded daily in the log. At the end of each month, the average daily flow during the month shall be determined by using all the valid data collected during the month (total flow divided by days of operation).
B. BOD and Suspended Solids. The monitoring facility shall be equipped with an automatic liquid sampling device which shall be integrated with the flow‑metering installation in such a manner that wastewater samples can be collected on a flow‑weighted basis and stored. A composite sample shall be prepared weekly, as directed by the city, from all samples collected during a uniform 24‑hour period. The BOD and SS of each sample shall be determined and recorded in the log. At the end of each month, the average BOD and TSS during the month shall be determined by using all the valid data collected during the month. After a period of one year, the city may reduce the frequency of monitoring (provided there are no other constraints such as a Department of Ecology permit precluding less frequent monitoring).
C. Records. The facility shall maintain records of all information resulting from any monitoring activities. Such records for all samples shall include:
1. The date, exact place, method and time of sampling;
2. The names of persons taking the sample;
3. The date the analysis was done;
4. The names of persons doing the analysis;
5. The analytical techniques used;
6. The results of the analysis.
D. Calculation of Maintenance and Operation Expenses. The data collected shall be used by the city to calculate the share of the total maintenance and operation expenses which shall be charged to the facility. The method of calculation of maintenance and operation expenses to be charged shall be as follows:
1. O&M charge to the facility during billing period = cost factor x monthly city treatment facility O&M cost.
2. Cost factor = (Vf/Vc)(0.2 + 0.4 BODf/BODc + 0.4 TSSf/TSSc).
where:
|
Vf = |
average daily wastewater flow (in gallons) from the facility during billing period. |
|
Vc = |
average daily wastewater flow for the city of Port Townsend wastewater treatment facility plant during billing period (gallons). |
|
BODf = |
average daily five‑day BOD concentration of wastewater from the facility during billing period. |
|
BODc = |
average daily five‑day BOD concentration of total plant wastewater during billing period. |
|
TSSf = |
average daily TSS concentration of wastewater from the facility during billing period. |
|
TSSc = |
average daily TSS concentration of wastewater of total plant during billing period. |
E. Lab Testing. One set of BOD, FOG (fat, oil and grease), TSS (total suspended solids), VSS (volatile suspended solids) and pH tests will be required on a composite sample collected by the sewer customer on a weekly basis, or other tests and/or testing intervals as determined by the director, while the facility discharges to the city sewer system. Fees for the required tests shall be paid by the facility. The facility shall have all testing done by a lab that is certified by the Washington State Department of Ecology to perform the required analysis.
F. Operation. The city shall have free access to the facility and the records of operation and maintenance. The records of operation and maintenance shall be kept at the facility and shall be made available to the city during the site visit by the city. The city shall have access to the facility at reasonable hours without prior notice. (Ord. 2579 § 1, 1997; Ord. 2343 § 1, 1993).