Report Prepared by: Lorraine M. Carrasquillo, Supervisor, Water Quality Control Division
Title
SUBJECT: Introduction of Ordinance No. 2474 Amending Section 15.24.110 of the Merced Municipal Code Regarding Specific Pollutant Limitations and Local Industrial Discharge Limitations
REPORT IN BRIEF
Staff Recommends that the City Council Approve the Introduction of Ordinance No. 2474 which will amend Municipal Code Section 15.24.110 to Lower the City’s Existing Specific Pollutant Limitations and Local Industrial Discharge Limitations For Arsenic, Copper and Zinc.
RECOMMENDATION
City Council - Adopt a motion introducing Ordinance No. 2474, an Ordinance of the City Council of the City of Merced, California, amending section 15.24.110, “Specific Pollutant Limitations,” of the Merced Municipal Code.
Body
ALTERNATIVES
1. Approve, as recommended by Staff; or
2. Approve, subject to modifications as conditioned by Council; or
3. Deny; or
4. Refer to Staff for reconsideration of specific items; or
5. Continue to a future meeting
AUTHORITY
Merced Municipal Code section 200
Merced Municipal Code Chapter 15.24 - Use Restrictions
Federal Regulations: 40 Code of Federal Regulations, Part 403.8(f)(1) and (f)(4)
CITY COUNCIL PRIORITIES
As provided for in the 2016-17 Adopted Budget
DISCUSSION
Every five (5) years the Wastewater Treatment Facility (WWTF) receives a new National Pollutant Discharge Elimination System (NPDES) permit. As a requirement in the renewal of the permit cycle, the WWTF must re-evaluate the Specific Pollutants Limitation (local limits). Moreover, due to the fact that the facility has undergone several significant treatment process improvement upgrades since the adoption of the current local limits, the review and re-evaluation of the City’s local limits was appropriate. The establishment of local limits keep pollution levels below the Federal and State limits, and from interfering with the local WWTF maximum allowable loadings. Industrial dischargers are controlled entities monitored through permitting and sampling of their waste stream. Discharges from the industries affect the WWTF Maximum Allowable Industrial Loadings (MAILs).
The purpose of enforcing local limits is to protect the collection system, the operation of the WWTF, City workers, the environment, and to ensure compliance with State and Federal regulatory requirements described in the NPDES permit.
The City’s Consultant (Stantec), reviewed current local limits and evaluated pollutants of concern. Local limits are based on maximum allowable headworks loadings (MAHLs) calculated for each pollutant of concern. The MAHL is the estimated maximum loading of a pollutant that can be received at the WWTF without causing pass through or interference and without exceeding EPA cumulative ceiling limits. The evaluation report determined lower levels of arsenic, copper and zinc would protect biological processes in the Facility and land application loading rates. Metals that enter the WWTF are cumulative loadings in the biosolids. Since the biosolids are used in land application area, it is important to keep these at a lower limit. Metals typically remain in the soil as they cannot be removed by farming practices. The table below displays the proposed reduction of arsenic, copper, and zinc as recommended in the Consultant’s re-evaluation report.
City of Merced Uniform Concentration Local Limits
|
Pollutant |
MAHL (lbs/day) |
MAIL (lbs/day) |
Proposed Local Limit (mg/L) |
Current Limit (mg/L) |
|
Arsenic |
0.59 |
0.42 |
0.036 |
0.10 |
|
Copper |
5.7 |
3.7 |
0.32 |
2.0 |
|
Zinc |
12 |
7.1 |
0.60 |
3.0 |
IMPACT ON CITY RESOURCES
No impact of funds.
ATTACHMENTS
1. Local Limits Review and Re-Evaluation by Stantec
2. Regional Water Quality Control Board letter of approval
3. Amended Ordinance
4. Red line Amendment 15.24.110