15.48.170 Best management practices as industrial pretreatment limits.
A. Background. Industrial local pretreatment limits may be expressed through conditions in the user’s permit as narrative statements (typically prohibitions) such as in Section 15.48.020, numerical values such as those listed in Section 15.48.030, or a combination of both expressed as best management practices (BMPs) (40 CFR 403.5(c)(4)). Historically, BMPs only applied to groups of low flow discharges that had similar processes and discharged similar types of wastewater (e.g., photo processors and dentist offices). However, with the recent lowering of indirect discharge limitations and improved analytical methods, the city will begin using BMPs in cases where it is not practical or economically feasible for an industrial user to monitor for or attain specific numerical pretreatment limits. This section gives the city the ability to shift from numerical end-of-pipe chemical controls on an industrial user to BMPs and pollution prevention as an effective way for the city to achieve compliance with NPDES permit limits. BMPs are enforceable under 40 CFR 403.5(d). In cases where the national pretreatment standard requires compliance with a best management practice or pollution prevention alternative, the industrial user shall submit documentation as required by the city or the applicable national pretreatment standards to determine compliance with the national pretreatment standard as a component of the baseline monitoring report as required by 40 CFR 403.12(b)(5)(ii), and industrial users not subject to categorical pretreatment standards must submit documentation regarding BMP or pollution prevention implementation required by the city to determine the compliance status of the industrial user as required by 40 CFR 403.12(h).
B. BMP use examples:
1. There is insufficient flow from an industrial user or a category of industrial users to obtain a representative wastewater sample (e.g., dentist offices, photo processors).
2. The proposed local limit is less than the detection limit and/or quantification level (40 CFR Part 136) of the most stringent analytical procedure.
3. The BMP is clearly the most economically feasible method for regulating the pollutant of concern.
C. BMP Removal from Permit. The city may consider a request to remove the BMP requirement from the indirect discharge permit if the permittee can demonstrate that the discharge is reasonably expected to meet the numeric local limit. In cases where the numeric local limit is calculated to be negative and where the industry’s effluent sampling results for pollutants with BMP requirements are below the quantification level, the city may also consider a permit modification request. Relaxation of the permit conditions does not allow the industry to return to its previous methods of operation.
D. Inspections, monitoring, and numeric effluent limits may still be required by the city to verify that the industry remains in compliance. At a minimum, a certification statement is required certifying that the industry is operating under its approved BMP and no changes have been implemented.
E. BMPs may be used at the discretion of the city where appropriate to meet such pretreatment standards in a practical and economical fashion.
1. Dental practices shall implement the following BMPs to reduce the amount of mercury entering the wastewater system as recommended by the California Dental Association in 2010 within six months of the adoption date of the ordinance codified in this section:
a. Do not rinse amalgam-containing traps, filters, or containers in the sink as required by CCR Title 22.
b. Do not place amalgam, elemental mercury, broken or unusable amalgam capsules, extracted teeth with amalgam, or amalgam-containing traps and filters with medical “red-bag” waste or regular solid waste.
c. Recycle, or manage as hazardous waste, amalgam, elemental mercury, broken or unusable amalgam capsules, and extracted teeth with amalgam-containing waste from traps and filters. Empty dental amalgam capsules containing no visible materials may be disposed of as a non-hazardous waste.
d. Collect and store dry dental amalgam waste in a designated, airtight container. Amalgam, which is designated for recycling, should be labeled “Scrap Dental Amalgam” with the name, address and phone number of your office and the date on which you first started collecting material in the container.
e. Keep a log of your generation and disposal of scrap amalgam; inspectors may ask to see this to verify that your office is managing it correctly.
f. Separate excess contact dental amalgam from gauze that is retrieved during placement and place in an appropriate container. Use chair side traps to capture dental amalgam.
g. Change or clean chair side traps frequently. Flush the vacuum system before changing the chair side trap.
h. Change vacuum pump filters and screens at least monthly or as directed by the manufacturer.
i. Check the p-trap under your sink for the presence of any amalgam-containing waste.
j. Eliminate all use of bulk elemental mercury and use only pre-capsulated dental amalgam for amalgam restorations.
k. Limit the amount of amalgam triturated (ground to a fine powder) to the closest amount necessary for the restoration.
l. Train staff that handle or may handle mercury-containing material in its proper use and disposal.
m. Install an amalgam separator compliant with ISO 11143.
n. Do not use bleach to clean the discharge system as this may mobilize legacy mercury and amalgam in the system.
F. Industrial users subject to BMPs as a means of complying with standards of this part shall maintain documentation to demonstrate compliance with all BMP standards for the term of the permit or five years, whichever is longer.
(Ord. 2402 NCS §2 (part), 2011; Ord. 2282 NCS §3 (part), 2007.)