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City of San Mateo Municipal Code.


(a) Categorical Pretreatment Standards. The categorical pretreatment standards provided in the pretreatment regulations shall apply to all applicable sources. Nothing in this chapter shall be construed as allowing less stringent limitations.

(b) Local Limits. Local limits for toxic pollutants shall be developed by the Director to protect the POTW from interference, pass-through, and the other general discharge prohibitions.

(c) Explosives. No solids, liquids, or gases shall be discharged which by themselves or by interaction with other substances may cause a fire or explosion hazard including, but not limited to, waste streams with a closed cup flashpoint of less than 140 degrees F (60 degrees C). Neither shall any substance be discharged which causes two (2) readings on an explosion hazard meter of more than five percent of the lower explosive limit, or any single reading over 10% of the lower explosive limit.

(d) Corrosives. Discharges with a pH of less than 5.0 or more than 10.5, or other discharges which may cause corrosive structural damage to the sanitary sewer system, are prohibited.

(e) Solids or Viscous Materials. No solid or viscous materials shall be discharged in amounts which will cause or contribute to obstruction of flow in the sanitary sewer system. Such materials include, but are not limited to, sand, glass, metal chips, bone, plastics, sludge, mud, straw, wood, bags, rags, grease from commercial kitchen operations, and particulate matter which cannot pass through a one-half inch screen.

(f) Incompatible Substances. No person shall discharge pollutants, including oxygen-demanding pollutants (BOD, etc.), at a flow rate and/or pollutant concentration that, either singly or by interaction with other pollutants, will cause interference with wastewater treatment processes.

(g) Heat. No waste shall be discharged in amounts that will inhibit POTW treatment processes resulting in interference; including heat in such quantities that the temperature at the POTW exceeds 40 degrees C (140 degrees F).

(h) Oil and Grease. Oil and grease shall not be discharged into the sewer system if average concentration of floatable oil and grease exceeds 20 mg/L, defined as that which is subject to gravity separation at a temperature of 20 degrees C and at pH 4.5; nor shall the total oil and grease concentration exceed 200 mg/L. In addition, the discharge of petroleum oil, non-biodegradable cutting oil, or products of mineral origin in amounts that will cause interfere and pass-through, are prohibited.

(i) Hazardous, Noxious or Malodorous Substances. No industrial waste shall be discharged which alone or in combination with other wastes may create a public nuisance, a hazard, make human entry into the sewers unsafe, or which constitutes a discharge of hazardous substances as defined by Title 22, Part II of the California Code of Regulations; or statutes of the United States government. Dissolved sulfides shall not be discharged in concentrations exceeding 0.1 mg/liter.

(j) Trucked or Hauled Wastes. Discharge of trucked or hauled waste is prohibited, except as expressly authorized in a waste discharge permit. The permit shall specify the exact point of discharge of the waste.

(k) Toxicity. No person shall discharge wastewater containing in excess of the following limitations at point of discharge. All concentrations are for "total," not "dissolved":

Pollutant Maximum
Arsenic 0.1 mg/Liter
Cadmium 0.2 mg/Liter
Chromium total 0.5 mg/Liter
Copper 2.0 mg/Liter
Cyanide 1.0 mg/Liter
Lead 1.0 mg/Liter
Mercury 0.01 mg/Liter
Nickel 1.0 mg/Liter
Silver 0.2 mg/Liter
Zinc 3.0 mg/Liter

(l) Color. Discharge of wastewater which imparts color which cannot be removed by the wastewater treatment processes, such as, but not limited to, dye wastes and vegetable tanning solutions, is prohibited.

(m) Radiologic Substances. Discharge of any radioactive wastes into the sewer system shall conform to the California Radiation Control Regulations Title 17, California Code of Regulations, Chapter 5, Subchapter 4, and its amendments.

(n) Foaming Agents. Detergents, surfactants, or other substances that may cause excessive foaming in the sewer system are prohibited.

(o) Unpolluted Water. Unpolluted water shall not be discharged through direct or indirect connection to the sanitary sewer system without authorization of the Director. As used in this section, unpolluted water shall include stormwater from roofs, yards, foundation or under-drainage, which meets all State and Federal requirements for discharge to surface waters of the United States.