16.09.040   Standards.
   (a)   The following standards shall apply to all discharges to the sewer at a designated sampling location determined by the superintendent to be consistent with the dilution prohibition contained in Section 16.09.115.
   (b)   Maximum allowable limitations at the point of sampling shall be specified in each discharge permit, based on flow and waste stream information supplied in the discharger's permit application, applicable National Pretreatment Standards for process wastewaters, and other pertinent information. Maximum allowable limitations may be expressed both in terms of total mass discharged and maximum allowable limits.
   (c)   The National Pretreatment Standards set forth in 40 CFR Chapter I, Subchapter N, Parts 405-471 shall apply to all applicable sources. The definitions and procedures for establishing individual effluent limitations shall be as specified therein. Nothing in this chapter shall be construed as allowing less stringent limitations.
   (d)   Local limitations, in addition to those specified in this section, shall be developed by the superintendent based upon the prohibitions contained in Section 16.09.035. These limitations will be imposed on appropriate dischargers via industrial waste discharge permits or modifications to existing permits.
   (e)   In addition to the requirements of subsections (c) and (d) above, the following requirements shall apply where they are more stringent:
Maximum Limits* mg/liter
Dissolved sulfides
Oil & grease**
Oil & grease (total)
*   Apply to both instantaneous and composite samples
**   Gravity separation at a temperature of 20°C and a pH of 4.5.
Minimum Limit
Maximum Limit
*   no units
Maximum Limits* mg/liter
Maximum Limits** mg/liter
Suspended solids
Total dissolved solids
*   Apply to instantaneous samples only
**   Apply to composite samples only
   (f)   Dyes. Wastes showing excessive coloration shall not be discharged into the sewer system. Excessive coloration shall be defined as any coloration in a waste which, for any wave length, displays less than 60% of the light transmissibility of distilled water under the following conditions:
   (1)   After filtration through a 0.45 micron membrane filter;
   (2)   In the pH range of 5.5 to 11.0;
   (3)   Through a one centimeter light path;
   (4)   A maximum spectrum band width of 10 nanometers;
   (5)   Through the wave length range from 400 to 800 nanometers.
   (g)   Oil and/or grease shall not be discharged into the sewer system if the average concentration of floatable oil and/or grease (defined as that which is subject to gravity separation at a temperature of 20°C and at a pH of 4.5) exceeds 20 mg/liter; nor shall the total oil and/or grease concentration exceed 200 mg/liter. In addition, the discharge of petroleum oil, non-biodegradable cutting oil, or products of mineral origin in amounts that cause interference or pass-through shall be prohibited.
   (h)   Hazardous, Noxious or Malodorous Substances. No industrial waste shall be discharged which alone or in combination with other wastes may create a public nuisance or hazard, make human entry into the sewers unsafe, or which constitutes a discharge of hazardous waste.
   (i)   Permitted dischargers shall be required to certify at least every six months in their periodic report of continued compliance (PRCC) that their discharged waste does not constitute a hazardous waste and that during the previous six months no discharge of hazardous waste has occurred. Dischargers shall be required (as a condition to permission to discharge) to file with the Palo Alto fire department a current hazardous materials business plan (HMBP) pursuant to Title 17 of this code and to have on site copies of material safety data sheets for all hazardous materials stored, generated, or used at the discharger's site. Should any discharge of a hazardous waste occur, the discharger shall immediately verbally notify the Superintendent and shall also verbally notify the EPA and the Regional Water Quality Control Board as soon as possible, but in no event later than twenty-four hours after such discharge. The discharger shall also notify the superintendent, EPA and the Regional Water Quality Control Board in writing no longer than twenty-one days after such discharge.
   (j)   Records of hazardous waste disposal manifests, inventories of stored virgin and used hazardous materials, and other documentation required by the HMBP shall be maintained and made available for inspection as described in Section 16.09.160.
   (k)   Explosives. No solids, liquids, or gases which by themselves or by interaction with other substances may create fire or explosion hazards, including waste streams with a closed cup flashpoint of less than 140°F (60°C) shall be discharged to the sewer system. Flammable substances including, but not limited to, acetone, alcohols, benzene, gasoline, xylene, hexane and naphtha, shall not be discharged into the sanitary sewer system except where present in contaminated groundwater discharges being discharged under an exceptional waste permit issued by the superintendent. Where groundwater discharges contain such contaminants, the discharger shall monitor the sewer atmosphere for explosivity and flammability using a properly calibrated meter designed for this purpose. The frequency of such monitoring shall be defined in the permit. Whenever 10% of the lower explosive level is exceeded, the discharger shall immediately notify the superintendent of the potential hazard in the sewer once the determination of threatened explosivity has been made. The discharger shall follow verbal notification within five days with a written explanation of the cause of the explosive hazard, corrective actions taken to alleviate the situation, and measures taken to prevent reoccurrence. The discharger shall not recommence discharge without prior written approval of the superintendent. Where flammable substances are used in processes, separate collection and disposal outside the sanitary sewer system shall be provided.
   (l)   Organic Solvents. Except as permitted by other sections of this chapter, the sewer shall not be used as a means of disposal for organic solvents. Wastewater discharged to the sanitary sewer system shall not contain a sum total greater than 1,000 mg/liter of acetone, ethanol, methanol, or isopropyl alcohol, in any combination. Dischargers having organic solvents on site or using same shall provide and use a separate collection and disposal system outside the sewer system and shall provide safeguards against their accidental discharge to the sewer. An approved toxic organic management plan (TOMP) that includes control measures to prevent entry of toxic organics and other solvents into the sanitary sewer system shall be filed by the discharger as a condition of permission to discharge to the sanitary sewer. The TOMP shall be updated whenever any significant change in the inventory, usage, or management of toxic organic compounds occurs. The updated TOMP shall be submitted to the city for approval within thirty days. Records documenting appropriate disposal and handling of organic solvents shall be maintained and made available for inspection as described in Section 16.09.160.
   Organic solvents shall include, but shall not be limited to those used in dry cleaning establishments, and shall also include separator water generated by dry cleaning equipment. Neither the organic solvent nor the separator water may lawfully be discharged to the sewer or storm drain system.
   (m)   Toxic Organics. The prohibition against disposal of organic solvents contained in Section 16.09.040(l) may be replaced by a specific limitation on single toxic organics (STO) and total toxic organics (TTO). Any such limitation must be contained in an industrial waste permit.
   The maximum allowable limit for TTO shall be 1.0 mg/liter. The maximum allowable limit for STO shall be 0.75 mg/liter.
   Additionally, dischargers subject to a National Pretreatment Standard shall comply with any toxic organics standard defined by the applicable National Pretreatment Standards.
   The maximum allowable limit for phenols shall be 1.0 mg/liter.
   (n)   Radioactivity. The discharge of radioactive wastes or isotopes into the sewer system is prohibited except when in conformance with all applicable state and federal regulations.
   (o)   Solids or Viscous Substances. No material shall be discharged to the sanitary sewer system that will obstruct or damage the sanitary sewer system. Specific prohibitions are as follows:
   (1)   Inert Solids. The discharge of inert solids including, but not limited to sand, glass, metal chips, bone, plastics, etc., into the sanitary sewer system is prohibited. Settling chambers or treatment works shall be installed where necessary to prevent the entry of inert solids into the sanitary sewer system.
   (2)   Solid Particles. Industrial wastes shall not contain particulate matter that will not pass through a one-half-inch screen; this subsection shall not apply to domestic sewage from industrial establishments.
   (p)   Stored Liquid Wastes. Liquid aqueous-based wastes that have been collected and held in tanks or containers shall not be discharged into the sanitary sewer system except at locations authorized by the superintendent to collect such wastes. Wastes of this category include but are not limited to:
   (1)   Chemical toilet wastes;
   (2)   Pleasure boat wastes;
   (3)   Septic tank pumping;
   (4)   Trailer, camper, house car, or other recreational vehicle wastes;
   (5)   Industrial wastes collected in containers or tanks.
   (q)   Toxicity. The following is a nonexclusive list of toxic substances and the maximum allowable limit for each discharge:
Maximum Allowable Limits
Chromium, Hexavalent
Chromium total
Methyl Tertiary Butyl Ether (MTBE)
   All limits for metallic substances are for total metal unless indicated otherwise.
   For discharges with annual average flows greater than 50,000 gallons per day through any single sampling location, the maximum allowable limits shall be one-half the values listed in the table, with the exception of copper, mercury, MTBE, nickel, and silver, for which the limits shall remain 0.25 mg/liter, 0.010 mg/liter, 0.75 mg/liter, 0.50 mg/liter, and 0.25 mg/liter, respectively, regardless of flow.
   The maximum allowable limit for mercury set forth in this section shall not be applicable to dental facilities using mercury-containing amalgam. Dental facility requirements are set forth in Section 16.09.220.
   The maximum allowable limit for silver set forth in this section shall not be applicable to photographic materials processing. Silver limitations for photoprocessors are set forth in Section 16.09.215.
   The maximum allowable limit for zinc set forth in this section shall not be applicable to vehicle service facilities. Zinc limitations for vehicle service facilities are set forth in Section 16.09.225.
   The maximum allowable limit for copper set forth in this section shall apply to all discharges except where maximum allowable limitations are specified in Section 16.09.045.
(Ord. 5084 § 2 (part), 2010)