(A) Definitions. For the purpose of this chapter, the following definitions shall apply, unless the context clearly indicates or requires a different meaning.
ACT or THE ACT. The Federal Water Pollution Control Act, also known as the Clean Water Act, as amended, 33 USC 1251 et seq.
APPLICABLE COUNTY HEALTH DEPARTMENT. The Sanilac County Health Department.
AUTHORIZED REPRESENTATIVE OF INDUSTRIAL USER. One of the following, as applicable:
(a) If the user is a corporation, a principal executive officer of at least the level of vice president;
(b) If the user is a partnership or proprietorship, a general partner or proprietor respectively;
(c) If the user is a government facility, then the Director or highest official appointed to oversee the operation of the facility; or
(d) A designee, provided the designation specifies the individual person or position as being responsible for the facility operation or for environmental matters of the facility and is submitted in writing to the city by one of the above individuals. If a designee changes because a different individual has responsibility for the overall operation of the facility or for environmental matters of the company, a new written designation must be submitted to the city prior to or together with any documents signed by that representative.
BEST MANAGEMENT PROACTICES (BMPs). Schedules of activities, prohibitions of activities, maintenance procedures, and other management actions. May include but not limited to treatment requirements; operating procedures; control of site runoff, spillage, or leaks; waste or sludge disposal procedures; or control of drainage from material storage areas.
BIOCHEMICAL OXYGEN DEMAND (BOD). The quantity of oxygen utilized in the biochemical oxidation of organic matter under standard laboratory procedure, five days at 20°C expressed in terms of weight and concentration (milligrams per liter).
BUILDING DRAIN. That part of the lowest horizontal piping of a drainage system which receives discharge from drainage pipes inside the walls of the building and conveys it to the building sewer, beginning five feet outside the inner face of the building wall.
BUILDING SEWER. The extension from the building drain to the public sewer or other place of disposal.
BYPASS. The intentional diversion of waste streams from any portion of an industrial user’s pretreatment facility.
CATEGORICAL STANDARDS. National categorical pretreatment standards or pretreatment standard.
CHEMICAL OXYGEN DEMAND (COD). A measure of the oxygen consuming capacity of inorganic and organic matter present in water or wastewater. It is expressed as the amount of oxygen consumed from a chemical oxidant in a specified test. It does not differentiate between stable and unstable organic matter and thus does not necessarily correlate with biochemical oxygen demand. Also known as OC and DOC, oxygen consumed and dichromate oxygen consumed, respectively.
CHLORINE DEMAND. The difference between the amount of chlorine applied and the amount of free chlorine available at the end of the contact time, expressed in milligrams per liter.
CITY. The City of Croswell, Michigan, its agents and employees.
CITY ATTORNEY. The person designated by the Council to provide legal counsel to the city, and who is charged with certain duties and responsibilities by this chapter.
CITY MANAGER. The person designated by the Council to supervise the operation of the city, and who is charged with certain duties and responsibilities by this chapter.
COMBINED SEWER. A sewer receiving both surface runoff and sewage.
COMMERCIAL WASTE. A liquid or water-carried waste material from a commercial business engaged in buying, selling, exchanging goods or engaging in those goods or services.
COMPATIBLE POLLUTANT. A substance amenable to treatment in the wastewater treatment plant such as biochemical oxygen demand, suspended solids, pH and fecal coliform bacteria, plus additional pollutants identified in the NPDES permit if the publicly-owned treatment works was designed to treat the pollutants and in fact does remove such pollutant to a substantial degree. Examples of additional pollutants may include: chemical oxygen demand, total organic carbon, phosphorus and phosphorus compounds, nitrogen compounds, fats, oils and greases of animal or vegetable origin.
COMPOSITE SAMPLE. For continuous discharges, a sample collected via automatic sampler over the period of discharge contained within a 24-hour period and consisting of a series of 96 aliquots. Such aliquots shall be taken at a rate proportional to the flow, unless an alternate sample collection technique applies in accordance with § 51.048(E) of this chapter. For batch discharges, a series of aliquots collected from each batch at a volume approximately equal to the relative batch size and combined prior to laboratory analysis.
COOLING WATER. The water discharged from any use such as air conditioning, cooling or refrigeration, or to which the only pollutant added is heat.
COUNCIL. The Mayor and other elected officials of the city or their regular employees and duly authorized representatives.
DAILY MAXIMUM. The concentration or value of a pollutant parameter measured in a 24-hour composite sample or, if applicable for that pollutant, a grab sample. A daily maximum for a grab sample may apply to the average of up to four grab samples collected over the period of normal operation within a 24-hour period.
DEBT SERVICE CHARGE. Charges levied to customers of the wastewater system which are used to pay principal, interest and administrative costs of retiring the debt incurred for construction of the wastewater system. The DEBT SERVICE CHARGE shall be in addition to the USER CHARGE specified below.
DILUTION. Any thinning or weakening of a wastewater or waste by purposely mixing in water or other liquid as a partial or complete substitute for treatment necessary to achieve compliance with pretreatment standards and requirements
DIRECT DISCHARGE. The discharge of treated or untreated wastewater directly to the waters of the state.
DISSOLVED OXYGEN. The oxygen dissolved in water or wastewater expressed in mg/l or percentage of saturation.
DISSOLVED SOLIDS. The filterable residue, using standard methods, consisting of the anhydrous residues of the dissolved constituents in water.
DOMESTIC USER. Any user not covered under the definition of INDUSTRIAL USER.
DOWNSPOUT or LEADER. The water conductor from the roof to the storm drain or other means of disposal.
ENVIRONMENTAL PROTECTION AGENCY, or EPA. The U.S. Environmental Protection Agency, Administrator or other duly authorized official.
EXISTING SOURCE. Any building, structure, facility, or installation from which there is a discharge to the POTW, and for which construction or operation commenced prior to publication by EPA of proposed national categorical pretreatment standards applicable to such a source.
FLOW. The quantity of waste or liquid that flows in a certain period of time.
GARBAGE. Solid wastes from the preparation, cooking and dispensing of food and from the handling, storage and sale of produce.
GARBAGE, PROPERLY SHREDDED. The wastes from the preparation, cooking an dispensing of food that have been shredded to such a degree that all particles will be carried freely under the flow conditions normally prevailing in public sewers, with no particle greater than one half inch in any dimension.
GRAB SAMPLE. A sample which is taken from a waste stream on a one-time basis with no regard to the flow in the waste stream and without consideration of time.
GROUNDWATER. Water beneath the surface of the earth.
HEAVY METALS. Metals that can be precipitated by hydrogen sulfide in acid solution, such as, but not limited to Cadmium, Mercury, Zinc, and Lead.
HOLDING TANK WASTE. Any waste from holding tanks such as vessels, chemical toilets, campers, trailers, septic tanks, and vacuum-pump tank trucks.
INCOMPATIBLE POLLUTANTS. Any pollutant which is not a compatible pollutant.
INDIRECT DISCHARGE. The discharge or the introduction of non-domestic pollutants into the POTW (including holding tanks waste discharged into the system).
INDIRECT WASTES. The wastewater discharges from industrial, manufacturing, trade or business processes, or wastewater discharge from any structure with these characteristics, as distinct from their employee’s domestic wastes or wastes from sanitary conveniences.
INDUSTRIAL WASTES, or PROCESS WASTE. Any water, wastewater, sludge, waste, or residual which potentially may come into direct contact with any raw material, intermediate product, finished product, byproduct, or waste product during a manufacturing or processing operation. This definition does not include domestic wastewater, noncontact cooling water, or boiler water.
INFILTRATION. Any waters entering the system from the ground, through such means as, but not limited to, defective pipes, pipe joints, connections or manhole walls. INFILTRATION does not include and is distinguished from INFLOW.
INFILTRATION/INFLOW. The total quantity of water from both infiltration and inflow.
INFLOW. Any waters entering the system through such sources as, but not limited to, building downspouts, footing or yard drains, cooling water discharges, seepage lines from springs and swampy areas and storm drain cross-connections.
INSTANTANEOUS MAXIMUM. The concentration or value of a pollutant parameter measured in any sample at any instant in time, independent of the flow rate or duration of the sampling event.
INTERFERENCE. The inhibition or disruption of the POTW treatment processes or operations which contributes to a violation of any requirement of the NPDES permit or reduces the efficiency of the POTW. The term also includes prevention of sewage sludge use or disposal by the POTW.
LABORATORY DETERMINATION. The measurements, tests and analysis of the characteristics of waters and wastes in accordance with the methods approved by EPA and contained in 40 CFR Part 136, as amended, or in accordance with any other method prescribed by the rules and regulations promulgated pursuant to this division.
LATERAL LINE. That portion of the sewer system located under the street or within the street right-of-way from the property line to the trunk line and which collects sewage from a particular property for transfer to the trunk line.
MONTHLY AVERAGE. The average concentration or value of a pollutant parameter measured in a calendar month, and calculated by the sum of daily concentration or values determined during said month divided by the number of daily concentration or values determined during said month.
NATIONAL CATEGORICAL PRETREATMENT STANDARD or PRETREATMENT STANDARD. Federal regulations containing pollutant discharge limits promulgated by the EPA which apply to specific categories of industrial users. The associated regulations 40 CFR Parts 405 through 471, which are hereby incorporated by reference and made an integral part of this chapter, include but are not limited to the following:
(a) Airport deicing (40 CFR Part 449);
(b) Aluminum forming (40 CFR Part 467);
(c) Asbestos manufacturing (40 CFR Part 427);
(d) Battery manufacturing (40 CFR Part 461);
(e) Canned and preserved fruits and vegetable processing (40 CFR Part 407);
(f) Canned and preserved seafood; seafood processing (40 CFR Part 408);
(g) Carbon black manufacturing (40 CFR Part 458);
(h) Cement manufacturing (40 CFR Part 411);
(i) Centralized waste treatment (40 CFR Part 437);
(j) Coal mining (40 CFR Part 434);
(k) Coil coating (40 CFR Part 465);
(l) Concentrated animal feeding operations; CAFOs (40 CFR Part 412);
(m) Concentrated aquatic animal production; aquaculture (40 CFR Part 451);
(n) Construction and development (40 CFR Part 450);
(o) Copper forming (40 CFR Part 468);
(p) Dairy products processing (40 CFR Part 405);
(q) Electrical and electronic components (40 CFR Part 469);
(r) Electroplating (40 CFR Part 413);
(s) Explosives manufacturing (40 CFR Part 457);
(t) Ferroalloy manufacturing (40 CFR Part 424);
(u) Fertilizer manufacturing (40 CFR Part 418);
(v) Glass manufacturing (40 CFR Part 426);
(w) Grain mills (40 CFR Part 406);
(x) Gum and wood chemicals (40 CFR Part 454);
(y) Hospitals (40 CFR Part 460);
(z) Ink formulating (40 CFR Part 447);
(aa) Inorganic chemicals (40 CFR Part 415);
(bb) Iron and steel manufacturing (40 CFR Part 420);
(cc) Landfills (40 CFR Part 445);
(dd) Leather tanning and finishing (40 CFR Part 425);
(ee) Meat and poultry products (40 CFR Part 432);
(ff) Metal finishing (40 CFR Part 433);
(gg) Metal molding and casting; foundries (40 CFR Part 464);
(hh) Metal products and machinery (40 CFR Part 438);
(ii) Mineral mining and processing (40 CFR Part 436);
(jj) Nonferrous metals forming and metal powders (40 CFR Part 471);
(kk) Nonferrous metals manufacturing (40 CFR Part 421);
(ll) Oil and gas extraction (40 CFR Part 435);
(mm) Ore mining and dressing; hard rock mining (40 CFR Part 440);
(nn) Organic chemicals, plastics, and synthetic fibers (40 CFR Part 414);
(oo) Paint formulating (40 CFR Part 446);
(pp) Paving and roofing materials; tars and asphalt (40 CFR Part 443);
(qq) Pesticide chemicals formulating and packaging (40 CFR Part 455);
(rr) Petroleum refining (40 CFR Part 419);
(ss) Pharmaceutical manufacturing (40 CFR Part 439);
(tt) Phosphate manufacturing (40 CFR Part 422);
(uu) Photographic (40 CFR Part 459);
(vv) Plastic molding and forming (40 CFR Part 463);
(ww) Porcelain enameling (40 CFR Part 466);
(xx) Pulp, paper, and paperboard (40 CFR Part 430);
(yy) Rubber manufacturing (40 CFR Part 428);
(zz) Soap and detergent manufacturing (40 CFR Part 417);
(aaa) Steam electric power generating (40 CFR Part 423);
(bbb) Sugar processing (40 CFR Part 409);
(ccc) Textile mills (40 CFR Part 410);
(ddd) Timber products processing (40 CFR Part 429);
(eee) Transportation equipment cleaning (40 CFR Part 442); and
(fff) Waste combustors (40 CFR Part 444).
NATIONAL POLLUTION DISCHARGE ELIMINATION SYSTEM PERMIT or NPDES PERMIT. A permit issued pursuant to Section 401 of the Act (33 USC 1342).
NATIONAL POLLUTION DISCHARGE STANDARD or PROHIBITIVE DISCHARGE STANDARD. Any regulation developed under the authority of 307(b) for the Act and 403.5.
NATURAL OUTLET. Any outlet into a watercourse, pond, ditch, lake or other body of surface or groundwater.
NEW SOURCE.
(a) Any building, structure, facility, or installation from which there is or may be a discharge, and for which construction commenced after publication by EPA of proposed national categorical pretreatment standards applicable to such a source, provided any of the following provisions apply:
1. The building structure, facility, or installation is constructed at a site at which no existing source is located;
2. The building, structure, facility, or installation totally replaces the production equipment or processes that causes the discharge of pollutants to the POTW from an existing source; or
3. The wastewater-generating production equipment or processes of the building, structure, facility, or installation are substantially independent of an existing source at the same site, where factors used to determine substantial independence include the extent to which the new facility is integrated with the existing plant and the extent to which the new facility is engaged in the same general type of activity as the existing source.
(b) Construction of a NEW SOURCE is considered to have commenced when the owner/operator has begun significant site preparation, begun assembly of equipment or facilities, or has entered into a binding contractual obligation for the purchase of equipment or facilities intended for use in the operation within a reasonable time. Construction on a site at which an existing source is located is considered a modification rather than a new source if the construction does not create a new building, structure, facility, or installation meeting the criteria of division (a)2. herein but otherwise alters, replaces, or adds to the wastewater-generating production equipment or processes.
NORMAL DOMESTIC SEWAGE or NDS. Wastewater which, when analyzed, shows a daily average concentration of not more than 200 mg/l of BOD; nor more than 240 mg/l of suspended solids; nor more than 5 mg/l of phosphorus; nor more than 100 mg/l of fats, oils and grease.
OBJECTIONABLE WASTE. Any wastes that can harm the sewers, sewer treatment process, or equipment, have an adverse effect on the receiving stream, or endanger life, health, or property, or constitutes a nuisance.
OBSTRUCTION. Any object of whatever nature which substantially impedes the flow of sewage from the point of origination to the trunk line. This shall include, but not be limited to objects, sewage, tree roots, rocks and debris of any type.
OPERATION AND MAINTENANCE. All work, materials, equipment, utilities and other effort required to operate and maintain the wastewater transportation and treatment system consistent with insuring adequate treatment of wastewater to produce an effluent in compliance with the NPDES permit and other applicable state and Federal regulations, and includes the cost of replacement.
OWNER. Owner or owners of record of the freehold of the premises or lesser estate therein; a mortgagor or vendee in possession, assignee of rents, receiver, executor, trustee, lessee, or other person, firm or corporation in control of a building.
PERSON. Any individual, partnership, co-partnership, firm, company, corporation, association, joint stock company, trust estate, governmental entity or any other legal entity, or its legal representatives, agents or assigns. The masculine gender shall include the feminine, the singular shall include the plural where indicated by the context.
pH. The negative logarithm (base 10) of the concentration of hydronium ions expressed in equivalents per liter of solution, which is used as a measure of the acidity or basicity of a solution.
POLLUTANT. Any of various chemicals, substances, and refuse materials such as solid waste, sewage, garbage, sewage sludge, chemical waste, biological materials, radioactive materials, heat, and industrial, municipal and agricultural wastes which impair the purity of the water and soil.
POLLUTED WATER OR WASTE. Any water, liquid, or gaseous waste containing any of the following.
(a) Soluble or insoluble substances of organic or inorganic nature which may deplete the dissolved oxygen content of the receiving streams;
(b) Settleable solids that may form sludge deposits;
(c) Grease and oils;
(d) Floating solids which may cause unsightly appearance;
(e) Color;
(f) Phenols and other substances to an extent which would impart any taste or odor to the receiving stream; and
(g) Toxic or poisonous substances in suspension, colloidal state, solution, or gasses.
POLLUTION. The man-made or man-induced alteration of the chemical, physical, biological, and radiological integrity of water.
POTW or PUBLICLY-OWNED TREATMENT WORKS. A treatment works as defined by section 212 of the Act (33 USC 1292), which is owned in this instance by the city. This definition includes any sewers that convey wastewater to the POTW treatment plant. For the purposes of this chapter, POTW shall also include any sewers that convey wastewaters to the POTW from persons outside the city who are, by contract or agreement with the city, users of the POTW.
POTW DISCHARGE. The introduction, including infiltration, of pollutants into the POTW which is either intentional or unintentional.
POTW TREATMENT PLANT. That portion of the POTW designed to provide treatment to wastewater.
PRETREATMENT or TREATMENT. The reduction of the amount of pollutants, the elimination of pollutants, or the alteration of the nature of pollutants, or the alteration of the nature of pollutant properties in wastewater to a less harmful state prior to or in lieu of discharging or otherwise introducing the pollutants into a POTW. The reduction or alteration can be obtained by physical, chemical or biological processes, or process changes by other means, except as prohibited by 40 CFR Section 403.6(d).
PRETREATMENT STANDARDS AND REQUIREMENTS. Any substantive or procedural requirement imposed on an industrial user for treating of a waste prior to inclusion in the POTW, including but not limited to local prohibitions, state requirements, and national categorical pretreatment standards.
PRIVATE SEWER LINES. All service lines and equipment for the disposal of sewage installed or located on any property, from the property line to and including any structure or facility which exists on the property.
PROPERTY OWNER. The owner of the property which abuts the street.
PUBLIC SEWER. A sewer in which all owners of abutting properties have equal rights, and is controlled by public authority.
REPLACEMENT. The replacement in whole or in part of any equipment, appurtenances and accessories in the wastewater transportation or treatment systems to insure continuous treatment of wastewater in accordance with the NPDES permit and other applicable state and Federal regulations.
SANITARY SEWER. A sewer which carries sewage and to which storm, surface and groundwater are not intentionally admitted.
SEWAGE. A combination of the water-carried wastes from residences, business buildings, institutions and industrial establishments, together with such groundwater as may be present.
SEWAGE TREATMENT PLANT or WASTEWATER TREATMENT PLANT. Any arrangement of devices and structures used for treating sewage.
SEWER. A pipe or conduit for carrying sewage.
SEWER SERVICE CHARGE. The sum of the applicable user charge, surcharges and debt service charges.
SHALL is mandatory; MAY is permissive.
SIGNIFICANT INDUSTRIAL USER. Any user of the city’s POTW which:
(a) Is subject to national categorical pretreatment standards;
(b) Discharges an average of 25,000 gallons or more of process waste per normal work day to the POTW;
(c) Contributes a discharge of process waste to the POTW that makes up 5% or more of the POTW’s average dry weather hydraulic, or 5% or more of the POTW’s organic treatment capacity of the POTW; or
(d) Is designated as such by the WWTP Superintendent bases on potential to discharge to the POTW pollutants that may be deleterious to the POTW, worker health, or public health and safety.
SLUG LOAD. Any discharge to the POTW which, in concentration of any given constituent or in quantity of flow, exceeds for any 15-minute period more than five times the average concentration or flow over 24 hours during normal operation; or any POTW discharge which, in concentration of any given constituent or in quantity of flow, causes a temporary violation of pretreatment standards and requirements.
STANDARD INDUSTRIAL CLASSIFICATION or SIC. A classification pursuant to the Standard Industrial Classification Manual issued by the Executive Office of the President, Office of Management and Budget, 1972 or later.
STATE. State of Michigan.
STORM SEWER or STORM DRAIN. A sewer which carries storm and surface waters and drainage, but excludes sewage and polluted industrial wastes.
STORM WATER. Any flow occurring during or following any form of natural precipitation and resulting therefrom.
SURCHARGE. As part of the service charge, any customer discharging wastewater having strength in excess of normal domestic strength shall be required to pay an additional charge to cover the cost of treatment of the excess strength wastewater.
SUSPENDED SOLIDS. The total suspended matter that floats on the surface of, or is suspended in, water, wastewater or other liquids, and which is removable by laboratory filtering.
TOXIC POLLUTANT. Any pollutant which is or can potentially be harmful to public health or environment, including those listed as toxic in regulations promulgated by the Administrator of the Environmental Protection Agency under the provisions of the Clean Water Act 307(a) or other Acts.
TRUNK LINE. The main sewer line located under any street or within any street right-of-way which collects and transmits the sewage of the various properties served by the sewer system.
UNCONTAMINATED INDUSTRIAL WASTE. Wastewater which has not come into contact with any substance used in or incidental to industrial processing operations and to which no chemical or other substance has been added.
UPSET. An abnormal incident in which there is unintentional and temporary violation of pretreatment standards and requirements because of factors beyond the reasonable control of the user.
USER. Any person who contributes, causes or permits the contribution of wastewater into the POTW.
USER CHARGE. A charge levied on users of a treatment works for the cost of operation and maintenance of treatment works pursuant to section 204(b) of the act.
USER CLASS. The kind of user connected to sanitary sewers including but not limited to residential, industrial, commercial, institutional and governmental.
(a) COMMERCIAL USER. An establishment listed in the Office of the Management and Budget’s Standard Industrial Classification Manual or SICM, involved in a commercial enterprise, business or service which, based on a determination by the city, discharges to the POTW primarily segregated domestic wastes or wastes from sanitary conveniences and which is not a RESIDENTIAL USER or an INDUSTRIAL USER.
(b) GOVERNMENTAL USER. Any Federal, state or local government facility that discharges to the POTW.
(c) INDUSTRIAL USER. Any user who discharges industrial wastes, as defined in this chapter, to the POTW.
(d) INSTITUTIONAL USER. Any establishment listed in the SICM involved in a social, charitable, religious, or educational function which, based on a determination by the city, discharges to the POTW primarily segregated domestic wastes or wastes from sanitary conveniences.
(e) RESIDENTIAL USER. A discharger to the POTW whose premises or buildings are used primarily as a domicile for one or more persons, including dwelling units such as detached, semi-detached and row houses, mobile homes, apartments, or permanent multi-family dwellings (transit lodging is not included, it is considered commercial).
WASTEWATER. The liquid and water carried industrial or domestic wastes from dwellings, commercial buildings, industrial facilities and institutions, together with any groundwater, surface water, and storm water that may be present, whether treated or untreated.
WASTEWATER CONTRIBUTION PERMIT. A permit, developed and issued by the WWTP Superintendent on behalf of the city, that specifies terms and conditions under which a user may discharge wastewater or other wastes to the POTW.
WATERCOURSE. A channel in which a flow of water occurs, either continuously or intermittently.
WATERS OF THE STATE. All streams, lakes, ponds, marshes, watercourses, waterways, wells, springs, reservoirs, aquifers, irrigation systems, drainage systems and all other bodies or accumulations of water, surface or underground, natural or artificial, public or private, which are contained within, flow through, or border upon the state or any portion thereof.
WWTP SUPERINTENDENT. The person designated by the city to supervise the operation of the POTW, and who is charged with certain duties and responsibilities by this chapter. At his/her discretion, the WWTP SUPERINTENDENT may delegate certain duties and responsibilities to one or more subordinates as appropriate.
(B) Abbreviations. The following abbreviations shall have the designated meanings:
(1) BOD. Biochemical oxygen demand.
(2) CFR. Code of Federal Regulations.
(3) COD. Chemical oxygen demand.
(4) EPA. Environmental Protection Agency.
(5) l. Liter.
(6) mg. Milligrams.
(7) mg/l. Milligrams per liter; equivalent to ppm.
(8) NDS. Normal domestic sewage.
(9) NPDES. National pollutant discharge elimination system.
(10) P. Phosphorus.
(11) ppm. Parts per million; equivalent to mg/l.
(12) SIC. Standard industrial classification.
(13) SICM. Standard Industrial Classification Manual.
(14) SS. Suspended soils.
(15) SWDA. Solid Waste Disposal Act, 42 USC 6901, et. seq.
(16) O&M. Operation and maintenance.
(17) CWA. Clean Water Act.
(18) MDEQ. Michigan Department of Environmental Quality, or its successor.
(Ord. 216, passed 6-16-80; Am. Ord. 257, passed 6-3-91; Am. Ord. 333, passed 5-16-16)