Missouri Code of State Regulations
Title 10 - DEPARTMENT OF NATURAL RESOURCES
Division 20 - Clean Water Commission
Chapter 8 - Minimum Design Standards
Section 10 CSR 20-8.140 - Wastewater Treatment Facilities

Universal Citation: 10 MO Code of State Regs 20-8.140

Current through Register Vol. 49, No. 6, March 15, 2024

PURPOSE: This amendment will retain and add minimum design standards for wastewater treatment facilities that are required to protect or improve public health, safety, and water quality.

PURPOSE: This rule contains the minimum standards for the design of systems that are part of wastewater collection and treatment systems. This rule is to be used with rules 10 CSR 20-8.110 through 10 CSR 20-8.210. It does not address all possible aspects of design, and the design engineer may refer to other appropriate reference materials so long as these minimum standards set forth in this rule are met.

PUBLISHER'S NOTE: The secretary of state has determined that the publication of the entire text of the material which is incorporated by reference as a portion of this rule would be unduly cumbersome or expensive. This material as incorporated by reference in this rule shall be maintained by the agency at its headquarters and shall be made available to the public for inspection and copying at no more than the actual cost of reproduction. This note applies only to the reference material. The entire text of the rule is printed here.

(1) Applicability. Wastewater systems shall be designed based on criteria contained in this rule, published standards, applicable federal and state requirements, standard textbooks, current technical literature, and applicable safety standards. In the event of any conflict between the above criteria, the requirement in this rule shall prevail.

(A) This rule shall not apply to treatment units covered in 10 CSR 20-8.300.

(B) This rule shall not apply to treatment units covered in 10 CSR 20-8.500.

(2) General.

(A) Location. Criteria to be considered when selecting a site are listed in 10 CSR 20-8.110(5)(E) 6.

(B) Flood Protection. Flood protection shall apply to new construction and to existing facilities undergoing major modification. The wastewater facility structures, electrical equipment, and mechanical equipment shall be protected from physical damage by not less than the one hundred- (100-) year flood elevation.

(C) Minimum Separation Distances.
1. Potable water sources. Unless another distance is determined by the Missouri Geological Survey or by the department's Public Drinking Water Branch, the minimum distance between wastewater treatment facilities and all potable water sources shall be at least three hundred feet (300').

2. Residences. No treatment unit with a capacity of twenty-two thousand five hundred gallons per day (22,500 gpd) or less shall be located closer than the minimum distance provided in Table 140-1 below. See 10 CSR 20-2.010(68) for the definition of a residence.

Table 140-1. Minimum Separation Distance for 22,500 gal/d or less.

Type of Facility

Separation Distance

Lagoons

200' to a neighboring residence and 50' to property line

Open recirculating media filters following primary treatment

200' to a neighboring residence

All other discharging facilities

50' to a neighboring residence

3. Plant Location. The following items shall be considered when selecting a plant site: proximity to residential areas; direction of prevailing winds; accessibility by all-weather roads; area available for expansion; local zoning requirements; local soil characteristics, geology, hydrology and topography available to minimize pumping; access to receiving stream; downstream uses of the receiving stream and compatibility of the treatment process with the present and planned future land use, including noise, potential odors, air quality and anticipated sludge processing and disposal techniques. Where a site must be used which is critical with respect to these items, appropriate measures shall be taken to minimize adverse impacts.

(D) Accessibility. Facilities shall be readily accessible by authorized personnel from a public right-of-way at all times.

(3) Quality of Effluent. The degree of wastewater treatment shall be based on 10 CSR 20-7.015, Effluent Regulations, 10 CSR 20-7.031, Water Quality Standards, and/or appropriate federal regulations including the provisions of the operating permit.

(4) Pump and Haul.

(A) General.
1. Accessibility. Conform to subsection (2)(D) of this rule.

2. Security. Follow the provisions in subsection (8)(A) of this rule for fencing.

3. Protection of water supplies. Provide the separation and crossing of water supplies in accordance with subsection (2)(C) of this rule and 10 CSR 20-8.120(5).

(B) Septic Tank Design. Conform to 10 CSR 20-8.180(2) for septic tank design.

(C) Earthen Basin Design. Follow the provisions in 10 CSR 20-8.200 for earthen basin design.

(D) Alarm system. The alarm shall be activated in cases of high water levels. Follow the provisions in subsection (7)(C) of this rule for alarm systems.

(5) Design.

(A) Type of Treatment. Items to be considered in selection of the appropriate type of treatment are presented in 10 CSR 20-8.110(5).

(B) New and Innovative Technology. Follow the provisions in 10 CSR 20-8.110(6).

(C) Design Period. Identify the design period in the facility plan per 10 CSR 20-8.110(5)(B).

(D) Design Loads.
1. Hydraulic design.
A. Identify flow conditions critical to the design of the wastewater treatment facility as described in 10 CSR 20-8.110(3).

B. The design peak hourly flows shall be used to evaluate the effect of hydraulic peaks on unit processes, pumping, piping, etc.

C. The design of treatment units that are not subject to peak hourly flow requirements shall be based on the design average flow.

2. Organic design. Base organic loadings for wastewater treatment facility design on the information given in 10 CSR 20-8.110(3). When septage is accepted at a wastewater treatment facility, the effects of septage flow shall be evaluated in the design.

(6) Outfalls.

(A) Protection and Maintenance. The outfall shall be so constructed and protected against the effects of flood water, ice, or other hazards as to reasonably ensure its structural stability and freedom from stoppage.

(B) Sampling Provisions. All sampling points shall be designed so that a representative and discrete twenty-four (24) hour automatic composite sample or grab sample of the effluent discharge can be obtained at a point after the final treatment process and before discharge to or mixing with the receiving waters.

(C) All outfalls shall be posted with a permanent sign indicating the outfall number (i.e., Outfall #001).

(7) Essential Facilities.

(A) Emergency Power Facilities.
1. General. All wastewater treatment facilities shall be provided with an alternate source of electric power or pumping capability to allow continuity of operation during power failures.

2. Power for disinfection. Disinfection and dechlorination, when used, shall be provided during all power outages.

(B) Electrical Controls. Electrical systems and components in raw wastewater or in enclosed or partially enclosed spaces where hazardous concentrations of flammable gases or vapors that are normally present, shall comply with the NFPA 70 National Electric Code (NEC) (2017 Edition), as approved and published August 24, 2016, requirements for Class I, Division 1, Group D locations. This standard shall hereby be incorporated by reference in this rule, as published by National Fire Protection Association® (NFPA), 1 Batterymarch Park, Quincy, MA 02169-7471. This rule does not incorporate any subsequent amendments or additions.

(C) Alarm Systems. An audiovisual alarm or a more advanced alert system, with a self-contained power supply, capable of monitoring the condition of equipment whose failure could result in a violation of the operating permit, shall be provided for all waste-water treatment facilities.

(D) Water Supply.
1. General. No piping or other connections shall exist in any part of the wastewater treatment facility that might cause the contamination of a potable water supply.

2. Direct hot water connections. Hot water for any direct connections shall not be taken directly from a boiler used for supplying hot water to a digester heating unit or heat exchanger.

3. Indirect connections.
A. Where a potable water supply is to be used for any purpose in a wastewater treatment facility other than direct connections, a break tank, pressure pump, and pressure tank or a reduced pressure backflow preventer consistent with the department's Public Drinking Water Branch shall be provided.

B. A sign shall be permanently posted at every hose bib, faucet, hydrant, or sill cock located on the water system beyond the break tank or backflow preventer to indicate that the water is not safe for drinking.

4. Separate non-potable water supply. Where a separate non-potable water supply is to be provided, a break tank will not be necessary, but all system outlets shall be posted with a permanent sign indicating the water is not safe for drinking.

(E) Flow Measurement. A means of flow measurement shall be provided at all wastewater treatment facilities.

(F) Sampling Equipment. Effluent twenty-four (24) hour composite automatic sampling equipment shall be provided at all mechanical wastewater treatment facilities and at other facilities where necessary under provisions of the operating permit. See 10 CSR 20-7.015.

(G) Housed Facilities. Where wastewater treatment units are in a housed facility, follow the provisions in subsection (8)(J) of this rule for ventilation.

(8) Safety. Adequate provisions shall be made to effectively protect facility personnel and visitors from hazards. The following shall be provided to fulfill the particular needs of each wastewater treatment facility:

(A) Fencing. Enclose the facility site with a fence designed to discourage the entrance of unauthorized persons and animals;

(B) Gratings over appropriate areas of treatment units where access for maintenance is necessary;

(C) First aid equipment;

(D) Posted "No Smoking" signs in hazardous areas;

(E) Appropriate personal protective equipment (PPE);

(F) Portable blower and hose sufficient to ventilate accessed confined spaces;

(G) Portable lighting equipment complying with NEC requirements. See subsection (7)(B) of this rule;

(H) Gas detectors listed and labeled for use in NEC Class I, Division 1, Group D locations. See subsection (7)(B) of this rule;

(I) Appropriately-placed warning signs for slippery areas, non- potable water fixtures (see subparagraph (7)(D)3.B. of this rule), low head clearance areas, open service manholes, hazardous chemical storage areas, flammable fuel storage areas, high noise areas, etc.;

(J) Ventilation. Ventilation shall include the following:
1. Isolate all pumping stations and wastewater treatment components installed in a building where other equipment or offices are located from the rest of the building by an air-tight partition, provide separate outside entrances, and provide separate and independent fresh air supply;

2. Force fresh air into enclosed screening device areas or open pits more than four feet (4') deep. Also see 10 CSR 20-8.130(3)(F);

3. Dampers. Dampers are not to be used on exhaust or fresh air ducts. Avoid the use of fine screens or other obstructions on exhaust or fresh air ducts to prevent clogging;

4. Continuous ventilation. Where continuous ventilation is needed (e.g., housed facilities), provide at least twelve (12) complete air changes per hour. Where continuous ventilation would cause excessive heat loss, provide intermittent ventilation of at least thirty (30) complete air changes per hour when facility personnel enter the area. Base air change demands on one hundred percent (100%) fresh air;

5. Electrical controls. Mark and conveniently locate switches for operation of ventilation equipment outside of the wet well or building. Interconnect all intermittently operated ventilation equipment with the respective wet well, dry well, or building lighting system. The manual lighting/ventilation switch is expected to override the automatic controls. For a two (2) speed ventilation system with automatic switch over where gas detection equipment is installed, increase the ventilation rate automatically in response to the detection of hazardous concentrations of gases or vapors; and

6. Fans, heating, and dehumidification. Fabricate the fan wheel from non-sparking material. Provide automatic heating and dehumidification equipment in all dry wells and buildings. Follow the provisions in subsection (7)(B) of this rule for electrical controls;

(K) Explosion-proof electrical equipment, non-sparking tools, gas detectors, and similar devices, in work areas where hazardous conditions may exist, such as digester vaults and other locations where potentially explosive atmospheres of flammable gas or vapor with air may accumulate. See subsection (7)(B) of this rule;

(L) Provisions for local lockout/tagout on stop motor controls and other devices;

(M) Provisions for an arc flash hazard analysis and determination of the flash protection boundary distance and type of PPE to reduce exposure to major electrical hazards in accordance with NFPA 70E Standard for Electrical Safety in the Workplace (2018 Edition), as approved and published August 21, 2017. This standard shall hereby be incorporated by reference in this rule, as published by National Fire Protection Association®, 1 Batterymarch Park, Quincy, MA 02169-7471. This rule does not incorporate any subsequent amendments or additions.

(9) Chemical Handling.

(A) General.
1. Containment materials. The materials utilized for storage, piping, valves, pumping, metering, and splash guards, etc., shall be specially selected considering the physical and chemical characteristics of each hazardous or corrosive chemical.

2. Secondary containment. Secondary containment storage areas contain the stored volume until it can be safely transferred to alternate storage or released to the wastewater treatment plant at controlled rates that will not damage the facilities, inhibit the treatment processes, or contribute to stream pollution. Secondary containment shall be designed as follows:
A. A minimum volume of one hundred twenty-five percent (125%) of the volume of the largest storage container located within the containment area plus the space occupied by any other tanks located within the containment area when not protected from precipitation;

B. A minimum volume of one hundred ten percent (110%) of the volume of the largest storage container located within the containment area plus the space occupied by any other tanks located within the containment area when protected from precipitation; and

C. Walls and floors of the secondary containment structure constructed of suitable material that is compatible with the specifications of the product being stored.

3. Splash guards. All pumps or feeders for hazardous or corrosive chemicals shall have guards that will effectively prevent spray of chemicals into space occupied by facility personnel.

4. Piping, labeling, and coupling guard locations.
A. All piping containing or transporting corrosive or hazardous chemicals shall be identified with labels every ten feet (10') and with at least two (2) labels in each room, closet, or pipe chase.

B. All connections (flanged or other type), except those adjacent to storage or feeder areas, shall have guards that will direct any leakage away from space occupied by facility personnel.

5. Alarm system. Facilities shall be provided for automatic shutdown of pumps and sounding of alarms when failure occurs in a pressurized chemical discharge line.

6. Dust. Dust collection equipment shall be provided to protect facility personnel from dusts injurious to the lungs or skin and to prevent polymer dust from settling on walkways that become slick when wet.

(B) Chemical Housing. The following shall be provided to fulfill the particular needs of each chemical housing facility:
1. Provide storage for a minimum of thirty (30) days' supply, unless local suppliers and conditions indicate that such storage can be reduced without limiting the supply;

2. Construct the chemical storage room of fire and corrosion resistant material;

3. Equip doors with panic hardware. To prevent unauthorized access, doors lock but do not need a key to exit the locked room using the panic hardware;

4. Provide chemical storage areas with drains, sumps, finished water plumbing, and the hose bibs and hoses necessary to clean up spills and to wash equipment;

5. Construct chemical storage area floors and walls of material that is suitable to the chemicals being stored and that is capable of being cleaned;

6. Install floor surfaces to be smooth, chemical resistant, slip resistant, and well drained with three inches per ten feet (3"/10') minimum slope;

7. Provide adequate lighting;

8. Comply with the NEC recommendation for lighting and electrical equipment based on the chemicals stored. See subsection (7)(B) of this rule;

9. Store chemical containers in a cool, dry, and well-ventilated area;

10. Design vents from feeders, storage facilities, and equipment exhaust to discharge to the outside atmosphere above grade and remote from air intakes;

11. Locate storage area for chemical containers out of direct sunlight;

12. Maintain storage temperatures in accordance with relevant Material Safety Data Sheets (MSDS);

13. Control humidity as necessary when storing dry chemicals;

14. Design the storage area with designated areas for "full" and "empty" chemical containers;

15. Provide storage rooms housing flammable chemicals with an automatic sprinkler system designed for four tenths gallons per minute per square foot (0.4 gpm/ft2) and a minimum duration of twenty (20) minutes;

16. Store incompatible chemicals separately to ensure the safety of facility personnel and the wastewater treatment system. Store any two (2) chemicals that can react to form a toxic gas in separate housing facilities;

17. Design and isolate areas intended for storage and handling of chlorine and sulfur dioxide and other hazardous gases. Follow the pro- visions in 10 CSR 20-8.190(3) and 10 CSR 20-8.190(4) for chlorine and dechlorination;

18. Design an isolated fireproof storage area and explosion proof electrical outlets, lights, and motors for all powdered activated carbon storage and handling areas in accordance with federal, state, and local requirements;

19. Vent acid storage tanks to the outside atmosphere, but not through vents in common with day tanks;

20. Keep concentrated acid solutions or dry powder in closed, acid-resistant shipping containers or storage units; and

21. Pump concentrated liquid acids in undiluted form from the original container to the point of treatment or to a covered storage tank. Do not handle in open vessels.

(C) Chemical Handling Design. The following shall be provided, where applicable, for the design of chemical handling:
1. Make provisions for measuring quantities of chemicals used for treatment or to prepare feed solutions over the range of design application rates;

2. Select storage tanks, piping, and equipment for liquid chemicals specific to the chemicals;

3. Install all liquid chemical mixing and feed installations on corrosion resistant pedestals;

4. Provide sufficient capacity of solution storage or day tanks feeding directly for twenty-four- (24-) hour operation at design average flow;

5. Provide a minimum of two (2) chemical feeders for continuous operability. Provide a standby unit or combination of units of sufficient capacity to replace the largest unit out-of-service;

6. Chemical feeders shall-
A. Be designed with chemical feed equipment to meet the maximum dosage requirements for the design average flow conditions;

B. Be able to supply, at all times, the necessary amounts of chemicals at an accurate rate throughout the range of feed;

C. Provide proportioning of chemical feed to the rate of flow where the flow rate is not constant;

D. Be designed to be readily accessible for servicing, repair, and observation;

E. Protect the entire feeder system against freezing;

F. Be located adjacent to points of application to minimize length of feed lines;

G. Provide for both automatic and manual operation for chemical feed control systems;

H. Utilize automatic chemical dose or residual analyzers, and where provided, include alarms for critical values and recording charts;

I. Provide screens and valves on the chemical feed pump suction lines; and

J. Provide an air break or anti-siphon device where the chemical solution enters the water stream;

7. Dry chemical feed system shall-
A. Be equipped with a dissolver capable of providing a minimum retention period of five (5) minutes at the maximum feed rate;

B. Be equipped with two (2) solution vessels and transfer piping for polyelectrolyte feed installations;

C. Have an eductor funnel or other appropriate arrangement for wetting the polymer during the preparation of the stock feed solution on the makeup tanks;

D. Provide adequate mixing by means of a large diameter, low-speed mixer;

E. Make provisions to measure the dry chemical volumetrically or gravimetrically; and

F. Completely enclose chemicals and prevent emission of dust;

8. Provide for uniform strength of solution consistent with the nature of the chemical solution for solution tank dosing;

9. Use solution feed pumps to feed chemical slurries that are not diaphragm or piston type positive displacement types;

10. Provide continuous agitation to maintain slurries in suspension;

11. Provide a minimum of two (2) flocculation tanks or channels having a combined detention period of twenty to thirty (20 - 30) minutes. Provide independent controls for each tank or channel;

12. Insulate pipelines carrying soda ash at concentrations greater than twenty percent (20%) solution to prevent crystallization; and

13. Prohibit bagging soda ash in a damp or humid place.

(D) Chemical Safety. The following shall be provided in addition to the safety provisions in section (8) of this rule:
1. Appropriate personal protective equipment (PPE).

2. Eye wash fountains and safety showers. Eye wash fountains and safety showers utilizing potable water shall be provided in the laboratory and on each level or work location involving hazardous or corrosive chemical storage, mixing (or slaking), pumping, metering, or transportation unloading. The design of eye wash fountains and safety showers shall include the following:
A. Eye wash fountains with water of moderate temperature, fifty degrees to ninety degrees Fahrenheit (50°-90°F), suitable to provide fifteen to thirty (15-30) minutes of continuous irrigation of the eyes;

B. Emergency showers capable of discharging twenty gallons per minute (20 gpm) of water of moderate temperature, fifty degrees to ninety degrees Fahrenheit (50°-90°F), and at pressures of thirty to fifty pounds per square inch (30-50 psi);

C. Eye wash fountains and emergency showers located no more than twenty-five feet (25') from points of hazardous chemical exposure; and

D. Eye wash fountains and showers that are to be fully operable during all weather conditions; and

3. Warning signs. Warning signs requiring use of goggles shall be located near chemical stations, pumps, and other points of frequent hazard.

(E) Chemical Container Identification. The identification and hazard warning data included on shipping containers, when received, shall appear on all containers (regardless of size or type) used to store, carry, or use a hazardous substance.

The secretary of state has determined that the publication of this rule in its entirety would be unduly cumbersome or expensive. The entire text of the material referenced has been filed with the secretary of state. This material may be found at the Office of the Secretary of State or at the headquarters of the agency and is available to any interested person at a cost established by state law.

*Original authority 1972, amended 1973, 1987, 1993.

Disclaimer: These regulations may not be the most recent version. Missouri may have more current or accurate information. We make no warranties or guarantees about the accuracy, completeness, or adequacy of the information contained on this site or the information linked to on the state site. Please check official sources.
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