5 Colo. Code Regs. § 1002-43.12

Current through Register Vol. 47, No. 11, June 10, 2024

Section 5 CCR 1002-43.12 - Design Criteria - Other Facilities

A. Evapotranspiration and Evapotranspiration/Absorption Systems:

1. Non-Pressurized Drip Dispersal System (NDDS):

a. An NDDS is considered a type of evapotranspiration/absorption system. However as specific design criteria is provided for an NDDS, they are exempt from the additional requirements of section 43.12.A.2, 3 and 4.

b. The design of a NDDS must follow the procedures stated in the document titled: The Colorado Professionals in Onsite Wastewater Guidelines for the Design and Installation of Non-Pressurized Drip Dispersal Systems (NDDS), Revision: September, 2016. The document is available from Colorado Professionals in Onsite Wastewater (www.cpow.net).

c. The width of an NDDS system may be wider than 12 feet.

2. The following section provides general criteria which must be followed when an evapotranspiration or evapotranspiration/absorption bed is proposed.

a. The design may only be permitted in arid climates where the annual evaporation rate exceeds the annual precipitation rate by more than 20 percent, and where site characteristics dictate that conventional methods of effluent dispersal are not appropriate.

b. The design may only be permitted in soil types 4, 4A and 5.

c. The system must be designed by a professional engineer.

d. If data for the Pan Evaporation Rate is provided, it must be multiplied by 0.70, or less, to obtain the equivalent Lake Evaporation Rate.

e. The width of the bed may be wider than 12 feet.

f. The required capillary or wicking sand must meet the gradation requirements in Table 12-1 and be approved by the design engineer. This sand is to be covered by a crowned, thin layer of loamy-sand mix and appropriate vegetation that will assist in drawing the water to the surface.

g. Adjustment factors as provided in Tables 10-2 and 10-3 must not be used.

Table 12-1 Gradation of Wicking Sand for Evapotranspiration Beds (Fine Sand)

Sieve Size	Percent Passing
4	100
40	50-70
200	<15

3. For systems designed strictly as an evapotranspiration bed, the following criteria must be met:

a. Design data to be furnished must include, but shall not be limited to: system dimensions, distribution system design, specifications of distribution media and wicking sand, liner material if used, bedding, properties of the soil under the system, vegetation cover, and a water balance calculation including annual precipitation and storage requirements for periods of the year when evapotranspiration does not occur..

b. The following formula must be used for determining the minimum area necessary for total evapotranspiration of septic tank effluent:

Click to view image

* Additional area may be required based on the annual water balance calculations.

c. Designs will include a rock and pipe, or other Division approved proprietary distribution product, with the centerline of the distribution system 6 to 8 feet on center. A thin non-woven fabric may be placed above the distribution system. Capillary wicking of the effluent is accomplished by a uniform depth layer of the specified sand media (capillary wicks), no more than 24 inches deep, placed between and above the distribution media. The base of the evapotranspiration bed may be no more than 30 inches below finished grade.

d. Capillary wicks which penetrate between the distribution system to the bottom of the bed, must be at least 15 percent of the bed surface area. The wicks must be uniformly spaced throughout the system.

e. Except for dwellings, if the system is designed for summer use only, as determined by the local public health agency, the surface area may be multiplied by 0.6 to obtain the required area.

4. For systems designed as an evapotranspiration/absorption bed, the following criteria must be met.

a. Data to be furnished must include, but is not limited to: system dimensions, distribution system design, specifications of wicking sand, properties of the soil under the evapotranspiration/absorption bed, provision for vegetation cover, and a water balance calculation including annual precipitation and storage requirements for periods of the year when evapotranspiration does not occur.

b. Design will include a rock and pipe, or other Division approved proprietary distribution product, with the centerline of the distribution system 6 to 8 feet on center. A thin non-woven fabric may be placed above the distribution media. Capillary wicking of the effluent is accomplished by a uniform depth layer of the specified sand media (capillary wicks) no more than 24 inches deep placed between and above the distribution media. The infiltrative surface may be no more than 30 inches below finished grade.

c. Capillary wicks which penetrate between the distribution system to the bottom of the bed, must be at least 15 percent of the bed surface area. The wicks must be uniformly spaced throughout the bed.

d. Amount of storage and evapotranspiration capacities may be reduced by the volume of effluent absorbed by the underlying soil based on the long-term acceptance rate for that soil type and the formulas provided in section 43.12.A.4.e below.

e. The following formula must be used for determining the minimum area necessary for evapotranspiration/absorption of septic tank effluent:

Click to view image

(i) LTAR refers to the long-term acceptance rate of the underlying soil as provided in Table 10-1 for TL1 effluent.

(ii) ETR refers to the evapotranspiration rate derived from the following formula:

Click to view image

* Additional area may be required based on the annual water balance calculations.

B. Seepage Pits

1. The construction of new seepage pits for the treatment and dispersal of on-site wastewater on new sites is prohibited unless:

a. A trench or bed system will not meet the design, sizing or setback requirements of this regulation on the proposed site;

b. The seepage pit is designed by a professional engineer; and

c. The design includes higher level treatment of at least TL2.

2. The design requirements for new seepage pits must also comply with requirements as defined in 43.10.I.6.c and d.

3. Pressure distribution is not required for dispersal into a seepage pit.

C. Vaults Other Than Vault Privies

1. Vaults for full time use in new construction are prohibited where a property can accommodate an OWTS with a soil treatment area.

2. A local board of health may allow or prohibit vaults for use at a permanently occupied facility, except where section 43.12.D.1 applies.

3. Vaults for full time use may be permitted when a failing OWTS cannot be replaced.

4. Vaults may be permitted for limited use occupancy on a property which cannot accommodate an OWTS with soil treatment area.

5. A vault may be permitted if the facility is on land where the installation of an OWTS with soil treatment area is not permitted.

6. Vaults may be permitted for systems where some of the wastewater flows are separated, such as toilet wastes only, into a vault. The portion not retained in the vault must be treated in an OWTS sized per the requirements of this regulation.

7. Variances may be granted for specialized commercial uses.

8. A vault, if permitted by the local public health agency, must have a minimum 500 gallon effective volume or be capable of holding a minimum of the 48-hour design wastewater flow, whichever is larger.

9. A visual or an audible signal device or both, indicating filling to a maximum of 75 percent capacity, must be installed to indicate when pumping is necessary.

10. Concrete vaults must meet the strength and watertightness requirements for septic tanks. Prefabricated fiberglass, fiberglass-reinforced polyester, and plastic tanks may be used as vaults, if the tank manufacturer provides testing criteria certifying them for this use.

D. Privies

1. Vault Privy

a. A local board of health may prohibit the new construction of vault privies.

b. A local board of health may prohibit the continued use of existing vault privies.

c. Effective volume of the vault must be no less than 400 gallons and it must be constructed of concrete or plastic. The vaults for privies must meet the structural and watertightness standards of vaults.

d. A vault privy must be built to include: fly- and rodent-tight construction, a superstructure affording complete privacy, an earth mound around the top of the vault and below floor level that slopes downward away from the superstructure base, a floor, and a riser of concrete or other impervious material with hinged seats and covers of easily cleanable, impervious material. All venting must be fly-proofed with No. 16 or tighter mesh screening.

2. Pit Privy

a. A local board of health may prohibit the new construction of pit privies.

b. A local board of health may prohibit the continued use of existing pit privies.

c. If pit privies are permitted by the local public health agency:

(1) The bottom of the pit must be located above at least four feet of suitable soil and four feet above a limiting layer;

(2) The pit must have at least 400 gallons of effective volume; and

(3) The superstructure must provide complete privacy and have fly- and rodent-tight construction, an earth mound around the top of the pit and below floor level that slopes downward away from the superstructure base, a floor, and a riser of concrete or other impervious material with hinged seats and covers of easily cleanable, impervious material. All venting must be fly-proofed with No. 16 or tighter mesh screening.

E. Incinerating, Composting and Chemical Toilets

1. The local board of health may permit incinerating, composting and chemical toilets. The use of an incinerating, composting or chemical toilet will not reduce the required size of the OWTS as noted in section 43.8.A.

2. Permitting of an incinerating or composting toilet may also be subject to the jurisdiction of a local agency regulating plumbing or the Colorado Plumbing Board, whichever has jurisdiction over plumbing in the location.

3. An incinerating or composting toilet may be used for toilet waste where an OWTS is installed for treating wastewater remaining after removal of toilet waste. Subject to local board of health or other applicable regulations or codes (e.g., Colorado Plumbing Code if a local code does not exist), the compartment may be located within a dwelling or building provided the unit complies with the applicable requirements of this regulation, and provided the installation will not result in conditions considered to be a health hazard as determined by the local public health agency. Compartment and appurtenances related to the unit must include fly-tight and vector-proof construction and exterior ventilation.

4. Incinerating Toilets: An approved incinerating toilet must be designed and installed in accordance with all applicable federal, state, and local air-pollution requirements and manufacturer's instructions.

5. Composting Toilets

a. Composting toilets must meet the requirements of NSF/ANSI Standard 41 (2016 version) and bear the seal of approval of the NSF or an equivalent testing and certification program.

b. An approved composting toilet must treat deposits of feces, urine, and readily decomposable household garbage that are not diluted with water or other fluids and are retained in a compartment in which aerobic composting will occur.

c. The effective volume of the receptacle must be sufficient to accommodate the number of persons served in the design of the unit installed. The effective volume of the unit must include sufficient area for the use of composting materials which must not be toxic to the process or hazardous to persons and which must be used in sufficient quantity to assure proper decomposition.

d. Residue from the composting toilet must be removed when it is filled to 75 percent of capacity. Residue from the unit must be properly disposed of by methods recommended by the manufacturer and acceptable to the local public health agency. Disposal methods must prevent contamination of water and not cause a public health nuisance. Disposal using solid waste practices is recommended.

e. If a system will be installed where low temperature may be a factor, design and installation must address the effects of the low temperature.

f. Composting toilets must be operated according to manufacturer's specifications.

6. Incinerating Toilets Acceptance Requirements

a. Incinerating toilets must meet the requirements of the NSF Protocol P157 (2014 version) and bear the seal of approval of the NSF or an equivalent testing and certification program.

b. Incinerating toilets must be operated according to manufacturer's specifications.

7. Portable Chemical Toilets

a. A portable chemical toilet may be used by permit from the local public health agency or other agency with authority to issue permits for portable chemical toilets.

b. Use of a portable chemical toilet in permanently occupied buildings is prohibited except during construction or under emergency circumstances as determined by the local public health agency. Proper ventilation of a chemical toilet used inside must be required.

F. Slit Trench Latrine

1. If permitted by the local board of health, a slit trench latrine must be utilized only in remote or emergency situations when other approved sanitary means are unavailable. Other agencies may have more stringent regulations that must be adhered to.

2. A slit trench latrine must be considered a temporary convenience to be used no longer than seven days and must be backfilled and graded to match its surroundings when its use is discontinued.

3. A slit trench latrine must be located only in a place that does not adversely affect public health or the environment. The location must provide ample privacy and should be exposed to several hours of sunlight each day. A slit trench latrine must not be located:

a. In a building;

b. In a covered or partially covered location such as a cave or overhanging cliff; or

c. On a slope of greater than 30 percent.

4. A slit trench latrine must be installed only in suitable soil.

5. A slit trench latrine must be excavated approximately one foot wide and two feet deep for the required length. All human waste and tissue placed into the slit trench latrine must be covered with at least two inches of soil at least once a day or more frequently if requested by the local public health agency.

G. Treatment Systems Other Than Those Discharging Through a Soil Treatment Area or Sand Filter System

1. For systems discharging to State Waters, see section 2.C.

2. Systems that discharge other than through a soil treatment area or a sand filter system must:

a. Be designed by a professional engineer;

b. Be reviewed by the local board of health; and

c. Not pose a potential health hazard or private or public nuisance or undue risk of contamination.

d. Not allow drainage of effluent off of the property of origin.

3. The local board of health may choose to permit only systems that do not allow drainage of effluent off the property of origin.

4. The following minimum performance criteria must be required for all permitted systems pursuant to this section:

a. If effluent discharge is made into areas in which the possibility exists for occasional direct human contact with the effluent discharge, the effluent at the point of discharge must meet the minimum treatment criteria of TL3 effluent and specifically adhere to each of the following standards:

(1) The geometric mean of the E. coli density must not exceed 15 per 100 milliliters when averaged over any five consecutive samples, and no single sample result for E. coli can exceed 126 per 100 milliliters.

(2) The arithmetic mean of the standard five-day carbonaceous biochemical oxygen demand (CBOD5) must not exceed ten milligrams per liter when averaged over any three consecutive samples.

(3) The arithmetic mean of the total suspended solids must not exceed ten milligrams per liter when averaged over any three consecutive samples.

b. If the effluent discharge is made into an area so restricted as to protect against the likelihood of direct human contact with the discharged effluent, the effluent at the point of discharge must meet the treatment criteria of TL2 effluent and specifically adhere to each of the following standards:

(1) The geometric mean of the E. coli density must not exceed 126 per 100 milliliters when averaged over any five consecutive samples, and no single sample can exceed 325 E. coli per 100 milliliters.

(2) The arithmetic mean of the standard five-day carbonaceous biochemical oxygen demand (CBOD5) must not exceed 25 milligrams per liter when averaged over any three consecutive samples.

(3) The arithmetic mean of the total suspended solids must not exceed 30 milligrams per liter when averaged over any three consecutive samples.

5. To determine compliance with the standards contained in this section, the required sampling frequency for E. coli, CBOD5, and total suspended solid levels must be performed at least once per month when the system is in operation and the results submitted to the local public health agency for compliance with the permit requirements.

6. Methods of Analysis - Sampling Points:

a. All effluent samples must be analyzed according to the methods prescribed in the American Public Health Association, American Water Works Association, and Water Environment Federation: Standards Methods for the Examination of Water and Wastewater, 22nd edition, 2012 (International Standard Book Number: 9780875530130).

b. The sampling point must be a location that is representative of final discharge from the system.

5 CCR 1002-43.12

40 CR 11, June 10, 2017, effective 6/30/2017

41 CR 07, April 10, 2018, effective 4/30/2018