Pursuant to the Weld County Home Rule Charter, Ordinance Number 2026-07 published below, was introduced and, on motion duly made and seconded, approved upon first reading on May 13, 2026. A public hearing and second reading is scheduled to be held in the Chambers of the Board, located within the Weld County Administration Building, 1150 O Street, Greeley, Colorado 80631, on June 1, 2026. All persons in any manner interested in the reading of said Ordinance are requested to attend and may be heard.
In accordance with the Americans with Disabilities Act, if special accommodations are required in order for you to participate in this hearing, please contact the Clerk to the Board's Office at (970) 400-4225 prior to the day of the hearing.
Any backup material, exhibits or information previously submitted to the Board of County Commissioners concerning this matter may be examined in the office of the Clerk to the Board of County Commissioners, located within the Weld County Administration Building, 1150 O Street, Greeley, Colorado 80631, between the hours of 8:00 a.m. and 5:00 p.m., Monday through Friday, or may be accessed through the Weld County website (www.weld.gov). Email messages sent to an individual Commissioner may not be included in the case file. To ensure inclusion of your email correspondence into the case file, please send a copy to egesick@weld.gov.
Ordinance No. 2026-07
Ordinance Title: In the Matter of Repealing and Reenacting, with Amendments, Chapter 30 Weld County Department of Public Health and Environment On-Site Wastewater Treatment System Regulations of the Weld County Code
Date of Next Reading: June 1, 2026, at 9:00 a.m.
Board of County Commissioners
Weld County, Colorado
Dated: May 13, 2026
Published: May 20, 2026, in the Greeley Tribune
Ordinance Language:
Weld County Code Ordinance 2026-07
In the Matter of Repealing and Reenacting, with Amendments, Chapter 30 Weld County Department of Public Health and Environment On-Site Wastewater Treatment System Regulations, of the Weld County Code
Be it ordained by the Board of County Commissioners of the County of Weld, State of Colorado:
Whereas, the Board of County Commissioners of Weld County, Colorado, pursuant to Colorado statute and the Weld County Home Rule Charter, is vested with the authority of administering the affairs of Weld County, Colorado, and
Whereas, the Board of County Commissioners, on December 28, 2000, adopted Weld County Code Ordinance 2000-1, enacting a comprehensive Code for the County of Weld, including the codification of all previously adopted ordinances of a general and permanent nature enacted on or before said date of adoption, and
Whereas, the Weld County Code is in need of revision and clarification with regard to procedures, terms, and requirements therein.
Now, therefore, be it ordained by the Board of County Commissioners of the County of Weld, State of Colorado, that Chapter 30 of the Weld County Code be, and hereby is, repealed and re-enacted, with amendments, to read as follows.
Chapter 30
Weld County Department of Public Health and Environment On-Site Wastewater Treatment System Regulations
Article I - Authority
Amend Sec. 30-1-20. Jurisdiction, Severability, Savings Clause.
A. - No change.
B. If any section of these Regulations adopted hereunder or its application to any person or circumstance is held invalid, unconstitutional, void or inoperative, such holding shall not affect other provisions or applications of the ordinance adopted hereunder. The Board of Public Health and the Board of County Commissioners hereby declares that in this regard, the ordinance adopted hereunder is severable, and that said Boards would have adopted the remaining ordinance hereof notwithstanding such holding.
C. through E. – No change.
F. Chapter Coverage: These Regulations adopted by the Weld County Board of Public Health, pursuant to current On-site Wastewater Treatment System Regulations of the Colorado Department of Public Health and Environment, Water Quality Control Commission, Regulation #43 (5 CCR 1002-43) and adopted in compliance with Section 25-10-104, C.R.S., shall govern all aspects of permits, performance, location, construction, alteration, installation, and use of Onsite Wastewater Treatment Systems of less than or equal to 2,000 gallons per day design capacity. Site approval, design review and a discharge permit from the Water Quality Control Division are required for a system with design capacity greater than 2,000 gallons per day average flow.
Remainder of Section – No change.
Amend Sec. 30-1-30. Effective date.
Upon adoption, the Regulations shall become effective June 30, 2026.
Article II – Scope and Purpose
Amend Sec. 30-2-30. Effluent discharged to surface waters.
Any system that will discharge into surface waters must be designed by a professional engineer. The discharge permit application must be submitted for preliminary approval to the public health agency. Once approved by the public health agency, the application must be submitted to the Water Quality Control Division for review in accordance with the Water Quality Control Act, Section 25-8-101, et seq., C.R.S., and all applicable regulations of the Water Quality Control Commission. Compliance with such a permit will be deemed full compliance with this Regulation.
Article III – Definitions
Amend Sec. 30-3-10. Definitions.
The following definitions shall apply in the interpretation and enforcement of these Regulations. The words “shall,” and “must” as used herein indicates a mandatory requirement.
Change all definitions in Sec. 30-3-10 from Italics to quotations.
Insert the following after “Accessible”:
“Alteration” (Alter) means to change in character or composition of the OWTS. This includes any modification to the OWTS resulting in a small yet significant difference.
Insert the following after “Applicant”:
“Auxiliary building” means a non-residential structure, located on the same lot or parcel as the principal structure, and for an incidental use to the principal structure.
Chamber means an arch-shaped structure providing an open-bottom soil interface with permeable sidewalls, used for distribution of effluent in a soil absorption system.
Cistern means an enclosed unpressurized reservoir or tank for storing water as part of a potable water supply system.
Insert the following after “Designer, On-site Wastewater Treatment System”:
“Disinfection” means the process of destroying pathogenic microorganisms in sewage through the application of ultraviolet light, chlorination, or ozonation.
Distribution means the process of dispersing wastewater or effluent to one (1) or more components, devices or throughout a soil treatment area.
Drop box means a device used for sequential distribution of effluent by gravity flow to a lateral of a soil treatment area.
Effluent filter means a removable, cleanable (or disposable) device installed on the outlet piping of a septic tank for the purpose of retaining solids larger than one-eighth inch and/or modulating effluent flow rate. An effluent filter may be a component of a pump installation. An effluent filter may also be installed following the septic tank but before higher level treatment components or a soil treatment area.
Delete Effluent screen.
Insert the following after “Groundwater”:
“Groundwater condition” means a condition in the soil profile where a seasonal or current ground water surface has been identified, thus creating a vertical separation requirement to the infiltrative surface of a soil treatment area.
Gulch, dry means a deep, narrow ravine that receives discontinuous storm influenced flows, for a short duration, in direct response to a rain event and is not interconnected to a groundwater source.
Lateral means a pipe, chamber or other component used to transport and to distribute effluent.
Limiting layer means a horizon or condition in the soil profile that exhibits a limited capability for treatment, but will readily accept the effluent. Generally speaking, this includes fractured bedrock, and type R-0 soils (see Table 30-10-1A).
Malfunction means the condition in which a component is not performing as designed or installed and is in need of repair or modification in order to function as originally intended.
Media, Enhanced Manufactured means an accepted proprietary manufactured distribution product, that includes synthetic media contained within one or more external permeable outer layers which promote the movement of the effluent, and is placed on a specified sand base or media that does not mask the infiltrative surface of the in-situ soil.
Professional engineer means an engineer licensed in Colorado, in accordance with Section12-120-201, et seq., C.R.S., and practicing within their areas of expertise, consistent with 4 CCR 730-1.
Professional geologist means a person who is a graduate of an institution of higher education which is accredited by a regional or national accrediting agency, with a minimum of thirty (30) semester (forty-five [45] quarter) hours of undergraduate or graduate work in a field of geology and whose post-baccalaureate training has been in the field of geology with a specific record of an additional five (5) years of geological experience, to include no more than two (2) years of graduate work. Section 23-41-208, C.R.S.
Repair means restoration of functionality and/or treatment by reconstruction, relocation, or replacement of an On-site Wastewater Treatment System or any component thereof in order to allow the system to function as intended.
Insert the following after “Riser”:
“Restrictive layer” means a condition in the soil profile that restricts the vertical movement of the effluent. This may include impervious bedrock, glacial till, platy soils, sodic soils, or soils with a cementation class of “strongly cemented” or greater.
Sequential distribution means a distribution method in which effluent is loaded into one (1) trench and fills it to a predetermined level before overflowing to the succeeding trench through a drop box. Effluent does not pass through the distribution media before it enters any succeeding trenches. The effluent is dispersed through a drop box at the proximal end of the system, allowing for portions of the absorption area to be isolated.
Systems cleaner means a person engaged in and who holds themselves out as a specialist in the cleaning and pumping of on-site wastewater treatment systems and removal of the residues deposited in the operation thereof.
Systems contractor means a person who is engaged in and holds themselves out as a specialist in the installation, renovation and repair of on-site wastewater treatment systems.
Insert “Systems maintenance provider” means a person engaged in and who holds themselves out as a specialist in routine or periodic actions taken to assure that the On-site Wastewater Treatment System is functioning as intended, and/or that the On-site Wastewater Treatment System is meeting performance requirements.
Insert “Tiny home” means a structure (a non-recreational vehicle) that has only one bedroom and has 400 sq.ft. or less of livable space, including lofts. In this instance, the OWTS may be sized for only one bedroom.
Insert the following after “Transfer of Title”:
“Transfer of Title Inspector” means a person engaged in and who holds themselves out as a specialist in conducting evaluations and observations of an existing On-site Wastewater Treatment System serving a structure that is proposed for property transfer, to assess if the system is functioning as intended.
Insert the following after “Wastewater pond”:
“Watercourse means a natural or artificial channel through which water flows, either continuously or intermittently, and exhibits a connection to an actual or elevated groundwater table. A watercourse includes the bed of a channel that flows only seasonally (e.g., creek, stream, irrigation ditch). Hollows, ravines, or roadside ditches that are normally dry are not considered a watercourse.
Vault means a watertight, covered receptacle, which is designed to receive and store excreta or wastes either from a building sewer or from a privy and is accessible for the periodic removal of its contents. If the vault is intended to serve a structure or structures that are projected to generate a domestic wastewater flow of greater than two thousand (2,000) gallons per day at full occupancy, the vault would be considered a domestic wastewater treatment works. Vaults are On-Site Wastewater Treatment Systems.
All other definitions in this section remain unchanged.
Amend Sec. 30-3-20. Abbreviations and acronyms.
Table 30-3-1 Abbreviations and Acronyms
(Contact the Clerk to the Board’s Office to View the Table)
Article IV – Administration and Enforcement
Amend Sec. 30-4-30. Permit Application Requirements and Procedures.
A. through E. – No change.
F. Other fees.
1. – No change.
2. Surcharge. The Division must collect a fee for each permit issued for a new, repaired or upgraded OWTS and transmit funds to the Colorado Department of Public Health and Environment for use in funding the state’s OWTS program, as identified in the On-Site Wastewater Treatment System Act 25-10-107(3) C.R.S. until replaced by a fee(s) becoming effective in Regulation 102 adopted under Section 24-8-210(1)(a)(X) C.R.S.
G. through H – No change.
I. A permit must be required for a change of use, or the expanded use of an OWTS where it has been determined that the existing OWTS is not sized to accommodate the expected additional hydraulic or organic load. The OWTS must be replaced or modified to handle such an increase unless it is determined that the existing system is adequately designed and constructed.
Remainder of Section – No change.
Amend Sec. 30-4-80. Final approval of OWTS permit.
A. Final approval of the OWTS permit by the Division must include, but is not limited to:
1. Receipt of letter from the professional engineer certifying construction of the OWTS as per the approved design, if the OWTS was engineer-designed. This letter must include any modifications to the permitted and approved design, general observations noted during the inspection(s), and the corresponding dates of all inspections.
a. For designs that include a pressurized distribution system, a residual head test (squirt height), at the distal end of each lateral, must be conducted to determine the adequacy of system design and construction. Results from this inspection must be included within both the engineer’s certification and the final permit acceptance documents.
Remainder of Section – No change.
Amend Sec. 30-4-100. Product development permit.
A. – No change.
B. For products or types of systems which have not been otherwise accepted by the Colorado Water Quality Control Division pursuant to section 43.13.D of Regulation 43, the Board of Public Health may approve an application for product development permit only if the system has been designed by a professional engineer, and only if the application meets all requirements of Section 30-4-100, items C through J.
C. Before a product development permit is issued by the (WCDPHE) division, the Water Quality Control Division must determine that the product to be tested qualifies for testing under the product development evaluation based on information submitted to the Division.
Remainder of Section – No change.
Amend Sec. 30-4-110. Systems contractor license.
A. No person, except as in Section 30-4-110.B below, shall install, engage in the installation of, or repair an OWTS unless such person holds a valid systems contractor license issued by the Division. Employees of a validly licensed Systems Contractor shall not be required to be licensed. The initial fee for a systems contractor license shall be set by separate Chapter of the Board of Weld County Commissioners. The fee for the initial license and for renewal of the license shall not exceed actual costs. A license shall expire on December 31 of each year, and shall be renewed within thirty (30) days prior thereto, and an annual renewal fee, as set by separate Chapter of the Board of Weld County Commissioners, shall be charged. A license which lapses because of failure to renew or is revoked shall be subject to the fee established for a new license upon re-application.
Remainder of Section – No change.
Amend Sec. 30-4-120. Regulations of systems cleaners.
A. No person shall engage in the cleaning of sewage treatment works and OWTS or the transportation of septage to a disposal site unless such person holds a valid systems cleaner license issued by the Division. Employees of a validly licensed systems cleaner shall not be required to be licensed. The initial fee for a systems cleaner license shall be as set by separate chapter by the Board of County Commissioners. The fee for the initial license and for renewal of the license shall not exceed actual costs. Licenses shall expire on December 31 of each year and an annual renewal fee, as set by separate chapter by the Board of County Commissioners, shall be charged. A license which lapses because of failure to renew or is revoked shall be subject to the fee established for a new license upon reapplication.
Remainder of Section – No change.
Amend Sec. 30-4-130. Variance procedure.
A. through B.2. – No change.
3. Requests must be accompanied by:
a. A site specific request identifying the specific criteria from which a variance is being requested;
b. Technical justification by a professional engineer or professional geologist, which indicates the specific conditions which exist and/or the measures which will be taken to result in no greater risk than that associated with compliance with the requirements of the Regulation. Examples of conditions which exist or measures which might be taken include, but are not limited to, the following: evidence of a natural or man-made physical barrier to the movement of effluent to or toward the feature from which the variance is requested; placement of a man-made physical barrier to the movement of effluent to or toward the feature from which the variance is requested; soil amendment or replacement with sand filter media to reduce the infiltration rate of the effluent such that the travel time of the effluent from the absorption field to the physical feature is no less than the travel time through the native soils at the prescribed setback; and higher level treatment.
c. through e. – No change.
4. and 5. – No change.
C. Variances for repair of failing systems.
1. When a proposed variance for a system repair or upgrade would result in encroachment on minimum distances to physical features on neighboring properties required by the Division, the hearing procedures in Section 30-4-130.B. and Section 30-4-130.D. must be followed.
2. – No change.
Remainder of Section – No change.
Amend Sec. 30-4-140. General prohibitions.
A. No city, county, or city and county shall issue to any person:
1. A permit to construct or remodel a building or structure which includes plumbing, that is not serviced by a sewage treatment works until the Division has issued a permit for an OWTS.
2. – No change.
B. and C. – No change.
D. No person shall construct or maintain any dwelling or other occupied structure which is not equipped with adequate facilities for the sanitary disposal of sewage. “Adequate facilities” do not include OWTS that are deemed to be failed, or any such condition that the local public health agency determines to be a public health and/or safety concern.
E. Construct a new occupied structure that includes plumbing, without connecting to a domestic wastewater treatment works or obtaining an OWTS permit issued by the local public health agency and installing a compliant OWTS.
F. An OWTS must receive only such biodegradable wastes for treatment and distribution as are compatible with those biological treatment processes that occur within the septic tank, any additional treatment unit, and the soil treatment area. This does not include industrial, animal, or process waste.
G. All persons shall dispose of septage removed from systems in the process of maintenance or cleaning at an approved site and in an approved manner.
Amend Sec. 30-4-170. Penalties.
A. Any person who commits any of the following acts or violates any of the provisions of this Section commits a civil infraction as defined in Section 18-1.3-503, C.R.S.:
1. Constructs, alters, installs or permits the use of any OWTS without first applying for and receiving a permit as provided for in these Regulations, the OWTS Act and any other applicable rules and regulations adopted thereunder;
2. through 7. – No change.
B. – No change.
C. Upon a finding by the local board of health that a person is in violation of this regulation, or of rules adopted and promulgated pursuant to Section 25-10-104, the local board of health may assess a penalty of up to fifty dollars for each day of violation. In determining the amount of the penalty to be assessed, the local board of health shall consider the seriousness of the danger to the health of the public caused by the violation, the duration of the violation, and whether the person has previously been determined to have committed a similar violation.
Remainder of Section – No change.
Amend Sec. 30-5-20. Preliminary Investigation.
A. Preliminary site investigation: Research of information relative to the site and anticipated conditions must be conducted. Information gathered as part of the preliminary investigation must include, but is not limited to:
1. – No change.
2. Existing Division OWTS records.
3. Location of physical features, on and off the property, that will require setbacks, as identified in Table 30-7-1.
4. Preliminary soil treatment area size estimate based on information on existing or planned facility and local regulations.
5. Other information required by the Division.
6. Additional published information that may be useful to the site-specific evaluation, as available:
a. Soil Information;
b. Topography;
c. Survey;
d. Easements;
e. Floodplain maps;
f. Delineated wetland maps;
g. Geology and basin maps and descriptions;
h. Climate information; and
i. Aerial photographs.
Amend Sec. 30-5-30. Reconnaissance.
A. Reconnaissance: A visit to the property to evaluate the topography and other surface conditions that will impact the location and design of the OWTS must be conducted. Information gathered as part of the site reconnaissance may include, but is not limited to:
1. through 5. – No change.
Note: The reconnaissance evaluation may be conducted concurrently with the detailed soil investigation.
Amend Sec. 30-5-40. Detailed soil investigation.
A. – No change.
B. Procedure for performing visual and tactile evaluations of soil in order to determine a long-term acceptance rate:
1. The soils evaluation shall be performed by or under the supervision of a professional engineer, professional geologist, competent technician, or other similarly qualified professional as approved by the Division.
2. Evaluation of two (2) or more soil profile test pit excavations must be performed to determine soil types, limiting layers, restrictive layers, groundwater conditions, and the best depth for the infiltrative surface. The total number of soil profile test pit excavations beyond the required two shall be based on the judgment of the competent technician.
3. At least one (1) of the soil profile test pit excavations must be performed in the portion of the soil treatment area anticipated to have the most limiting or restrictive conditions.
4. The minimum depth of the soil profile test pit excavation must be to any limiting layer, groundwater condition, or four feet below the infiltrative surface of the in-situ soil, whichever is encountered first.
5. Layers and interfaces that interfere with the treatment and dispersal of effluent must be noted. Thus, any restrictive soil characteristic such as consistence, as defined by cementation class, also needs to be evaluated.
a. When cemented soils are encountered, the evaluation must identify the cementation class from rupture resistance as provided in Table 5-1, “Rupture Resistance”.
b. Per the “Rupture Resistance” Table noted in item d.1 above, when the “Cementation Class” is identified within the soil profile as “strongly”, “very strongly cemented”, or “indurated” that layer will be classified as a “restrictive layer”.
c. Note: Cemented soils will typically have characteristics of Type 3A or 4A soils (Table 10-1). Long term acceptance rates should coincide with the appropriate soil type classification or be adjusted to address the level of cementation.
Table 5-1: Rupture Resistance: Blocks, Peds, Clods – Estimate the class by the force required to rupture (break) a soil unit.
(Contact the Clerk to the Board’s Office to View the Table)
43.5 Site and Soil Evaluation
Source: NRCS Field Book for Describing and Sampling Soils, Version 3.0; 2021 Reprint; Consistence section, pg. 2-63. Dry Rupture Resistance applies to soils that are moderately dry or drier.
6. through 11. – No change.
C. – No change.
D. When a percolation test is determined to be necessary to obtain additional information regarding soil permeability, the following procedures for performing percolation tests must be followed:
1. through 5.b. – No change.
c. Presoak.
1) The hole must be presoaked adequately to accomplish both saturation, which is filling the void spaces between the soil particles, and swelling, which is the intrusion of water into the individual soil particles.
2) To presoak the hole, carefully fill the hole with clean water to a minimum depth of twelve (12) inches over the gravel placed in the bottom of the hole. In most soils, it is necessary to refill the hole by supplying a surplus reservoir of clean water, possibly by means of an automatic siphon, to maintain water in the hole for at least four (4) hours and preferably overnight. Determine the percolation rate twenty-four (24) hours after water is first added to the hole. This procedure is to ensure that the soil is given ample time to swell and to approach the condition it will be in during the wettest season of the year. In type 1 soils, (sand and loamy sand; Table 10-1) the swelling procedure is not essential and the test may be conducted after the water from one (1) filling of the hole has completely seeped out of the hole.
d. Percolation rate measurement.
1) With the exception of type 1 soils, percolation rate measurements must be made on the day following the presoak procedure.
Remainder of Section – No change.
Amend Sec. 30-5-50. Evaluation and Marking of soil profile test pit excavations or percolation holes.
A. The engineer or technician conducting the soil profile test pit excavations or percolation tests, must, upon completion of the tests, adequately mark and identify each excavation to allow easy location by others.
B. The objective of the regulation is to ensure a detailed and accurate identification of the soils on each site, while concurrently ensuring the safety of the practitioner, general public and wildlife. In order to accomplish this, the following items are noted:
1. Percolation holes must remain open until after evaluation by the Division. The soil profile test pit excavations may be backfilled after evaluation by the third-party professional (professional engineer, geologist, competent technician or other similar professional). If the profile test pit excavation is backfilled prior to inspection by the Division, a monitoring port shall be installed prior to backfilling for evaluation by the Division. The monitoring port should be a minimum of 3 inches in diameter and be perforated pipe, or notched at the bottom of the pipe.
2. In order to address public safety concerns, the regulatory intent is to backfill all soil profile test pits promptly after the soil evaluation is complete.
3. Soil test pit excavations that are left open must be suitably barricaded to prevent unauthorized access and to address safety concerns.
Amend Sec. 30-5-60. Soils Report and site plan.
A. A written report must describe the results of the preliminary investigation, reconnaissance and detailed evaluations. The report may be in text and/or tabular form and must include a drawing locating features relative to the proposed OWTS location and test locations. The report may be included as part of the OWTS design document. The report must include, but is not limited to:
1. through 6. – No change.
7. A drawing created to a scale that provides the complete property boundary lines. The minimum drawing size is eight and one-half (8.5) inches by eleven (11) inches. If the property is too large to adequately show site evaluation information, a detailed drawing that includes the information required from the site and soil evaluation that will impact the location of the OWTS must be submitted. Drawings must indicate dimensions, have a north arrow and graphic scale and include:
Remainder of Section – No change.
Amend Sec. 30-5-70. Design document.
A. through B. – No change.
C. The design document must contain all plan detail necessary for permitting, installation and maintenance, including:
1. Assumptions and calculations for each component, including dose volume total dynamic head (TDH) and gallons per minute (GPM) for all dosing systems;
2. – No change.
3. A scale drawing showing the location of each OWTS component and distances to water supplies, surface water, easements, physical and health impact features on both the subject and adjacent properties requiring setbacks;
4. – No change.
5. Contours or slope direction and percent slope for the area of the OWTS;
6. Elevation or depth of infiltrative surface of the soil treatment area, the septic tank invert, and all other components of the OWTS. For sites with minimal elevation change, providing the depth of the components from grade is acceptable. However, where the site has noticeable elevation changes, it is the expectation that the proposed elevations of all components, relative to a site benchmark, be provided;
Remainder of Section – No change; renumber accordingly.
Amend Sec. 30-5-90. Qualifications for competent technician.
A. Percolation tests.
1. Competencies needed:
a. Set up equipment;
b. Perform and run percolation tests according to the procedures identified in Section 30-5-40.D in this Regulation; and
c. – No change.
2. – No change.
B. Visual and tactile evaluation of soil.
1. Competencies needed:
a. through c. – No change.
d. Identify soil consistence/cementation;
e. Recognize evidence of highest seasonal water surface;
f. Identify limiting layers, restrictive layers, and groundwater conditions;
g. Determine the appropriate depth for infiltrative surface of OWTS, soil profile pits, and for percolation tests, if used; and
h. Understand basic principles of OWTS siting and design.
Remainder of Section – No change.
Article VI Wastewater Flow and Strength
Amend Sec. 30-6-10. Wastewater flows.
A. – No change.
B. Single-family residential homes.
1. Design flow per person must be at least seventy-five (75) gallons per day (gpd).
2. The minimum design flow for a new home must be for a two-bedroom house, unless otherwise noted in this regulation. The minimum design flow for the repair or replacement of an OWTS of an existing one-bedroom home must, at a minimum, be for one (1) bedroom, unless bedrooms are added.
3. and 4. – No change.
5. A local public health agency may increase the number of persons per bedroom to two for all bedrooms for design purposes.
6. Table 30-6-1 summarizes the design flows for single-family residential homes up to six (6) bedrooms.
7. If a new home has unfinished areas, a local public health agency may increase the number of bedrooms used for the design of the OWTS by one (1) or two (2) bedrooms based on an assumption that 150 square feet of unfinished space can be converted into a bedroom, if the space can meet building code requirements for a bedroom.
8. Accessory Dwelling Units
a. An “accessory dwelling unit” is considered a smaller, independent residential dwelling located on the same lot or parcel as a stand-alone single-family home.
b. A new or expanded OWTS must be sized for the number of bedrooms proposed within the accessory dwelling unit.
Table 30-6-1 Single-Family Residential Design Flows – No change.
C. Auxiliary buildings.
1. and 2. – No change.
3. If the auxiliary building will have users in addition to residents and the flow from the auxiliary building will flow to the OWTS of the home, the design flow of the home must include the increased use of each fixture proposed.
4. If the auxiliary building has a separate OWTS, the system must be sized on the basis of Table 30-6-2 and a septic tank detention time of forty-eight (48) hours.
D. Multi-family and commercial on-site wastewater treatment systems.
1. Design flow values and strengths for multi-family and commercial systems must be determined from:
a. – No change.
b. An analysis of peak flows and strengths from at least three (3) comparable facilities or from the facility, if it is an existing facility, must be submitted to the Division for approval. The analysis must include:
1) through 3) – No change.
c. When a specific use is proposed which is not addressed within Table 6‑2, and where flow data from similar facilities is not available, the design document must provide reference to an alternate regulatory or industry standard for OWTS from where the proposed flow and water quality data was obtained. Estimates must include peak flows relative to full occupancy.
E. Flow equalization.
1. through 5. – No change.
6. Contingency plans must be specified for expanding the capacity of the OWTS, in the event of changed use at the facility.
Table 30-6-2
Estimate of Average Daily Wastewater Flow and
BOD5 Load Per Person Unless Otherwise Noted
(Contact the Clerk to the Board’s Office to View the Table)
1. BOD levels may require further verification depending on the specific use of the facility.
2. Laundry facilities are to be calculated on a per-commercial washer basis in accordance with other elements of this table.
3. For a “tiny home” the OWTS may be sized as a one-bedroom home.
4. As stated in section 43.6.A.2.i, the local public health agency may increase the “per bedroom” design flows for vacation home rentals relative to the expected maximum occupancy of the home. These flows are in addition to the 150 gal./bedroom requirement.
5. Note that discharges from non-domestic sources such as process waste, industrial waste, microbreweries, dog kennels, veterinary clinics, horse barns, etc. are not addressed in this regulation. Such discharges must obtain permitting as a Class V Injection Well through the EPA, as appropriate.
6. A “Luxury Resort” will typically include a spa, restaurant/bar, pool, etc.
7. Wastewater from convenience stores will likely meet the requirements of high strength waste. Studies indicate that BOD5 effluent levels will range between 500 –1500 mg/l. The exact levels will depend on products available (i.e.: coffee, soda, etc.), number of patrons, and how often the excess from each product is disposed. Flows from each facility can also vary substantially depending on location and the size of the store. Locations adjacent to freeways could have significantly more flow than a site located in a residential area. Subsequently, the design engineer must provide data from similar facilities in order to afford an estimation of projected peak daily flows.
8. Wastewater from coffee shops will likely meet the requirements of high strength waste. Studies indicate that BOD5 effluent levels may exceed 500 mg/l. The exact levels will depend on the drink options (i.e.: latte, espresso, etc.), number of patrons, and how often the excess from each product is disposed. Flows from each facility can also vary substantially depending on location and the size of the store. Subsequently, the design engineer must provide data from similar facilities in order to afford an estimation of projected peak daily flows.
Amend Sec. 30-6-20. Wastewater strength.
A. and B. – No change.
Table 30-6-3
Treatment Levels
(Contact the Clerk to the Board’s Office to View the Table)
(Shading indicates higher treatment levels)
1. Requirements for CBOD5 are only related to effluent samples from a higher level treatment system.
2. Domestic septic tank effluent prior to soil treatment or higher level treatment has a wide range of concentrations. These values are typical, but values used for design must account for site specific information.
3. Total Nitrogen does not apply to Treatment Levels TL2 and TL3. Processes intended to reduce total nitrogen are addressed in Treatment Levels TL2N and TL3N. Any total nitrogen reductions that may be observed for TL2 and TL3 are as a result of the treatment process for BOD5 and TSS reductions.
4. NSF/ANSI Standard 245 - Wastewater Treatment Systems - Nitrogen Reduction requires reduction of 50 percent rather than an absolute value.
5. TL3ND requires effluent to be treated to TL3N standards prior to disinfection. The disinfection must meet the requirements of section 43.12.H.
6. With the exception of fecal coliform, treatment level requirements are based on values obtained from composite sampling.
Table 30-6-4 High Strength Wastewater* - No change, with exception to modify footnote below:
*High strength wastewater prior to a septic tank has a wide range of concentrations. The values are typical, but values used for design purposes must account for site-specific information.
Article VII Minimum Distances Between Components of an On-Site Wastewater Treatment System and Physical Features
Amend Sec. 30-7-10. Minimum horizontal distances.
A. Horizontal distances from the various components of an OWTS to pertinent terrain features, including streams, lakes, watercourses, springs, wetlands, wells, subsurface drains, cisterns, water lines, suction lines, dry gulches, cut banks, dwellings, other occupied buildings and property lines must be in accordance with Table 30-7-1. The setback requirements are applicable for minimum system performance and treatment as provided in Table 30-7-2. All distance setback modifications must be analyzed and approved by the Board of Public Health and be in complete compliance with the variance or administrative procedures identified within this Regulation. Acceptable methods of analyzing horizontal separation distances with higher treatment levels include, but are not limited to:
1. Analyzing the intended uses of impacted surface and/or groundwaters;
2. Contacting adjacent property owners for potential conflicts with property line encroachments; and
3. Analyzing potential impacts that system locations may have on building foundations and other potentially affected features.
Amend Sec. 30-7-20. Dry gulches, cut banks and fill areas.
A. and B. – No change.
C. The separation distance between a component and the crest of a dry gulch or cut bank will be evaluated for potential erosion or slope instability if the components and the slope are in close proximity. If there is potential for erosion or instability, the separation distance must be increased until the risk is minimized.
Insert new Sec. 30-7-30. Components of an OWTS.
A. Components of an OWTS listed in Table 7-1 must be installed or located in accordance with the minimum distance requirements provided in the table or such increased distances provided by local board of health regulations, unless otherwise noted below:
1. A local board of health may choose to allow the local public health agency to permit the installation of an OWTS at a reduced property line setback in accordance with the following criteria:
a. If a property can accommodate the installation of an OWTS no closer than the required minimum 10-foot property line setback, it must do so. If the proposal complies with the requirements of this section and is deemed acceptable by the local public health agency, the local public health agency may administratively allow a reduction to the setback.
b. The property line setback must not be reduced to any less than three (3) feet, unless a variance by the Board of Health is provided.
c. The property line setback encroachment must be proposed at the time of permit application and must include the following information:
2. A statement from the applicant and/or designing engineer providing the reason for the reduced property line setback request.
3. The applicant must demonstrate that the allowance of encroachment of the property line setback will not inhibit the development of surrounding properties (i.e. by allowing the encroachment of the property line setback, a neighboring property would not be able to meet the minimum setback requirement between the subject OWTS and a proposed adjacent well).
4. The applicant must demonstrate that all activities associated with the installation of the proposed OWTS will not encroach on a neighboring property, and/or provide written permission from the adjacent owner or property manager of said property allowing the encroachment of machinery or excavated materials in order to install the proposed OWTS.
5. The proposed OWTS must comply with all other required setbacks noted in Table 7-1. The local public health agency approval of the encroachment must only be for the referenced property line setback.
6. The applicant must submit a survey of the property line(s) that the proposed setback encroachment will impact. The survey must include:
a. A survey completed by a Colorado registered professional land surveyor in accordance with Section 12-120-301, et seq., C.R.S.
b. A legal description and drawing of the subject property. Said drawing must also include the location of the proposed OWTS, onsite and adjacent wells.
c. The surveyor must clearly mark the surveyed property line(s) in a manner that is clearly defined and will not degrade over time due to exposure to the elements. The markings must remain in place until after system construction and final approval by the local public health agency.
Prohibitions
(1) Approval for an encroachment of the property line setback must not be provided after installation of the OWTS. Any post-construction reduction will require a variance by the Board of Health.
(2) A reduction in the setback to a property line may only be granted where a minimum separation of six (6) feet between soil treatment areas on all adjacent properties is provided.
(3) The size of the soil treatment area must comply with section 43.10.C of Reg. 43.
(4) Property line setback reductions are prohibited where multiple systems on the subject property are proposed and the combined capacity of the systems exceeds 2,000 GPD.
Amend Sec. 30-7-40. On-site Wastewater Treatment System design consideration and treatment requirements - Separation distances from soil treatment area.
A. – No change.
B. Items 1, 2 and 3 in Table 30-7-2 address the allowable horizontal setback distance between the soil treatment area and the following physical features:
1. Setback distance from soil treatment area to on-site well (Item 1);
2. Setback distance from soil treatment area to water features (Item 2); and
3. Setback distance from soil treatment area to a dry gulch or cut bank (Item 3).
C. Item 4 in Table 30-7-2 addresses the required vertical separation distance between the infiltrative surface of the soil treatment area and the limiting layer or the required depth of soil comprising the soil treatment area.
Amend Table 30-7-1
Table 30-7-1
Minimum Horizontal Distances in Feet Between Components of an On-Site Wastewater Treatment System
Installed After November 15, 1973 and Water, Physical and Health Impact Features
(Contact the Clerk to the Board’s Office to View the Table)
Note: The minimum distances shown above must be maintained between the OWTS components and the features described. Where soil, geological or other conditions warrant, greater distances may be required by the Board of Public Health or by the Water Quality Control Commission pursuant to Section 25-8-206, C.R.S., and applicable regulations. For repair or upgrading of existing OWTS where the size of lot precludes adherence to these distances, a repaired OWTS shall not be closer to setback features than the existing OWTS, as reviewed and approved by the Water Quality Control Division.
1. Includes potable wells, irrigation wells and monitoring wells set within a potable aquifer and infiltration galleries permitted as wells by the Division of Water Resources. All horizontal setbacks to a potable water supply must be met unless a variance by the Board of Examiners of Water Well Construction and Pump Installation Contractors is granted per Section 18.2 of the Water Well Construction Rules, 2 CCR 402-2, (Division of Water Resources). Setback requirements which may necessitate a variance are found within Section 10.2 or 11.4 of the Water Well Construction Rules, as applicable. The minimum horizontal setback that may be granted for new construction through a variance is to 75 feet; and must meet the requirements of Table 7-2 of this regulation. Setbacks for existing wells must comply with requirements of Section 43.10.I.2.
2. Crossings or encroachments may be permitted at the points as noted above, provided that the potable water or wastewater conveyance pipe is encased for the minimum setback distance on each side of the crossing. A length of pipe with a minimum Schedule 40 rating (ASTM Standard D3034-24 (2024 version) of sufficient diameter to easily slide over and completely encase the conveyance must be used. Rigid end caps of at least Schedule 40 rating (ASTM Standard 3034-24 (2024 version)) must be glued or secured in a watertight fashion to the ends of the encasement pipe. A hole of sufficient size to accommodate the pipe must be drilled in the lowest section of the rigid cap so that the conveyance pipe rests on the bottom of the encasement pipe. The area in which the pipe passes through the end caps must be sealed with an approved underground sealant compatible with the piping used. Piping of equal or higher strength may also be used. Other methods of separation between the potable water pipe and a component of the OWTS that provide equal protection are allowed. These may include, but are not limited to, concrete or controlled flowable fill encasement extending no less than 10 feet each side of the crossing, or an impermeable geo-membrane curtain extending at least two feet below the potable water pipe and no less than 10 feet each side of the crossing that provide equal protection are allowed. These may include, but are not limited to, concrete or controlled flowable fill encasement extending no less than 10 feet each side of the crossing, or an impermeable geo-membrane curtain extending at least two feet below the potable water pipe and no less than 10 feet each side of the crossing. These methods must be designed by a professional engineer and approved by the local public health agency.
3. Add eight (8) feet additional distance for each 100 gallons per day of design flows between 1,000 and 2,000 gallons per day, unless it can be demonstrated by a professional engineer or geologist by a hydrologic analysis or the use of a barrier, consisting of a minimum 30 mil PVC liner or equivalent, that contamination will be minimized.
4. All horizontal setbacks to an underground potable water supply cistern must be met unless a variance by the Board of Examiners of Water Well Construction and Plumb Installation Contractors is granted per Section 11.4 of the Water Well Construction Rules, 2 CCR 402-2. The minimum horizontal setback that may be granted through a variance is to 25 feet. Noted setbacks are not required to above ground cisterns.
5. If the structure is not used as a habitable unit, the isolation may be reduced by the local board of health to no less than 50 feet.
6. Building sewer installations shall meet the design requirements of the Colorado Plumbing Code.
7. Where ditch companies have a specific right of easement for “reasonable and necessary use to access, operate, and maintain ditches”, all OWTS components must maintain a minimum of 25 feet setback from the crest of the ditch/channel.
8. Sites with multiple OWTS on a single property where the total flows are > 2,000 gpd must meet the increased required setbacks as provided in WQSA-6 (Policy 6).
9. Per 2 CCR 402-10 (6.4.2) Geothermal wells shall be located at least 100 feet to the nearest source or potential source of contamination, unless a variance has been obtained from the state engineer.
10. Setback from a utility easement: While a specific setback for components of an OWTS to a utility easement is not specifically identified, the intent of the regulation is provided herein. The setback from utility easements is dependent on whether the utility is above or below ground. For above ground utilities, components of an OWTS must not be installed in areas where construction or maintenance vehicles may be required to travel in order to gain access to the utility. For utilities installed below grade, the objective is to setback the utility far enough away from the soil treatment area so that sewage will not seep into a utility trench excavation. The setback is also necessary to prevent construction or maintenance vehicles from driving on any component of an OWTS. Where remote properties have a blanket utility easement, the owner/operator of the OWTS will be responsible for providing signage or physical barriers, as needed, to reduce the risk of vehicular traffic or other disturbance to the OWTS. In all instances, a five foot setback will typically address most concerns.
11. In specific circumstances, the local public health agency may allow for a reduced setback from a property line to the OWTS; per the requirements of section 43.7.D.1.
Amend Table 30-7-2
Table 30-7-2
Minimum Separation Distance Requirements in Feet from Soil Treatment Area, Relative to Treatment Level Provided
(Contact the Clerk to the Board’s Office to View the Table)
Note: Treatment levels are defined in Table 30-6-3.
1. All setback distance reductions to the 100 foot requirement for wells and soil treatment areas must be in full compliance with the minimum standards and variance requirements of the State of Colorado Division of Water Resources: Rules and Regulations for Water Well Construction, Pump Installation, Cistern Installation, and Monitoring and Observation Hole/Well Construction. For TL 3N and TL3ND effluent, a reduction to 75 feet is allowed if a variance from the Water Well Construction Regulations is obtained. Note that the Division of Water Resources does not address inquiries for existing wells. Local agencies must follow the same review principles, as provided within division’s guidance document; “Variances for water wells”; March 2019.
2. Reductions in the vertical separation requirements for the use of higher level treatment systems with seepage pits are not allowed. The bottom of the excavation of a seepage pit must be a minimum of four feet above a limiting layer.
3. Refers to the quality of effluent applied to the distribution media.
4. Pressure dosing is required for all TL2N, TL3, TL3N, and TL3ND systems 43.8 Design Criteria - General 57.
5. Includes potable wells, irrigation wells and monitoring wells set within a potable aquifer and infiltration galleries permitted as wells by the Division of Water Resources.
Article VIII Design Criteria – General
Amend Sec. 30-8-10. Performance.
A. The OWTS for single-family homes shall be designed to accommodate the proposed flows from the structure as defined in Section 30-6-10.B. Flow estimates for multi-family or commercial OWTS must comply with Section 30-6-10.D.1. Expected waste strength as noted in Table 30-6-3 and Table 30-6-4 must also be addressed, where applicable. Installation of low flow fixtures or the separation of toilet waste or other sources of wastewater does not allow for the reduction in the size of an OWTS, except as provided in Section 30-12-40.
B. – No change.
Amend Sec. 30-8-30. Accessibility for inspection, maintenance and servicing.
A. Septic tanks must have watertight risers over each access manhole. All risers must be a minimum of 20 inches inside diameter and extend to or above final grade, unless otherwise specified in this regulation.
B. and C. – No change.
D. Riser lids.
1. Each riser lid must be watertight, brought to or above the surface, and must have a secure closing mechanism, such as a lock, special-headed bolts or screws, or sufficient weight (defined as 59 pounds) to prevent unauthorized access.
2. Access risers for all new septic tanks or vaults must include a structurally sound interior grate, or other similar secondary safety feature, securely installed below the tank lid to prevent persons, pets, or wildlife from falling into the tank.
E. Components that require access for maintenance must be accessible from the ground surface. This includes, but not be limited to, maintenance of pumps, siphons, valves, distribution boxes, drop boxes, cleanouts, effluent filters, inlet and outlet baffles, aerators, treatment equipment and other devices.
Remainder of Section – No change.
Amend Sec. 30-8-100. Floodplains.
A. A new, expanded or repair/replacement OWTS installed in a 100-year floodplain must meet or exceed the requirements of the Weld County Floodplain Management Ordinance contained in Chapter 23 and the Federal Emergency Management Agency. Repairs of an existing system must meet the requirements as feasible. The system, as approved by the Division, must be designed to minimize or eliminate infiltration of floodwaters into the system and discharge from the system into the floodwaters. The OWTS must be located to avoid impairment to floodwaters or contamination from them during flooding. The Division has available a floodplain guidance document.
B. OWTS installations in floodplain zones beginning with letters “A” or “V” are considered high-risk areas. Systems installed in these areas must be designed by a professional engineer.
C. A new or expanded OWTS must not be installed in a floodway designated in a 100-year floodplain where a conforming OWTS outside the floodway can be installed. For any new OWTS or system repair that may affect the floodway delineation, appropriate procedures must be followed, including revision of the floodway designation, if necessary.
1. Installations within a floodway requires a professional engineer to certify that an OWTS cannot be installed outside of the floodway.
2. OWTS installations in a floodway must be designed by a professional engineer.
Amend Sec. 30-8-110. Business, commercial, industrial, institutional or multi-family dwelling wastewater systems.
A. An OWTS that will serve a business, commercial, industrial or institutional property or a multi-family dwelling must:
1. – No change.
2. Receive only such biodegradable wastes for treatment and distribution as are compatible with those biological treatment processes that occur within the septic tank, any additional treatment unit, and the soil treatment area. This does not include industrial, animal, or process waste; and
Remainder of Section – No change.
Article IX Design Criteria - Components
Amend Sec. 30-9-10. Tanks and vaults.
A. Watertightness.
1. through 3. – No change.
B. Tank Installation: All tanks are to be installed level, and placed on a uniform surface or bedding which does not contain rocks, roots or other items that could create point loading on the tank.
1. If imported bedding is needed, common options include a 5-inch depth of compacted pea gravel or similar material.
Remainder of Section – No change; Reletter as appropriate.
Amend Sec. 30-9-20. Septic tanks.
A. through B.4. – No change.
5. Where a grinder pump is installed prior to the septic tank, the required tank volume must be increased by at least 500 gallons above the required volumes provided in Table 9-1.
6. If a proprietary aerobic treatment component is installed, the minimum septic tank (or trash tank) volume may be reduced to the volume as determined by the manufacturer. This volume will typically be provided on the CDPHE product acceptance document, which can be found on the CDPHE OWTS webpage.
C. Inspection and Testing of septic tank watertightness.
1. Testing of septic tanks must be performed and evaluated as specified in Section 9 of ASTM C1227-22 (2022 version or earlier) (Standard Specification for Precast Septic Tanks) for concrete tanks or in Standard IAPMO/ANSI Z1000 (2019 version) (American Standards for Prefabricated Septic Tanks) for other prefabricated septic tanks.
2. through 4. – No change.
D. Septic tank design and dimension criteria.
1. A septic tank must have two (2) or more compartments or more than one (1) tank may be used in a series, unless otherwise noted in this regulation. The first compartment of a two-compartment tank or the first tank in a series must hold no less than one-half (½) of the required effective volume.
2. Inlet invert must be at least two (2) inches higher than the outlet invert. In instances where the inlet invert cannot be installed at least two (2) inches above the outlet invert, a lift station or a pump may be installed after the septic tank, so that septic tank and absorption area function are not compromised.
3. – No change.
4. Outlet tee or baffle must extend at least five (5) inches above and fourteen (14) inches below the outlet invert, however, it must not extend to more than 40 percent of the liquid depth measured from the liquid surface. The outlet tee or baffle that accommodates an effluent filter must be located so that the effluent filter has sufficient clearance to be removed through the access opening with a riser in place.
5. through 9. – No change.
10. Tanks proposed to be located below vehicular traffic areas must have the appropriate AASHTO H-20 or HS-20 ratings for such use.
E. Concrete septic tank structural design.
1. Concrete septic tanks must comply with the structural design criteria of ASTM C1227-22 (2022 version) (Standard Specification for Precast Septic Tanks).
2. through 4. – No change.
F. Fiberglass, fiberglass-reinforced polyester and plastic tanks.
1. All fiberglass, fiberglass-reinforced polyester and plastic tanks must meet the minimum design and structural criteria of IAPMO/ANSI Z1000 (2019 version) (American Standards for Prefabricated Septic Tanks) and be certified by a professional engineer as meeting these standards. The professional engineer certifying the criteria must be registered or licensed in the United States but need not be registered in Colorado.
Remainder of Section – No change.
Amend Sec. 30-9-40. Pipe standards and bedding requirements.
A. Pipe standards.
1. – No change.
2. Where unperforated plastic pipe and fittings are used for gravity flow, the minimum wall thickness of the pipe must conform to ASTM Standard D 3034-21 (2021 version) or equivalent or greater strength. Schedule 40 pipe is preferred.
3. Perforated distribution pipe surrounded by rock within a soil treatment area must have a minimum wall thickness and perforations conforming to ASTM Standard D 2729-21 (2021 version) or equivalent or greater strength. Corrugated polyethylene pipe with a smooth interior that meets ASTM F667/F667M (2021 version) or AASHTO M252-24 (2024 version) specifications or equivalent may be used.
4. Schedule 40 (ASTM Standard D3034-24 (2024 version) or pipe of equivalent or greater strength must be used where pipe is installed in the following locations:
a. under driveways or roadways, or other areas where vehicular traffic is expected. Properly compacted select bedding material must be installed in such cases. Additional frost protection, such as installing two (2) inch foam board or double-encasement of the pipe, is recommended.
b. Five (5) feet prior to and beyond all tanks; and
c. In instances where sewer line setback distances are granted a variance for any reason.
5. Tile pipe, open-joint pipe and cast iron pipe must not be used in an OWTS.
6. Pressure pipe must be rated for the intended use to accommodate pump discharge pressure. Cellular (foam) core piping must not be used in pressurized systems.
B. Sewer lines, installed from the outside of the foundation to the septic tank, must have a minimum of 1/8 inch fall per foot or 1% fall. A 1/4 inch fall per foot or 2% fall is preferred.
C. Effluent lines, for gravity installations, from the outlet of the septic tank to the inlet to the distribution box or the distribution tee must have a minimum of 1/8 inch fall per foot, or 1% fall.
D. Bedding. All system piping, except for distribution laterals within the soil treatment area, must be bedded with select material before final inspection by the Division. Select bedding material must consist of loose, granular material free from stones, clods, frozen soil or other deleterious material. Select material may consist of on-site job-excavated or imported material. Bedding material must be mechanically compacted to support piping.
E. Pipe identification and data marking must be visible for the purpose of inspection before backfilling.
Amend Sec. 30-9-50. Cleanouts.
A. Cleanouts required between the building and the septic tank:
1. – No change.
2. If a cleanout is not already provided outside of the building, a two-way cleanout, no smaller than the building sewer, must be installed between the building and the septic tank, as close to the building as practical, but at a distance no further than 50 feet of the outside wall. Local Building Codes may also apply.
a. For long runs of piping, building sewers must have a cleanout installed at intervals of not more than 100 feet.
3. – No change.
Amend Sec. 30-9-70. Drop box.
In sequential distribution, a watertight box may be used to transfer the effluent to the following trench when the effluent in a trench has received the designed level for overflow to the next trench. A drop box shall have a riser at or above final grade if the top of the box does not reach final grade. Outlet pipes in a sequential distribution must be designed and installed so that they may be capped off for resting periods.
Amend Sec. 30-9-80. Stepdown/relief pipe.
In sequential distribution, an unperforated pipe may be used to transfer the effluent to the following trench when the effluent in a trench has received the designed level for overflow from that trench.
Amend Sec. 30-9-90. Wastewater pumping and dosing siphon systems.
A. Pumps.
1. and 2. – No change.
3. Grinder pumps must also be certified to NSF/ANSI Standard 46 (2022 or earlier version) and bear the seal of approval of the NSF or equivalent testing and certification program.
a. Where a grinder pump is used prior to the septic tank, an effluent filter is required to be installed on the outlet of the septic tank. Additional tank requirements are provided in Section 43.9.B.2.e.
b. Where a grinder pump is used prior to the septic tank, the effluent pipe from the grinder pump must be connected to the sewer line prior to the inlet of the septic tank.
B. Floats and switches.
1. – No change.
2. Floats must be mounted on a stem separate from the pump discharge piping to allow for removal, adjustment and replacement of the float from grade without removing the pump. Components used to hold the floats must be securely attached and of a material that is resistant to corrosion and will not absorb water.
3. and 4. – No change.
C. Location of pump or siphon.
1. – No change.
2. The second compartment of a two-compartment septic tank may only be used as the pump tank when the tank is specifically designed for this purpose and it can be demonstrated, to the satisfaction of the Division, that the minimum forty-eight-hour detention time will not be decreased. The pump must be screened to remove solids greater than 1/8”, assuring that only liquid effluent will be discharged. The transfer of liquid from the first to the second compartment must be at an elevation that is between the inlet and outlet invert elevations, and through a standard tee designed and located as per the requirements of section 30-9-20.D.4. Siphons must not be installed in the second compartment of a two compartment tank.
3. – No change.
D. Pump or siphon discharge piping. – No change.
E. Access.
1. The pump or dosing system tank, chamber or compartment must have a minimum 24-inch nominal diameter access riser, made of corrosion-resistant material, extending to or above ground level. A smaller diameter riser may only be installed if it is accepted by the Water Quality Control Division as an integral component of a specific product during the product review process.
2. – No change.
F. Splice box (Junction Box).
1. and 2. – No change.
G. Controls.
1. Control panels or other electrical boxes used to control the functions of an OWTS must comply with the following, as appropriate:
a. through d. – No change.
e. Must bear the seal indicating acceptable produce testing from a U.S. Department of Labor, Occupational Safety and Health Administration Nationally Recognized Testing Laboratory (NRTL), (https://www.osha.gov/dts/otpca/nrtl/nrtllist.html), such as UL or ETL.
f. The bottom of the control panel must be at least 30 inches above grade.
Amend Sec. 30-9-100. Effluent screens.
A. When effluent filters are required, the septic tank outlet, or the outlet of the last septic tank in series, must include an effluent filter that retains solids greater than one-eighth (1/8) inch in size. Effluent filters must be sized to meet the estimated daily design flow and waste strength.
B. If a pump is used to remove septic tank effluent from the final compartment of the septic tank, the effluent must be filtered prior to dispersal into the soil treatment area. An effluent filter, pump vault equipped with a filter cartridge, or a filter on the discharge pipe, would all be considered acceptable.
C. The effluent filter, if used, must be cleaned at manufacturer-recommended intervals or more often, if use patterns indicate.
D. An alarm may be installed on an effluent filter indicating need for maintenance.
E. Where an ejector pump, grinder pump or non-clog pump is proposed for use prior to the septic tank, an effluent filter must be installed on the outlet of the septic tank.
F. The handle of the effluent filter must extend to within 12 inches of grade.
Article X Design Criteria - Soil Treatment Area
Amend Sec. 30-10-10. Soil treatment area general.
A. – No change.
B. At proposed soil treatment area locations receiving domestic wastewater where any of the following conditions are present, the OWTS must be designed by a professional engineer and approved by the Division:
1. For OWTS installed in soil types, 3A, 4, 4A, 5, FBR, DBR, R-0, R-1, R-2, and R‑3, as specified in Tables 30-10-1 and 30-10-1A of this Regulation;
2. For OWTS that include components which provide Treatment Levels TL2, TL2N, TL3, TL3N, and TL3ND effluent, or an NDDS;
3. The maximum seasonal level of the groundwater surface is less than four (4) feet below the bottom of the proposed infiltrative surface;
4. Where a limiting layer, restrictive layer, or groundwater condition exists less than four (4) feet below the bottom of the proposed infiltrative surface;
5. In floodplains or floodways, as required in section 30-8-100;
6. The ground slope is in excess of thirty percent (30%);
7. Pressure distribution is used; or
8. OWTS for business, commercial, industrial, institutional use, or multi-family dwellings.
Amend Sec. 30-10-20. Calculation of infiltrative surface of soil treatment area.
A. through C. – No change.
D. The required area for a soil treatment area is determined by the following formula:
Soil treatment area in feet required = Design flow (in gallons per day) LTAR (in gallons per day per square foot)
1. through 3. – No change.
4. A soil treatment area may be multiplied by the size adjustment factors within Table 30-10-2, and Table 30-10-3.
5. A soil treatment area receiving TL2, TL2N, TL3, TL3N, or TL3ND effluent must be pressure dosed.
a. For products that combine distribution and higher level treatment within the same component, pressure distribution of the effluent over the soil treatment area must be used.
b. TL2 – TL3ND effluent may be applied by gravity flow in soil types 3, 3A, or 4, 4A, or 5 for designs where reductions in the soil treatment area size or vertical/horizontal separation reductions are not being requested.
Amend Table 30-10-1
Table 30-10-1
Soil Treatment Area Long-Term Acceptance Rates by Soil Texture, Soil Structure, Percolation Rate and Treatment Level
(Contact the Clerk to the Board’s Office to View the Table)
Note: Shaded areas require system design by a professional engineer.
1. Treatment levels are defined in Table 30-6-3.
2. The determination of long-term acceptance rates must also include an evaluation of soil consistence (identification of “cementation class”). Refer to the Rupture Resistance chart, Table 5-1, in Section 43.5.D. Moderately to Very strongly cemented soils will typically have characteristics of Type 3A or 4A soils. Long term acceptance rates should be reduced to coincide with the expected permeabilities.
3. Soil types 4A and 5 will require the effluent to be dispersed via pressure distribution, with a minimum of two alternately dosed zones.
Delete Table 30-10-1A Design Criteria for Soils with High Rock Content (Type "R" Soils) 1, 2, 3, 4
Add Table 30-10-1A1 Design Criteria for Soils with High Rock Content (Type “R” Soils) 2,5,6
(Contact the Clerk to the Board’s Office to View the Table)
1. General guidance for Table 10-1A:
a. FBR: Fractured Bedrock – As this category encompasses a variety of site conditions where the percentage of rock, excavation difficulty, and permeability may vary substantially, all information must be used by the design engineer to determine the proper long term acceptance rate. Table 10‑1B provides guidance for this determination.
b. DBR: Deteriorated Bedrock – As this category encompasses a variety of site conditions where the percentage of rock, excavation difficulty, and permeability may vary substantially, all information must be used by the design engineer to determine the proper long term acceptance rate. Table 10‑1C provides criteria for this determination.
c. Soil Type R-0 is a limiting layer due to rapid permeability and a high rock content that provides limited surface area for adequate treatment.
d. Soil Type R-2 and R-3 are restrictive layers due to reduced permeability and/or a high rock content, each providing a limited surface area for adequate treatment. In many cases, the only difference between an R-2 and R-3 soil type will be the “excavation difficulty” and/or soil permeability.
e. An OWTS installed in “Type R Soils” must disperse effluent through an unlined sand filter, unless one of the following conditions are met:
i) Treatment Level 3ND is attained and the requirements of 43.12.F are met.
ii) Site conditions are determined to be a soil Type DBR, or R-1, and Treatment Level 3 or 3N effluent is attained prior to dispersal to the soil treatment area.
f. “Excavation Difficulty” is provided in Table 10-1C.
2. Provisions for determining the long-term acceptance rates for soils referenced in this chart are provided in section 43.11.C.3. The design of systems in type “R” soils must conform to the requirements of sections 43.11.C.2 and 3.
3. The “Soil Matrix Type, Percentage and Size of Rock” column references the soil types described in Table 10-1.
4. The percentage of rock may be determined by a gradation conducted per ASTM standard D6913-17 (2017 version), or a visual determination as per pgs. 7-1 through 7-9 of the NRCS Field Book, Version 3, 2021 reprint.
5. All systems installed in a type “R” soil must be designed by a professional engineer.
6. Pressure distribution is required for all “R” Soil Types and shall comply with the requirements of sections 43.10.E.3.
7. Minimum imported sand depths are provided in this table. NOTE HOWEVER THAT AN ADDITIONAL VERTICAL SEPARATION ABOVE A LIMITING LAYER OR GROUNDWATER CONDITION MAY BE NECESSARY TO MEET THE REQUIREMENTS OF TABLE 7-2.
8. Type “R” soil treatment systems that are designed per the criteria noted in the Treatment Level 1 column of this table do not require operation and maintenance oversight by the local public health agency.
Add Table 30-10-1B: Fractured Bedrock (FBR), LTAR Guidance
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FBR: Distance between fractures*
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Code
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LTAR
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< 4 inches
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1
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Soil Type 1
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4 to < 18 inches
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2
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Soil Type 1
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18 to < 40 inches
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3
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Soil Type 2
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40 to < 80 inches
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4
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Soil Type 3
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≥ 80 inches
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5
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Soil Type 4
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Table 30-10-1B is intended to provide guidance to the design engineer in determining the appropriate LTAR for the soil treatment area. Fractured bedrock formations typically consist of many variables, resulting in a wide range of permeabilities. The design engineer should take all factors into consideration before identifying a specific LTAR for each site. In certain instances, percolation tests may be necessary to more accurately identify the appropriate LTAR.
*Describes the dominant (average) horizontal spacing between vertical joints (geogenic cracks or seams) in the bedrock layer.
Reference: NRCS Field Book for Describing and Sampling Soils, Version 3.0; 2021 Reprint; Geology section, pg. 1-24. Note: The LTAR identified in this table is not included in the NRCS Field Book.
Add Table 30-10-1C: LTAR Determination for Deteriorated Bedrock (DBR)
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Excavation Difficulty: The relative force or energy required to excavate the soil/rock. Class
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Criteria
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Low
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Excavation by tile spade requires arm pressure only; impact energy or foot pressure is not needed
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Moderate
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Excavation by tile spade requires impact energy or foot pressure; arm pressure is insufficient
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High
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Excavation by tile spade is difficult but easily done by pick using over-the-head swing
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Very High
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Excavation by pick with overhead swing is moderately to markedly difficult. Backhoe excavation by 50 – 80 hp tractor CAN be made in moderate time.
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Extremely High
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Excavation by pick is nearly impossible. Backhoe excavation by 50 – 80 hp tractor CANNOT be made in a reasonable time.
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Note: Depending on the “Excavation Difficulty” in a DBR soil, the proposed LTAR must increase by the following: one soil type for “moderate”, two soil types for “high”, and three soil types for “very high” or “extremely high” excavation difficulty from the soil type of the observed soil texture; with a maximum soil type 5 LTAR. Soil types provided in Table 10-1.
Source: NRCS Field Book for Describing and Sampling Soils, Version 3.0; 2021 Reprint; Consistence section, pg. 2-69.
Amend Sec. 30-10-30. Allowable soil treatment area sizing adjustments.
A. – No change.
For the purpose of Table 30-10-1, a "baseline system," i.e., adjustment factor of 1.00, is considered to be Treatment Level 1 (TL1) applied by gravity to a gravel-filled trench.
Table 30-10-2 – No change.
Amend Table 30-10-3
Table 30-10-3
Size Adjustment Factors for Types of
Distribution Media in Soil Treatment Areas
(Contact the Clerk to the Board’s Office to View the Table)
1. All proprietary distribution products must receive acceptance and the applicable reduction through Colorado Water Quality Control Division review per the applicable requirements of Regulation 43 section 43.13.
Amend Sec. 30-10-40. Design of distribution systems.
A. General.
1. The infiltrative surface and distribution laterals must be level.
2. The infiltrative surface must be no deeper than four (4) feet below grade. The depth of the infiltrative surface will be measured on the up-slope side of the trench or bed.
3. Where a conforming soil treatment area is reasonably accessible, the soil treatment area must not be placed below a paved surface, or an area where vehicular traffic occurs or is expected. If a compliant site for the soil treatment area cannot be identified, it may be placed below a paved surface when all of the following conditions are met:
a. The effluent must be treated to TL2 or higher prior to being applied to the distribution media.
b. The distribution system must be designed to accommodate the vehicular loading.
c. Size adjustment factors identified in Table 10-3 must not be applied.
4. Trenches must follow the ground surface contours so variations in infiltrative surface depth are minimized. Beds must be oriented along contours to the degree possible.
5. Pipe for gravity distribution must be no less than three (3) inches in diameter.
6. A final cover of soil suitable for vegetation at least ten (10) inches deep must be placed from the top of the geotextile or similar pervious material in a rock and pipe system, chamber or manufactured media, up to the final surface grade of the soil treatment area. The backfill material must be void of cobbles, boulders, building debris, or other non-permeable material. The preferred soil cover is sandy loam textured material, topped with two to three inches of topsoil.
Renumber 6. through 8., to be 7. through 9.
B. Distribution Laterals; Must meet the requirements of Section 30-90-40, as applicable.
1. through 5. – No change.
6. To promote equal distribution to the soil treatment area, the effluent pipe on a gravity flow system must be connected to as near to the middle of the distribution header as possible. However, it must be offset from any distribution lateral so as to not provide a direct pathway into a single lateral. Note that the installation of a distribution box with flow levelers is preferred, as this will further assist in better distribution of the effluent.
7. – No change.
C. Pressure Distribution.
1. Design of plans for distribution systems must identify the exact specifications for the following items:
a. General Design Parameters: Not all combinations of the variables noted below will result in a proper distribution system design. The design engineer must justify through calculations and/or design software that the selected values will concur with industry standards the requirements noted below.
(1) Distribution pipe size: 3/4 inch – 1.5 inches (PVC Class 200, min.). 2-inch distribution pipe may only be used where other design modifications cannot overcome a greater than 10% variation in the pressure head between the initial and distal orifices.
(2) Distribution pipe spacing: 18 inches - 48 inches
(3) Orifice size: 1/8 inches - 3/8 inches (Also see section 43.11.C.b.5 below) Orifice spacing: 18 inches - 48 inches
(4) Proposed dose volume: Will vary with design (0.25 - 1.0) gallons/orifice/dose, or 3 - 5 times distribution pipe volume.
(5) To promote equal distribution within the soil treatment area, the forcemain within a pressure distribution system must be connected to as near to the middle of the distribution header as possible. This connection must be offset from any distribution lateral to prevent preferential flow to a single lateral. An allowable alternative to this configuration is provided below:
(a) Connections to the end of the distribution header are only allowed for soil treatment areas having a width of 12 feet or less, and no more than 4 laterals. For such configurations, a minimum 2 inches diameter manifold is required.
(6) Operating head at the distal end of distribution pipes: 30 inches - 72 inches (60 inches typ.). Larger orifices allow for an operating head at the lower end of this range, while smaller orifices will necessitate an operating head at the higher end of this range.
(a) For systems with orifices 5/32 inch or less, the minimum squirt height is five feet.
(b) For systems with orifices 3/16 inch or greater, the minimum squirt height must be at least 12 inches above final grade, but never less than 30 inches above the lateral invert.
(c) As part of the final inspection of an OWTS installation with pressure distribution, a residual head test (squirt height), at the distal end of each lateral, must be conducted to determine the adequacy of system design and construction. Results from this inspection must be included within both the engineer’s certification and the final permit acceptance documents.
b. Pump/siphon information; Total Dynamic Head; gallons/minute; and
c. Drain-back volume from forcemain, when applicable; and
d. The separating distance between parallel distribution pipes in a pressure distribution absorption bed must not exceed four feet, and the outer distribution pipe must be located within two feet of each sidewall and endwall. Specific requirements for the design of sand filters are noted in Section 30-11-30.B.
e. Flushing assemblies must be installed at the distal end of each lateral and be accessible from finished grade. A sweeping 90 degree or bends limited to 45 degree must be provided.
f. Effluent must be screened to retain solids 1/8” or greater prior to dosing a pressure distribution system. An effluent filter may be installed at the tank outlet, or within a screened pump vault. The filter may also be installed within the discharge line, inside the pump chamber.
Amend Sec. 30-10-50. Soil treatment area requirements.
A. and B. – No change.
C. Serial and sequential distribution.
1. New serial distribution systems, where the effluent must pass through the first trench in order to access subsequent trenches, are prohibited.
2. A serial or sequential distribution system may be used where the ground slope does not allow for suitable installation of a single level soil treatment area, unless a distribution box or dosing chamber is used.
3. The horizontal distance from the side of the absorption system to the surface of the ground on a slope must be adequate to prevent lateral flow and surfacing.
4. Adjacent trenches or beds must be connected with a stepdown/relief line or a drop box arrangement such that each trench fills with effluent to near the top of the gravel or chamber outlet before flowing to succeeding treatment areas. Note that in sequential distribution configuration, effluent does not pass through the first trench before it enters subsequent trenches.
D. and E. – No change.
F. Inspection ports.
1. through 4. – No change.
5. Perforations/slots in the inspection ports of a rock and pipe installation shall be provided from near the base of the pipe, and extending to at least eight inches above the infiltrative surface. Multiple slots or orifices must be provided.
Amend Sec. 30-10-60. Storage/distribution media.
A. – No change.
B. Chambers.
1. Chambers must be installed with the base of the unit on in-situ soil or, if placed on acceptable media, the manufacturer's installation instructions must be followed so as to prevent chambers from settling into the media.
2. Effluent pipes from the distribution box or manifold must enter the chamber at least six inches above the base of the chamber on standard height chambers, and at least three (3) inches above the base of the chamber on the low profile models.
3. Installation must be according to manufacturer's instructions.
4. Effluent may be distributed by gravity, pump or siphon.
5. If the width of a proprietary manufactured distribution product is within 90 percent of the width of the excavation, it may be approved as being equivalent to the full width of the excavation, if information is provided that demonstrates distribution of the full width. Thus, the product must cover at least 90 percent of the excavated area in either a trench or bed configuration in order to receive sizing adjustments provided in Table 30-10-3.
C. – No change.
D. Drip Dispersal Systems.
1. The infiltrative surface area must be calculated using the long-term acceptance rate for the site or a more conservative value if recommended by the manufacturer. Adjustment factors in Tables 30-10-2 and 30-10-3 may not be used.
2. through 4. – No change.
5. Provisions must be made for filtering, back-flushing, or other required maintenance.
Remainder of Section – No change.
Amend Sec. 30-10-80. Soil replacement systems.
A. The construction of a soil replacement system is permitted to bring the soil treatment area into compliance with the requirements of this regulation.
1. When a soil type "R" is removed, the following requirements must be met:
a. All added soil must comply with the following specifications:
1) Added soil must meet the specifications of imported treatment sand media, as specified in section 30-11-30 B.4.
2) and 3) – No change.
4) All added soil must be completely settled prior to installation of components as specified and approved by the design engineer.
5) Pressure distribution must be used.
2. When a sand media is added to soil treatment area or to an excavation where a soil type 1-5 (Table 30-10-1) is the underlying soil, the following requirements must be met:
a. Added soil must meet the specifications of imported sand media, as specified in Section 30-11-30.B.4.
b. Unless the design follows the criteria for a sand filter or mound system design where >24 inches of sand is installed as required in Section 30-11-30, the TL1 long-term acceptance rate of the most restrictive soils within 12 inches below the sand base must be used.
c. For sites where the proposed soil treatment area had been previously filled, the existing fill material must be removed and replaced with imported treatment sand meeting the specifications of Section 30-11-30.B.4. The excavation must also extend at least 12 inches below the original grade (grade prior to fill). Only existing fill material meeting the requirements of a soil type 1 will be allowed to remain.
Remainder of Section – No change.
Amend Sec. 30-10-90. Repairs.
A. and B. – No change.
C. Soils information obtained for the previous OWTS installation may be used if the information meets the requirements of Section 30-5-40. Otherwise, an additional soils investigation will be required.
D. Wide beds. For repairs, beds may be wider than twelve (12) feet without being required to receive effluent meeting Treatment Level 2 quality or better.
E. Deep beds. For repairs, the infiltrative surface of a bed may be no deeper than five feet. Size adjustments as provided for in Tables 30-10-2 and 30-10-3 must not be applied. System sizing will be based strictly on the soil type and corresponding LTAR.
F. Deep gravel trenches.
1. Deep gravel trenches may only be installed in soil type 1, 2, 2A, and 3. Installation in soil types 3A, 4, 4A, 5 and R are prohibited.
Remainder of Section – No change; Renumber and Re-letter as appropriate.
Article XI Design Criteria - Higher Level Treatment Systems
Amend Sec. 30-11-20. Treatment levels.
The treatment levels identified in Table 30-6-3 are specified in this Section for public domain technology. Proprietary systems will be assigned to a treatment level approved by the Water Quality Control Division. Adequate maintenance and operation plan as required by the Water Quality Control Division must be submitted to the Division. Adequate maintenance for each system must be required and documented as in Section 43.14.D
Amend Sec. 30-11-30. Sand filters.
A. A lined intermittent sand filter or a recirculating sand filter, may be used as a higher level-treatment system prior to dispersing the effluent into a soil treatment area.
B. Intermittent (single-pass) sand filters; general requirements.
1. – No change.
2. Size adjustment factors provided in Tables 30-10-2 and 30-10-3 are not applicable for sand filters.
3. Dosing:
a. Pressure distribution is required. The design of the distribution system must also comply with the requirements of Section 30-10-40 C.1.
4. Sand Filter Treatment Media:
a. The depth of the sand media below the distribution system must be at least 24 inches unless otherwise noted in Table 30-10-1A for type "R" soils.
b. Imported Treatment Sand media requirements:
(1) and (2) – No change.
(3) Percent fines passing #200 sieve must be ≤ 3.0.
c. A gradation of the sand media used must be provided.
(1) The gradation must be dated no more than four months prior to the installation date. However, a gradation of the actual material placed in the excavation is recommended.
(2) The gradation must be provided to the local public health agency on letterhead from either the source gravel pit, or independent materials testing laboratory.
5. through 7. – No change.
8. Sand filters must not be used to treat wastewater that does not conform to TL1 treatment level or better.
C. Unlined (open bottom) sand filters.
1. All requirements for Section 30-11-30.B.1. - 7. will apply to unlined sand filters.
2. Application rates for the distribution media where a minimum of 24 inches of imported treatment sand is installed:
a. Maximum hydraulic loading rate for TL1 effluent applied to “imported treatment sand” in an unlined sand filter is 0.8 gal./sq. ft./day, or the long-term acceptance rate of the receiving soil for TL1 (Table 10-1) whichever results in the larger area.
b. Maximum hydraulic loading rate for TL2, TL2N, TL3, TL3N, or TL3ND effluent applied to “Imported Treatment Sand” a. is the soil type 1 LTAR for the treatment level of the effluent received, TL2 or TL3 (Table 30-10-1).
c. Application rates for the in-situ soil where a minimum of 24 inches of imported treatment sand is installed:
(1) Maximum hydraulic loading rate for the in-situ soil when TL1 - TL3ND effluent is applied to the “Imported treatment sand” is TL3 LTAR, (Table 10‑1) of the most restrictive soil within 12 inches below the sand base.
d. The upper infiltrative surface of an unlined sand filter receiving TL1 effluent must be at least three (3) feet above a limiting layer, or groundwater condition.
e. The upper infiltrative surface of an unlined sand filter receiving TL2N- or TL32N effluent must be at least two and one-half (2.5) feet above a limiting layer, or groundwater condition.
f. The upper infiltrative surface of an unlined sand filter receiving TL3, or TL3N effluent must be at least two (2) feet above a limiting layer, or groundwater condition.
g. The upper infiltrative surface of an unlined sand filter receiving TL3ND effluent must be at least one (1) foot above a limiting layer, or groundwater condition.
h. Where adjacent sand filters are installed, the base of the excavation for each sand filter must be no closer than six (6) feet, sidewall to sidewall.
D. Lined, Single-Pass sand filters:
1. All requirements for application rates provided within Section 30-11-30 B.1-9 will apply to lined sand filters.
2. The minimum depth of the sand media in a lined sand filter must be two feet.
3. An intermediate layer of pea gravel, two inches in thickness, must be placed between the sand filter media and the coarse under-drain media to prevent the migration of sand into the lower layer of under-drain gravel. ASTM C 33-23 (2021 version), No. 8, coarse aggregate meets this specification.
4. A minimum four-inch diameter slotted SCH40 PVC (ASTM Standard D2729-21 (2021 version) under-drain pipe must be used to collect the treated effluent. The under-drain pipe must be installed in the center of a 5 inches thick bed of washed, graded gravel, or rock ranging in size from ½ inch to 2½ inches. AASHTO M 43, No. 3 coarse aggregate meets this specification. Lined sand filters must have an impervious liner on the sides and bottom of the filter. The liner must consist of a minimum 30 mil thick PVC material or equivalent.
5. Effluent collected by the under-drain must be dispersed to a soil treatment area. The soil treatment area may be sized with a maximum long-term acceptance rate of the receiving soil for TL1 effluent.
6. The base of the liner must be at least two (2) feet above an actual or seasonal high ground water elevation.
E. Lined, Recirculating sand filter:
1. through 5. – No change.
6. Under-drain requirements:
a. A minimum four-inch diameter slotted SCH40 PVC (ASTM Standard D 2729-21 (2021 version) under-drain pipe must be used to collect the treated effluent. The under-drain pipe must be installed in the center of a 5 inches thick bed of washed, graded gravel, or rock ranging in size from ½ inch to 2½ inches. AASHTO M 43, No. 3 coarse aggregate meets this specification.
7. PVC liner requirements:
a. Lined sand filters must have an impervious liner on the sides and bottom of the filter. The liner must consist of a 30 mil thickness PVC material or equivalent.
b. The base of the liner must be at least two (2) feet above an actual or seasonal high ground water elevation.
c. Effluent collected from the recirculating sand filter must be discharged to a soil treatment area. The soil treatment area may be sized with a maximum long-term acceptance rate of the receiving soil for TL1 effluent.
Amend Sec. 30-11-40. Mound systems.
A. When the infiltrative surface area of the imported sand media receiving wastewater effluent is at or above the natural ground surface at any point, it shall be considered a mound system. Mound designs can include a variety of parameters:
1. A mound installation where all of the imported sand is installed above existing grade.
2. A mound installation where the top of the imported sand is installed entirely above existing grade but the base of the imported sand is installed below existing grade.
3. A mound installation where the top of the imported sand is installed both above and below existing grade.
B. Sand Fill Loading Rate (Top of imported treatment sand)
1. For mound systems that receive TL1 effluent, and provide A MINIMUM OF 24 INCHES of imported treatment sand media, the LTAR for the imported treatment sand is 0.8 gal./sq/ft/day.
2. For mound systems that receive TL2 - TL3ND effluent, and provide A MINIMUM OF 24 INCHES of imported treatment sand media, the upper infiltrative surface of the imported treatment sand is to be sized on the soil type 1 LTAR for the treatment level of the effluent received, as provided in Table 10-1; TL2 or TL3.
3. Where TL1 effluent dispersed to the distribution media in mound systems where LESS THAN 24 inches of sand is installed, the LTAR of the imported treatment sand is the TL1 LTAR of the most restrictive soil layer within 36 inches of the upper infiltrative surface (top of imported sand).
4. Where TL2 – TL3ND effluent dispersed to the distribution media in mound systems where LESS THAN 24 inches of sand is installed, the system is to be sized on the LTAR of most restrictive soil layer within 36 inches of the upper infiltrative surface (top of imported sand), relative to the treatment level of the effluent received; TL2 or TL3. Note that in order to utilize the loading rates provided by the treated effluent, the local public health agency must have adopted a program for oversight of inspection and maintenance as provided in Section 30-12-60. Otherwise, the TL1 application rates noted in section 2.c above apply.
C. Soil Loading Rate (Base of imported treatment sand)
1. Mound systems that provide a minimum of 24 inches of sand treatment media may use the application rates for the in-situ receiving soil for TL1 effluent (Table 10-1). Size adjustment factors within Table 30-10-3 may be applied if TL1.
2. A mound system may include less than 24 inches of imported treatment sand media on a site where a lesser depth of sand media is sufficient to meet vertical separation requirements above a “limiting layer” or “groundwater condition”, as specified in Table 7-2. When less than 24 inches of treatment sand is imported, the following criteria apply:
a. Where TL1 effluent is applied, TL1 application rates for the most restrictive in-situ soil layer within 36 inches of the top of the imported sand must be used. Size adjustment factors within Table 10-3 may be used.
b. Where the local public health agency PROVIDES an oversight program as referenced in 30-12-60, and the effluent is treated to TL2 – TL3ND quality prior to dispersal into the distribution media, the LTAR is the soil loading rate of the most restrictive in-situ soil layer within 12 inches of the imported sand base for the treatment level of the effluent received, as provided in Table 10-1; TL2 or TL3. Vertical separation requirements of Table 7-2 must be met, relative to the treatment level of the effluent received. Size adjustment factors within Table 10-3 may not be used.
c. Where the local public health agency DOES NOT PROVIDE an oversight program as referenced in 30-12-60, and the effluent is treated to TL2 – TL3ND quality prior to dispersal into the distribution media, TL1 application rates noted in section 30-11-40 above must be used. Size adjustment factors within Table 10-3 may be used.
D. Linear Loading Rates
1. The design engineer must evaluate many factors to achieve an accurate determination of the linear loading rates. While application rates for the in-situ receiving soil under the mound is a main component, placement on the slope, and percent of the slope must also be addressed when defining the linear loading rate. If the movement of the effluent is primarily vertical, then the linear loading rate is not as critical. However, if the movement of the effluent will be primarily horizontal, as would be expected in soil types 3A through 5 (Table 30-10-1), then the linear loading rate is extremely important and long narrow mounds are necessary.
a. When TL1 effluent is applied to the distribution media of a mound system installed above in-situ soil types with permeabilities less than 60 min./inch (Table 30-10-1) and (Table 30-10-1A), the suggested linear loading rate is between 6 gpd/lin. ft. and 12 gpd/lin. ft. The maximum width of the distribution media in a mound system installed above these soil types is 12 feet when TL1 effluent is applied to the distribution media of a mound system.
b. When TL2 - 3ND effluent is applied to the distribution media of a mound system installed above in-situ soil types with permeabilities less than 60 min./inch (Table 30-10-1) and (Table 30-10-1A), the linear loading rate may exceed 12 gpd/lin. ft.; subsequently the mound may be wider than 12 feet.
c. When TL1 - TL3ND effluent is applied to mound systems installed above in-situ soil types with permeabilities exceeding 60 min./inch (Table 30-10-1), the suggested linear loading rate is between 3 gpd/lin. ft. and 5 gpd/lin. ft. The maximum width of the distribution media in a mound system placed above these soil types is 12 feet; however, once calculated, a lesser width may be required.
d. Mound systems must conform to the design requirements of Sections 30-11-30.B and C, unless otherwise specified within this Section 30-11-30.
e. The basal area must be determined using the requirements for the soil loading rate and linear loading rate provided above.
f. The final cover over a mound system must extend at least twelve inches horizontally beyond the perimeter of the distribution media prior to sloping down to existing grade. The final slope of the mound must be no greater than three feet horizontal to one foot vertical.
g. The surface of the mounded area must be planted with a suitable vegetative cover.
h. Suggested reference for the design and installation of mound systems are “The CDPHE Mounded Wastewater Treatment Systems Technical Guidance” and "The Wisconsin Mound Soil Absorption System: Siting, Design, and Construction Manual, January 2000". Note that these are suggested guidance, and where the requirements of this regulation differ from those in the referenced mound documents, the requirements of this regulation will govern in those cases.
Article XII Design Criteria - Other Systems
Amend Sec. 30-12-10. Evapotranspiration and evapotranspiration/absorption systems.
A. Non-Pressurized Drip Dispersal System (NDDS):
1. An NDDS is considered a type of evapotranspiration/absorption system. However, as specific design criteria are provided for an NDDS (See Section 30-12-10.A.2. and 3.), they are exempt from the additional requirements of pressure distribution, and items within Section 30-12-10 B, C and D.
2. New NDDS installations are prohibited unless the local public health agency has a maintenance oversight program.
3. 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), October, 2024. The document is available from Colorado Professionals in Onsite Wastewater (www.cpow.net)
4. The width of an NDDS system may be wider than 12 feet.
B. The following section provides general criteria which must be followed when an evapotranspiration or evapotranspiration/absorption bed is proposed.
1. through 5. – No change.
6. 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.
a. The gradation of the wicking sand must be submitted to the local public health agency on letterhead from either the source gravel pit, or independent materials testing laboratory. The gradation must be dated not more than one month prior to the installation date.
7. 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.
8. Adjustment factors as provided in Tables 30-10-2 and 30-10-3 must not be used.
Table 30-12-1 – No change.
C. For systems designed strictly as an evapotranspiration bed, the following criteria must be met:
1. and 2. – No change.
3. Designs will include a rock and pipe, or other Water Quality Control Division approved proprietary distribution product, with the centerline of the distribution system laterals no more than six (6) feet on center and within three (3) feet of the sidewall or endwall. 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.
4. and 5. – No change.
D. For systems designed as an evapotranspiration/absorption bed, the following criteria must be met.
1. – No change.
2. Design will include a rock and pipe, or other Water Quality Control Division approved proprietary distribution product, with the centerline of the distribution system laterals no more than six (6) feet on center. A thin non-woven fabric as defined within Section 30-10-60.A.3 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.
Remainder of Section – No change.
Amend Sec. 30-12-20. Vaults other than vault privies.
A. The Board of Public Health may allow or prohibit vaults for use at a permanently occupied facility, except where section 30-12-20.B applies.
B. Vaults are prohibited where any of the following conditions exist:
1. Sites that cannot provide access for pumping and general system maintenance.
2. Full-time or limited use in new construction where the property can accommodate an OWTS with a soil treatment area.
C. Vaults may be permitted where any of the following conditions exist:
1. For full-time use when an existing OWTS is in a state of failure and cannot be replaced.
2. For full-time or limited use on a property which cannot accommodate an OWTS with soil treatment area.
3. If the Facility structure is on land where the installation of an OWTS with soil treatment area is not permitted.
4. For systems where a portion of the wastewater flows are separated, such as toilet wastes only, or a private recreational vehicle dump station, into a vault. The portion not retained in the vault must be treated in an OWTS sized per the requirements of the regulation.
5. Variances may be granted for specialized commercial uses.
D. Design and Capacity Requirements
1. A vault must be accessible for routine pumping and maintenance.
2. A vault 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.
3. A vault must provide visual or an audible signal device or both, indicating filling to a maximum of 75 percent capacity, must be to indicate thus indicating when pumping is necessary.
4. Concrete, fiberglass, and plastic tanks are allowed for use as a vault. All tanks must meet the structural design requirements of Section 30-9-20.E. or F., as applicable.
5. Vaults must be watertight, and meet the requirements of Sections 30-8-30 and 30-9-10.A.1.
6. Metal vaults are prohibited.
E. Contents of the vault must be pumped by a County-licensed systems cleaner, and records of maintenance and proper disposal shall be maintained by the owner and available for review by the Division.
Amend Sec. 30-12-30. Vault privies.
A. Effective volume of the vault privy must be no less than four hundred (400) gallons, and it must be constructed of concrete, fiberglass, or plastic. The vaults for privies must meet the structural and watertightness requirements of Section 30-9-20.E. or F., as applicable.
B. through D. – No change.
Amend Sec. 30-12-40. Incinerating, composting and chemical toilets.
A. The use of an incinerating, composting or chemical toilet will not reduce the required size of the OWTS as noted in Section 30-8-10; except under the following conditions:
1. The local board of health may choose to permit reductions in the size of soil treatment areas based on incinerating, or composting toilets, only if:
a. There is no flush toilet available in the structure(s),
b. The septic tank size must meet the requirements of Table 9-1 with no reductions allowed,
c. Before permitting a reduction in the size of a soil treatment area for the use of incinerating or composting toilets, the local public health agency must implement the following programs:
(1) A Transfer of Title inspection program per section 43.4.L. All acceptance documents must include a notation of the alternative toilet system that is installed;
(2) A Use permit program per section 43.4.M with required inspections and permit renewals no greater than three years apart. Inspections must confirm that no flush toilets have been installed, and provide observations relative to general maintenance of the alternative fixtures, and
d. The reduction in the soil treatment area will be calculated by reducing the estimated wastewater flows (as provided in section 43.6) from the structure by no more than 25%, unless the structure has no water source or plumbing fixtures (e.g., remote access structure with composting toilet only).
B. through D. – No change.
E. 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.
1. Incinerating Toilets Acceptance Requirements
a. Incinerating toilets must meet the requirements of the NSF Protocol P157 (2022 version) and bear the seal of approval of the NSF or an equivalent testing and certification program.
b. An approved incinerating toilet must be designed, installed, and maintained in accordance with all applicable federal, state, and local building, plumbing, and air pollution requirements, and manufacturer’s instructions.
F. Composting toilets.
1. Composting toilets must meet the requirements of NSF/ANSI Standard 41 (2023 version) and bear the seal of approval of the NSF or an equivalent testing and certification program.
2. through 6. – No change.
G. Portable chemical toilets.
1. and 2. – No change.
H. Disinfection Systems 43.12 Design Criteria – Other Facilities Systems 105.
1. Disinfection components must meet the requirements of NSF/ANSI Standard 385 (version 2022), or prior acceptance through NSF/ANSI Standard 46 – version 2022 or earlier, and bear the seal of approval of the NSF or an equivalent testing program. This component may be installed between the higher level treatment system and the pump tank, or within the pump tank.
a. All methods of disinfection shall effectively reduce the fecal coliform count to ≤200 organisms per 100 mL.
b. If chlorination is used as the disinfection method, a free chlorine residual of two tenths of a milligram per liter (0.2 mg/l) must be maintained in the pump tank.
c. The use of disinfection systems is only allowed provided the effluent is treated to TL3N quality prior to entering the disinfection system, and the local public health agency has implemented an inspection and maintenance oversight program, as specified in the requirements of section 43.14.D.
Amend Sec. 30-12-50. Treatment systems other than those discharging through a soil treatment area or sand filter system.
A. through E. – No change.
F. Methods of analysis - sampling points.
1. 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, 24th edition, 2022 (International Standard Book Number: ISBN-10: 0875532993, ISBN-13: 978-0875532998).
Remainder of Section – No change.
Article XV Materials Incorporated by Reference
Amend Sec. 30-15-10. Materials incorporated by reference.
Throughout these regulations, standards and requirements by outside organizations have been adopted and incorporated by reference. The materials incorporated by reference cited herein include only those versions that were in effect as of March 30, 2024, and not later amendments to the incorporated material.
Be it further ordained by the Board that the Clerk to the Board be, and hereby is, directed to arrange for Municode to supplement the Weld County Code with the amendments contained herein, to coincide with chapters, articles, divisions, sections, and subsections as they currently exist within said Code; and to resolve any inconsistencies regarding capitalization, grammar, and numbering or placement of chapters, articles, divisions, sections, and subsections in said Code.
Be it further ordained by the Board, if any section, subsection, paragraph, sentence, clause, or phrase of this Ordinance is for any reason held or decided to be unconstitutional, such decision shall not affect the validity of the remaining portions hereof. The Board of County Commissioners hereby declares that it would have enacted this Ordinance in each and every section, subsection, paragraph, sentence, clause, and phrase thereof irrespective of the fact that any one or more sections, subsections, paragraphs, sentences, clauses, or phrases might be declared to be unconstitutional or invalid.
First Reading: May 13, 2026
Publication: May 20, 2026, in the Greeley Tribune
Second Reading: June 1, 2026
Publication: June 5, 2026, in the Greeley Tribune
Final Reading: June 15, 2026
Publication: June 19, 2026, in the Greeley Tribune
Effective: June 30, 2026