5 Colo. Code Regs. § 1002-72.7

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

Section 5 CCR 1002-72.7 - STORMWATER PERMIT REQUIREMENTS

1. Definitions

(a) "Applicable MS4 permit" means the Division-issued MS4 permit that authorizes discharge of stormwater to state waters in accordance with Regulation #61, including anti-backsliding provisions. The Division authorizes several different types of MS4 permits in the basin including individual permits for large MS4s, a general permit for regulated small MS4s that drain to the Cherry Creek Reservoir Basin, and a non-standard small MS4 permit. Section 72.7 of this regulation establishes the minimum requirements for applicable MS4 permits in the Cherry Creek Basin, whereas detailed conditions to meet these minimum requirements are described in the applicable MS4 permits.

(b) "Construction activity" refers to ground surface disturbing and associated activities (land disturbance), which include, but are not limited to, clearing, grading, excavation, demolition, installation of new or improved haul roads and access roads, staging areas, stockpiling of fill materials, and borrow areas. Construction activity does not include routine maintenance to maintain the original line and grade, hydraulic capacity, or original purpose of the facility. Activities to conduct repairs that are not part of regular maintenance or for replacement are construction activities and are not routine maintenance. Repaving activities where underlying and/or surrounding soil is cleared, graded, or excavated as part of the repaving operation are considered construction activities unless they are otherwise excluded. Construction activity is from initial ground breaking to final stabilization regardless of ownership of the construction activities.

(c) "Common Plan of Development or Sale" means a contiguous area where multiple separate and distinct construction activities may be taking place at different times on different schedules, but remain related. "Contiguous" means construction activities located in close proximity to each other (within 1/4 mile).

(d) "Control Measure (CM)" means any best management practice or other method used to prevent or reduce the discharge of pollutants to waters of the state. Control Measures include, but are not limited to, best management practices. Control Measures can include other methods such as the installation, operation, and maintenance of structural controls and treatment devices.

(e) "Design Standard" means post-construction Control Measure design standards or base design standards. These performance-based standards include, but are not limited to, options to meet post-construction stormwater quality requirements by treating the Water Quality Capture Volume, implementing runoff reduction measures, attaining a pollutant reduction standard, and treating runoff with a regional stormwater quality control measures or facility. Design standards are further described in the applicable MS4 permits.

(f) "Development Tiers" mean the three categories of land disturbance associated with development or redevelopment referenced in this regulation for purposes of post-construction stormwater quality requirements:

"Tier 1 development and redevelopment" means land disturbance that results in less than or equal to 500 square feet of impervious area for new development or 500 square feet of increased imperviousness for redevelopment and disturbs less than one acre and is not part of a larger common plan or development or sale that disturbs one acre or more.

"Tier 2 development and redevelopment" means land disturbance that results in greater than 500 square feet of impervious area for new development or more than 500 square feet of increased impervious area for redevelopment and disturbs less than one acre of land and is not part of a larger common plan or development or sale that disturbs one acre or more.

"Tier 3 development and redevelopment" means land disturbance of one acre or more or land disturbance that is part of a larger common plan of development or sale that disturbs one acre or more. Tier 3 projects are subject to MS4 permit requirements.

(g) "Disturbed areas" means any site, area or lands in the Cherry Creek watershed where a land disturbance has commenced but has not been permanently stabilized and/or revegetated.

(h) "Individual home construction" means a land disturbance or development for a single home, not including land disturbances for roads, road gutters or road improvements, that disturbs less than one acre of land and is not part of a larger common plan of development or sale, and where the owner of the single home holds a permit for construction of only one dwelling within the subdivision, if any, containing the single home.

(i) "MS4 permittee" for the purposes of this section of the regulation only, means the Municipal Separate Storm Sewer System or MS4 that has been issued a stormwater discharge permit by the Division.

(j) "Owner" for the purposes of this section of the regulation only, means the owner or authorized representative of the facility or construction project.

(k) "Receiving pervious area" means land area that is capable of infiltrating runoff from impervious areas. Examples of receiving pervious areas include grass buffers, grass swales, other landscaped areas, and permeable pavement. Receiving pervious areas can be used to minimize directly connected impervious area.

(l) "Stream restoration" means stream or channel improvements including practices such as bed and bank stabilization, riparian buffers, in-stream enhancement, floodplain reconnection and other practices that improve hydrologic, geomorphic and ecological stream function. The term includes "stream or channel bank stabilization," "stream or channel reclamation," and "stream or channel rehabilitation."

(m) "Water Quality Capture Volume (WQCV)" means the volume equivalent to the 80th percentile storm, meaning that 80 percent of the most frequent occurring storms are fully captured and treated and larger events are partially treated.

2. The following requirements, at a minimum, shall be incorporated into any Stormwater Permit issued to a Municipal Separate Storm Sewer System (MS4) in the Cherry Creek watershed, in addition to the requirements included in Regulation #61 (5 CCR 1002-61). Permittees may also incorporate requirements into their programs that are more restrictive than those outlined in this control regulation.

At a minimum, the MS4 permit will require that the regulated MS4 develop, implement, and enforce a stormwater management program designed to reduce the discharge of pollutants from the MS4 to the maximum extent practicable (MEP), to protect water quality, and to satisfy the appropriate water quality requirements of the Colorado Water Quality Control Act (25-8-101 et seq., C.R.S.). Implementation of CMs consistent with the applicable MS4 requirements included in Regulation #61 (5 CCR 1002-61) and the requirements of the subsection herein constitute compliance with the standard of reducing pollutants to the MEP.

(a) Public education and outreach on stormwater impacts. The MS4 permittee must implement a public education program that includes the following:

(1) Distribution of educational materials or equivalent outreach focused on residential, industrial, agricultural, and/or commercial sources that have the potential to contribute significant nutrient concentrations to State waters at a rate that could result in or threaten to result in exceedance of the chlorophyll a standard in Cherry Creek Reservoir. Examples of sources that may need to be addressed by the MS4's program include chemical deicing, retailers with outdoor storage of fertilizers, concentrated agricultural activities such as turf farms and landscape plant facilities, and animal feeding operations.

(b) Construction site stormwater runoff control.

(1) Regulated Activities. For disturbances that are greater than or equal to one acre or part of a larger common plan of development or sale that disturbs one acre or more, the MS4 permittee must comply with the applicable MS4 permit and the additional requirements in section 72.7.2.(b)(4)(iii).

For disturbances less than one acre and not part of a larger common plan or development or sale that disturbs one acre or more, the MS4 permittee must develop, implement, and enforce a program to reduce pollutants in any stormwater runoff to the MS4 from construction activities that disturb land, including, but not limited to, the following, unless otherwise excluded in section 72.7.2(b)(2):

(i) Clearing, grading, or excavation of land;

(ii) Construction, including expansion or alteration, of a residential, commercial or industrial site or development; and

(iii) Construction of public improvements and facilities such as roads, transportation corridors, airports, and schools.

(2) Exclusions.

(i) Automatic Exclusions. The MS4 permittee may exclude the following activities from the requirements in section 72.7.2(b) of this regulation.

(A) Agricultural activities (i.e., agricultural and silvicultural activities generating nonpoint source discharges, including runoff from orchards, cultivated crops, pastures, range lands, and forest lands, but not Concentrated Animal Feeding Operations. This exclusion does not extend to the construction of facilities or other activities generating stormwater runoff associated with industrial (i.e., construction) activity).

(B) Emergency and routine repair and maintenance operations for all underground utilities that does not result in a land disturbance greater than or equal to one acre, or otherwise part of a larger common plan of development or sale.

(C) Land disturbances at residential or commercial subdivisions that already have adequate Construction CMs installed and operating for the entire subdivision, approved in compliance with this regulation and the MS4 permit, as applicable, provided the original owner who obtained approval retains legal authority. If residential, as lot specific development or redevelopment occurs, the homeowner or the original owner shall prevent the erosion and transport of sediment from the property and are required to provide permanent stabilization of the lot, in accordance with the MS4 permittee's regulations.

(D) Individual home construction that disturbs less than one acre of land is not part of a larger common plan of development or sale and meets conditions in section 72.7.1 . Roads, road gutters or and road improvements associated with individual home construction are still required to meet section 72.7.2 of this regulation.

(E) Routine maintenance that is performed to maintain the original line and grade, hydraulic capacity, or original purpose of a facility (maintenance operations performed by the MS4 permittee may still be covered under the Municipal Operations minimum control measure).

(F) Emergency operations related to flood, fire, or other force majeure that does not result in a land disturbance greater than or equal to one acre, or otherwise part of a larger common plan of development or sale.

(ii) Authorized Exclusions. The MS4 permittee may exclude the following activities from the requirements in section 72.7.2(b) of this regulation, if authorized through a developed procedure for determination that water quality is adequately protected without imposing the requirements. This procedure may either be on a site-specific basis, upon submission by the owner of a written request for exemption to the MS4 permittee, or, if the determination can be simplified to allow for determination by the owner, through certification by the owner to the MS4 permittee that the waiver criteria have been met.

(A) Construction Activities with R-Factor Waiver, for the purposes of this section, means the MS4 permittee may exclude the waived activity from being an applicable construction activity if the Division waives requirements for stormwater discharges associated with a small construction activity in accordance with Regulation 61.3(2)(f)(ii)(B) (the "R-Factor" waiver).

The Division may waive the otherwise applicable requirements in a general permit for a stormwater discharge from a small construction activity that disturbs less than five acres where the value of the rainfall erosivity factor ("R" in the Revised Universal Soil Loss Equation) is less than five during the period of construction activity. The rainfall erosivity factor must be determined using a State Approved method. The operator or owner must certify to the Division that the construction activity will only take place during a period when the value of the rainfall erosivity factor is less than five. If unforeseeable conditions occur that are outside of the control of the applicant for a waiver, and that will extend the construction activity beyond the dates initially applied for, the owner or operator must reapply for the waiver or obtain coverage under a general permit for stormwater discharges. The waiver reapplication or permit application must be submitted within two business days after the unforeseeable condition becomes known. This waiver does not relieve the operator or owner from complying with the requirements of local agencies.

(B) Construction of a sidewalk or driveway that does not result in a land disturbance greater than or equal to one acre, or otherwise part of a larger common plan of development or sale. A driveway is limited to access for residential development. A sidewalk may be attached or detached from the roadway but where possible should be detached.

(C) Underground utility construction that does not result in a land disturbance greater than or equal to one acre, or otherwise part of a larger common plan of development or sale, including the installation and maintenance of all utilities under hard surfaced roads, streets, or sidewalks, provided such land disturbance activity is confined to the area which is hard surfaced and provided that stormwater runoff and erosion from soil and materials stockpiles are confined and will not enter the drainage system.

(iii) Additional Exclusions. The Division may allow, at the request of the MS4 permittee, additional automatic and/or authorized exclusions, with recommendation from the Authority, when it can be reasonably shown that excluding the activity will not pose an increased threat to water quality, or that the cost of administering the program for a specific activity with low risk of stormwater pollution outweighs the benefits to water quality and the Additional Exclusion does not conflict with the applicable MS4 permit. The Division reserves the right to not allow any additional exclusions.

(3) Submittal requirements.

(i) For land disturbances that are greater than or equal to one acre or part of a larger common plan of development or sale that disturbs one acre or more, the MS4 permittee is regulated by the applicable MS4 permit. For land disturbances less than one acre, and not part of a larger common plan of development or sale that disturbs one acre or more, a Plan describing MS4 Permittee-approved construction CMs for land disturbance regulated by this program must be submitted to and, following adequate review, approved by the MS4 permittee prior to the commencement of land disturbances.

(4) Required Construction CMs.

(i) For land disturbances that are greater than or equal to one acre or part of a larger common plan of development or sale that disturbs one acre or more, the MS4 permittee is regulated by the applicable MS4 permit. For land disturbances less than one acre, not part of a larger common plan of development or sale that disturbs one acre or more, the following requirements for construction CMs to be implemented by the owner prior to the commencement of land disturbances must be included in the MS4 permittee's program.

(A) Reduce stormwater runoff flow to non-erosive velocities when practicable using CMs.

(B) Protect state waters located on construction sites from erosion and sediment damages resulting from land disturbance, using CMs.

(C) Control sediment before it leaves a construction site. All stormwater runoff from disturbed areas must be managed by at least one sediment entrapment CM before the stormwater exits the site.

(ii) In addition, the following construction CMs must be required where ground disturbing construction activity has permanently ceased, or temporarily ceased for more than 14 calendar days. Schedules for requiring stabilization and revegetation may be modified by the MS4 permittee to allow for physical considerations, including, but not limited to, constraints on establishing vegetation due to weather, such as temporary excessive soil moisture conditions that are adverse to stabilization or revegetation goals.

(A) Stabilize soils. All disturbed areas that remain exposed and where construction activities are not taking place for longer than 14 days shall be stabilized to protect the soils from erosion, using CMs.

(B) Revegetate disturbed areas. Within 14 days after construction activity has temporarily or permanently ceased, owners must plant temporary or, where applicable, permanent vegetative cover on disturbed areas, as follows:

(I) Temporary revegetation. Owners must provide temporary revegetation on all disturbed areas that will be exposed prior to completion of land disturbance activities. When seeding is not practicable (e.g., growing season constraints) the MS4 permittee may allow for temporary stabilization until planting is practicable.

(II) Permanent revegetation. Owners must provide permanent revegetation and/or stabilized landscaping on all disturbed areas that will be exposed for more than two years.

(C) Variances. Schedules for requiring stabilization may be modified by the MS4 permittee to allow for special considerations such as stabilizing access areas and areas in close proximity to continuing construction. Additionally, the MS4 permittee may allow for alternative approaches to stabilization if they can be shown to have erosion control capabilities similar to temporary or permanent revegetation.

(iii) Additional requirement to minimize disturbed areas for section 72.7.2 . The following requirements for construction CMs to be implemented prior to the commencement of land disturbances must be included in the permittee's program.

Owner shall schedule construction activities to minimize the total amount of soil exposed, including stockpiles, at any given time in order to reduce the period of accelerated soil erosion. Areas of land disturbance equal to 40 acres or greater must not be exposed for more than 30 consecutive days without temporary or permanent stabilization.

The MS4 permittee may allow authorized exemptions to the 40-acre limit for removal and storage of cut material where geotechnical limitations restrict the use of temporary or permanent stabilization of the stored material (e.g., swelling soils, rock).

The MS4 permittee may allow authorized exemptions to the 40-acre limit when the owner can demonstrate that the 40-acre limit is physically and/or financially impracticable. For sites granted this exemption, a phasing and earthwork quantities plan shall be submitted to and, following adequate review, approved by the MS4 permittee prior to the commencement of land disturbance activities.

(5) Inspection.

(i) For land disturbances greater than or equal to one acre or part of a larger common plan of development or sale that disturbs one acre or more, the MS4 permittee is regulated by the applicable MS4 permit.

(ii) For land disturbances less than one acre, not part of a larger common plan of development or sale that disturbs one acre or more, these requirements apply:

(A) The owner must be held responsible for inspection of construction CMs at the following times and intervals at a minimum:

After installation of any construction CM;

After any runoff event; and

At least every 14 days.

(B) For sites where construction activities are completed but final stabilization has not been achieved due to a vegetative cover that has been planted but has not become established, the MS4 permittee may allow for the owner to reduce inspection frequency to once per month.

(6) Operation and Maintenance.

(ii) For land disturbances less than one acre that are not part of a larger common plan of development or sale that disturbs one acre or more, the owner must be held responsible for operation and maintenance of CMs, and must make any necessary repairs to CMs immediately after a defect or other needed repair is discovered.

(c) Post-construction stormwater management in new development and redevelopment.

(1) Regulated Activities include:

(i) Tier 3 Development or Redevelopment: The MS4 permittee must comply with the applicable MS4 permit and the additional requirements in section 72.7 .2.(c)(6) and 72.7.2(c)(7).

(ii) Tier 2 Development or Redevelopment: MS4 permittee must develop, implement, and enforce a program that ensures that a combination of structural and/or nonstructural controls are in place that would prevent or minimize water quality impacts to the MS4 from new development and redevelopment projects unless otherwise excluded in section 72.7.2(c)(3).

(2) Provisions for specific CMs or equivalent protection included in section 72.7, that for the purpose of reducing nutrient concentrations to Cherry Creek Reservoir go beyond the requirements in the Colorado Discharge Permit Regulations, Regulation #61, for post-construction CMs, do not need to be required prior to discharge to a State water as long as CMs are in place to control stormwater runoff from new development and/or redevelopment in compliance with Regulation #61 (5 CCR 1002-61) and a regional facility(ies) is(are) in place to control phosphorus concentrations to Cherry Creek Reservoir, that result in pollutant removal in compliance with sections 72.7.2 , 72.7.2(c)(6), and/or 72.7.2(c)(7) of this regulation.

(3) Exclusions.

(i) Automatic Exclusions. The MS4 permittee may exclude the following activities from the requirements in section 72.7.2 of this regulation:

(B) Emergency and routine repair and maintenance operations for all utilities for disturbances less than one acre and not part of a larger common plan of development or sale.

(C) Individual home construction.

(D) Land disturbances at residential or commercial subdivisions that already have adequate post-construction CMs installed and operating for the entire subdivision, approved in compliance with this regulation, and with adequate capacity to treat any additional discharges.

(F) Emergency operations related to flood, fire, or other force majeure that maintain the original line and grade, hydraulic capacity, or original purpose of the facility, provided the land disturbance is less than one acre and not part of a larger common plan of development or sale.

(G) Land disturbance to undeveloped land that will remain undeveloped following disturbance.

(H) Excluded roadway projects. Activities associated with the maintenance, repair, preservation, and associated minor modifications to roadways, and associated appurtenant features, that do not permanently expand the original footprint of the roadway and do not increase the impervious area.

(I) Large lot single family development means a land disturbance greater than one acre on a single-family residential lot, or agricultural zoned lands, with an area greater than or equal to 2.5 acres in size and having a total site impervious area that is equal to or less than 20 percent of the site.

(J) Aboveground and underground utility construction, where the activities or maintenance of underground utilities or infrastructure that does not permanently alter the terrain, ground cover, or drainage patterns from those present prior to the construction activity. This includes, but is not limited to, activities to install, replace, or maintain utilities under roadways or other paved areas that return the surface to the same condition.

(K) Stream restoration, as defined in section 72.7.1(l).

(L) PRFs.

(M) Stormwater facilities. MS4 permittees may exclude the installation or maintenance of stormwater facilities associated with flood control and water quality, including but not limited to flood control ponds and post-construction control measures.

(ii) Authorized Exclusions. The MS4 permittee may exclude the following activities from the requirements in section 72.7.2(c) of this regulation on a site-specific basis, upon submission by the owner of a written request for exemption to the MS4 permittee and following adequate review and determination by the MS4 permittee that a permit is not needed to ensure adequate protection of water quality:

(A) Construction of a sidewalk or driveway. Construction of a sidewalk or driveway for disturbances less than one acre and not part of a larger common plan of development or sale. A driveway is limited to access for residential development. A sidewalk may be attached or detached from the roadway.

(B) Rural road construction and maintenance, where road construction and maintenance means land disturbances less than one acre, not part of a larger common plan of development of sale, for rural residential roads and rural collector roads that serve or are adjacent to large lot single family developments. Rural roads are typically characterized by having parallel ditches for conveyance of storm runoff, rather than curb and gutter. Although urban roadways sometimes use roadside ditches for runoff conveyance, they are not classified as rural roads. In the context of this regulation, the word road does not include temporary haul roads used for construction purposes.

(C) Trails, where trails mean bike or pedestrian trails. Bike lanes for roadways are not included in this exclusion.

(D) Maintenance trails, which are permanent access areas constructed primarily for the purpose of recreation but also provide access for operations and maintenance, for disturbances less than one acre and not part of a larger common plan of development or sale. This includes trails that consist, for at least some portion of the trail, of sidewalks adjacent to roadways.

(iii) Additional Exclusions. The Division may allow for additional automatic and/or authorized exclusions, at the request of the MS4 permittee, with recommendation from the Authority, when it can be reasonably shown that excluding the activity will not pose an increased threat to water quality, or that the cost of administering the program for a specific activity with low risk of stormwater pollution outweighs the benefits to water quality. The Division reserves the right to not allow any additional exclusions.

(4) Submittal requirements.

(i) Post-construction Plan. For Tier 3 development and redevelopment, the owner must comply with the post-construction CM requirements of the applicable MS4 permit, including, but not limited to, design standards. For Tier 2 development and redevelopment, the owner must submit a post-construction plan in accordance with the requirements in section 72.7.2 to the MS4 permittee for review and approval prior to the construction of the Tier 2 stormwater CM(s).

(ii) Inspection and Maintenance. For Tier 3 development and redevelopment, the owner must comply with the CM inspection and maintenance requirements of the applicable MS4 permit. For Tier 2 development and redevelopment, the post-construction plan must contain, at a minimum, the following information to address long-term operation and maintenance of post-construction Tier 2 stormwater CMs:

A) Procedures for maintenance and inspection protocols to ensure continued effectiveness of CMs, and commitments from responsible agency/owner to maintain post-construction CMs.

B) Procedures for dedication by easements or other legal means for access at the post-construction CM sites for operation, maintenance, and inspection of post-construction CMs.

(5) Post-construction CMs. TheMS4 permittee must require the installation, operation, and maintenance of post-construction CMs as follows:

(i) For all Tier 3 development and redevelopment, the MS4 permittee must comply with the post-construction requirements for CMs in the applicable MS4 permit. Minimum performance-based design standards in the MS4 permit must include one or more of the following:

A) Install post-construction CMs that provide a WQCV designed to capture and treat, at a minimum, the 80th percentile runoff event. The design standard will be further described in the applicable MS4 permit.

B) Implement runoff reduction practices using CMs designed to infiltrate, evaporate, or evapotranspire a quantity of water equal to 60% of what the calculated WQCV would be if all impervious area for the applicable development site discharged without infiltration. The design standard will be further described in the applicable MS4 permit.

C) Implement other performance-based CMs allowed in the applicable MS4 permit, such as pollutant removal CMs and regional WQCV facilities. Additional performance-based CMs allowed in the applicable MS4 permit may be implemented provided they are at least as protective as section 72.7(2)(c)(5)(i)(A) or 72.7(2)(c)(5)(i)(B).

D) Demonstrate that an alternative CM or site condition provides comparable or better nutrient load reduction relative to one or more of the criteria in section 72.7(2)(c)(5)(i)(A) through 72.7(2)(c)(5)(i)(C).

(ii) For all Tier 2 development and redevelopment, the MS4 permittee must require post-construction CMs that meet one or more of the following criteria:

A) Comply with Tier 3 CM requirements in section 72.7(2)(c)(5)(i).

B) Incorporate receiving pervious areas that are designed to infiltrate at least 60% of the WQCV for the added or increased impervious area. Such practices minimize directly connected impervious areas by reducing unnecessary impervious areas and routing runoff from impervious surfaces over permeable areas to reduce runoff rates and volumes. Where feasible, natural areas should be protected from disturbance and used for this purpose.

C) Demonstrate that an alternative CM or site condition provides nutrient load reduction that is as least as protective as one or more of the criteria allowed in section 72.7 or section 72.7(2)(C)(5)(ii)(B).

(iii) For all Tier 1 development and redevelopment, the MS4 permittee need not require installation of post-construction CMs.

(iv) Long-term Operation and Maintenance. For post-construction CMs implemented for Tier 3 development and redevelopment, the MS4 permittee must comply with the applicable MS4 permit. For Tier 2 development and redevelopment, the MS4 permittee must develop a program that requires owners to operate and maintain Tier 2 CMs. For structural Tier 2 CMs, the MS4 permittee must require the owner to provide sufficient legal access for inspection, operation and maintenance by dedicating easements, including plan notes on the Site Plan, or other legal means.

(6) Additional Requirements. The MS4 permittee must develop, implement, and enforce a program that ensures that facilities with a potential for increased nutrient sources implement source control management strategies to reduce nutrient loading, including a program with these provisions:

(i) The MS4 permittee must require the owner(s) to satisfy additional source control management strategies or measures at the time of plan review for uses that have a significant potential to contribute nutrient concentrations to state waters at a higher rate than typical. These facilities must be designed to prevent or reduce the amount of nutrients generated and/or released from the area of land disturbance. This can include the MS4 permittee developing a program to designate commercial facilities on a case-by-case basis or by addition of a general commercial sector, based on a determination that they have a significant potential to contribute nutrient concentrations to state waters at a rate higher than typical for other commercial or industrial land uses (e.g., stores with outdoor fertilizer storage, facilities with deicing operations). Source control practices at these facilities include, but are not limited to:

(A) Covering or enclosing activity in buildings or roofs;

(B) Providing secondary containment area to collect leaks and spills of fuels, lubricants, and other chemicals;

(C) Segregating or diverting stormwater runoff away from or around pollutant generating activity; and/or

(D) Routing site drainage to recycling or otherwise preventing direct discharge of vehicle or equipment wash-water.

(7) Stream Preservation Areas. Additional standards and procedures are required for Tier 2 and Tier 3 development and redevelopment in Stream Preservation Areas, which include Cherry Creek Reservoir, all of Cherry Creek State Park, drainage and discharges to the park within 100 feet of the park boundary; lands overlying the Cherry Creek 100-year floodplain; and all lands within the 100-year floodplain of Cherry Creek tributaries, as defined by the Mile High Flood District.

(i) Additional CM Requirements. For Tier 2 and Tier 3 new development and redevelopment in Stream Preservation Areas, the MS4 permittee must, in addition to meeting all the post-construction CM requirements in section 72.7.2 and /or (6), require owners to select and implement CMs that promote filtration and/or infiltration processes to treat the WQCV or meet runoff reduction design standards for all Tier 2 and Tier 3 new development and redevelopment within the Stream Preservation Area.

(ii) Authorized Exclusions. The MS4 permittee may exclude the following activities from the requirements in section 72.7.2(c)(7)(i) if

A) The disturbance is the result of implementation of an approved CM, in accordance with requirements in section 72.7.2(c),

B) Construction of roadway, highway, and underground utility crossings, provided construction CMs are implemented as required in section 72.7.2 and post-construction CMs are implemented as required in section 72.7.2(c).

C) Rural road construction and maintenance, except for a land disturbance associated with a rural road within a Stream Preservation Area, and provided that MS4 permittee requires post-construction CMs specific to this activity.

D) Those exclusions defined in section 72.7.2(c)(3).

5 CCR 1002-72.7

45 CR 11, June 10, 2022, effective 6/30/2022