To: Board of County Commissioners
Through: Bryan D. Weimer, Director, PWD
Prepared By:
prepared
Chuck Haskins, P.E., CFM, Engineering Services Division Manager
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presenter
Presenter: Lisa Knerr, Environmental Manager, Engineering Services Division
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Subject:
title
Updates to the County’s Grading, Erosion, and Sediment Control (GESC) Manual
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Purpose and Request:
recommended action
The purpose of this General Business Item is to update the Board and seek direction on proposed changes to the County’s Grading, Erosion, and Sediment Control (GESC) Manual. This item was discussed at the Board’s November 1, 2022 Study Session. Public Works and Development staff recommend that the Board approve this update to the GESC Manual.
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Background and Discussion: The County has a permit certification from the Colorado Department of Public Health and Environment under the General Permit COR080000 Stormwater Discharges Associated with Municipal Separate Storm Sewer Systems (MS4s) that Discharge to the Cherry Creek Reservoir Drainage Basin Authorization to Discharge under the Colorado Discharge Permit System. The County’s permit number under that general permit is COR080010. The County’s MS4 permit requires the County to have a Construction Sites Program that requires “control measures to be implemented for all applicable development sites.” The MS4 permit defines an “applicable development site” as a site that results in “land disturbance of greater than or equal to one acre, including sites less than one acre that are part of a larger common plan of development or sale, unless excluded below.” The exclusions are not pertinent to the proposed revisions. The MS4 permit also requires the County to comply with Regulation 72-Cherry Creek Reservoir Control Regulation, which further requires the County to regulate all “land disturbances”. The County’s current GESC Manual meets all requirements of the MS4 permit.
In general, these proposed revisions clarify that the County can implement the GESC Manual requirements, better describes the partnership between the Southeast Metro Stormwater Authority (SEMSWA) and the County, removes unclear or unnecessary language, and provides other language to clarify sections of the GESC Manual. These proposed revisions should not change any day-to-day operations of either SEMSWA or County staff or affect any costs to GESC permittees. The BOCC last approved changes to the GESC Manual on June 25, 2019 (Resolution Number 190350).
Minor Changes-Should not affect permittee applications, staff application review times, or costs to GESC permittees.
Throughout
*Updated the formatting to be consistent throughout the document.
*Removed references to “SEMSWA” only or changed “SEMSWA” to “SEMSWA or the County, as applicable”. This clarifies that the County has the legal authority to implement the GESC Manual in unincorporated areas of the County. For example, the Prosper development is within the County’s MS4 permit area (considered a “growth area”), but is outside of SEMSWA’s service area. Therefore, the County must implement the GESC Manual in this part of the MS4 permit area.
Table of Contents
*The Table of Contents has been updated to reflect the proposed changes.
Chapter 1
*Revised language in Chapters 1 and 2 to remove references to the City of Centennial, delete outdated or unnecessary information, streamline the background and introduction information for the GESC Manual, clarify potentially confusing sentences, and add a reference to Chapter 4 in the County’s Rural Engineering Standards. Note that the redlined document indicates several sections that were deleted. Rather, these sections were most likely moved to another location in Chapters 1 and 2. For example, some of the information in Chapter 12 was moved to Chapter 1.
*Removed or reworded potentially confusing sentences. For example, Chapter 1 states that “The County is also classified by the State as a Standard MS4 Permittee, and SEMSWA operates the GESC Permit Program for the County in the County’s MS4 Permit area within the SEMSWA Service Area.” This is technically incorrect. SEMSWA does not “operate” the County’s entire GESC Program within the SEMSWA service area. Specifically, SEMSWA does not implement the GESC Program in Copperleaf due to a unique Subdivision Improvement Agreement. In addition, SEMSWA does not conduct more stringent enforcement actions, such as civil and criminal enforcement actions. This would be the County’s responsibility. Lastly, this implies that the SEMSWA service area corresponds to the County’s entire MS4 permit area, which is incorrect because the County’s MS4 permit area also includes the growth areas of the County, such as Prosper. The Prosper development is outside SEMSWA’s current service area.
*Removed unnecessary Information. There are several references to the City of Centennial (City). SEMSWA holds the MS4 permit for the City. References to the City and their processes is unnecessary to the County’s GESC Manual and may be confusing to some readers. Note that SEMSWA also holds the MS4 permit certifications for several special districts within the County, including East Cherry Creek Valley Water & Sanitation District; Arapahoe County Water & Wastewater Authority, and Inverness Water and Sanitation District. SEMSWA will continue to use this GESC Manual to implement the GESC Permit Program in the permit areas of those special districts. SEMSWA will develop a very similar GESC Manual for the City of Centennial with an introduction tailored to the GESC process in the City. SEMSWA will present this City-specific GESC Manual to their Board of Directors at their January 18, 2023 meeting. The SEMSWA Board of Directors does not meet in December. In addition, the introduction cites requirements from Colorado Regulation 61. This is unnecessary background information that might not be of interest to a reader.
*Updated outdated information. For example, Chapter 1 states that “The State issues a permit for ‘Discharges Associated with Construction Activities’ to manage dewatering discharges from construction projects. The permit establishes water quality standards and Control Measures for dewatering discharges.” Recently, this dewatering permit was been divided into four dewatering general permits for different activities.
*Referenced the County’s Rural Engineering Standards. The GESC Manual was developed for the urbanized areas of the County. Chapter 4 of the County’s Rural Engineering Standards addresses grading, erosion, and sediment controls for the design and construction of proposed residential developments within the rural areas of Arapahoe County. A reference to the Rural Engineering Standards was added to the introduction of the GESC Manual.
Chapter 2
*Added text to Chapter 2 to clarify the goal of the GESC Manual and define a “construction activity”.
Chapter 4
*Clarified that SEMSWA and the County will continue to not collect permit fees or collateral for County public improvement projects.
Substantial Changes-Most likely will affect permittee’s applications and/or staff application review times.
*Added three appendices that were removed after the last revision-Utility Construction Activity,Oil and Gas Construction Activity, and Single Family Lot Certificates. The County has found that these documents are still used and it would be important to have them back in the GESC Manual. The Utility Construction and Oil and Gas Construction appendices have been updated with current information.
*Updated the Curb Cut Detail to replace the complicated table with a simplified graphic and standard measurements for the sediment accumulation and tributary areas. A new “Sizing” description was added for further clarification.
Fiscal Impact: The adoption of the revised GESC Manual is not anticipated to result in a significant increase in staff resources.
Alternatives: The alternative would be for the BOCC to decline to approve the proposed changes to the GESC Manual, but this would result in a lack of clarity that the County has the legal authority to implement the GESC Manual in all of the County’s MS4 permit area.
Alignment with Strategic Plan:
☒Be fiscally sustainable
☒Provide essential and mandated service
☒Be community focused
Staff Recommendation: For the reasons stated above, staff recommends the proposed changes to the GESC Manual.
Concurrence: Public Works and Development, County Attorney, SEMSWA
Suggestion Motion(s): Please see attached.
Resolution: Attached is a copy of the draft resolution.