To: Honorable Mayor and Members of Town Council
From: Mark Marlowe, P.E., Director of Castle Rock Water
Title
Ordinance Repealing and Reenacting Chapters 15.34 and 15.36 of the Castle Rock Municipal Code; Adopting by Reference as Primary Codes the Temporary Erosion and Sediment Control Manual and the Storm Drainage Design and Technical Criteria Manual; Providing Penalties for Violations thereof; and Amending Chapter 4.03 Concerning Illicit Discharge and Connection (Second Reading, Approved on First Reading on May 21, 2019 by a vote of 7-0)
Body
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Executive Summary
Second Reading - Approved on First Reading on May 21, 2019 by a vote of 7-0. The purpose of this memorandum is to request approval of an Ordinance (Attachment A) repealing and reenacting Chapters 15.34 and 15.36 of the Castle Rock Municipal Code; adopting by reference as primary codes the Temporary Erosion and Sediment Control Manual and the Storm Drainage and Technical Criteria Manual; providing penalties for violations thereof; and amending Chapter 4.03 concerning Illicit Discharge and Connection. With this Ordinance Chapter 15.34 would be repealed, adopting by reference as a Primary Code the Town of Castle Rock Temporary Erosion and Sediment Control (TESC) Manual (Attachment B). Changes to the TESC Manual generally include a name change to provide clarity on the coverage of the program, updates to improve program efficiency, and added criteria and details to address common areas of concern and program modifications to align with the current Phase II Stormwater Discharge Permit the Town is regulated under through the Colorado Water Quality Control Division.
With this Ordinance Chapter 15.36 would be repealed, adopting by reference as a Primary Code the Town of Castle Rock, Colorado Storm Drainage Design and Technical Criteria Manual (Storm Drainage Manual) (Attachment C). Changes to the Storm Drainage Manual generally include modifications to align with the current Phase II Stormwater Discharge Permit, add subsurface drain requirements for lot-to-lot residential applications, and other criteria revisions to reduce the maintenance burden on storage and water quality treatment facilities.
This Ordinance would also amend Chapter 4.03 of the Castle Rock Municipal Code, Illicit Discharge and Connection (IDC). Changes to the IDC Code generally include modifications to the allowable discharge list to align with the current Phase II Stormwater Discharge Permit.
Changes since the first reading include minor editorial revisions, responses to public comment and clarifying language to the TESC Manual and Storm Drainage Manual. No changes have been made to the IDC Code.
Notification and Outreach Efforts
For Chapters 15.34 and 15.36, Town staff provided public notification on May 10, 2019 to the local Home Builders Association and Economic Development partners outlining the proposed changes, including a copy of the draft revision made available on the Town’s website. Public notice was provided on this item in accordance with Municipal Code.
A formal presentation was provided to the Developer’s Roundtable on May 29, 2019. Announcements regarding the criteria changes were made at the April and June contractor luncheons. Public comments were received from the local Homebuilder’s Association resulting in minor clarifications to the revised criteria.
History of Past Town Council, Boards & Commissions, or Other Discussions
The TESC Manual (formerly the Grading, Erosion and Sediment Control (GESC) Manual and Drainage, Erosion and Sediment Control (DESC) Manual), was originally adopted by Municipal Code in 2006 and updated in 2011, and again in 2015.
The Storm Drainage Manual was originally adopted by Municipal Code in 2006 and updated in 2012.
The Illicit Discharge and Connection Code was originally adopted in 2005 and updated in 2012.
This ordinance was presented to the Castle Rock Water Commission at their meeting on April 24, 2019. The Commission voted to recommend approval to Town Council.
The Storm Drainage Manual was presented to the Planning Commission at their meeting on May 9, 2019. The Commission voted to recommend approval to Town Council.
This ordinance was presented to Town Council for First Reading on May 21, 2019, where the Council voted unanimously for approval by a vote of 7-0.
Discussion
Temporary Erosion and Sediment Control (TESC) Manual (Chapter 15.34)
Staff recommends the following amendments to the TESC Manual:
1. Rename the manual from “Grading, Erosion and Sediment Control (GESC) Manual and Drainage, Erosion and Sediment Control (DESC) Manual” to “Temporary Erosion and Sediment Control (TESC) Manual”.
2. Add clarifying language for the minimum qualifications for Low Impact TESC Permits.
3. Add criteria for temporary substitutes to sediment basins when site conditions are not feasible for sediment basin implementation.
4. Update the TESC Permit issuance process based on current practices.
5. Add clarifying language on the field change order process to provide for varying levels of approval.
6. Add clarifying language regarding permit extensions, fees and surety renewals.
7. Add restrictions for seeding and mulching during a Red Flag Warning.
8. Incorporate state standards for required coverage at vegetation acceptance to include a uniform vegetative cover with an individual plant density of at least 70 percent of pre-disturbance levels.
9. Discontinue the Drainage, Erosion and Sediment Control (DESC) Permit and institute a new TESC Permit for vertical residential construction on single-family residential sites.
10. Continue administering minimum site drainage requirements for single-family residential construction under the building permit.
11. Remove requirements for permanent stabilization following release of Certificate of Occupancy on single-family residential lots.
12. Revise TESC Standard Notes and Details based on current practices and to account for vertical residential construction requirements.
a. Add TESC Standard Detail for Temporary Road Crossings.
b. Add TESC Standard Details for single-family residential A Lots and B Lots.
13. Add example TESC Plans for vertical residential construction sites.
Storm Drainage and Technical Criteria (Storm Drainage) Manual (Chapter 15.36)
Staff recommends the following amendments to the Storm Drainage Manual:
1. Modify the definition for Development, Redevelopment and Constrained Development Sites in accordance with current Stormwater Phase II Permit requirements.
2. In accordance with State regulations, allow for up to twenty percent of a development site, not to exceed one acre, to bypass a water quality control measure when site constraints make this unfeasible.
3. In accordance with State regulations, allow for up to fifty percent of a constrained redevelopment site to bypass a water quality control measure when site constraints make this unfeasible.
4. In accordance with State regulations, allow for exclusions to water quality control measures for applicable roadway projects, trails, large rural residential property, stream stabilization projects, and temporary disturbances.
5. In addition to the current water quality capture volume standard, add design standards for water quality control measures including pollutant removal standard and runoff reduction standard, and modify the regional water quality capture volume standard in accordance with State regulations.
6. Add design criteria for allowable release volumes in accordance with Colorado Revised Statute 37-92-602(8), “Concerning a Determination that Water Detention Facilities Designed to Mitigate the Adverse Effects of Storm Water Runoff Do Not Materially Injure Water Rights.”
7. Improve operation and maintenance performance by prohibiting the use of well screens on stormwater outlet structures, except through special variance approval and add clarifying language regarding maintenance access for detention facilities.
8. Add clarifying language regarding operation and maintenance documentation in drainage reports including inspection and maintenance frequencies.
9. Due to excessive groundwater issues in residential neighborhoods that impact design life of streets, discourage lot-to-lot drainage on residential development and add requirement for
sub-surface drainage collection systems where lot-to-lot drainage or where significant upstream open space is designed.
Illicit Discharge and Connection (Chapter 4.03)
1. Replace allowable discharge list as found in Paragraph 4.03.080 - Discharge Prohibitions with updates as per the current Phase II Stormwater Discharge Permit. The list generally provides for more specificity and in some cases more flexibility for common discharges that do not pose a threat to receiving waters. An example where more specificity is identified includes potable water discharges as long as they are not used in any additional process prior to discharge. Examples where more flexibility are given include dye testing and stormwater runoff with incidental pollutants.
Budget Impact
There are no budget impacts associated with this Ordinance.
Staff Recommendation
Staff recommends approval of an Ordinance repealing and reenacting Chapters 15.34 and 15.36 of the Castle Rock Municipal Code; adopting by reference as primary codes the Temporary Erosion and Sediment Control Manual and the Storm Drainage and Technical Criteria Manual; providing penalties for violations thereof; and amending Chapter 4.03 concerning Illicit Discharge and Connection.
Proposed Motion
“I move to approve the Ordinance as introduced by title.”
Attachments
Attachment A: Ordinance
Attachment B: TESC Manual
Attachment C: Storm Drainage Manual