To: Honorable Mayor and Members of Town Council
From: Mark Marlowe, P.E., Director of Castle Rock Water
Title
Resolution Approving a Variance Pursuant to Chapter 9.16.070E of the Castle Rock Municipal Code for the 2019 Cured-in-Place Pipe Sewer Projects
Body
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Executive Summary
Castle Rock Water is seeking Town Council approval of a variance (Attachment A) to allow four nights of overnight construction work for the 2019 Cured-in-Place Pipe (CIPP) Sewer Project. Insituform Technologies, LLC (Insituform) was retained by the Town to construct the project in December 2019 and began CIPP installation in March 2020. In order to complete the project, Insituform needs to install CIPP overnight at the Winrock Apartments and a second location near Wolfensberger Road and Prairie Hawk Drive (see Attachment B for location maps). Night installation is necessary to minimize wastewater flows and mitigate the risk of wastewater backups. Insituform will complete the overnight construction work in four or less nights from May through July 2020. All residents that will be impacted by the night work will be notified in advance of the work.
Notification and Outreach Efforts
Castle Rock Water and Insituform have been coordinating with the Winrock Apartment property management company on project specifics. The management company and apartment residents will be notified in advance with details about the night work including schedule, construction activities, and anticipated noise disturbances. They will also be asked to reduce water usage during the overnight construction hours. Night work at the Wolfensberger Road and Prairie Hawk Drive location is not anticipated to impact any residential properties.
History of Past Town Council, Boards & Commissions, or Other Discussions
On December 11, 2019 Castle Rock Water Commission voted unanimously to recommend approval of the construction contract with Insituform for the 2019 CIPP Sewer Project.
On December 17, 2019 Castle Rock Town Council voted unanimously to approve a resolution approving a construction contract with Insituform Technologies, LLC for the 2019 Cured-in-Place Pipe Sewer Project.
Discussion
Every year Castle Rock Water conducts sewer cleaning and video inspection as part of annual operations and maintenance. As a result of the video inspection, sewer system deficiencies are identified, such as cracked, broken or deformed pipe and offset joints. The sewer rehabilitation program is designed to rehabilitate, repair or replace sewer system components throughout the Town that have reached or are nearing the end of their useful life. The 2019 CIPP Project identified more than two miles of existing clay sewer pipe near the Memmen Young neighborhood of Town that was suffering from root intrusion, increased annual maintenance, and pipe defects. Through a competitive request for proposals, Insituform was retained to construct the 2019 CIPP Project. Insituform began CIPP installation in March 2020.
A portion of the project includes rehabilitation of several deteriorated sewer mains adjacent to the Winrock Apartments at 1000 South Street. Installation of CIPP typically requires a temporary (4 to 6 hour) blockage of all sewer service pipes connected to the mainline. Residents in single family homes are notified to reduce water usage temporarily for this short period of time and there is typically enough volume in single family sewer service pipes to store some wastewater and avoid backups into homes. In contrast, apartment units with shared sewer service lines represent an increased challenge for CIPP construction. There are 63 total units in the Winrock Apartments. Each of the apartment’s sewer services are shared between approximately 8 units and thus flows in these services are significantly higher than those from single family service lines. In addition, the current Covid-19 health crisis is resulting in an increased number of people at home during the day and Castle Rock Water has observed corresponding increases in residential daytime water use. Asking apartment residents to restrict their water use during CIPP construction will not reduce wastewater backup risk to an acceptable level. Temporary shut-off of apartment water services would be effective, but is not an acceptable solution given increased sanitation and hygiene practices necessitated by the Covid-19 health crisis.
To mitigate wastewater backup risk at the Winrock Apartments, Castle Rock Water is seeking Town Council approval of a variance to allow overnight construction work. Castle Rock Water data indicates that residential water usage is significantly reduced between the hours of 10pm and 7am. The equipment utilized by Insituform includes a few large trucks, a steam boiler, mechanical winches, and other small power tools. There will be some night time noise disturbance to the apartment residents. However, staff is of the opinion that completing the CIPP construction at night is the best option to minimize wastewater backups at the Winrock Apartments.
There is also a second location of potential night work for the 2019 CIPP Sewer Project. Castle Rock Water video inspections recently discovered broken sewer main near the intersection of Wolfensberger Drive and Prairie Hawk Drive. This 15-inch pipe carries flows under the railroad and is a critical component of the Town’s sanitary sewer collection system. Castle Rock Water is in the process of soliciting proposals for open trench point repair and subsequent CIPP rehabilitation of this sewer main. Because of the amount of daytime wastewater flow in this pipeline, night construction is recommended to simplify bypass pumping operations.
All overnight construction work will occur from 10 pm to 7 am. Depending on existing conditions encountered, the construction work may be completed in as little as two nights, but Council authorization for up to four nights is requested.
Budget Impact
There is currently no anticipated project budget impact related to the night construction work.
Staff Recommendation
Staff requests Council approval of a Resolution approving a variance pursuant to Chapter 9.16.070E of the Castle Rock Municipal Code for the 2019 Cured-In-Place Pipe Sewer Projects.
Proposed Motion
“I move to approve the Resolution as introduced by title.”
Attachments
Attachment A: Resolution
Attachment B: Maps of Areas Impacted by Night Work