Item Coversheet

Agenda Item - 2.


Staff Report



City Council Study Session Meeting
March  4, 2019

Beautiful, Desirable, Safe and Environmentally Responsible City
Financially Sustainable Government Providing Excellence in City Services
Subject:  
Big Dry Creek Interceptor Sewer Improvements Predesign Project Update and Proposed Recommendation for Early Removal of Development Moratorium

Prepared By: 

Kent Brugler, Senior Engineer

David Loseman, City Engineer

John Burke, Downtown Development & Construction Manager

 
Recommended City Council Action:
 

Receive a presentation by Staff to update City Council on the findings of the Big Dry Creek Interceptor Sewer Improvements Predesign Project and provide direction to Staff  on a recommendation to remove the moratorium imposed by the Emergency Ordinance Providing for a 12-Month Moratorium on the Acceptance of New Development Applications for Projects that Increase Sewer Demand in the Big Dry Creek Interceptor Sewer on April 29, 2019.

Summary Statement:

 

  • On July 23, 2018, City Council passed Councilor's Bill No. 27, An Emergency Ordinance Providing For a 12-Month Moratorium on the Acceptance of New Development Applications for Projects That Increase Sewer Demand in the Big Dry Creek Interceptor Sewer (BDCIS).

  • Staff has advanced critical and concurrent work efforts on the Big Dry Creek Interceptor Sewer Improvements Predesign Project and is able to recommend that the 12-month development moratorium be completely removed effective April 29, 2019. The proposed date to remove the moratorium is planned to coincide with the completion of the comprehensive technical work and the capital improvement project to rehabilitate an approximately four-mile section of the BDCIS system, and is approximately three months in advance of the planned expiration of the moratorium.

  • Staff will provide a presentation to City Council briefly reviewing activities undertaken over the past seven months and discuss findings leading to the recommendation for the early removal of the moratorium.
Fiscal Impact:

$0 in expenditures.

Source of Funds:

Not Applicable.

 

Policy Issue(s):

 

Not Applicable.
Alternative(s):

 

City Council could choose to not listen to the presentation. Staff does not recommend this alternative as the presentation will provide important background information to precede a future City Council meeting. This is also not recommended as Staff is seeking direction on the recommendation to remove the BDCIS development moratorium on April 29, 2019. 

Background Information:

 

Wastewater from approximately two thirds of the City flows through a large wastewater collection system known as the BDCIS. This 22-mile long wastewater system provides service to residents and businesses and generally flows north of West 92nd Avenue from Standley Lake to the Big Dry Creek Wastewater Treatment Facility (BDCWWTF), as shown in Exhibit A. The system consists of large pipes, also knows as interceptors, ranging in size from 15 to 54 inches in diameter, that convey sewage for subsequent treatment at BDCWWTF.

An assessment of the BDCIS condition and capacity was performed and documented in a report in 2012 and updated in 2015. This report measured flow and confirmed that several segments of the BDCIS were reaching the end of their useful lifespan and/or had insufficient capacity to support continued development and redevelopment of the area.  Plans were made to initiate a BDCIS project over a multi-year horizon beginning in late 2018 with targeted completion by 2026. However, the need for improvements became critical sooner than anticipated with available pipeline capacity being consumed by the development that had occurred and was permitted to occur.

Leading up to the time the moratorium was recommended, it was estimated that peak flows from development approved from 2012 to early 2018 were projected or forecasted to add 40% to the base flow measured in 2012. This projected flow increase would consume remaining capacity in the BDCIS and increase risk of sanitary sewer overflow. Based on the best information available at the time, a 12-month moratorium on the acceptance of new development applications for projects that increase sewer demand in the Big Dry Creek Interceptor Sewer was approved by City Council on July 23, 2018.

In the past seven months Staff has worked diligently to advance critical and concurrent work efforts including but not limited to:

 

  • Bringing a $1.2 million contract to City Council for approval of a predesign services contract for the BDICS system, resulting in the completion of a field survey of 22 miles of interceptor pipe and 515 manholes to verify pipe locations, alignments and manhole invert and rim elevations to accurately determine installed pipeline capacity, as well as resulting in the evaluation of the condition of the system to refine the conceptual level cost estimate of needed improvements that will form the basis of recommendation for design-phase work.
  • Bringing a $3.4 million contract to City Council for a capital project to rehabilitate an approximately four-mile section of the BDCIS system to install a liner in  a parallel 30inch concrete pipe interceptor installed in the early 1970’s to enable its full use. City Council approved this contract in December 2018. The work is underway to be completed by April 29, 2019.
  • Continuing to process development applications already underway in the BDCIS area, for a total of 90 applications approved to date, while conducting a comprehensive analysis of future development scenarios.
  • Updating the wastewater hydraulic model with actual field survey data resulting in improved model capability.

 

Based on the above progress, Staff is recommending the early removal of the 12-month development moratorium in the Big Dry Creek basin on April 29, 2019. This date coincides with the completion of the comprehensive technical work and the capital improvement project to rehabilitate an approximately four-mile section of the BDCIS system, and is approximately three months in advance of the planned expiration of the moratorium.

Allowing Staff to present an update on the BDCIS work and the accompanying recommendation  for the early removal of the BDCIS development moratorium helps achieve the City's Strategic Plan goals of Beautiful, Desirable, Safe, and Environmentally Responsible City, and Financially Sustainable Government Providing Excellence in City Services.

Respectfully submitted,


Donald M. Tripp
City Manager
ATTACHMENTS:
DescriptionUpload DateType
Exhibit A: Big Dry Creek Interceptor Sewer Moratorium Update and Recommendation - Basin Map2/21/2019Map