Agenda Date: 4/18/2017
Subject:
Title
A resolution approving an Intergovernmental Agreement (IGA) with Urban Drainage and Flood Control District regarding High Line Canal funding for stormwater planning and an operational model.
Body
|
Presented By: |
Mark Relph, Public Works and Utilities Director |
POLICY QUESTION:
Does city council support committing Storm Drainage Utility funds to prepare an outfall systems planning and operational model for the High Line Canal?
BACKGROUND:
The High Line Canal is an irrigation and water supply canal meandering through Littleton, from about Colorado State Highway No. C-470 to South Grant Street extended. The High Line Canal is owned and operated by Denver Water, who divert water from the South Platte River and deliver this water to their customers in the metro area. Denver Water has proposed to stop utilizing the canal for irrigation and water supply due to excessive water losses caused by evaporation and seepage.
The Urban Drainage and Flood Control District (UDFCD), along with many local governments, completed the High Line Canal Feasibility Study for Stormwater Runoff Reduction and Treatment in August, 2014. The study determined it may be possible to collect urban stormwater runoff within portions of the canal. This water may be able to be passively treated and utilized to support the diverse vegetation, wildlife and other uses along its banks. Most local governments along the canal have expressed interest in participation in a study to develop a model as to how to utilize stormwater as a resource.
Council approved in the 2016 budget, $50,000 for a project similar to what is proposed in the IGA, but just between the UDFCD and the City of Littleton; however, these funds were no expended due to interest from other local jurisdictions. The unexpended Storm Drainage funds were left in the utility and are reflected in the fund balance. It is now proposed to broaden the participation and for the City to enter into an Intergovernmental Agreement with UDFCD to prepare a plan and model to utilize the canal for stormwater collection, treatment and support of other uses.
UDFCD will manage the project, with participation from Littleton and other local jurisdictions.
STAFF ANALYSIS:
The existing use of the High Line Canal is not efficient for water conveyance. However, the water losses to seepage support the many cottonwood trees and other plant species along its banks. If the river water no longer flows in the canal, the trees and related vegetation along with the wildlife may suffer and decline.
There are several locations within Littleton where storm water runoff either flows under or into the canal. The 2014 feasibility study determined it may be viable to collect some of this stormwater within the canal and improve its quality through means such as extended detention, bioretention, infiltration and similar forms of passive treatment. This treated stormwater may then be used to support and sustain the current environmental and recreational uses of the canal.
The proposed planning and operation model for the storm water outfall systems will look at multiple alternatives and locations. It will be necessary to consider hydrology, storm inflow locations, drainage or flooding problems, right-of-way, wetlands, legal issues, in particular water rights and other factors. The end result of this effort will be a report listing specific improvements that could be constructed, along with phasing and costs.
OPTIONS/ALTERNATIVES:
A proposal was made in 2016 for the city and UDFCD for a limited study of High Line Canal in the city limits of Littleton. The scope of this study could not be determined but evolved into the current proposed plan and model encompassing most of the metro area. Council could again propose a separate study, but that is not likely to gain consensus with UDFCD since there is now this larger interest in the metro area.
FISCAL IMPACTS:
Littleton’s contribution would be a lump sum amount of $16,241 and would come from the Storm Drainage Fund; professional and consulting account. This amount is less than the 2016 budget amount of $50,000 with an outcome identical to what was proposed in 2016.
It is now proposed UDFCD and other local governments contribute funding for this project, bringing the total budget to $400,000. Each party’s share is based on a percentage of the total canal length located within their boundary. To date, Southeast Metro Storm Water Authority, Denver, Cherry Hills Village, Greenwood Village, Denver Water, Aurora and Douglas County have expressed interest in participation. There are no funds proposed at this time for construction. If the plan and model prepared by this effort is supported by local governments, it is anticipated there might be a multi-year project, requiring additional contributions from the cities, counties and UDFCD for future construction.
STAFF RECOMMENDATION:
Staff recommends the city council approve the Intergovernmental Agreement with the UDFCD for the High Line Canal plan.
PROPOSED MOTION:
Proposed Motion
I move to approve the resolution authorizing an Intergovernmental Agreement (IGA) with Urban Drainage and Flood Control District regarding High Line Canal funding for stormwater planning and an operational model.