Stormwater Section News Items

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PDF Documents: LID Manual; LID Standards; Drainage Improvement Prioritization List

Kinnikinick Lake

Marshall Lake

Lake Mary

Low Impact Development (LID)

On February 17, 2009, the Flagstaff City Council approved Ordinance No. 2009-07, which requires Low Impact Development integrated management practices (IMP's) be used to retain/infiltrate the first one inch of runoff from all impervious area on sites that also are required to provide stormwater detention.

Implementation of the LID Standards will be phased. During the first year, beginning March 17, 2009, the program will be voluntary. During this phase, developers will be encouraged to use LID measures.

During the second phase, developers will be required to retain/infiltrate the first ½ inch of runoff from all additional impervious areas.

In Phase 3, developers will be required to retain/infiltrate the first one inch of runoff from all additional impervious areas beginning on March 17, 2011.

Project Manager: Connor Boyle, 779-7685 X 7224, email Cboyle@flagstaffaz.gov

Download the Low Impact Development Spreadsheet

What is LID?

LID is an ecologically friendly approach to site development and stormwater management that aims to mitigate development impacts to land, water, and air. This approach emphasizes stormwater management at the source, using small, cost-effective landscape features located at the lot level. The goal is to conserve natural systems and hydrologic functions on a site through the integration of site design and planning techniques.

Benefits of LID	Examples of LID
Use runoff for landscape irrigation	Bio-rentention/rain gardens
Reduces non-point source pollution	Rainwater harvesting
Groundwater recharge	Permeable pavements
Reduces the volume of runoff (less flooding)	Green roofs
Water conservation	Vegetated swales
Credit toward LEED accreditation	Curb cuts
Aesthetically pleasing	Green streets

Specifically, LID aims to: 
Preserve Open Space and Minimize Land Disturbance 
Protect Natural Systems and Processes (drainage ways, vegetation, soils, sensitive areas) 
Re-examine the Use and Sizing of Traditional Site Infrastructure (lots, streets, curbs, gutters, sidewalks) and Customize Site Design to Each Site 
Incorporate Natural Site Elements (wetlands, stream corridors, mature forests) as Design Elements; and 
Decentralize and Micro-manage Stormwater at its Source. 

Drainage Channel Maintenance Project

City stormwater staff is presently completing a comprehensive inventory of all city-owned watercourses within the City. Inspection and maintenance scheduling will then occur. Data on maintenance activities will be collected and assessed to determine proper maintenance activities and scheduling. The result will be a comprehensive maintenance program to ensure that work is scheduled and performed to ensure the flood-carrying capacity of all city-owned watercourses.

The City has established draft maintenance guidelines that are being applied and tested in the field. These guidelines attempt to provide for environmental protections while maintaining the flood-carrying capacity of the watercourse. In general, grasses will not be removed and channel banks will be left relatively undisturbed. Typically, the bottoms of the watercourse will have all trees removed.

Project Manager: Malcolm Alter, 779-7685 X 7388, email Malter@flagstaffaz.gov

City-Wide Stormwater Master Plan

Purpose: The goal of this project is to develop a comprehensive drainage plan for the entire city that addresses existing drainage and flooding problems and avoids creating future ones.

Areas: The drainage basin is the logical physical unit for developing drainage plans. A map of the drainage basins being used to develop the Master Drainage Plan is shown below.

Process: In order to complete the plan in a timely manner Stormwater staff have obtained the assistance of the WLB Group, an engineering firm from Flagstaff, working with J.E. Fuller Hydrology and Geomorphology, from Tempe. These consultants will develop drainage plans for the following basins: Switzer Canyon Wash, Spruce Avenue Wash, Steve’s Blvd. Wash, Fanning Drive Wash, and Penstock Wash. City staff will complete the work for the remaining drainage basins. It should be noted, however, that most of the drainage and flooding issues in the Upper Rio de Flag and Clay Avenue Wash drainage basins are being addressed by the Rio de Flag Flood Damage Reduction Project, which is a joint project between the City and the U.S. Army Corps of Engineers. More information on this project can be found at this link: http://www.spl.usace.army.mil/cms/index.php?option=com_content&task=view&id=113&Itemid=31

Methods: In general, the Master Drainage Plan will be developed by identifying and quantifying drainage and flooding problems throughout the city (for both existing and future conditions), proposing a variety of solutions to mitigate these problems (both structural and nonstructural solutions), and developing plans to fund and build any solutions that require major construction work. Though major construction may be the only means to address some problems, the Master Drainage Plan seeks to identify and promote non-structural and low-impact solutions that meet the City Council’s goals of being cost-effective and promoting a sustainable community. Public input will also be an integral part of developing solutions.

Progress: To date, the following has been completed on the Master Plan project.

Obtained aerial photography and 2-foot contour mapping for the entire city. (This information was needed to accurately map flood hazard areas and develop solutions.)
Completed an inventory and Geographic Information Systems database of all surface and subsurface drainage features within the city. (More than 10,000 drainage features have been identified.)
Completed field investigations, problem identification and future-conditions hydrology and flood hazard mapping for most of the drainage basins within the city.

The WLB Group is currently working to identify potential solutions for many of the drainage and flooding problems that have been identified. Public input will be sought once feasible solutions have been determined.

Project Manager: Tom Hieb 779-7685 x 7213 , e-mail thieb@flagstaffaz.gov

Drainage Improvement Program (DrIP)

Overview

As the result of the increase in the stormwater utility fee, funding has been allocated to construct drainage projects to resolve long-standing neighborhood drainage problems. The City has received hundreds of drainage complaints over the years and has had no financial assets to resolve the problems. Some of these problems are severe, resulting in flooded residents and businesses.

The scope of these projects is relatively small. Typically the cost of an individual project will be $20,000 to $80,000. Larger flooding issues on major watercourses will be assessed and addressed as part of the ongoing city-wide Stormwater Master Plan.

Funding Level

A specific portion of the increased utility fee is dedicated to the Drainage Improvement Program (DrIP). At the end of the first year of the increase (July 2007), about $100,000 was generated for the program. An increase of $100,000 applies for each year after until the full funding level of $400,000 is reached in July 2011.

DrIP Project List

Staff has developed a prioritized 5-year project listing. The list includes preliminary cost estimates. The list and prioritization changes from time to time as the result of completed projects and newly identified projects. A summary of projects follows this overview.

DrIP FIVE YEAR PLAN

FY 08/09 (July 1, 2008 to June 30, 2009)
Budget = $160,000

   Projects:
     Izabel Rec Center
     Cherry Ave & Dupont Study/design
     Hilltop Study/design
     1220 Aztec Stormdrain addition
_________________________________________________

FY 09/10 (July 1, 2009 to June 30, 2010)
Budget = $295,000

   Projects:
     Hilltop stormdrain construction
     Schultz Creek Design
     E. RTE 66 Culvert Design and Construction
_________________________________________________

FY 10/11 (July 1, 2010 to June 30, 2011)
Budget = $400,000

Project:
Cherry Ave Stormdrain Upgrade Construction Phase I
_________________________________________________

FY 11/12 (July 1, 2011 to June 30, 2012)
Budget = $400,000

   Project
     Schultz Creek Construction
     Cherry Ave Stormdrain Upgrade Construction Phase II
     Construction of Upper Switzer Drainage solutions
     Linda Vista Construction
_________________________________________________

FY 12/13 (July 1, 2012 to June 30, 2013)
Budget = $400,000

Project
Cherry Ave Stormdrain Upgrade Construction Phase III & IV
_________________________________________________

Project Manager: Connor Boyle, 779-7685 X 7224, email Cboyle@flagstaffaz.gov

See the summary detail and maps below for an overview of projects that are in development.