Innovative Solution Springs Life to Wetlands A dual purpose flood reduction and wetland restoration project

Cynthia Grizzle PWS, CFM

OverviewHISTORIC IMPACTS

PROJECT OBJECTIVES

EVIDENCE OF SUCCESS

Location

Background

Owners

Background

Wholesale Water Supplier

Non-Profit, Special District of the State of Florida created to plan, develop and deliver a high-quality drinking water supply and protect water supply sources

Funded through sale of water to member governments (Hillsborough County, Paso County, Pinellas County, New Port Richey, St. Petersburg and Tampa) who all share the cost of operation

Background

The RegulatorEstablished as a flood protection agency, its responsibilities have grown to include managing the water supply, protecting water quality, and preserving natural systems that serve important water-related functions

Issue water use permits to ensure withdrawals from water bodies will not harm existing users, the water resources, or the environment

Background

1) Reduce downstream flood flows

2) Maximize use of low and flood-prone lands for flood-water storage

3) Maximize well field production

Purpose of the Property

Background

Groundwater Pumping

Impacts

Reduced Water LevelsHistorically high rates of pumping reduced water levels

Tampa Bay Water diversified water sources and reduced pumping

Candidate Mitigation Sites Evaluation Study 2000

Identified Sites Not Expected to Fully Recover Following Pumpage Reductions

Impacts

Floodplain Encroachment

Impacts

Existing Flow Patterns

Impacts

35.2644.39

50.84

75.58

63.91

0

10

20

30

40

50

60

70

80

2000 2001 2002 2003 2004

Water Year (October through September)

Tota

l Rai

nfal

l (In

ches

) Cypress Creek Wellfield Average Yearly Total1976 through 2004

51 Inches

Above Normal Rainfall and Residential Flooding in 1997/1998; 2003; & 2004

Impacts

Impacts

Timeline1) A Series of Community Meetings with SWFWMD, Tampa Bay Water, and Pasco County Staff Occur in 2003 and 2004

2) SWFWMD Performs a Preliminary Feasibility Study (February 2004)

-Assessed options to redirect floodwater onto the wellfield

3) Tampa Bay Water Recognizes the Potential for SWFWMD’s Flood Mitigation Project to act as Wetland Restoration

-Initiates the CCWF Surface Water Management Project (June 2004)

Objectives

Four Project Objectives

Improve flow through Dye’s Crossing by replacing existing structures

Utilize existing storage south of Dye’s Crossing

Control surface water flows leaving the wellfield

Redistribute water to target wetlands via culvert connections and open ditches

Objectives

Stages Feasibility -2004/2005 Design and Permitting – 2005/2006 Construction - 2007 Monitoring- Ongoing

Objectives

Redirect Historic Flow

Weir Elevation 68.29 ftNorth of Dye’s Crossing Rd

6, 18” Diameter PipesSouth of Dye’s Crossing Rd

Improve Flow Through Dye’s Crossing

Objectives

Weir Bottom Elevation 68.29 ftRoad Elevation ~71.00 ft

4 (4 ft x 8 ft) Type H Structures with Double 30” Diameter Pipes (North of Dye’s Crossing)

8 - Tideflex Backflow Preventers (South of Dye’s Crossing)

Dye’s Crossing Today

Objectives

274 ft Long Concrete Weir at Main Flow Channel along Berm A1a – West End

Utilize Storage South of Dye’s Crossing

Objectives

30” Diameter Low Flow Pipe (Invert Elevation 65.0 ft)

Top of Weir Elevation 70.0 ft

18” Diameter High Flow Pipe Elevation 67.93 ft

Control Surface Water Leaving the Wellfield

Objectives

Weir Height ~ 5 feet

Down Stream

Functioning As Designed

Objectives

Redistribute Water to Target Wetlands

Objectives B2 Ditch Before Construction

B2 Ditch During Construction

B2 Ditch Following Construction

Key Project Achievements Minimize impacts to

natural areas and wildlife during construction

Reduce flooding conditions in adjacent residential areas

Improve wetland hydrology and functions in the target wetlands

Success

B2 Ditch Following Construction (Pop Off Elevation 68.0 ft) – West of Ten Cent Road

Functioning As Designed

Success

Reduce Impacts to Natural Areas

Construct in previously disturbed areas

Protect gopher tortoises and their burrows

Shorten pipe lengths to reduce impacts and maintain aesthetics

Reduce the construction footprint

Construct in Disturbed Areas

Success

Restrict Construction Footprint

Success

Minimized Impacts to Undisturbed Areas

Success

Shorten Pipe Lengths to Lessen Impacts

Success

Protect Gopher Tortoises

Success

Reduce Flooding Conditions Offsite

Success

Improve Wetland Hydrology

Success

Depth of Wetland Inundation- W43

Success

Depth of Wetland Inundation – W16

Success

Duration of Wetland Inundation Wetlands with

Hydroperiods WY2015 – 26/26 WY2014 - 23/26 WY2013 - 24/26 Wy2012 - 24/26 WY2011 -18/26 WY2010 - 8/26 WY2009 - 2/26 WY2008 - 0/26 WY2007 - 0/26

Success

Vegetative Recovery

Pines in the wetland are stressed and/or dead

Success

Project Summary Nearly 2 miles of Berm Constructed

Retains water on the wellfield to allow for storage and aquifer recharge

4,000 feet of Ditches Installed Increased hydrologic connectivity

has improved hydroperiod and stage in several target wetlands

Construction Footprint was Reduced by Half

Project Ended $300,000 Under Budget

Florida Chapter of APWA 2010 Consultant of the Year

The Next Phase

Thank You