T7 wetlands hydrologicmodeling-nehrke

Brevard County US 192 Solid Waste Management FacilityContinuous Simulation Wetland Modeling April 23, 2013

Seth M. Nehrke, P.E., D.WRE

APWA Florida State Conference

Agenda

• Project Overview• Selection of Keystone Indicator Wetlands• Model Updates• Model Results• Next Steps

Proposed Brevard County Solid Waste Management Facility

Why Do We Model?

• Guide wetland mitigation decisions 

• Aid in the design & permitting process

• Enhance the rate of wetlands survivability

• Optimize system operation and performance protocols

Existing WetlandsSystems: 581 Ac

Effect of Shutting Off Wells: Groundwater Drops 0.5 Feet

Notes: 1) Potential groundwater effects on wetlands are based on an anticipated 0.5' drop from a wells‐on to a wells‐off condition

2) Anticipated Minor Affect (loss of minor amount of fringing wet prairie component of polygon and/or minor shift in vegetative cover to include reduced cover by obligate/facultative wet species)

3) Anticipated Moderate Affect (loss of significant portion of herbaceous component of polygon and/or moderate shift of vegetative cover from obligate and facultative wet species to species less tolerant of inundation/saturation)

4) Anticipated Significant Affect (anticipated that the majority of the polygon to shift to cover by facultative and upland species and/or significant loss of other wetland indicators ‐ i.e., reduction in hydric soils, loss of expected hydrologic regime, etc.)

KeystoneWetlands

Wetlands Distribution

Wet Freshwater  Mixed Prairie Marsh Cypress Hardwood

Adjacent to Proposed Development D‐O; F‐O D‐O; F‐M F‐O F‐M

Adjacent to Ex/Prop DitchE‐H; F‐D; F‐O; G‐E

A‐T; C‐M;      C‐P/Q; E‐H;     F‐D; G‐E; I‐N

A‐T; C‐A; C‐M; C‐P/Q; E‐H;     F‐O; G‐B; I‐N

C‐A; E‐H;    G‐B

In or Adjacent to Proposed PondA‐J; D‐O; F‐D; F‐O; 

G‐E

A‐J; B‐Q; C‐M; C‐P/Q; D‐H;    D‐O; F‐D;       

F‐M; G‐E; I‐N, 

A‐J; B‐Q; C‐A;   C‐M; C‐P/Q;    D‐H, F‐O; G‐B;  

I‐N

C‐A; F‐M; G‐B

Removed from Proposed Development E‐H; I‐F E‐H; I‐F E‐H E‐HNote: 16 Systems and all 8 community types are represented

Herbaceous Wooded

Geographic Location

Indicator Wetlands Distribution

Development of a Comprehensive Survey Plan

Update Hydrology

• Refine basins• Dynamic soil storage• Existing calibrated HSPF

Representative Hydrologic Year

Update Hydraulics

• Connectivity• Evaporation• Infiltration• Use site‐specific information 

when available

Multiple Community Systems

LABEL ACRES Community TypeI‐N 9.70 621 ‐ CypressI‐N 2.45 641 ‐ Freshwater MarshI‐N 3.79 641 ‐ Freshwater Marsh

Surface Water Driven

KeystoneWetlands

Groundwater/Evaporation Driven

Reduced Stages

KeystoneWetlands

Elevated Stages

Summary Results and Recommendations

WETLAND ID Phase I Conceptual RecommendationA-J +0.5' to +1.5' +0.5' - 1.5' Construct connection to eastA-T Good Match Good Match N/AB-Q Good Match Good Match N/AC-A -1.0' to +0.5' -1.0' to +0.5' Modify proposed control structure from BP1C-M +0.5' to +1.5' +0.5' to +1.5' Divert water to create wetlands

C-P/Q Good Match Good Match N/AD-H Good Match Good Match N/AD-O match to +0.5' match to +0.75' Divert water to create wetlandsE-H -0.5' -0.5' Construct ditch block in proposed ditches

F-D(N) Good Match N/A N/AF-D(S) Good Match match to +/-0.25' N/A

F-M match to -0.5' match to +0.5' Could Connect to SWM4 in Phase I F-O Good Match Good Match N/AG-B +0.5' to +1.0' +0.5' to +1.0' Divert flow into adjacent ditchG-E Good Match Good Match N/AI-F Good Match Good Match N/AI-N Good Match Good Match N/A

Next Steps

• Continuous simulation• Design storm simulation• Development of wetland 

creation plan

Special Thanks to