eau gallie river & elbow creek — muck dredging
TRANSCRIPT
• Indian River Lagoon (IRL)
o 156 miles long
o Six coastal counties
• North America’s most diverse estuary
• IRL Economic Assessment & Analysis (2007)
o $3.7 billion in benefits overall
2
Background
• Muck deposits within the IRL, the Eau Gallie River, & Elbow Creek negatively affect: o Water quality & natural resources o Shoals within the waterbodies o Navigability of the waterbodies o Recreational activities & property values
3
Project Introduction
Project Objectives Phase I • Dredging Feasibility Study
• Conceptual Dredging Plans
• Order of Magnitude Cost Estimates
11
Project Objectives Phase II • Funding
• Final Data Collection & Permitting
• Final Plans & Specification
• Bid Documents
12
Phase I • Dredging Feasibility Study
o Permitting
o Construction
• Conceptual Dredging Plans
• Detailed Order of Magnitude Cost Estimates
14
Project Methods
15
Ballard Park Boat Ramp
• Define the magnitude of the problem
• Identify desired post-dredging conditions
• Document project assumptions
• Develop a detailed scope of work
Project Permits • Dredging and DMMA construction
will require permits
o U. S. Army Corps of Engineers (USACE)
o FDEP
o City of Melbourne
o Brevard County
16
Project Assumptions • Exclude mechanical dredging
• Florida Fish & Wildlife Conservation Commission (FFWCC) seasonal Manatee dredging restrictions
• May require future sediment chemistry testing
• Minimal bathymetric & geotechnical data collection for verification purposes
17
Sediment Characteristics
18
• Physical characteristics of muck sediment
o Average solids content of ~24%
o Specific gravity of 2.43
o Settling test results ranged from 10% to 30% after 30 days
o Muck sediment dewatering will likely require binding agents
Bathymetric & Geotechnical
• Data from 2000, 2005, & 2013 bathymetric surveys
• 30 cross sections for each top of muck layer
• Probed the muck thickness in the general vicinity of deepest probe for previously collected cross-sectional data (2000)
19
Bathymetric & Geotechnical
• Created DTM for the 2000, 2005, & 2013 surveys
o Top of the muck layer for each year
o Bottom layer based on 2000 survey
• Compared the DTM data
o In 2000 average muck thickness of 7.5 ft
o In 2005 average muck thickness of 8.3 ft
o In 2013 average muck thickness of 9.6 ft 20
• Average shoaling rate of 3,300 cy/yr
• District should anticipate higher shoaling rates, especially for the 1st & 2nd maintenance dredging
o Dredging template exclusions
o Watershed is 79.5% urban & residential
o Increased currents & velocities
o Easterly winds transport muck from the IRL 23
Sediment Shoaling Rates
• Initial shoaling rate of 7,500 & 17,500 cy/yr for the first & second maintenance cycles
• Sustainable shoaling rate of 5,000 & 15,000 cy/yr
24
Dredging Template
Sediment Shoaling Rates
• During dredging, in situ material will bulk due to adding water & handling the material
• Bulking factor of 1.75
• 625,000-cy dredging template requires 1,094,000-cy DMMA capacity
25
Sediment Bulking Factor
• Each option involves hydraulically dredging sediments via pipeline
o Intracoastal Waterway DMMA sites
o Non-traditional dewatering at the City site
o DMMA at Florida Recyclers of Brevard site
o DMMA at the Washington Park site
26
DMMA Investigation
29
Line Project Element FIND Sites City of
Melbourne
Florida
Recyclers
Washington
Park
1 Permitting $749,000 $514,000 $533,000 $533,000
2 Construction (Engineering) $717,500 $939,500 $857,500 $832,500
3 Construction (Contractor) $18,821,250 $15,559,750 $15,860,000 $14,938,750
4 Contingency (10%) $2,029,000 $1,701,000 $1,725,000 $1,630,000
TOTAL COST (ROUNDED): $22,300,000 $18,700,000 $19,000,000 $17,900,000
Total Project Cost Estimate
30
Services (Months) FIND Sites City of Melbourne
Florida Recyclers
Washington Park
1 P-1 through P-5 10.5 10.0 10.2 11.7
2 CE-1 through CE-5 8.3 7.4 7.8 8.3
3 CE-6 through CE-7 34.2 37.4 38.4 31.1
4 C-1 through C-10 34.2 37.4 38.4 31.1
TOTAL: 53.0 54.8 56.4 51.1
Estimated Project Schedule
31
Line Evaluation Factor FIND Sites City of Melbourne
Florida Recyclers
Washington Park
1 Total Project Cost 4 2 3 1
2 Total Project Schedule 2 4 3 1
3 Property Ownership 1 2 3 2
4 Construction Method 3 4 2 1
5 Maintenance Dredging Cost 4 2 3 1
Raw score 14 14 14 6
Overall Rank 2.8 2.8 2.8 1.2
Option Comparison Matrix
• Project funding & DMMA
• Regulatory agency permits
• Final construction documents
• Bidding assistance & contractor selection
• Project construction & DMMA site restoration
• Project closeout & certification
32
Future Tasks
Estimated Project Schedule (Construction Windows)
34
Services (Months) FIND Sites City of Melbourne
Florida Recyclers
Washington Park
SUBTOTAL: 53.0 54.8 56.4 51.1
HYDRAULIC DREDGING: 22.8 32.1 19.3 17.9
CONSTRUCTION WINDOWS: 18 22.5 13.5 13.5
TOTAL: 71.0 77.3 69.9 64.6
Cost Estimate – Permitting
35
Line Engineering Services FIND Sites City of Melbourne Florida Recyclers Washington Park
P-1 Geotechnical & Surveying $527,000 $377,000 $391,000 $391,000
P-2 Seawall, Dock, & Shoreline Condition $72,000 $72,000 $72,000 $72,000
P-3 Environmental Impact Avoidance $30,000 $20,000 $22,000 $22,000
P-4 Booster Pump & Pipeline Routes $88,000 $13,000 $16,000 $16,000
P-5 Regulatory Agency Dredging Permits $32,000 $32,000 $32,000 $32,000
TOTAL COST $749,000 $514,000 $533,000 $533,000
Cost Estimate – Preparation & Observation
36
Line Engineering Services FIND Sites City of Melbourne Florida Recyclers Washington Park
CE-1 Booster Pump & Pipeline Route
$300,000 $47,000 $65,000 $65,000
CE-2 Geotechnical & Surveying Services
$- $125,000 $150,000 $225,000
CE-3 Final Site Design $- $150,000 $175,000 $200,000
CE-4 Final Construction Documents
$65,000 $65,000 $65,000 $65,000
CE-5 Bidding Assistance Contractor Selection
$18,000 $18,000 $18,000 $18,000
CE-6 Construction Observation
$325,000 $525,000 $375,000 $250,000
CE-7 Project Closeout & Certification
$9,500 $9,500 $9,500 $9,500
TOTAL COST: $717,500 $939,500 $857,500 $832,500
Cost Estimate – Construction
37
Line Contractor Services FIND Sites City of
Melbourne Florida Recyclers Washington Park
C-1 Site Acquisition (BCPA Assessment) $- $730,000 $1,160,000 $820,000
C-2 Mobilization / Demobilization $2,750,000 $2,610,000 $1,870,000 $1,870,000
C-3 Site Construction $- $1,250,000 $2,600,000 $3,200,000
C-4 Mitigation & Monitoring (Wetland Impacts) $- $- $- $277,500
C-5 Booster Pump Water Collection System $180,000 $56,000 $80,000 $80,000
C-6 Hydraulic Dredging $10,373,750 $9,132,500 $8,316,250 $8,003,750
C-7 Dredging Flocculants & Coagulants $937,500 $1,406,250 $468,750 $312,500
C-8 Dredge Offloading $1,955,000 $- $575,000 $-
C-9 Final Disposal of Dredged Material $1,875,000 $- $390,000 $-
C-10 Site Restoration & Closeout $750,000 $375,000 $400,000 $375,000
TOTAL COST: $18,821,250 $15,559,750 $15,860,000 $14,938,750