Mudboils

AEES Pre-Conference WorkshopWednesday, June 6, 2012

Nate BarletBrandon Winfrey

Roy Wood

Problem Statement

• Turbidity in Onondaga Creek too high to support species historically present• Sediment load to the creek

from mudboils has been identified as major contributor to turbidity

Goals and Objectives

• Improve Onondanga Creek to support fish species present upstream of the mudboils– Intercept 100% of sediment load from mudboils. • This will protect river ecosystem from ever being

affected by mudboil sediments that increase turbidity

Design Constraints

• Landowner– Honeywell

• Hydrogeology– Unclear

• Environmental• Energy• Cost– Dredging may

be required

Potential Solutions (1)

• One Large Relief Well– Attempt to create mudboil in the existing area to

control source of sediment• “One Well to Rule them All”

• Advantages:• Control source• Easier to design sediment

abatement

• Disadvantages:

• Unclear if control is possible• Low flexibility if other

mudboils appear

Potential Solutions (2)

• Divert Creek around mudboils, Contain mudboils– Build impoundment around entire area– Move creek channel into field adjacent

• Advantages:• Creek avoids sediment loading

(never impacted)• Mudboils potentially capped by

hydraulic head

• Disadvantages:• Expensive

• May create mudboils down gradient

• Creek channel may migrate back to mudboil area

Potential Solutions (3)

• Impoundment around rogue mudboil, Wetland for smaller particle removal, relief wells– Build impoundment around rogue mudboil followed by

wetland– Surround impoundment by relief wells– Construct levee to protect creek

• Advantages:• Protects creek from incoming

sediment• Provides ecological and aesthetic

service• Flexible design

• Disadvantages:

• Storm events could decrease sediment capacity

• Annual dredging required• Large land area required

Design Overview

• Relief Wells assumed to control flow from mudboils to not exceed 400 gpm

• Impoundment designed to contain particles > 4 μm

• Wetland designed to remove smaller particles (< 2 μm)

• Levee high enough to protect creek from storm events

Relief Well Design

• Install 4 relief wells surrounding impoundment berm – 5” diameter with screens excluding sand

size particles– Installing 1 well next to mudboil can

potentially reduce hydraulic head by 15 ft.

– Install wells 20 ft. from mudboil vent to prevent intercepting sediment flow in vent

Impoundment Design (1)

• Dredging is unavoidable– Annual dredging– Design to remove 4

μm particles • Settling velocity of 6

x 10-4 cm/s• 38 hr detention• design driven by

solids dredging annually, not settling time requirements

Impoundment Design (2)

• 35 meter diameter• 6 ft high• 3 feet water level design• walls are 3 foot wide top, 3:1 slope, 13 ft

bottom

Profile View: Impoundment

Mudboil cone

Drains to Wetlands

Wetland Design (1)

• Sheet flow over vegetation to remove particles smaller than 2 μm.

• 155 acres• size driven by solids limit to 2 cm/yr depth• <1 acre needed for solids removal retention

time

Profile View: Wetland

4 % slope

Design Overview

Estimated Cost

• $45,000 based on $15/cu. yd.– Includes berms for access to impoundment and

levee• $5 million for bio-swale– Based on estimated cost per acre of $35,000

Other Considerations• Problem of source too large to contain• Salinity diluted in stream to lower levels

– Salinity in relief wells presumed to decrease (drawing from freshwater aquifer)

– Not included in treatment goal• Snowfall my decrease residence time in winter• Do relief wells control flow from mudboils to below historic high flows?

– Studies on effects of relief wells on mudboil flow should be done• Pilot-scale study on effectiveness of wetland

– Vegetation response to sediment over time– Fine particle removal rates

• Construction should occur in phases– Install relief wells first, allow some time for mudboils to react (1-2 years)– Build levees and impoundment around stabilized mudboils (1-2 years)– Construct wetland, route water from impoundment through wetland (20-

year design life)

Summary

• As designed, sediment load from mudboils intercepted before entering Odondanga Creek– Ecological buffer (wetland) between mudboils and

creek should enhance recovery of fish populations – Levee would prevent resuspension and

conveyance of sediment to creek during storm events

– While dredging required, sediment has astringent qualities that could have market value as a cosmetic product

Questions?