wildman - engineering removal techniques

Engineering Removal Techniques for

Small Dams

Presented By:LAURA WILDMAN, PE

Director, New England Regional OfficeEcological Restoration & Fisheries Engineer

Princeton Hydro931 Main Street, Suite 2

S. Glastonbury, CT 06073

[email protected]

Presented By:LAURA WILDMAN, PE

Director, New England Regional OfficeEcological Restoration & Fisheries Engineer

Princeton Hydro931 Main Street, Suite 2

S. Glastonbury, CT 06073

[email protected]

Dam Removal Demystified:Workshop hosted by American RiversJune 14, 2011 Chapel Hill, NC

Talk Outline

• History of the Dam • Construction Sequencing – Reverse Engineering

• Technical Specifications• Expect the Unexpected• Access• Dewatering• Water Control• Infrastructure Retrofits• Remove Dam & Assoc. Structures• Site Restoration • Site Protection/Safety • Construction Oversight• Lessons Learned• Monitoring

Dam Types

Earth Gravity Earth and Rock Timber/Rock Fill Variable Radius Arch Hydraulic Fill Constant Radius Arch Flashboard & Buttress Multiple Arch Reinforced Concrete Tank Slab and Buttress Inflatable Rubber Crib Other (sheetpile, tailings, etc)

Removal Sequencing –

Reverse EngineeringC

ON

STR

UC

TIN

G A

DA

M

• Free flowing river

• Construct water controls

• Divert water

• Build primary portion of dam

• Redirect water

• Fill dam notch

• Remove equipment & water controls

• Fill with water

REM

OVI

NG

A D

AM

• De-water

• Mobilize & install water controls

• Notch dam

• Divert water through notch

• Remove primary portion of dam

• Redirect water

• Removed water controls

• Free flowing river

“The New Water Power of the Hartford Electric Company” written in 1900

“three waste pipes were capable of carrying normal flow…(later) permanently sealed with 12 x 12 in. southern pine”“old surface of the rock was taken off by squib blasting..surfaces of rock were made to slope upstream””

Reverse Engineering: Spoonville Dam, CT

© Princeton Hydro © Princeton Hydro

Know Your Dam: Wiley-Russell Dam, MA

Typical Construction Sequencing

• Legacy dams• Unknown utilities• Big storms• Excessive woody debris• Unexpected organism

relocation• Tributary reaction/down cutting• Oil tank• Illegal discharges or

nonconforming wells

Expect the Unexpected

Bear Lake Dam, CA – legacy dam upstream

Tributary head cutting

Legacy Dam

Pipe exposed when lake was drained

• Trash (tires, shopping carts, asbestos tiles)• Tree stumps• Hidden reinforcing• Hot spots or hot layer• Streambank seepage• Excessive erosion• Bodies/cars/guns/teeth• A church


Tires and Shopping Carts

Tree StumpsArt made from recovered

items from drained LA lake

Venezuelan Church uncovered when lake drained

A typical impoundment?


Dunkard Creek Dam, PA - Turn of the century cooling systems for a gas pumping station

No, the worlds largest radiator!

Additional Lessons Learned:• Hire The Right Contractor – experience with rivers/dams, their own

equipment, good foreman, good machine operator

• Plan For The Unexpected - in permits, plans and construction contract- flexibility in area of impact on permits - allow contractor flexibility in approach- decide on pricing for potential unknowns upfront in contract

Include Bid Items on:Water ControlContaminated SedimentUtility RetrofitsPlanting Plans Trash Removal Invasive Species ControlConstruction Monitoring

(i.e turbidity & nearby wells)

TECHNICAL SPECIFICATIONS & CONTRACT

TECHNICAL SPECIFICATIONS

Working in a river– plan for variable flows– emergency high flows

Unknown reinforcing– plan for worst case

Sediment moves daily– plan to dig it only once– Take precautions for

unknown contaminants

Unexpected reinforcing

High flow Mean Flow

© Princeton Hydro

© Princeton Hydro © Princeton Hydro

Double check– quality & quantities

during construction

Access

© Princeton Hydro

Access from crest of dam

Easy

Internal access for explosivesEmbry Dam - VA

Hard

But with easy internal access

Helicopter access onlyBluebird Dam - CO

Dam Hard

Reservoir Drawdown

Milltown Reservoir Drawdown - 2002

Edwards Reservoir Drawdown - 1999 Embry Reservoir Drawdown - 2004

Reservoir DrawdownTime for Vegetation to Reestablish

•Can make equipment access easier

•Can reduce the amount of sediment transported

Zemko Dam Removal - CT

During drawdown

Last day of dam removal

Source: American Rivers


Reservoir Drawdownpartial breach / notch

low level outlets

siphons

bypass pipe or channel

riser with outlet

Source: PA Fish & Game

Source: PA Fish & Game

Plan to relocate organisms as needed (i.e. mussels, fish)

Reservoir Drawdown –

Ecological Precautions

Dewatering such that fish stranding is minimized

Source: American RiversSource: American Rivers

Source: NH DES

Source: NH DES

© Princeton Hydro

Water Control

Diversion SystemsPumps, siphonsExcavated channelExcavated channel w/ linerPipe bypassBox culvert, tunnel, …

Cofferdam SystemsEarthen cofferdamsSheetpile cofferdamsTilt-up panelsWater bubble dam

Lessons Learned:

Water control & S&E are never as pretty as on the plansHave good inspectors Take care when inviting spectators or press to site Don’t rely too heavily on water control measuresWorking in the wet is preferred (in & out faster)Design/Plan for a potential blow out

Water Control

• Docks/Access• Boat Ramps• USGS Gages• Powerhouse & Assoc. Apparatus• Streambanks

• Utilities• Bridges/Culverts• Retaining Walls• Bldg. Foundations• Water Supply Wells

Retrofit or Remove Infrastructure

Pipe exposed when lake was drained Historic covered bridge with central pier upstreamSource: NH DES

Retrofit Water Intakes

Goldsboro Dam, Little River, NC Cumberland Dam, Potomac River, MD

1. Modify Existing Intake Pipes or Pumps2. Off line bypass channel or pond3. Perforated pipe or screened intake w/ air

scour sys.4. Stoplog structure5. Sunken intake6. Well

Amount of original delta eroded by different channel positions under the single and triple

notch scenarios

0

10

20

30

40

50

60

70

80

0 2,000 4,000 6,000 8,000 10,000Run time (minutes)

Perc

enta

ge e

rode

d

1x L3x L3x C3x R

Methods of Removal

Extent & Timing of RemovalFullPartial (height or width)

Staged (timing, delta migration, % remaining)

Bypass Dam

Source: Saint Anthony Falls Lab & Gordon Grant

Image courtesy of National Park Service

Dam sill remains – Mad River partial dam removalSource: Wildman

Source: Saint Anthony Falls Lab & Gordon Grant

Methods of Removal

Bypass Dam

California Coastal Conservancy, NMFS, Planning & Conservation League Foundation, and Cal Am

Methods of Removal

Concrete Demolition

Mechanical impact methods

Expansive grout methods

Sawcutting methods

Blasting methods

Excavator w/ Bucket

Grapples/Splitters/Thumb

Crane and Dragline

Dozer

Embankment and Timber Demolition

Mechanical Removal –

Excavator© Princeton Hydro

© Princeton Hydro

© Princeton Hydro


Mechanical Removal –

Crane & Excavator Attachments

Thumb

Splitter

Grapples

Crane &Wrecking

Ball

© Princeton Hydro

© Princeton Hydro

Source: MMI

http://www.rocklandmfg.com/excavator/strut.html

Franklin Dam removal Sheboygan River, Wis. 2001

Orienta Dam, Iron River, Wis. Removed, 2001

Source: Stephanie Lindloff

Mechanical Impact Methods

© Princeton Hydro

© Princeton Hydro

Blasting Methods

Embry Dam Removal, VA, 2004


Example: Bristar non-explosive demolition agent

Expansion Material Methods

Waddel Dam - AZ

Saw Cutting Removal

Clear Creek Dam - WA

© Princeton Hydro

Pursel Mill Dam - NJ

Site Protection

Source: Laura Wildman

• Protection of equipment

• Protection of plantings

• Site safety (spectators & boaters)

Source: Laura WildmanSource: Stephanie Lindloff

Historic Restoration



Creative ways to incorporate historic preservation in a dam removal.

What Not To Do!

ExtremelyShallowWater depths

TrapezoidalChannel withNo low flowChannel

Excessive Channel Armorment

Only lowered the dam. Left the dam sill in, now river dynamics & fish passage are not restored.

Source: Wildman

Source: Wildman Source: Wildman

Leaving the Dam Sill in PlaceMeans Leaving the Dam in Place

Dam Removal in MA

Dam Removal in PA

Dam Removal in CT

Removing a Structure Only to Install More StructuresWeirs, J-Hooks, Ramps, Etc.

Excessive Use of J-Hook Veins/Deflectors

Excessive Use of Stone Channel Constrictors

Engineering designer should help to supervise construction

Construction Oversight

• Most familiar with the site• Ensure that dam is removed in a manner

consistent with plans, permits and vision for the site

• Link design quality & responsibility to the design firm

Listen & learn from the contractor

Determining level of oversight needed

Document/photograph/video

Historic (reuse of material) and Ecological oversight

• Check access route

• Think in terms of constructability• Check quantities twice (3 times, etc..)• Have sediment testing results and arrange for a disposal

site, & onsite staging/stockpile sites• Get contractors advice on creative/cost saving approaches• Show actual proposed elevations/grades• Show dam material/construction/quantity• Fish timing and turbidity restrictions• Installing useless E&S controls• Strength of concrete underwater or cured under water

Listen to the Contractor

• Permission for use• Check bridge capacities• Requirements for repairs post use• Check for utilities and low wires

• Bid at end of winter or early spring – before the contractors plate is full

• Do not make the project look like a big deal – don’t have a huge complex plan set and technical specs unless you really need it – don’t have 20 people at the pre-bid meeting – don’t express fears too loudly

• Use photographs if necessary to explain odd/unique requests (i.e. rootwad placements, etc.)

• Don’t try to shift all the risk & liability to them

Keeping the Bid Price Down

• Embrey Dam – difficulty with explosives and lots of public attention

• Pizzini Dam – permit fee; unexpected aquatic organism relocation (lamprey & mussels)

• Billington Dam – Military Readiness Initiative (great, lots of equipment, no restoration); Asbestos tiles

• Smelt Hill Dam – don’t need huge riprap on bedrock

Lessons Learned -

Examples

Pho

to S

ourc

e: L

aura

Wild

man

Des

ign

by: M

ilone

& M

acB

room




• Zemko Dam – bids too high (contractor felt all the risk was on him); regulators wanted tons of weirs; mucky soil (difficult construction); left a sill; wetland wars

• Anaconda Dam – dam breached before removal; persistent downstream sediment bar; emergency permit sped things up

• Union Dam – Unexpected pipe U/S; provide flexibility in permit applications; removed sediment twice

• Freight St. Dam – lousy contractor; rented equipment; water control extras; sheet pile core reinforcing

Lessons Learned -

Examples

STREAM BARRIERREMOVALMONITORINGGUIDE

http://www.gulfofmaine.org/streambarrierremoval/

STREAM BARRIER REMOVAL MONITORING GUIDE

Published in December 2007 (85 pages long)

Zemko Dam RemovalEightmile River -

Connecticut

Impounded water line

Former Zemko Dam site

Source: 10 Dam Removals 10 Years Later by Laura Wildman, American Rivers

Primary Project Lead: TNCEngineering: Gomez & Sullivan / Milone & MacBroomTechnical oversight: American Rivers


Connecticut

High bids!• Changed plans

from big to small but original bids based on big

• Too many people at mandatory pre- bid meeting

• Bid during wrong time of year

• Non-typical items on plans (rootwads)

• Difficult soil conditions

• Made project seem like a big deal (risky, press, sensitive, lg. bid package)

When a contractor feels like they are taking on risk the price goes up!



Connecticut

Source: American Rivers Source: American Rivers

Source: American Rivers Source: American Rivers

Anaconda Dam RemovalNaugatuck River -

Connecticut

Removed in 1999 – 11 ft high & 330 ft long

N

Former Anaconda Dam site

FLOW


Primary Project Lead: City of Waterbury & CT DEPEngineering: Milone & MacBroom

Anaconda Dam RemovalNaugatuck River -

Connecticut

Time and materials delays by

contractor, but emergency permit sped

things upDesign & Photo Source: Milone & MacBroom

Anaconda Dam Removal

1997 – with dam, looking upstream

2008 – 10 years post removal1997 – with dam, looking upstream

2002 – 3 ½ yrs post removal 2008 – 10 years post removal

Design & Photo Source: Milone & MacBroom


Source: Wildman Source: Wildman

Source: Wildman

Union City Dam RemovalNaugatuck River -

Connecticut


N

Former Union City Dam site

FLOW



Primary Project Lead: CT DEPEngineering: Milone & MacBroom


Union City Dam RemovalNaugatuck River -

Connecticut

Upstream pipe exposed – provide for flexibility in

permit applications

Removing sediment

twiceDesign & Photo Source: Milone & MacBroom

Union City Dam Removal1997 – with dam looking upstream

2008 ~10yrs post removal

1999 – just post removal 2008 ~10 yrs post removal

Design & Photo Source:Milone & MacBroom


Photo Source:Wildman


Freight Street Dam RemovalNaugatuck River -

Connecticut



N

Former Freight Street Dam site


Primary Project Lead: City of Waterbury & CT DEPEngineering: Milone & MacBroom

Freight Street Dam RemovalNaugatuck River -

Connecticut

Sheetpile core

Poor contractor with rented equipment

Water control extras


Freight Street Dam Removal

1997 – with dam, looking upstream 1999 - just post removal 2008 ~10 years post removal

1997 – with dam, looking downstream 2008 ~10 years post removal






wildman - engineering removal techniques

Documents