Board of Directors MWRAs Dam Safety Program 2005 - 2015 March 11, - - PowerPoint PPT Presentation

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Board of Directors MWRAs Dam Safety Program 2005 - 2015 March 11, - - PowerPoint PPT Presentation

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Massachusetts Water Resources Authority Presentation to Board of Directors MWRAs Dam Safety Program 2005 - 2015 March 11, 2015 Dams and Dikes By The Numbers 27 Individual Structures Spread across 18 geographic locations Representing:

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Massachusetts Water Resources Authority

Presentation to

Board of Directors MWRA’s Dam Safety Program 2005 - 2015

March 11, 2015

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27 Individual Structures

– Spread across 18 geographic locations – Representing: 17 High Hazard Class dams 8 Significant Hazard Class dams 2 Low Hazard Class dams – Dams range in age (149 - 60 years old)

Dams and Dikes By The Numbers

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MWRA/ DCR Dams under MA Office of Dam Safety Jurisidiction

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  • Administered by DCR- Office of Dam Safety (ODS)
  • Requires biennial inspections
  • Modeled on Federal Regulations:

– US Army Corps of Engineers – FEMA Dam Safety Regulations

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  • 2004 MOU - specified roles of MWRA and DCR on dams:

– DCR Routine Maintenance and Smaller Dams – MWRA Capital Maintenance/Improvements Large Dams MWRA-DCR MOU

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Emergency I nspections 2005 – “laundry

ry list ” of dam issues

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Required Studies: – Hydrology and Hydraulics (H&H) – Seepage and Stability (S&S) – Safety Inspections (Phase I’s) – Emergency Action Plans Led to Major Improvements at: – Spillways – Earthworks – Masonry needs – Tree Clearing

I nspections Determine Dam Needs

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Dams Improvements 2005 - 2015 Dams Capital Projects Crest Gate $ 5,400,000.00 Wachusett Dam Promenade - PCB $ 2,220,000.00 Wachusett Dam Face - PCB $ 4,300,000.00 Dam Safety Mods (5 dams): $ 3,443,440.00 Dams Major Maintenance Projects Quabbin Spillway Repointing $ 157,827.00 South Dike Tree Removal 1 $ 352,950.00 South Dike Tree Removal 2 $ 100,000.00 North Dike Tree Removal $ 395,000.00 Foss Dam Tree Removal 1 $ 60,000.00 Foss Dam Tree Removal 2 $ 70,000.00 Blue Hill Dam Repairs $ 88,800.00 Fells Trees 1 $ 129,310.00 Fells Trees 2 $ 42,173.00 Norumbega Trees $ 135,900.00 Goodnouh Dike Tailwater Analysis $ 28,650.00 Quabbin Spillway Fence Rehab $ 400,000.00 Foss Dam Stump removal $ 12,531.00 Dam Safety Tech Assist Consulting Emergency Inspections 2005 $ 50,000.00 T.O. Dam Safety Inspections 2006 $ 66,135.00 T.O. for Fells Dam seeps analysis $ 12,955.00 H&H Analyses $ 60,011.00 Sudbury Spillway Insp. + weepholes $ 15,000.00 Dams Inundation Mapping $ 17,912.00 Emergency Action Plans Updates $ 54,000.00 OP-160 (incl inspections) $ 172,017.00 OP-228 (incl inspections) $ 166,500.00 Subtotal Dams $ 17,951,111.00

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I nspections I dentify Required Studies, Which Reveal Needs

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Major Spillway Projects

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Wachusett Reservoir, Dam and Spillway

Wachusett Dam Wachusett Spillway Wachusett North Dike

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Wachusett Dam 1908

Updated H&H 2007

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Wachusett Spillway Dismantling and New Sill

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After

Wachusett Spillway Crest Gate I nstalled

Before

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Wachusett spillway east berm construction Before After

Wachusett Auxiliary spillway under construction

Spillway Constriction

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Quabbin Spillway Repointing and Grouting

Limits of work

Note grout tube

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Quabbin Spillway Repointing and Grouting

Downstream crest stone before Downstream crest after

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Wachusett Open Channel Lower Dam - Substantial mortar loss and offset training wall stones

Before After

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Major Earthwork Projects

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Before In process North Dike Structural Stabilization of Historic Failure Zone

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Spot Pond Dam Armoring – in-house project

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Chestnut Hill Dam I mprovements

Hydroseed Remove old CBs, fill depressions, re-grade toe area

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Major Masonry Projects

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Wachusett Dam Promenade PCB Demo/ rebuild

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Wachusett Dam PCB remediation and power washing

During After

Cleaned Uncleaned efflorescence

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Wachusett Dam Improvements

New drainage groins New piezometers Dam face cleaned and repointed Before After

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Foss Reservoir Spillway - repointing

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Foss Dam Gatehouse interior masonry grouting/ repointing

Repointing and Injection grouting Leakage through stone joints Steel plate for protection against erosion

  • f mortar
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Weston Reservoir Dam Parapet Wall

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Sudbury Dam/ Spillway Masonry Repointing

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Sudbury Spillway I nspection and Weep Hole Maintenance

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Chestnut Hill Dam riprap improvements – left abutment

Missing riprap Resetting riprap

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Major Tree Work

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ODS Policies

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Tree Roots are bad for Earthen Dams

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Proper Stumping/ backfill Critical to the I ntegrity of the Dam

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1904 Weston Reservoir Dam 2010 2010 2011 Dam Crest Dam Crest

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Earthen dam 09.22.11

Weston Reservoir Dam

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Earthen dam 09.23.11

Weston Reservoir Dam

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10.04.11 Earthen dam

Weston Reservoir Dam

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Weston Reservoir Dam

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Fells Dams, Stoneham

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Fells Reservoir Dam # 8 Tree Removal

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Fells Reservoir Dam # 6, # 7 tree and riprap work

Before After

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North Dike treeless condition

Wachusett Reservoir circa 1930 drought

South Dike treeless condition

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Rock outcrop. Note dense tree cover

South Dike Comparison

1904 2010

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Crest – note dense tree cover

South Dike Comparison

1904 2010

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South Dike 2010 – Tree Removal Zones and in 2011

Completed 2015 project – remove remaining trees

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South Dike

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South Dike Crest Before and After

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South Dike Final Grading and Hydroseed

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North Dike Tree Removal

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North Dike Tree Clearing

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Dike 3

Norumbega Dam/ Dikes Tree Removal

Before After

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MWRA /DCR Dam Condition Ratings

  • Significant Rehabilitation/Upgrades Completed
  • 2006- Dams Ranged from “Fair – Satisfactory”
  • 2014, Dams upgraded. Now range from “Satisfactory – Good”

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MWRA Dam I mprovements

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  • Foss Reservoir Spillway – increase capacity and/or armor the

earthen embankment. Pending ODS review on options.

  • Install new piezometers at earthen dams lacking them: (North

Dike and South Dike, Weston, Fells, Norumbega, Ware Diversion, Foss, Schencks, Chestnut Hill).

  • Continue to meet ODS Biennial Phase I safety inspections’

schedule.

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What’s next on the Horizon for Dam Safety Needs

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Wachusett el. 396.07’ on 04.01.10 @1.6 BGD

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Quabbin Spilling @ 0.6 BGD on 04.05.10

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Foss in spill @ 250 MGD Sudbury in spill 03.29.10 @ 200 MGD

Sudbury System Dams Under High I nflows

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Thank you.

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