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Sustainable Solutions to Mitigate Sediment and Contaminant Resuspension During Storm Surges and Tidal Inundation
Pete Hamscher
13 December 2013
Environmental, Earth and Ocean Sciences Capstone Project Professor Anamarija Frankic
University of Massachusetts Boston
Project Overview • Basic environmental & ecosystem assessment
• Early research
o Investigation of SHC Water Quality Monitoring Program and Morrissey Boulevard Drainage
Conduit Project
o Overview of 2005 Dredging Operation
• Identifying issues in previous projects and developing new goals
• Exploring sustainable solutions to moderate sediment accumulation and
contaminant resuspension in Savin Hill Cove
Image source: Myself
Current Status
• Environmental Assessment
o Water quality and turbidity
o Sediment quality
o Land use characteristics
o “Tide tracking”
• Ecological Assessment
o Fringing salt marsh
o Biodiversity: Salt tolerant plants, sea grasses, shrubs, oysters, soft shell and
hard shell clams, crabs, birds, worms
Image source: myself
Savin Hill Cove Water Quality Monitoring Program
• Studies and Evaluates water quality and sedimentation/erosion impacts
from stormwater discharges into Savin Hill Cove (ES 2013)
• Required for Morrissey Boulevard Drainage Conduit Project (MBDC) and
North Dorchester Bay CSO Storage Tunnel (NDBST)
• Presented in Event Mean Concentrations (EMC’s)
• Tested for:
o Fecal coliform bacteria (FC), levels were “At or below what might be expected for
an urban watershed” (ES)
o Total suspended solids (TSS), that were “well within the ranges reported in
Nationwide Urban Runoff Program (NURP) and National Stormwater Quality Data
(NSQD)”
o Salinity and biological oxygen demand (BOD), data only from 2010 & 2011
• Additional bathymetric surveying:
o No strong correlation between the recent changes in stormwater management
techniques and sediment accumulation.
Upper and lower subwatershed NDBST MBDC Special Manhole D Sluice Gate Manhole
Image Source: SHCWQMP Executive Summary
Summary of Testing and Results
• Results are inconsistent and provide little basis for drawing conclusions.
• Both FC and TSS are particularly variable under a number of different
circumstances including but not limited to:
o Density of residential area
o Rainfall intensity
o Antecedent dry periods
o Land use characteristics
o Snow and ice control
o Street sweeping schedules
Image source: www.victoriataftkpam.blogspot.com
*Measurements were only taken during large storm events
Savin Hill Cove Dredging Project
• Between 1983 and 2004, steady decrease in depth of water
• Removal and replacement of Fox Point pumps
• SHC habitat continued to show signs of stress with little evidence of
sustained improvement (between 1992-2005) (MWRA)
• Chris Sweeney, Director of Marine Operations at UMass Boston
• Project objectives:
o To increase overall water depth within the cove
o Remove sediment from the intake corridor of UMass Boston’s pump house
o Create navigation channels in the proper locations for appropriate drainage
techniques
Post Dredge, 2007
Image source: Chris Sweeney et al.
Summary of Results
• 22,000 cubic yards of contaminated, unwanted sediment removed
from the cove
• Offshore disposal approved by the Army Corps of Engineers
• Two main dredging locations:
o Basin closest to the pump house was
dredged 10 feet below mean sea level
o Drainage channel dredged 8 feet below
mean sea level
• Cost:
o Dredging operation: $3 million
o Repairing the pump house: $4.5 million
Image source: www.npr.org
Dredging: Cost/Benefit Analysis Pros
• Removes unwanted sediment and a high percentage of solids
• Can be used with highly consolidated sediments
• Allows a cleaner sediment bed to be formed
• Easier access for boats and less turbidity
Cons • High economic cost
• Ecologically harmful
• Removes unwanted sediment temporarily
• Without continuous monitoring, environment can still be affected
• Can resuspend contaminants found in bottom sediment, yet is typically minimal
Image source: www.instrumentalism.wordpress.com
Issues with Practices and Techniques
• Water Quality
o Inconclusive results in previous sampling
o Infrequent sampling, only during notable storm events
o Testing for watershed runoff, no recurrent sampling in SHC site
o Contamination and pollution in urban runoff
• Sediment Quality and Accumulation
o Sediment quality is not enhanced by dredging
o SHC as a “natural trap” for sediment
o Accumulation of sediment in dredge navigation channels
o No control or protection during intense storm surges and tidal inundation
Sustainable Solutions and Integration of Possibilities: Sediment Mitigation and Water Quality Improvement together?
Silt & turbidity barrier screens Pneumatic barriers Reef blocks/balls
Reef BLK
Other solutions:
Training dams
Bagged Shells
Top Left: http://www.erosionpollution.com/Type-II-Silt-Barrier.html Top Center: http://www.poseidonsgarden.com/images/photo2_large.jpg Right: http://www.remediationstrategies.com/wp-content/uploads/DSC00007mod.jpg Bottom Left: http://www.nature.org/ourscience/sciencefeatures/oyster-reef-interactive-graphic.xml
Remember the Title…
• The development of sustainable solutions to mitigate sediment and
contaminant resuspension during storm surges and tidal
inundation
• Practical, sustainable, affordable and appropriate alternatives
• Solutions that have displayed positive improvement and results in
former cases
• Almost all “sustainable” solutions need maintenance and upkeep
• Endurance of heavy storms and high tides
• One implementation or structure might not be enough
Investigation of necessary permits
Marine dredging project
Pneumatic barrier installation & Arduino software
Silt screen assembly and construction
Ongoing water quality and sediment
accumulation testing and monitoring
Timeline
Looking Ahead and Moving Forward
• Using these projects as a catalyst for new studies
and students
o Undergraduate & graduate research opportunities
o Sediment accumulation evaluation and monitoring
o EA-IRMS analyzation of captured sediment
o Water quality, TSS and CDOM sampling
o Tracking salt marsh restoration, biodiversity and
oyster repopulation
• Gaining interest and attention
• SFE, UMass Boston and the Cove
• Community appreciation
(All previous images from Google Maps)
Acknowledgements
• I would like to thank Anamarija Frankic, Allen Gontz and Chris Sweeney for
their interest and assistance throughout my project
Sources
Dredging: http://www.dredge.com/pdf/sierra_endorsement.pdf http://www.epa.gov/region02/water/dredge/ Stormwater Management: http://www.fstinc.com/index.php?option=com_sobi2&sobi2Task=sobi2Details&catid=39&sobi2Id=140&Itemid=144 WQMP: http://www.horsleywitten.com/wordpress/wp-content/uploads/2011/02/5106-Savin-Hill-Cove.pdf http://www.who.int/water_sanitation_health/resourcesquality/wqmchap13.pdf http://faculty.umb.edu/anamarija.frankic/files/BWSSavinHill.pdf MBDC: http://www.bchigh.edu/ftpimages/225/download/download_group5826_id284053.pdf Sediment Mitigation: http://www.waser.cn/journal/full%20text/2003-2/02.pdf http://a100.gov.bc.ca/appsdata/acat/documents/r16013/Mission_Sedimentation_1238541520666_7e6b0c07cf3119b7bc2ab4df 9a7e6828e989e54c4a554a80d951c1b684cbf1cb.pdf http://www.nature.org/ourscience/sciencefeatures/oyster-reef-interactive-graphic.xml Water Sampling: http://courses.washington.edu/envh452/water_sampling.pdf http://www.mwra.state.ma.us/harbor/enquad/pdf/1995-14.pdf http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.15.4373&rep=rep1&type=pdf
