MUDDY RIVER FLOOD RISK MANAGEMENT PHASE II Jennifer Flanagan - PowerPoint PPT Presentation

MUDDY RIVER FLOOD RISK MANAGEMENT – PHASE II Jennifer Flanagan Project Manager New England District/PPMD Date: 30 June 2020

2 MUDDY RIVER THE HEART OF OLMSTED PARK 1894 • The park was designed by Fredrick Law Olmsted & completed in the 1890’s • Olmsted designed some of America’s greatest city parks • “The Necklace” is the oldest remaining linear park in the United States Images from http://www.muddyrivermmoc.org/restoring-olmsteds-vision/

3 MUDDY RIVER – 1996 FLOODING Boston received 10.8 inches of rain A month’s worth in one day • Extensive damage to MBTA in Kenmore Square • Over $60M in damages to MBTA

4 MUDDY RIVER – ADDITIONAL FLOODING EVENTS • June 1998, March 2001, March 2010 (6” over 2 days with water levels 2.5 feet higher than normal)

5 MUDDY RIVER – COMPREHENSIVE PLAN • A comprehensive plan was developed to address • Flooding • Accumulated sediment • Reduced aquatic habitat quality (high SOD, low DO) • Contaminated sediments (metals, PCBs, PAHs) • Invasive species ( Phragmites ) impacting biodiversity & reduction of Sedimentation open water • Corps completed Decision Document and Environmental Assessment Flooding • Muddy River Flood Control and Ecosystem Restoration, September - Undersized culverts 2003 - Restrictions

6 MUDDY RIVER – COMPREHENSIVE PLAN • Decision Document approved – Director’s Report December 2003 • Review by ASA office – costs of ecosystem restoration features are prohibitive on a per acre basis. • OMB concurs with ASA recommendation NOT to fund ecosystem restoration components. Recommended Plan

7 MUDDY RIVER – FLOOD RISK MANAGEMENT PLAN

8 2001 2019

9 • Looking upstream from new UFP culvert

10 MUDDY RIVER – PHASE 2 Work Areas 1 – 12 EXCAVATION • Excavate the sandbar and island at Leverett Pond • Excavate five stretches of areas of constriction in the Riverway section of the river • Excavate the river in the Back Bay Fens area to create a continuous channel • Excavate deepened channel sections to delay need for maintenance dredging

11 MUDDY RIVER – PHASE 2 Work Areas 13 • Provide additional flood proofing at the Boston Fire Department Building in the Back Bay Fens.

12 PHASE 2 WHAT TO EXPECT – DURING CONSTUCTION In the Wet In the Dry Construction Construction Barge Mounted Excavator Long Reach Excavator https://www.youtube.com/watch?v=nXN__c_dwVI

13 PHASE 2 WHAT TO EXPECT – DURING CONSTUCTION Stockpile, Direct Loading & Transport

14 PHASE 2 WHAT TO EXPECT – DURING CONSTUCTION Tree Protection – Critical Element of Work

15 PHASE 2 WHAT TO EXPECT – DURING CONSTUCTION Some Tree Removal Work Area 2 – the river on both banks have lots of vegetation and trees. These various trees need to be Work Area 7 – both trees are within area of removed for access as well as the new channel slope will phragmites to be excavated 18” deep. Concern for cut into the existing tree root system. the tree root system and trees are not healthy.

16 MUDDY RIVER – PHASE 2 – RESTORATION EFFORTS • Remove Phragmites in the Back Bay Fens and Riverway areas where necessary to create flood risk management channel and provide ancillary benefits of ecological habitat improvements. • Restore wetland vegetation in dredged areas by seeding or planting appropriate wet meadow and emergent wetland plants. • Restore riparian vegetation in upland areas where Phragmites or oriental knotweed are removed by planting grass, trees, and shrubs.

17 MUDDY RIVER – PHASE 2 – RESTORATION EFFORTS - Work Area #6: - Wetland shelves - Wet meadow - Trees - Shrubs - Restored lawn

18 PHASE 2 WHAT TO EXPECT – AFTER COMPLETION Primary Project Goal - Improved water conveyance • Charles River will still strongly influence the Muddy River water level • Water will move through the system faster • Designed for 20-year’ storm

19 PHASE 2 WHAT TO EXPECT – AFTER COMPLETION Ancillary Project Benefit - Restored River Bank • Stabilized river bank reducing erosion and improving water clarity • Removal of poor quality sediment • Increased aquatic habitat quantity and quality • Increased plant diversity • Partial restoration of Olmsted’s vision

20 Contact Wendy Gendron, Civil Works Program Manager wendy.c.gendron@usace.army.mil Jennifer Flanagan, Project Manager jennifer.w.flanagan@usace.army.mil