Boston North Shore Study
Regional Saugus River Floodgate Project - Everett, Lynn, Malden, Nahant, Revere and Saugus, Massachusetts
Plans Evaluated
Option #1: Local Protection Plans
Developed areas in each community were surrounded with dikes, walls, revetments & sand dunes/beach
Option #2: Non-structural Plans
Individual buildings were flood proofed, or raised and warning systems developed
Option #3: A plan to protect the entire region using a Saugus River Floodgate with walls, dikes, beach & dunes along the shore front, purchase & protect the Estuary for runoff storage & environmental resources & non-structural measures.
Option #1: Local Protection Plans (LPPs)
The 5 separate LPPs were not supported due to 4-12 foot high walls & dikes along the shores impacting views & wetlands, and need to maintain & close 80 gated openings.
Option #1: SPN Flood + 1Ft Sea Level Rise
(Elevations in Ft. NGVD, or approx. feet above mean sea level)
Option #2: Nonstructural Plan For Residential & Commercial Buildings
Non-structural measures alone were not supported since only 7% of buildings were feasible for flood proofing or raising, and the uncertainty of evacuating over 4,000 to 10,000 people in such high levels of flooding.
Option #3: Regional Project Protects Entire Area
Plan Comparison
| Option #1 5 LPPs |
Option #2 Non-Structural |
Option #3 Regional Plan |
|
| Buildings Protected | 4,320 | 240 | 5,000 |
| Percent Protected | 86% | 7% | 100% |
| Length of Structures | 9.8 Miles | N/A | 3.5 Miles |
| Wetlands Lost, Mitigated | 34 Acres | None | 3 Acres |
| Estuary Protection | No | No | Yes |
| Loss of Views | High, up to 12 ft. High Walls/Dikes |
NIL | 15-20 Homes at Point of Pines |
| Level of Flood Protection | |||
| City of Lynn, East Saugus | 500 Yr | 0-100 Yr | SPN |
| Town Line Brook | 100 | N/A | SPN |
| Point of Pines w/Dunes Only | SPN | 0-100 | SPN |
| Revere Beach Backshore | 100-SPN | 0-100 | SPN |
| Northgate, Outer Oak Island | No | 0-100 | SPN |
| Upper Saugus River, Rt. 107, B&M | No | No | SPN |
| Crescent Beach | 100 | 0-100 | 100 |
| Plan Economics (2019 Price Level, $ Millions) | |||
| First Cost | $183 | $19 | $220 |
| Average Annual Benefits | $23.37 | $3.61 | $28.28 |
| Average Annual Cost | $17.80 | $1.81 | $22.29 |
| Average Annual Net Benefits | $5.57 | $1.8 | $5.99 |
| Benefit-to-Cost Ratio | 1.3 | 2.0 | 1.3 |
| National Economic Development Plan | No | No | Yes |
| Benefits & costs updated from 1988 with a construction cost index | |||
| Evaluation | |||
| Complete, Efficient | Yes | Yes | Yes |
| Effective | Partial w/ 80 Gates |
No | Highest |
| Acceptable to Sponsor | Minimal | Minimal | High |
| National Economic Development Plan | No | No | Yes |
| Selected | |||