Gloucester-01B
Gloucester, Mill Pond
42.632916, -70.677217
Technical Specifications
Basic Properties
- Type
- Multiple
- Material
- Metal
- Control
- Manual Gear
- Condition
- Good
- Geometry
- Rectangular
- Status
- Active
- Number of Gates
- 2
Operator & Management
- Operator Type
- PUBLIC
- Permits
- ACOE
- Purpose
- Flood Protection and Restoration
Dimensions & Elevations
- Dimensions
- 6ft diameter, 4ft height
- Invert Elevation
- -4.46 NAVD88
- Installation Date
- 2011
- Tidal Influence
- Upstream: 3.54 NAVD88, Downstream: 3.84 NAVD88
Culvert Details
- Restriction Type
- Roadway
- Geometry
- Other
- Material
- Corrugated Metal
- Bottom Material
- Riprap
- Number of Pipes
- 0
- Dimensions
- 13ft diameter, 12ft height
- Condition
- Fair
- Comments
- The culvert material was corrugated metal piping and was a semi-circle with an approximate width of 13’ and an approximate height of 12’. The upstream portion of the culvert appeared to be in good condition with no apparent deterioration; however, the downstream portion was slightly separating from the headwall in places. Additionally, portions of the downstream culvert were jagged and appeared to pose a potential safety hazard.
2024 Field Survey Results
Comprehensive field assessment conducted in 2024Physical Conditions Assessment
Channel Conditions
- Channel Alteration
- Limited (<133 ft/acre)
- Channel Constriction
- Narrower than channel
- Channel Erosion
- Little (<10% of bank)
- Sediment Deposits
- None
Blockages & Issues
- Debris Blockages
- None
- Evidence of Overtopping
- No
Transect Measurements
50 Yards
- Open Water
- 62
- Salt Marsh
- 0
- Brackish
- 0
- Freshwater
- 0
- Ditch
- 0
- Unvegetated
- 60
150 Yards
- Open Water
- 43
- Salt Marsh
- 0
- Brackish
- 0
- Freshwater
- 0
- Ditch
- 0
- Unvegetated
- 42
300 Yards
- Open Water
- 19
- Salt Marsh
- 0
- Brackish
- 0
- Freshwater
- 0
- Ditch
- 0
- Unvegetated
- 114
Ecological Assessment
Habitat Observations
- Crab Burrow Intensity
- None
- Phragmites Present
- Moderate (10-60%)
- Ecological Impairment
- Limited
Invasive Species
- Upstream Invasive Species
- Yes
- Downstream Invasive Species
- No
- Invasive Species Notes
- Limited to upland fringe
- Additional Comments (2024)
- Appears to have sufficient tidal exchange as indicated by lack of phragmites and abundant saltwater invertebrate populations. Town noted tide gate is sometimes closed for extended periods of time. Result of which may have I ncreased ponding and creation of mud flats adjacent to marshy areas. Tide gate was draining well during visit but long term management or o and m plan may help restore more salt marsh.
Historical Records
Environmental Data
- Invasive Species
- Yes
- Restoration Status
- In-Progress
- Invasive Comments
- Abundant phragmites was observed upstream. It appeared that the phragmites extended to the upstream dam in Mill Pond.
- Restoration Comments
- New tide gates installed in 2011, 1 gate is being opened an additional 6 inches each year over 6 years. 2016 opening will occur in May.
Notes & Comments
- General Comments
- Site was easily accessible and located directly off of Washington Street (Route 127). Parking was available at a convenience store to the northeast of the site.
- Operation Plan
- Yes
- Operation Comments
- It appears that the operational purpose of Gloucester-01A was for incremental restoration and flood protection purposes. It can be incrementally opened to enable increased tidal flushing with the ability to be completely closed before a storm. It appears that the operational purpose of Gloucester-01B was two-fold: 1) It could be installed towards the invert of the headwall and be incrementally opened to enable restoration while enable outward passage of stormwater flows and mitigating flood potential from the tides. 2) It could be installed at the high position to act as a high level barrier to storm surge while allowing stormwater out the bottom. It appeared that Gloucester-01C was installed for the sole purpose of flood protection and stormwater conveyance. It appears that this trio of tide gates was recently installed and configured in 2011 and are being actively managed to enable upstream restoration.
- Gate Comments
- There were three tide gates at the site. Gloucester-01A was an old sluice gate with a manual jack screw located at the bottom of the eastern portion of the headwall. It was open approximately 2’ at the time of the site visit. Gloucester-01B was a newer combination metal sluice / flap gate. The sluice gate was able to operated via jack screw to be installed either at the invert of the headwall or towards the top. It was located towards the top of the headwall during the site visit, enabling low level tidal flushing through the bottom opening. Gloucester-01C was a metal flap gate installed in the middle portion of the headwall (i.e., Gloucster-01B could be located either above or below Gloucester-01C) (see field notes for diagram). All three of the tide gates appeared to be in good condition at the time of the site visit. Gloucester-01A was rusty, but corrosion was not evident and it appeared that the manual gear had recently been maintained and greased.
- Elevation Comments
- Staining was apparent on the upstream (U/S) and downstream (D/S) ends of the headwall (HW) so approximate extent of U/S and D/S tidal influence was able to be assessed in addition to tide gate (TG) invert elevations. The below lists measuredowns taken with a surveyors rod and corresponding top of headwall LiDAR elevations (NAVD88 datum). 1a) TG Inv (Gloucester-01A = Gloucester-01B): Top of HW El (D/S) = 7.74’; Inv Measuredown = 12.2’; TG Inv = 7.74’ – 12.2 = -4.46’ 1b) TG Inv (Gloucester-01C): Top of HW El (D/S) = 7.74’; Inv Measuredown = 5.00’; TG Inv = 7.74’ – 5.00 = 2.74’ 2) Upstream Tidal Influence: Top of headwall LiDAR Elevation = 7.74’; Staining Measuredown = 4.20’; U/S Tidal influence = 7.74 – 4.20 = 3.54’. 3) Downstream Tidal Influence: Top of headwall LiDAR elevation = 7.74’; Staining Measuredown = 3.90’; D/S Tidal Influence = 7.74’ – 3.90’ = 3.84’
- External Data Comments
- US ACOE CENAE-R-2008-2941 Permit 5.11.2009 Mill Pond Operation and Maintenance Plan Revised 8.13.2010 Mill River Tidal Restoration Project Monitoring Summary 7.20.2015
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