Methodology
   PERMITTING
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Bioengineering
In the spring of 1994, the Franklin County Commission (now the Franklin Regional Council of Governments) convened the stakeholders to encourage a cooperative approach to assessing and mitigating the erosion in the Turners Falls Power Pool. The Connecticut River Streambank Erosion Committee (CRSEC) was formed and its membership is comprised of local officials, state and federal agencies, non-profit environmental groups, landowners, and utility representatives. This time, the stakeholders reached consensus and the utility prepared a Draft Environmental Impact Report which described a bank project that would stabilize several thousand feet of eroding riverbank using bioengineering techniques. The necessary environmental permits were secured and the utility committed $1.2 million over six years toward what would be called Phase I of the bank stabilization work.

Goals for Bioengineering Projects
The long-term goals for the bioengineering bank stabilization projects are to:
Background Image Reduce erosion in the Turners Falls Power Pool and thereby reduce a source of non-point pollution (sediment) to the Connecticut River;
Background Image Stabilize eroded riverbank;
Background Image Enhance habitat value by reintroducing native plant communities;
Background Image Protect private property and prime agricultural land that abut the River;
Background Image Identify successful bioengineering techniques.

Summary of s.319 - Funded Bioengineering Site Designs
Phase I
Three sites were restored under Phase I: Wickey, Shearer and Crooker. Construction at the Crooker site was partially funded with money from s.319 grant 96-03/319. Although s.319 funding was used for the construction of only one site, the final project report evaluated the design and construction of all three sites. Vegetation and habitat monitoring was performed at all three sites. The three bioengineering treatment types used on the Phase I sites included:
Background Image  Hard Toe: Sand or gravel fill was placed in the undercut/scour zone and then covered with rock rip-rap. Coir fascines were placed in vertical layers above the rock toe and cabled in place. The area above the coir fascines was protected by burlap or coir fabric and then planted with live stakes of woody species.
Background Image  Breakwater: This treatment was designed to be built at the mean water level and includes a rock toe and coir roll or fascine at the water’s edge. A flat area was created behind the toe and a pre-vegetated mattress was staked in place. The specified plants were designed to create an emergent wetland community. A gradual slope leads to the top of the bank. The upper slope was protected with coir fabric or burlap and seeded or planted with live stakes.
Background Image  Bank Reconstruction: Sand or gravel was used to fill the undercut/scour zone. A rock toe was constructed and coir fascines were placed above the toe. Fabric-wrapped geogrid lifts were placed in layers above the coir fascines to construct the new bank. Dormant live brush was placed in-between the layers.

Phase II
The construction of one site, known as the Urgiel Upstream site, was partially funded by the Phase II grant (00-04/319). The bioengineering design for this site was significantly different from the design techniques used for the Phase I sites. The Urgiel Upstream design used four bank treatment types:

Background Image  Top of Slope: Area was seeded with native seed mix and planted with Red Oak, Red Maple and Sycamore trees, 4”-5”dbh, and Gray Birch, Quaking Aspen, Pin Oak, White Ash and Cottonwood trees, 4 to 5 feet tall.
Background Image  Upper Bank: Area was seeded with native seed mix and planted with 1 gallon pot-sized woody vegetation, including: Arrow-wood, Staghorn Sumac, Gray Dogwood, Shadblow, American Hazelnut, Black Chokeberry and Nannyberry.
Background Image  Lower Bank: Area was seeded with native seed mix and planted with 1 gallon pot-sized woody vegetation, including: Speckled Alder and Silky Dogwood.
Background Image  Stone Toe: Area was planted with tubelings (rooted cuttings) of Pussy Willow, Purple-osier willow, and Sandbar willow.

The Urgiel design incorporated several new techniques that had not been previously used in this reach of the Connecticut River, including:
Background Image Planting willow tubelings in the stone toe to "soften" the appearance of the stone;
Background Image Reducing the size of the rocks used in the stone toe to 4 to 6-inch diameter stone;
Background Image Installing an erosion control blanket that would biodegrade more quickly;
Background Image Simplifying bank reconstruction and revegetation by grading the cleared bank to a 1.5:1 slope and using hand techniques and installation to plant native herbaceous and woody vegetation. Geogrid lifts, brush mattresses and brush fascines used on the Phase I sites were not used at Urgiel.
Phase III
The Phase III site, known as Urgiel Downstream, is 980 feet in length. The bioengineering design for this site is similar to the one used at the Phase II site (Urgiel Upstream). The design has four bank treatment types, like Urgiel Upstream, with the only difference being the addition of a coir bio-log above the stone toe.




This design change was made in response to problems encountered at the Phase II site. The interface between the upper elevation of the stone toe and the lower elevation of the vegetated bank bears the brunt of the erosive forces from the fluctuating water levels. The coir bio-log was added to strengthen this interface.



   

Phase IV


FirstLight Power provided funds for the remaining costs of the project.


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