OFFICE OF THE PLANNING COMMISSION
OFFICE OF THE SELECTBOARD
Town of Halifax, Vermont
PLANNING COMMISSION/SELECTBOARD SPECIAL MEETING
October 23, 2014
Halifax town officials and residents gathered at 7:00 p.m. in the Town Office for an informational meeting on the Green River Corridor Assessment project. Planning Commission members Sirean LaFlamme, Meggie Stoltzman, and Stephan Chait were present, as were Selectboard members Edee Edwards and Earl Holtz. John Bennett (Windham Regional Commission), Evan Fitzgerald (Fitzgerald Environmental, Colchester Vermont), Margo Avakian, Nick Bartenhagen, Maggie Bartenhagen, Marilyn Allen, Jesse Ferland, Mary Horne, Patrick Wilkins, Janet Taylor, Paul Taylor, Bonnie Brown, and Robbin Gabriel were also in attendance.
Following a round of introductions, Evan Fitzgerald began his presentation with a definition of geomorphology, along with some history and background of the science, while John Bennett orchestrated the accompanying slideshow. Pioneered by geologist and hydrologist Luna Leopold in the 1960s, fluvial geomorphology is the study of how flowing water interacts with the landscape and different landforms. If we understand a river in terms of geology, topography, climate, and drainage area, said Fitzgerald, we can then make fairly accurate predictions about its future size, behavior, and the area it will occupy in the valley. Bedrock rivers are relatively stable, but rivers carrying a lot of sand and silt are very sensitive to change occasioned by climate or human activity.
Fitzgerald explained degradation (erosion caused by excess water force) and aggradation (build-up of silt deposits), and illustrated with maps and aerial photography how it was possible to predict flood risks. Hydrology and precipitation patterns are changing, he said, making it more important than ever that we recognize the need to map and track hazard areas. Several maps and charts showed a high concentration of increased frequency and intensity of precipitation in the northeastern United States, as well as an increase in the occurrence of lower-magnitude floods. In response to a question from the audience about the character of the Green River, Fitzgerald said that as it courses through Halifax the river, while not bedrock, is narrow and populated with many large rocks, making it somewhat resistant to change. In Guilford, from approximately the Halifax/Guilford town line, the water channel widens and its composition changes to much finer sand and silt; thus the river is more prone to migration in that area.
The current Green River study was made possible by a Vermont Agency of Natural Resources Restoration Program grant to the Windham Regional Commission. The project’s objectives are to collect detailed information about the watershed and the river system, to understand the stability and habitat of various river stretches, to create a list of potential restoration projects, and finally to select five of those possible projects on which to focus.
The Green River is a tributary to the Deerfield River, which flows into the Connecticut. It has a 90-square-mile drainage area at its outlet to the Deerfield, and a 35-square-mile drainage area at the Massachusetts border. Phase One of the study consisted of a desktop approach to mapping soil types, topography, contour lines, elevation, and drainage areas. In this process the river network was sectioned into reaches approximately one mile long. In Phase Two a subset of these reaches was chosen for field study. Project partners walked each of these sections, redefining them as necessary based on this more accurate on-site review. Fitzgerald described the Phase Two on-the-scene research process in some detail, and said the data thus collected is then used to evaluate stability and the geomorphic and habitat health of each river segment. Bridges, culverts, and road crossings are examined for characteristics that might predict the possibility of failure during a flood. Culverts on smaller streams are assessed for ease of aquatic organism passage. Using graphs and some basic math, Fitzgerald demonstrated that during the 2005 storms and the 2011 Irene event Green River peak discharge reached levels far exceeding other Vermont rivers in terms of cubic feet per second per square mile of drainage area.
The Green River Corridor Plan being developed by Fitzgerald Environmentalists is now in draft stage, with completion projected for the end of October. John Bennett told the meeting there will be a link to the report on the Windham Regional web site in the near future. The Plan is a large document with numerous maps and four appendices containing information of value. Bennett invited citizens to review the material online and submit feedback; WRC would be happy to discuss the project at greater length.
As Bennett displayed slides of maps and photos by way of illustration, Fitzgerald went on to say that while the Green River’s geomorphic stability and habitat conditions are fair overall, his team noted some exceptions. In Halifax, seven specific areas were selected as possible sites for passive restoration and two more for active restoration. Fitzgerald defined active restoration as making physical changes such as stabilizing berms or moving banks. Passive restoration could include planting buffers or forming an agreement with landowners to preserve a flood plain. In Halifax, he noted, where much of the river is locked in along the roadway, there are fewer opportunities than in Guilford for preserving flood plain. There is, however, a small flood plain near Perry Road which is now separated from the river channel by armor built during the Hurricane Irene reconstruction. If the armor were moved the river would once again have access to the land beyond. Passive restoration locales included sections of newly-armored Green River roadway embankments which, at the base, now encroach farther into the riverbed than did the pre-storm natural bank, thus constricting the stream. While Fitzgerald agreed reworking these sections was probably impractical, he said that adding organic material to the rock slopes and reseeding would re-establish some semblance of a natural bank.
Earl Holtz pointed out that the town has just spent a few million dollars armoring these riverbanks. Meanwhile, the unarmored sides are falling into the river. Will we discuss what we can do on the unarmored sides? he asked. Fitzgerald allowed that he hadn’t planned to address that situation; those far-side banks are so high, and so extensive, that any attempt at stabilization could prove to be an endless and very expensive task. Responding to a query from Edee Edwards, Fitzgerald said another location marked for an active restoration recommendation was a footbridge rebuilt by a private landowner after Irene; the new abutments create some river constriction.
Edwards remarked that the town had worked very hard to put everything back together after the 2011 storm; she was discouraged by the implication that perhaps those labors needed to be redone. While she appreciates the WRC study for the valuable information it provides, she feels the town must be realistic in considering revisions to work already completed. How, Holtz asked, do we get to the point of actually doing it right in the first place? During Irene reconstruction the town had to follow the directives of the Army Corps of Engineers and ANR to the letter. Bennett noted that, as a result of Irene, ANR and AOT standards are better aligned than previously, which should reduce conflicting instructions in the future. There was further discussion regarding discrepancies between state and federal disaster repair mandates and the availability of grants and assistance for proactive, preventive projects.
The meeting concluded shortly after 8:30 p.m., with Sirean LaFlamme thanking Fitzgerald and Bennett for their presentation. No other Planning Commission or Selectboard business was conducted during this session.
Planning Commission Secretary, pro tem