A town-wide assessment of roads, paved and gravel

Stantec will spend the next 60 days studying Thetford's roads.

A town-wide assessment of roads, paved and gravel

As Li Shen reported in her article on the language of road cracks, the engineers at Stantec Inc. will be assessing town roads over the next few months. The project, approved at the last Selectboard meeting, has a "not to exceed" cost of $36,375. The work will be completed within 60 days, just in time for the start of budget season. The money for the assessment is being drawn out of the Planning and Consulting Fund, to which the Town has been contributing $4,000 per year. Its balance, before this project, is $40,771.

The assessment will collect information about every foot of road in Thetford, including both paved and gravel roads, and rate each road on a scale from 1 to 10 relative to the recommended amount of maintenance and repair. Stantec will be collecting information on roadway length, roadway width, shoulder width (if there are shoulders), and observable drainage systems. Specifically, they will be collecting data on culvert condition, swales, and ditches.

Two Rivers-Ottuaquchee Regional Planning Commission (TRORC) performed a culvert inventory last year, which Stantec will review and likely add more detail to. There are two parts to a culvert analysis: condition, which TRORC's inventory explored, and adequacy relative to culverts capacity. Stantec will be looking at culverts 18" and above, and will use the same criteria the State of Vermont uses for assessing culvert size. Culverts will be subjected to a design storm — a 10-, 25-, or 50-year storm — and it will be confirmed whether or not that culvert can handle the estimated flow of water.

If the Town finds itself reconstructing a road, Stantec will likely recommend replacing galvanized steel culverts marked as being in "Fair Condition" in TRORC's culvert inventory, adding to project costs. Aluminum and plastic culverts are less likely to need replacement.

In the fall of 2020, TRORC also conducted a road erosion inventory to evaluate hydrologically connected segments of road. The purpose of the inventory was to identify locations that have problematic road erosion, which is useful with grant funding and permit complaince. According to the study, there are "places that require continuous attention by town road crews to maintain quality or restore problems."

2021 Town of Thetford Road Erosion Inventory Report

From the erosion inventory report:

Many roads in Vermont traverse waterways since these are the lowest and flattest parts of the topography. Erosion, worsened by unpaved roads, has negative effects on nearby bodies of water. During rain events road sediment is deposited directly into the water resources. Water resources are defined as perennial and intermittent streams, wetlands, lakes, and ponds. Road sediment in water resources causes a wide spectrum of ecological problems including increased algae blooms and decreased levels of dissolved oxygen, both of which negatively impact fish habitat and the ecosystem.

Quinnibeck Road and Poor Farm Road South are two sections of gravel road in Thetford that were identified by TRORC as not meeting state standards (known as Municipal Roads General Permit, or MRGP).

TRORC's assessement of compliance with MRPG looks at ditches or whether there's a crown in the road, for example. However, Stantec will be getting into more detail since they have to measure the amount of ditch that needs work so they can put a dollar number to it.

Stantec will also be looking at observed roadway usage, planned roadway usage, roadway cross section information (how much gravel is known or is believed to be under the roadway), guardrails, signage, cursory roadway geometric observations (horizontal and vertical curves), and any other miscellaneous observations.

If there are sections of road with inadequate or missing cross-section information, Stantec will recommend soil borings, which will tell engineers what is going on below the road (in terms of soil and gravel sub-base) and what would be involved in a reconstruction. "Typically we go down 10 feet," Rene LeBranche of Stantec said at a recent Selectboard meeting. $8,000 of the quoted project proposal is slated for soil borings; a soil boring crew costs $2,500-2,600/day. Tucker Hill Road has already been identified as a road where borings will likely be necessary.

The assessment will recommend a five-year capital plan to repair the roads in the worst condition. "There might be 5 or 6 roads that are identified as in poor condition. We'll have to look at them more closely and determine which ones are more poor than others. The next part would be a priority list relative to what the Town believes they want to do, as far as which are high priority roads to reconstruct and which are low priority. We're going to need input from the Town on that part of it." Reconstruction of Latham Road — half finished — will likely stay at the top of the list after work was already delayed for another year, although it wasn't explicitly mentioned in the Selectboard meeting.

Stantec will also be assessing the amount of associated permitting. “If you're replacing a culvert, working on  ditch lines, or there's wetlands... all that would have to be considered relative to permits necesary to do the reconstruction."

Stantec's product will be a memorandum that will include standard conceptual construction costs for road reconstruction projected over the next 5 years. "Typically construction costs increase 3% a year, which is what we've seen historically." It will be up to the voters to determine how much road work the Town can afford in how many years. The Town budget still needs to increase roughly $200,000 (~6.7% increase in the total municipal budget) to cover the 15-year bond payment required for the reconstruction of Route 132 from the Norwich town line to Tucker Hill Road. That's in addition to the ~$118,000 the Town has already increased its budget for the bond payment, and the $125,000 it currently puts into the Paving Fund every year, and the $60,000 it budgets for gravel resurfacing.

Photo credit: Thetford Improvement Society, rebuilding of Route 132 during the Union Village Dam construction.

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