Extreme Weather
It is almost impossible to read or listen to the news without hearing about lives being disrupted and homes and businesses being destroyed by extreme weather events. Whatever one’s thoughts are about Climate Change there is no doubt that there is an increasing amount of extreme weather. Recently I heard an amazing statistic: In the last 20 years there have been 8 or 9 FEMA incidents in the Hanover area (FEMA is the Federal agency charged with responding to natural disasters), while in the prior 50 years there had been only 3.
While this is a sobering reality, I feel fortunate to live in a town that is continually working to build both the expertise and the facilities and equipment inventory to meet the weather challenges we are facing. Here is a broad description of what the Town of Hanover is doing.
This time of year, the weather challenge is keeping the streets safe during snow and ice storms. Hanover is sophisticated and has deep expertise to do this in ways that are effective and keep the damage to water, pipes, and vegetation at a minimum. This involves the use of brine to pre-treat the roads. When brine is used, 80 to 85% less salt needs to be used to keep roads safe. Brine has the advantage of staying where is it applied, unlike salt which bounces, with more that 25% of it bouncing off the roads. The brine mixture must have an exact concentration of salt to water and there is a real science behind when to apply it to the roads. The Town mixes it and has the storage facilities to have it ready when the right conditions are present. Road terrain (not all roads are suitable) and temperature must be taken into consideration. The Town personnel monitor conditions constantly. Just one example of having training, expertise and facilities.
Floods and droughts, along with high winds, are the weather patterns that impact us other times of year. Over the last few years, NH has experienced some drought conditions, but nothing like what is being experienced in the western part of the country. The Town uses a Safe Yield Analysis that indicates how much water would be available during a 100-year drought. There are 3 reservoirs in Hanover providing capacity for 2.5 times the average daily demand. Since 2000 incremental changes have steadily decreased the daily demand for water. These changes have occurred through application of better building codes and more efficient plumbing fixtures. Dartmouth College, a large user of water, has done upgrades to facilities that include using recycled water as well as reducing irrigation demands by changing some of the playing fields to Astro-turf. The Town’s grounds department is diligent about mowing and tree maintenance to keep risks from fires as low as possible. The grounds department is charged with keeping safe road access clear of debris and trees. Keeping trees maintained also minimizes risks during ice storms.
In my discussion with Peter Kulbacki, the Town’s Director of Public Works, I learned that rain storms have several categories. Type 2 storms have long durations, while type 1 storms, which may have as much precipitation as a Type 2 storm, have a shorter duration. Historically, New England had type 2 storms, and our infrastructure was built for that type of storm. Not many of us realize (at least I didn’t) how important culverts are, and the science that goes into their design. Effective culvert design considers the velocity of the water as well as the slope of the terrain. In shorter, fiercer storms, culverts built for type 2 storms are challenged. Prior to 2000, culverts were made of metal, which is prone to corrosion and their circumference was narrower. Replacing the metal with high density polyethylene that doesn’t corrode and increasing the circumference based on the hydraulics of the water velocity makes the culverts more effective in handling storm water. A more basic and simple maintenance approach is keeping the culverts and ditches cleaned out. Hanover does this more than most other communities. Have you wondered what those yellow arrows on the road and stakes are? The Town uses these to mark key culverts and ditches that are constantly monitored and cleared out before storms.
Our soil is not ideal for water penetration. Type 1 storms don’t allow as much time for rain to be adequately absorbed into the ground. The Town’s Planning Board emphasizes low-impact development in building designs. This includes ensuring that plans provide places for water to pool and dissipate, such as rain gardens and certain types of vegetation.
Maintenance in all forms as well as constant building of knowledge is key to mitigating the impacts of extreme weather. Yes, the cost is high, but the cost of not maintaining is even higher