NH 1A Maintenance – Going beyond the roadway ACEC/NHDOT Winter Technical Meeting NH 1A Maintenance – Going beyond the roadway Here to discuss current maintenance efforts along the coast and how those efforts are improving resiliency of transportation system in an area critical to support the states tourism. While I am going to discuss what we are doing, I am also going to highlight some of the unique challenges to maintaining a transportation system within a coastal area, providing you with items important to consider in designing coastal infrastructure. Roger Appleton, NHDOT Maintenance District 6

NH 1A Maintenance Resiliency Challenges Here to discuss current maintenance efforts along the coast and how those efforts are improving resiliency of transportation system in an area critical to support the states tourism. While I am going to discuss what we are doing, I am also going to highlight some of the unique challenges to maintaining a transportation system within a coastal area, providing you with insight that is important to consider in designing coastal infrastructure.

NH 1A Maintenance Extreme weather events Repair & replacement projects We can group maintenance efforts into 3 main groups. Extreme weather would include nor’easters, hurricanes, tropical storms and storm surges. Improvement projects – projects to address current deficiencies or deteriorating pipes and other structures Routine Maintenance – work to maintain the current functionality of the system Routine Maintenance

Extreme Weather Events March 2018 Nor’easter Presidentially declared disaster, significant damage to over 2 miles of NHDOT maintained seawalls. Repetetive astronomical high tide cycles combined with storm surge continually hammered and overtopped seawalls. Heaviest damages in the Bass beach and Foss Beach areas.

Extreme Weather Events $175,000 debris cleanup Initial cleanup by DOT forces, pushing “shale” back up was over 175K. Clean up covered only about 10 miles of 1A.

Extreme Weather Events >$2,000,000 est. wall reconstruction Currently working on a project to reconstruct over 2 miles of damaged sections of seawall. As you can see in this picture stone revetment on the ocean side and shale pile on the back side were heavily damaged. Preliminary damage estimates for this work was over $2M.

Extreme Weather Events Opportunity to improve resiliency Existing Wall Typical includes large stone revetment on ocean side with rounded ocean stone or “shale”. When wall is overtopped the shale pile is washed away and into route 1A. We are considering alternative designs or treatments to the wall to create a more resilient wall that won’t have to be pushed back up every time it is overtopped.

Repair & Replacement Projects Slip lining - $75,000 RYE – 1A near Causeway Rd. - 2017 - The existing culvert is old and constructed with 4' sectoins of RCP culvert. The majority of the joints had separated allowing seaweed and other debris to collect in the culvert causing flooding of adjacent properties. Project has been successful with no major problems since. Last photo shows the impacts and power of normal tide cycles as large stones block the outlet requiring additional maintenance.

Improvement Projects Pipe Replacement ~ $10,000 RYE – 1A near Janesse Beach- 2018 - Replaced CMP – Existing 36” CMP was failing, replaced with twin 36” HDPE pipes

Routine Maintenance Seawall $25,000 labor 23 crew days Labor cost is only for work on seawall and does not include additional maintenance required to maintain drainage. $25,000/yr labor >900 man hours 23 crew days

Routine Maintenance Unique Outlets

Resiliency Improve the existing infrastructure to better withstand the coastal impacts. Minimize effort to restore system. Resiliency – We know we are going to deal with flooding, splash over and extreme impacts of tides during high tides and extreme events now and increasingly in the future, our focus in maintenance is to make improvements where we can within limited resources, improving the resiliency of the overall system and reducing time and money needed to restore the system after these events.

NHDOT- Highway Maintenance District 6 Roger Appleton, PE roger.appleton@dot.nh.gov NHDOT- Highway Maintenance District 6