City of Portsmouth Water Transmission Main Valve Improvement Project

Wright-Pierce designed map

Project Overview

The Valve Improvement Project will replace obsolete valves on the existing cast iron water mains on either side of Little Bay. Construction of this Valve Improvement Project is the first phase of a larger, new transmission main project planned for the future. To prepare for the larger project, a new valve will be tapped into the existing concrete pipe on either side of Little Bay that will be used to connect the new transmission main to the existing main in the future. Additional background on the project is provided at the end of this website. 

During construction, there will be two work areas near the shore on either side of the crossing in Durham and Newington. The Durham work area will be accessed using a temporary construction access drive through Wagon Hill Farm. The Newington project area will be accessed using a temporary construction access drive through Fox Point. All of the proposed work for the Valve Improvement Project will be constructed on land. There will be no in-water work performed for this project.

Throughout construction, the City of Portsmouth will have a designated construction monitor to observe that the project is being constructed in accordance with the contract documents and in accordance with approved environmental permit conditions. 

Details

Restoration

The areas impacted by construction will be restored at the end of construction. Restoration includes removing the temporary access drives and reestablishing vegetation on all impacted areas.  

Schedule

The following schedule is anticipated for the Valve Improvement Project:

  • Winter/Spring 2024 – Construction
  • Spring/Summer 2024 – Site Restoration

Construction Project Area Maps

The locations of the project work areas are shown on the following maps: Wagon Hill Map and Fox Point Map. All work areas should be considered active construction sites. Access by the public is prohibited. 

QUESTIONS?

Project status is updated regularly via the Project Updates section of this website. If you have questions regarding these updates or on anything related to this project, please reach out to us by emailing Al Pratt at anpratt@cityofportsmouth.com or calling 603-520-0622.

Project Updates

April 12, 2024

Schedule

Work was executed on Monday through Thursday this week, then suspended on Friday due to inclement weather. Active construction is expected to resume on Monday, April 15, 2024.

Durham – Wagon Hill Site

Insertion valve support concrete thrust blocks were placed on Wednesday 4/10 and pipe specialty contractor installed the two insertion valves on Thursday 4/11. Trench backfill of the valve excavations will commence on Monday next week.

Newington – Fox Point Site

No significant work completed in Newington this week.

April 5, 2024

Schedule

Work was executed on Monday through Wednesday this week, then suspended on Thursday and Friday due to inclement weather. Active construction is expected to resume on Monday, April 8, 2024.

Durham – Wagon Hill Site

Test pits were excavated downstream of the existing valve vaults to determine acceptable locations for new insertion valve installations. Existing 20” cast iron pipes were cleaned and prepared for installation of the new insertion valves. New valves are scheduled to be delivered on Monday 4/8 and installed on Tuesday and Wednesday next week.

Newington – Fox Point Site

Insertion valve support concrete thrust blocks were placed on Tuesday 4/2 and pipe specialty contractor installed the two insertion valves on Wednesday 4/3. Valve excavation was backfilled in preparation of the impending storm. Trench clean up and preparation for installation of the tapping sleeve and valve are expected for the week of 4/8/2024.

April 1, 2024

Schedule

Work is progressing on both sides of the project. The contractor, SUR, completed the timber mat access road on the Newington side and on the Durham side this week.

Test pits were excavated on the Newington and Durham sides to verify existing pipe conditions.

Durham – Wagon Hill Site

Test pits were excavated at the existing valve vaults to determine acceptable locations for new insertion valve installations. Additional test pits are required and expected to be excavated the week of 4/1/2024. Excavation of test pits are needed to verify the conditions of the existing pipeline to determine placement conditions for the new valves.

Newington – Fox Point Site

Insertion valve locations were excavated, and pipe conditions verified. Existing cast iron pipelines were prepared for insertion valve installations, including form work for support concrete thrust blocks.

The pipe specialty contractor is mobilizing to the site to install the insertion valve bodies and cut in the valves the week of 4/1/2024.

March 22, 2024

Schedule

Work is progressing on both sides of the project. The contractor, SUR, completed the timber mat access road on the Newington side and mostly completed the access road and turn around area on the Durham side this week. Erosion control compost silt sock and barrier fencing were completed on either side of the access roads for site protection. Erosion control measures were inspected by Stoney Ridge Environmental with minor corrections recommended and completed by SUR.

Next week the contractor intends to install the insertion style isolation valves in the two 20-inch cast iron pipes on the Newington side and excavate exploratory test pits on the Durham side.

Durham – Wagon Hill Site

Timber mats continue to be placed from the temporary staging area toward the valve pit location at the shore. SUR completed the turnaround area and continued temporary access toward the valve locations.

Exploratory test pits are planned for next week to determine the exact size, location, and condition of the existing pipelines.

Newington – Fox Point Site

SUR excavated three exploratory test pits to determine the exact size, location, and condition of the existing pipelines. Formwork was started on Friday in preparation of installation of concrete support for the bodies of the 20-inch insertion valves.

Next week the schedule is to install the two 20-inch insertion style isolation valves in the 20-inch cast iron pipes. These valves will allow the water system the ability to shut off the flow to each individual crossing pipe under the bay.

March 14, 2024

Schedule

The contractor, SUR, is completing the timber mat access roads on both the Durham and Newington sides of the project this week and possibly into next week. Erosion control compost silt sock and barrier fencing is being installed on either side of the access roads for site protection.

They anticipate beginning exploratory excavation of test pits to determine pipeline existing conditions next week in Newington and possibly the following week in Durham.

Durham – Wagon Hill Site

Timber mats continue to be placed from the temporary staging area toward the valve pit location at the shore. SUR expects to get to the turnaround area by the end of the week. Orange barrier fencing is being installed to limit access to the temporary road and protect pedestrian traffic.

Newington – Fox Point Site

The timber mat temporary access road is complete, and SUR performed the tree clearing within the easement area on Wednesday and Thursday. Orange barrier fencing is being installed to limit access to the temporary road and protect pedestrian traffic.

March 12, 2024

Schedule

The contractor, SUR, is installing the timber mat access roads on both the Durham and Newington sides of the project this week. Erosion control compost silt sock and barrier fencing is being installed on either side of the access roads for site protection.

Durham – Wagon Hill Site

Timber mats are being placed from the temporary staging area toward the valve pit location at the shore. Temporary drainage pipes and hay bale protections are being installed at the wetland crossings.

Newington – Fox Point Site

Timber mats have been placed within the easement area from the Fox Point road toward the valve pit location. The timber mat access road will be complete this week. SUR plans to begin tree clearing within the easement area Wednesday 3/13/2024, starting with the trees along the temporary access drive and finishing with the limited clearing around the valve pit locations.

March 7, 2024

Schedule

The contractor, SUR, mobilized to the site and began work on the Wagon Hill site in Durham this week. No construction equipment was mobilized to the Newington Fox Point side this week. Construction project signs were installed on both sides of the project. A preconstruction conditions survey of the access roads from Route 4 to Fox Point was completed with Town of Newington representatives. For the week of 3/11/2024, work will continue at the Wagon Hill Site and construction equipment will mobilize to the Fox Point site on Monday.

Durham – Wagon Hill Site

SUR installed the stabilized temporary construction access driveway entrance and began work on the stabilized gravel staging area in preparation of delivery of the timber mats for the temporary access drive to the valve pit locations. Geotextile fabric was installed under the gravel to minimize impact to the area and erosion control compost silt sock was installed around the active construction zone to NHDES standards. SUR intends to complete the gravel staging area and begin emplacement of the timber mat access road next week.

Newington – Fox Point Site

SUR intends to begin emplacement of the timber mat access road to the valve pit site on Monday. Assuming the weather is acceptable, clearing of trees within the easement along the timber access road will begin next week. Erosion control compost silt sock will be installed around the active construction zone to NHDES standards as the temporary access road is advanced.

February 29, 2024

Schedule

Preparations for mobilization of construction equipment next Monday continued this week. The construction submittal process continued with the submission of project site preconstruction conditions videos, health and safety plan, traffic control plan, and stormwater pollution control plan to the Towns of Newington and Durham. Monday will also see the completion of a preconstruction conditions survey of the access roads from Route 4 to Fox Point with Town of Newington officials.

Durham – Wagon Hill Site

The contractor, SUR, performed stake out of the construction staging area, project access drive, and construction turn-around areas. SUR plans to mobilize construction equipment to the site on Monday for the week. The tentative plan is to install temporary erosion control measures, temporary driveway access, culvert, stone wall dismantling, and construction staging area installation.

Newington – Fox Point Site

Letters were mailed to Newington residents along Fox Point Road notifying them of the upcoming construction work. SUR marked the limited tree clearing required within the Newington pipeline 40-foot-wide easement at the valve installation locations with pink ribbons for visibility. For next week, on the Newington side, temporary erosion control measures will be installed. SUR will begin the installation of temporary timber mats and tree removal in the pipeline easement area.

Regarding surface restoration for the project: The current contract requires loaming and seeding all disturbed areas in the pipeline easement. A planting plan was not included in this contract, as any plantings other than grass restoration, would be damaged/destroyed by the next pipeline contract, which the City hopes to construct in late 2024/2025. A planting and surface restoration plan will be included in the construction documents for the second contract. The grass seed submittal is currently under review for conformance with NHDES standards for surface restoration.

February 23, 2024

Preparation for construction is ramping up. Surveyors were onsite Thursday, February 22 and Friday, February 23 to field locate the boundaries of the pipeline easements in Newington and Durham. SUR Construction’s (the contractor) preliminary schedule requested mobilization of construction equipment to the site on Monday, March 4, 2024. Notice to proceed was issued by the City to SUR to begin construction on Monday March 4, 2024. Site preparations are expected to continue next week in preparation for mobilization the following week.

December 18, 2023

A pre-bid meeting was held to familiarize potential contractors with the site conditions within the easements, access requirements, and working conditions on both the Newington and Durham sides of the Valve Replacement Project. Bids were received and reviewed, and the project was awarded to SUR Construction, Inc. of Rochester, NH.

Additional Project Background

The City of Portsmouth owns and maintains a 7 mile cross-country drinking water transmission main that brings treated drinking water from the Madbury Water Treatment Plant to Portsmouth. The 24-inch pipe carries approximately 60% of the water serving the City’s regional water system which includes Portsmouth, Newington, Greenland, New Castle and portions of Madbury, Dover, Durham, and Rye. The water main crosses the Little Bay, approximately 4,000 feet to the southwest of the Scammell Bridge (US Route 4). At the crossing, the 24-inch concrete pipe transitions to two, 20-inch cast iron pipes from the Durham shore to the Fox Point shore in Newington. The two parallel transmission mains, installed in the 1950s, are approximately 3,200 feet in length across the bay. A dive inspection completed in 2016 observed that portions of the two cast iron pipes have become exposed to salt water and have experienced significant exterior corrosion, with corrosion pits greater than 50% of the pipe wall thickness in some instances. The City has undertaken a project to install a new water transmission main at the Little Bay crossing to maintain a safe, reliable supply of drinking water to the regional water system. This Valve Improvement Project is the first phase in updating the water main.

CONTACT INFORMATION

City of Portsmouth

Al Pratt
Water Resource Manager
anpratt@cityofportsmouth.com

Brian Goetz
Deputy Director of Public Works
bfgoetz@cityofportsmouth.com

Wright-Pierce

Craig Maynard
Project Representative
craig.maynard@wright-pierce.com

Darrin Lary
Project Manager
darrin.lary@wright-pierce.com