THE EXISTING CONDITIONS of the circa 1967 twin culverts on the Ipswich River beneath Chestnut Street, near Rte. 62, are visible in this photo. The culverts provide an existing span of 32 feet, 9 inches. Each culvert is 9 feet, 2 inches high and 13 feet, 8 inches wide. From bank to bank, the Ipswich River is 40 feet wide in this section. (TEC Courtesy Photo)
By MAUREEN DOHERTY
NORTH READING — TEC, Inc., the Lawrence engineering firm hired by the town to design a solution for the failed 55-year-old culverts spanning the Ipswich River on Chestnut Street at Rte. 62, provided an update on their progress to the Select Board Monday night.
To date, TEC has completed field data collection for wetland delineation, a topographic survey, soil borings, hydraulic analysis and bankfull width determination in addition to an analysis of the proposed bridge structure type being recommended.
Professional Engineer Jody Trunfio, a principal with the firm, is recommending the town install a single span bridge with a clear span of 48 feet over the Ipswich River to replace the twin culverts which are each 13 feet, 8 inches wide and 9 feet, 2 inches high and provide a span of only 32 feet, 9 inches.
Due to the failure of these culverts and the formation of sinkholes in Chestnut Street earlier this year, MassDOT has required the closure of this section of the roadway near Park Street at Rte. 62 to all but local traffic, which includes several homes on Chestnut Street and vehicles going to and from Moynihan Lumber, Maguire Field, the DPW garage and the RMLD site within the DPW property. KidSpot is currently closed due to ongoing construction plans for that toddler/preschooler park.
Steel plates secured with asphalt currently span the width of Chestnut Street, above the culverts. Further down Rte. 62, at the intersection of Central and Park streets, temporary traffic lights have been installed to handle the diverted traffic coming from Haverhill, New and Chestnut streets that passes by Ipswich River Park on Central Street to avoid Chestnut Street.
Trunfio stated in his report that the single span bridge being recommended meets all six stream crossing standards of MassDEP. The proposed bridge would be constructed of precast concrete deck beams, abutments and wing walls, and would have steel railings. The “bankfull width” of the existing river in this section is 40 feet so the bridge design would create an extra eight feet in width allowing additional flow and flood control.
Trunfio added that an advantage to a prefabricated bridge is an accelerated construction process and an accommodation to relocate utilities such as the eight-inch water main that services Chestnut Street and the existing gas line. He noted that the area also abuts town Conversation land so the Wetlands Protection Act will also come into play in addition to the MassDEP requirements.
The recommended bridge design would provide two 12-foot wide travel lanes plus shoulder widths of 2 feet, 4.5 inches on both sides of Chestnut Street for a 28-foot, 9-inch curb-to-curb width.
With the measurements for the steel railings included beyond the shoulders, an additional 19.5 inches of width on both sides of the road would provide an “out-to-out” width of 32 feet.
Alternatively, spanning the river crossing with “four-sided culverts” would require “multiple cells” because these structures “typically do not exceed 30-foot span” and the bankfull width that must be crossed is 40 feet, his report noted.
Trunfio further stated that TEC is currently working on a similar precast bridge structure with a 36-foot span in another Massachusetts town. That contractor began the work last October and is on track to have the roadway opened this August for a total construction duration of 10 months.
Further complicating North Reading’s situation will be the need to replace the Park Street bridge, which is located about one quarter mile away, across from the Masonic Lodge. This project was already on the books prior to the failure of the Chestnut Street culverts.
Trunfio will return to a future meeting of the Select Board to provide updates on the progress of the design stage and to provide additional information from the firm’s hydraulics engineer as well as the permitting and construction timeline and a cost analysis of other bridge options.