Culverts – Page 2 – DuBois & King, Inc.

West Street Culvert Replacement

Evaluation, design, and construction-phase services for the replacement of an undersized stream culvert designed to promote aquatic organism passage and sediment transport. The existing 3-ft diameter culvert had inadequate hydraulic capacity, which led to significant sediment deposition upstream and scour downstream. Downstream scour left the outlet perched above the channel, forming an obstacle to aquatic organism passage. Following a geomorphic assessment to determine natural channel dimensions, D&K engineers identified and evaluated several alternatives. The selected option was a 14-ft-wide precast concrete box culvert with bed retention sills. Services included:

Coordinating and meeting with State regulators
Conducting a stream geomorphic assessment
Completing a topographic site survey
Computing peak stream flows and simulating flows with HEC-RAS
Designing a replacement culvert with bed retention sills
Preparing plans and specifications
Providing bid-phase and construction inspection services

VT Route 100 Bridge #165 Replacement

Bridge #165 was heavily damaged during Tropical Storm Irene and lost one of the two concrete deck slabs. VTrans temporarily created a fill-over structure by installing two large culverts; this significantly reduced the hydraulic capacity of the structure. DuBois & King was contracted by VTrans to evaluate the condition and safety of the bridge. D&K recommended that the bridge be replaced prior to spring run-off. VTrans concurred with the recommendation.

D&K engineers conducted a hydraulic study and retrieved geotechnical soil borings, which were used for the alternatives analysis. D&K compared cost and constructability of alternatives, as well as availability of bridge components. Consideration was given to availability of precast components to fit the construction phasing. The scope of services included complete topographic survey, design of a new 3-sided precast concrete rigid frame structure, and plans and cost estimates for the removal of the existing structure and the construction of a new permanent structure. The bridge was designed to allow phased construction, allowing one lane of traffic to be maintained at all times. D&K staff designed the detour layout and provided construction oversight.

USDA Forest Service Kiasutha Recreational Area

Inspection, evaluation, and design of improvements to the Kiasutha Recreational Area located in the Allegheny National Forest. Performed inspections of the project site to make improvements for new campsite locations, orientation, accessibility, slopes and grading, drainage, and utility connections. Services included:

Field Survey/Data Collection. Survey and inventory/base maps.

Roadway/Transportation. Design of cul-de-sacs, new parking areas, new roadway sections, replacement of culverts, new drainage ditches, and riprap ditch lining.

Campsite Improvements. Design for improvements and construction of new campsites.

New Campground Loop. Design for new campsite loop including 20 campsites.

Site Design. Design of amphitheater, two playground areas, and accessible pathways.

Facility Improvements. Water, electric, and sewer upgrade design including shower/restroom buildings, and picnic pavilions.

Water System Improvements. Design for new waterlines and replacement of existing waterlines including new valves, stops, and water system drains.

Sewer Systems. Design for new and rehabilitation of sewer lines and manholes, correct infiltration and inflow, and new hookups for campsites.

Electrical System Improvements. Upgrade and design of new electrical services and equipment, and increased capacity upgrades.

Towle Road Bridge Replacement

Alternatives analysis, design, and construction phase services for the replacement of a failing bridge that consisted of two 5-ft diameter steel culverts. D&K performed ground surveys, base map preparation, subsurface investigations, and a preliminary hydraulic analysis to size the new structure to pass the 50-year storm event. Alternatives considered included several suitable bridge types including a new precast concrete arch structure, a precast voided slab deck, and a cast-in-place concrete deck slab. The evaluations considered geometric, hydraulic, and structural requirements; detailed construction cost comparisons; roadway improvements; and environmental impacts and permitting requirements.

DuBois & King engineers proceeded to provide engineering services for a 20-ft span, precast concrete arch and prepared Preliminary Plans indicating engineering details of the new bridge and roadway with an updated construction cost estimate. Preliminary design work included preparation and submission of permits to the New Hampshire Department of Environmental Services. Bid and construction phase administration and engineering services were provided for the project. The project was developed in accordance with the NHDOT Municipally Managed Program bridge design procedures.

Plunkton Road Bridge Replacement

Plunkton Road Bridge over Freeman Brook was severely damaged by Tropical Storm Irene. The bridge was damaged, but stable enough to keep open until a new structure could be designed and constructed. D&K’s services included initial inspection of the bridge and assessment of the damage, documentation of field conditions, topographic field survey, preparation of a hydraulic and hydrologic analysis, evaluation of several options to replace the bridge, permitting, preparation of final design drawings, preparation of bid documents, and engineering services during construction. The most economical alternative was determined to be a precast 3-sided box culvert with a 26-ft span to replace the damaged and failing bridge.

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