SECTION 205 — TRENCH EXCAVATION — TRENCH EXCAVATION
205.01 Description.
This work includes the excavation, dewatering, and the backfill or disposal of all materials required for the construction of box culverts, pipe culverts, storm drains, drainage structures, utilities, utility structures, and ditches. Trench excavation is subdivided into four classifications. Trench Excavation – Earth. Trench Excavation – Earth includes all trench excavation not otherwise classified. Trench Excavation – Rock. Trench Excavation – Rock includes the removal of bedrock and boulders or detached rock fragments that have a volume of ½ cu yd or more. Boulders and detached fragments that have a volume of less than ½ cu yd are considered Trench Excavation – Earth. Trench Rock Excavation – Mechanical. Trench Rock Excavation – Mechanical will be used where blasting is prohibited. Ditches. This classification includes D itches at inlets and outlets of culverts, except those within normal cut and fill slopes.
205.02 Materials.
Not applicable.
205.03 Construction Methods.
Excavation of Trenches. Excavate all unsuitable material to a minimum depth of 12 in. below the specified invert elevation. For all pipe sizes up to 36 in. in diameter, extend the width of the trench 2 ft beyond each side of the inside diameter of the pipe. For pipe sizes greater than 36 in. in diameter, excavate trenches to 30 in. on each side of the inside diameter of the pipe. Ensure that t he material to replace this excavation includes suitable bedding placed and compacted under and around the pipe to the required horizontal and vertical dimensions. Bedding material may be from suitable trench or roadway excavation material. Backfill placed above the bedding may be from suitable trench or roadway excavation material, provided that it meets the minimum requirements for common borrow in Subsection 202.02.1. Use c ommon borrow to replace unsuitable material when no excess suitable material is available from onsite.
Part 200 — Earthwork and Erosion Control August 2025
SECTION 205 — TRENCH EXCAVATION 200-47 Shape the surface of bedding material along the bottom of the trench to fit the pipe bells to a depth equal to the thickness of the pipe or bell. Trench Protection. If trench protection is required according to either OSHA regulations or for the protection of the roadway or utilities, provide adequate timber sheeting, steel sheeting, or steel box type sheeting. Provide sheeting that is either timber of 3-in. minimum thickness, steel sheet piling, or a fabricated steel trench box. Except when fabricated steel trench boxes have been approved for use, submit Shop Drawings and computa tions showing the method and design of the sheeting proposed. Prepare the Shop Drawings according to Subsection 105.02. Design the sheeting and supporting systems to meet acceptable engineering criteria, which must be certified by a Rhode Island Registered Professional Engineer. The Engineer's written approval of the sheeting design is required before the use of any sheeting on the P roject and before commencement of any drainage or underground utility work. Where sheeting will remain in place, cut off the sheeting a distance of 2 ft below subgrade, unless otherwise required to support adjacent utilities and structures with elevations above the cut off. Do not use fabricated steel trench boxes where either permanent steel or permanent timber sheeting is required. Protect all structures (drainage or otherwise) and unsupported utilities encountered in the trench. Remove all sheeting and bracing used in trench excavation following the completion of work. Open Cuts in Lieu of Trenches. Ensure that all replacement work matches the existing in kind. This provision is applicable only if the requirements for the maintenance and protection of traffic are met and when trench protection is not stipulated. Dewatering. Ensure that trench excavation is dry at all times and perform all construction work in the dry. Remove any water that accumulates in the trenches by pumping, draining, bailing, well points, deep wells, or another approved method. Place forms around all pump wells, sumps, dams, flumes, or other works required to keep the trenches clear of water while pipes and structures are being constructed. Remove all water from the trench excavations, including water discharged from pumping systems and underdrains. Ensure that the discharge of the trench water is properly controlled to prevent discharge of any sediment downstream, including into the RIDOT drainage system.
Part 200 — Earthwork and Erosion Control August 2025
200-48 SECTION 205 — TRENCH EXCAVATION Backfill and Compaction. Backfill includes suitable bedding and soil materials placed and compacted in layers. Compact the layers to not less than 95 percent of maximum density according to AASHTO T180. Ensure that the layers are no more than 8 in. thick after compaction. Compact according to Subsection 202.03.3. Ensure that the backfill reaches the surface level of the surrounding ground and is properly graded. Do not place any backfill against newly constructed masonry or concrete structures.
205.04 Method of Measurement.
Trench Excavation – Earth. Trench Excavation – Earth will not be measured for payment. Trench Excavation – Rock and Trench Rock Excavation – Mechanical. Trench Excavation – Rock and Trench Rock Excavation – Mechanical will be measured by the cubic yard in its original position within the following horizontal and vertical pay limits:
a.Horizontal Pay Limits. For all pipe sizes up to and including 36 in. in diameter, measurement will be made between parallel vertical planes located at 2-ft offsets on each side of the inside diameter of the pipe. For all pipes greater than 36 in. in diameter, measurement will be made between parallel vertical planes located 30 in. on each side of the inside diameter of the pipe. The length of the trench will be measured from 1 ft beyond the outside face of a drainage structure to 1 ft beyond the outside face of the adjacent drainage structure.
b.Vertical Pay Limits in Cut Areas. Within the limits of roadway excavation, payment lines will extend vertically from 1 ft below the pipe to the subgrade. Outside the limits of roadway excavation, payment lines will extend vertically from 1 ft below the pipe to the existing ground surface.
c.Vertical Pay Limits in Fill. Within the limits of fill areas, payment lines will extend vertically from the invert elevation to a maximum cover of approximately 3 ft of fill over the pipe. Sheeting for Trench Protection.
a.Steel Sheeting. When required, Temporary Steel Sheeting, Temporary Steel Sheeting Abandoned in Place, and/or Permanent Steel Sheeting will be measured by the number of square feet calculated according to the following dimensions. The height will be the distance from the ground surface or the top of sheeting, whichever is less, to 2 ft below the bottom of the excavation.
Part 200 — Earthwork and Erosion Control August 2025
SECTION 205 — TRENCH EXCAVATION 200-49
b.Timber Sheeting. Temporary Timber Sheeting and/or Permanent Timber Sheeting will be measured by the number of square feet calculated according to the following dimensions. The height will be the distance determined using the vertical pay limits described in Para. a of this Subsection. The length of timber sheeting will be the continuous length measured as described in Para. c of this Subsection.
c.O dd Shapes . The inside face of sheeting will be the plane of the horizon tal pay limit for trench excavation as noted in Subsection 205.04.2(a). Regardless of the type of sheeting used (timber or steel), measurement will be on the horizontal plane area, not on any odd shapes developed by the sheeting based on its cross-sectional configurations.
d.O pen Cuts in- Lieu of Trenches. No measurement will be made for additional excavation, disposal of unsuitable material, borrow, compaction, or replacement of site features if the Contractor elects to excavate to the angle of repose in lieu of installing trench protection.
205.05 Basis of Payment.
The Department will pay for the completed and accepted quantities at the Contract unit prices as follows. Pay Item Pay Unit Trench Excavation – Rock CY Trench Rock Excavation – Mechanical CY Temporary Steel Sheeting SF Temporary Steel Sheeting Abandoned in Place SF Permanent Steel Sheeting SF Temporary Timber Sheeting SF Permanent Timber Sheeting SF If the Contractor elects to excavate to the angle of repose as specified in OSHA 2226 (Excavation and Trenching Operations) and the lines of the angle of repose intersect the ground beyond the pay limits of trench excavation as described in Subsection 205.04.2 , perform any required additional excavation, disposal of unsuitable material, backfill, borrow, compaction, replacement of pavement structure, curb, sidewalk, lawn area, etc., at no additional cost to the Department. Trench Excavation – Rock and Trench Rock Excavation – Mechanical. The accepted quantities of Trench Excavation – Rock or Trench Rock Excavation – Mechanical will be paid for at their Contract unit prices per cubic yard. Payment at the Contract unit price is full compensation for all resources, labor, materials, equipment, dewatering, and incidentals required to finish the work, complete and accepted.
Part 200 — Earthwork and Erosion Control August 2025
200-50 SECTION 205 — TRENCH EXCAVATION Backfilling of Trenches. The cost of placing and compacting backfill in trenches is not included in any of the classifications for Trench Excavation. These costs will be included in the Contract unit prices for the various classifications of pipe and drainage/utility structures. Excavated material that the Engineer determines is unsuitable or not appropriate for backfilling around or above utilities will be either removed to stockpile at the direction of the Engineer. Any additional borrow material required for trench backfill will be paid for at the Contract unit price. If no unit price is stated, the additional borrow material will be paid for under Subsection 104.05. Sheeting for Trench Protection. Temporary trench protection and fabricated steel trench box type sheeting required for drainage or utility installations will not be paid for separately . Include t he cost in the C ontract unit prices for the various classifications of pipe and drainage/utility structure. Do not use fabricated steel trench box type sheeting where either permanent timber sheeting or permanent steel sheeting is specified. If stipulated, the accepted quantities for the following items will be paid for at the C ontract unit prices per square foot: • Temporary Steel Sheeting • Temporary Steel Sheeting Abandoned in Place • Permanent Steel Sheeting • Temporary Timber Sheeting • Permanent Timber Sheeting Payment at the Contract unit price is full compensation for all resources, labor, materials, equipment, including driving, bracing, cutting off and removal of excess quantities, removal of temporary steel sheeting and incidentals required to finish the work, complete and accepted. Bedding and Backfill Borrow. If stipulated or if required to replace unsuitable materials, Bedding and Backfill Borrow will be paid for at its Contract unit price per cubic yard. Otherwise, Bedding and Backfill Borrow will be paid for under Subsection 104.05. Payment at the Contract unit price is full compensation for all resources, labor, materials, equipment, and incidentals required to finish the work, complete and accepted.
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Source: Standard Specifications for Road and Bridge Construction (Blue Book), 2022 (Aug 2025 compilation) Edition. Pages 172–176 of 951. View official source ↗