6-224 Crushed Stone Drainage Layer toward the limits of the excavatio n. Backfill shall be placed in lifts not to exceed 8 inches loose and compacted with lightweight, hand operated compaction equipment. Backfill beyond 3 feet from the back of the Crushed Stone Drainage Layer shall be compacted to 95% of the maximum d ensity as determined by AASHTO T-180, Method C or D. Backfill compaction shall be accomplished without disturbance or displacement of the FSRW st ones. Compaction adjacent to the FSRW shall be performed using hand-operated com paction equipment. Sheepsfoot rollers will not be allowed. Full size, ride on com paction equipment will not be allowed within 5 feet of the back of the FSRW. Whenever a compaction test fails, no additional backfill shall be placed over the area unt il the lift is recompacted and a passing test achieved. The moisture content of the backf ill material prior to and during compaction shall be uniformly distributed throughout eac h layer and shall be within 2 percentage points dry of optimum. At the end of the d ay’s operations, the Contractor shall shape the last level of backfill so as to dire ct runoff of rain water away from the FSRW face.
679.07 Method of Measurement FSRW shall be measured by the Sq uare Foot of front
surface not to exceed the measurements shown on the Contact Pla ns or as authorized by the Resident. Vertical dimension limits will be from the top of th e Crushed Stone Leveling Pad to the top of the cap stone layer. Horizontal dimension limits will be from each end of the wall.
679.08 Basis of Payment The accepted quantity of FSRW will be paid for at the
contract unit price per Square Foot complete, cleaned of debris and accepted in place. Payment shall be full compensation for wall construction, compa ction of the wall foundation soil, crushed stone drainage layer, backfill, drainage system, geotextile, construction of leveling pad, and FSRW installation, and other incidentals. There will be no allowance for excavating and backfilling for t he FSRW beyond the limits shown on the Plans and Special Details in the Contract D ocuments, except for excavation required to remove unsuitable subsoil in preparation for the foundation. Payment for excavating unsuitable subsoil shall be full compensation fo r all costs of pumping, drainage, sheeting, bracing and incidentals for proper executio n of the work and will be paid as Common Excavation in accordance with Standard Specification Section 203. Payment will be made under: P a y I t e m P a y U n i t
679.10 Field Stone Retaining Wall S q u a r e f o o t
SECTION 680 – ROCKERY WALL Reserved 6-225 SECTION 681 – PRECAST AGGREGATE-FILLED, CONCRETE BLOCK GRAVITY WALL
681.01 Description The work under this item shall consist of the design, fabrication,
furnishing and construction of a Precast Aggregate-filled Concr ete Block Gravity Wall in accordance with these specifications and in conformance with th e lines and grades shown on the Plans, or established by the Resident. The Precast Aggrega te-filled Concrete Block Gravity Wall shall consist of blocks made of Structural Precast concrete made from Portland cement, water, chemical admixtures, and aggregates, supported o n concrete leveling pads, and if required, geosynthetic reinforced backfill. Included in the scope of the precast gravity wall construction are: geotechnical design of any wall with an exposed height greater than 4.5 feet or as specified on the Plans, all grading necessary for wall construction, compaction of the wall foundation soil, backfill, piped drainage, construction of leveling pads, and concrete wal l unit installation. The top of the upper row of concrete wall units shall be at or above the t op of the face elevation shown on the Plans.
681.02 Quality Assurance The wall system shall be one of the approved
combinations of facing block and soil reinforcement systems not ed in the Plans or on the Department’s Qualified Products List (QPL). Alternate wall sys tems will not be considered for this Item. All design calculations and Shop Drawings shall be signed, che cked, and sealed by a Professional Engineer licensed in the State of Maine. The Contractor shall require the wall design-supplier to provi de an on-site, qualified experienced technical representative to advise the Contractor c oncerning proper installation procedures. The technical representative shall be on-site duri ng initial stages of installation and thereafter shall remain available for consultation as neces sary for the Contractor or as required by the Resident.
681.03 Materials Materials for walls shall meet the requiremen ts of the following
sections of Division 700: G r a v e l B o r r o w 703.20 Crushed Stone, ¾ -Inch 703.13 U n d e r d r a i n P i p e 706.06 or 706.09 Reinforcing Steel 709.01 Structural Precast Concrete Units 712.061 Reinforcement Geotextile 722.01 Drainage Geosynthetic 722.02 The Contractor is cautioned that all of the materials listed a re not required for every Precast Aggregate-filled Concrete Block Gravity Wall. The Cont ractor shall furnish the