94 ALASKA 2020 SECTION 203 EXCAVAT ION AND EMBANKMENT
203-1.01 DESCRIPTION. Excavate, haul, place, and compact or dispose of specified materials
necessary to construct the project. Conform to the lines, grades, depths and typical cross sections shown on the Plans or as established. The Contract will designate material to be removed within the excavation limits as classified or unclassified excavation.
203-2.01 Materials.
1.Unclassified Excavation. All materials of whatever character encountered in the work. May include rock, common, or muck.
2.Classified Excavation.
a.Common Excavation. Silt, sand, gravel, and granular material other than rock or muck.
b.Rock Excavation. Rock that cannot be excavated without blasting or ripping.
c.Muck Excavation. Soils, organic matter, and other material not suit able for foundation material regardless of moisture content.
3.Borrow . Approved material required for embankments or for other portions of the work, and obtained from sources outside the right -of-way limits for the project.
4.Rock Stabilization Materials . As specified on the Plans or Special Provisions.
5.Rockfall Mitigation Materials . As specified on the Plans or Special Provisions.
6.Crushed Glass: May be combined with soil -aggregate material to be used in embankment construction. Meet 703- 2.15 requirements. CONSTRUCTION REQUIREMENTS
203-3.01 GENERAL. Perform all necessary clearing and grubbing prior to beginning excavation,
grading, and embankment operations in any area. Keep excavation and embankment areas free draining at all times as the work progresses. Finish the excavation and embankments to reasonably smooth and uniform surfaces. Excavate and embank material only within the limits on the Plans or as directed. Prevent disturbing material and vegetation outside of the slope limits. The Engineer may designate excavated soils, that cannot be properly compacted in embankments, as unsuitable. When unsuitable material is encountered at the required depth of excavation, remove the unsuitable material to the depth specified or directed. Allow for measurements to be taken before backfill is placed. Dispose of unsuitable material or excess usable material at approved locations. Obtain the property owner’s written permission to dispose of unsuitable material or excess usable material at locations outside the right -of-way limits and a waiver of all claims against the State for any damage to such land which may result. Obtain all permits required by law for such disposal. Furnish a copy of such permission, waiver of claims, and permits to the Engineer before commencing work. 95 ALASKA 2020 Ensure that all disposal areas are properly graded and drained. Blend the outer limits of unsuitable material into surrounding grounds with no noticeable break or variation readily discernible. When existing roadway embankment slopes are used as disp osal sites for unsuitable or excess useable material, finish the slopes with a motor grader or other approved method. When the volume of suitable excavation is not sufficient for constructing the fill to the grades indicated, furnish the necessary borrow f rom approved sources. Borrow may be necessary even though not shown on the Plans. The source and acceptability of the borrow is subject to approval. Do not place borrow material until after the usable roadway excavation has been placed in the fill. If you place more borrow than is required, resulting in or as a result of the unnecessary disposal of usable excavation, the amount of such disposed material will be deducted from the borrow quantity. Obliteration of Roadways includes all grading operations necessary to incorporate the existing roadway into the new roadway and surroundings in order to provide a pleasing appearance from the new roadway. Fill ditches not required for drainage and grade to the approximate original ground contour. Do not place soil -aggregate containing glass cullet:
1.Within four feet from the face of any embankment slope,
2.Within 150 feet from any surface water body,
3.In embankment areas where culvert placement is required,
4.In contact with any geosynthetic material.
203-3.02 ROCK EXCAVA TION. Excavate rock by blasting, ripping, or both.
Unless Subgrade Blasting is specified, excavate material which would classify as rock within the limits of the roadbed to a minimum depth of 6 inches below subgrade.
1.Blasting .
a.Blasting Plan . Prior to comm encement of drilling, submit a Blasting Plan prepared by a qualified Blaster . Include the details of test blasting, controlled blasting and production blasting. Include station limits, date and time of each blast, layout details of each blast, trade names, types and sizes of explosives and accessories, delay sequences of the blast holes, and powder factors. Submit a revised Blasting Plan any time there is a change in the drilling or blasting methods.
b.Blaster . Use a qualified blaster licensed or otherwise authorized under all applicable federal, state and local laws or regulations to possess, transport, store and use explosives of the type used on the Project. Provide the Blaster’s resume and copies of all applicable licenses to the Engineer with the Blasting Plan. Have the Blaster on site during all loading and blasting operations. Require the Blaster to take responsible charge for safety procedures as set forth below and to maintain a detailed record for each day of blasting work.
c.Pre-Blast Conference. Hold a pre- blasting meeting at the jobsite prior to commencement of any drilling and blasting operations with the Contractor, the Blaster and representatives of the Engineer. Discuss the Blasting Plan and visit such specific sites as are necessary to familiari ze the participants with the details of the blasting operations.
d.Safety . Submit a Safety Plan that includes descriptions of road closures, warning signals, and plans for notification of affected local, state, and federal agencies. Discuss in the 96 ALASKA 2020 Safety Plan methods for protection of life and health, public and private property, new work or existing work on the project, nearby structures, wetlands, waters and wildlife. Hold a safety meeting prior to commencement of blasting operations to address safety issue s.
e.Controlled Blasting. Controlled blasting holes are closely spaced, lightly loaded holes drilled along the plane of the final design slope. Controlled blasting is either preshear blasting with holes detonated before the production blasting or cushion (tr im) blasting with holes detonated after the production blasting. Drill holes parallel to each other and within 12 inches of the staked slope plane. Use controlled blasting techniques for all rock slopes higher than 10 feet to produce a stable cut face sheared along the designed neat excavation line. If at any time during the progress of the work, the approved methods of blasting and drilling fail to produce the desired result of a smooth, stable backslope, modify the blasting method to achieve the desired r esult. Do not construct benches in finished rock back slopes unless approved by the Engineer. The Engineer may permit an offset for drilling equipment clearances. Do not use ANFO in controlled blasting holes.
f.Production Blasting. Use materials and methods as necessary to fragment and loosen the rock inside the design excavation limits, while leaving a smooth, stable back slope using the controlled blasting methods set forth above. Use appropriately designed delay sequences and charge weights per delay to m inimize ground vibrations and prevent damage to buildings, structures, utilities, sensitive fish or wildlife habitat and other facilities. Prior to blasting, remove all loose objects, and render safe all dangerous conditions, in or near the cut slope area. Detonate production hole charges in a delay sequence toward the free face. Remove and dispose of loose material from rock slope failures or slides at the contract price for unclassified excavation if the Engineer determines the failure did not occur as a result of the Contractor’s methods. The Engineer will determine the amount of loose material at the time of removal.
g.Scaling. Remove all loose, hanging, or potentially dangerous rock from newly excavated slopes and from surrounding existing slopes as the excavation progresses to ensure the rock slopes are stable. Do not commence work on subsequent lifts or shots until scaling is complete. Accomplish scaling with hand tools, hydraulic splitters, machine scaling with excavators or other equipment, high press ure water spray, light explosive charges, or other approved methods.
h.Ditch Line/Subgrade Blasting. Construct a free- draining fractured rock zone below the ditch line and the bottom of the structural section as shown on the Plans and Specifications or as d irected. Blast or rip rock below the bottom profile of the ditch line and below the bottom of the structural section to depths as indicated or directed.
2.Stabilization . Stabilize excavated or existing rock surfaces with rock bolts, rock dowels, shotcrete, or other techniques, as indicated in the Plans and Specifications or as directed. The Engineer may increase or decrease the extent and type of stabilization methods depending on the geologic conditions encountered during the work. Obtain approval from the Engineer for rock bolts, dowels, shotcrete, resin grout, cement grout, mortar, and other stabilization accessories prior to ordering the items. Conduct performance testing as required by the Engineer to confirm the stabilization methods and equipment produc e the required capacities and functions.
3.Rockfall Mitigation . Use rockfall mitigation methods such as rock catchment fences, wire mesh draping, flexible or rigid barriers, ditch width modification, and other techniques to intercept rockfall and control it before it reaches the roadway or other facilities. Construct according to the Plans and Specifications or as required by the Engineer. The Engineer may increase or decrease the extent and type of mitigation methods depending on the geologic conditions enc ountered during the work. Obtain approval from the Engineer for fence 97 ALASKA 2020 material, wire mesh, barrier design and accessories prior to ordering the items. Conduct performance testing as required by the Engineer to confirm the methods and equipment produce the required capacities and functions.
4.Drain Holes . Drill drain holes in rock slopes to relieve excess water pressure as specified or directed. The Engineer will determine the location and construction details of the drain holes, depending on the conditions encountered in each slope.
203-3.03 EMBANKMENT CONSTRUCTION. Prepare the areas upon which embankments are to
be placed, construct dikes within or outside the right -of-way when required, place and compact approved material within the roadway areas where unsuitable material has been removed, and place and compact embankment material in holes, pits, and other depressions within the roadway area. Use only approved materials in the construction of embankments and backfills. Embankment material will be approved for gradation following placement but prior to compaction. Construct the embankment with selected material meeting the requirements of Subsection 703-2.07. Selected material may be obtained from unclassified excavation, rock excavation, common excavation or borrow. Do not place rocks, broken concrete or other solid materials in embankment areas where piling is to be placed or driven, or where culvert placement is required. Bench slopes that are steeper than 4:1, when measured at right angles to the roadway, when embankment is to be placed and compacted on hillsides, or when new embankment is to be compacted against existing embankments, or when embankment is built half -width at a time. Continuously bench over those areas as the work is brought up in layers. Make benches wide enough to permit placing and compacting operations. Begin each horizontal cut at the intersection of the original ground and the vertical side of the previous bench. Incorporate material cut out, and deemed suitable, into the new embankment and recompact along with the new material. Scarify existing roadways, lying within 3 feet of subgrade, to a depth of 6 inches and recompact to meet Subsection 203- 3.04 or 203- 3.05. When permanently frozen soils are encountered, place backfill or embank ment materials in a timely manner, as directed, to minimize degradation of the foundation material. Do not place embankment over seasonally frozen ground unless authorized in writing. Thaw and drain frozen material deemed acceptable for fill before placing in the embankment. Frozen cuts may require stage excavation: remove thawed material and allow the cut to thaw while work continues on some other portions of the project. After the material in the cut has thawed to a sufficient depth, remove the thawed mat erial. Repeat this operation until all frozen material is removed or the cut is excavated to grade. When excavation is performed when freezing weather is imminent, place the specified backfill promptly, following the excavation work, at least up to a leve l which will allow the surface to adequately drain. Make arrangements for the timely availability of such embankment or backfill materials prior to commencement of the stripping or excavation operations, when required. If embankment can be deposited on one side only of abutments, wing walls, piers or culvert headwalls, prevent the overturning of or excessive pressure against the structure. Do not place the fill adjacent to the abutment of a bridge higher than the bottom of the backwall of the abutment unti l the superstructure is in place. When embankment is to be placed on both sides of a concrete wall or box type structure, keep the embankment at approximately the same elevation on both sides of the structure. Place roadway embankment of earth materials i n horizontal layers not to exceed 8 inches (uncompacted) for the full width of the embankment, except as required for traffic, and compact 98 ALASKA 2020 as specified before the next layer is placed. Use spreading equipment on each lift to obtain uniform thickness prior to compacting. Maintain uniform density, during compaction. Add or remove water, as necessary, to obtain the required density. Route compaction equipment uniformly over the entire surface of each layer. Place rock embankment in lifts not thinner than the thickness of the largest rocks. Restrict maximum rock dimension to 3 feet. Distribute spalls and finer rock fragments to level and smooth each lift. Place succeeding lifts without damaging previously completed lifts. Dump rock on the lift being constructed and distribute by blading or dozing to fill voids and to form a dense, well - compacted embankment . Do not place rocks over 8 inches within 2 feet of finished subgrade. Rock is considered usable material, regardless of size. Rocks too large to be embanked, as specified above, may either be reduced to a suitable size for incorporation into the embankment or disposed of in approved areas, at your option. Replace all wasted rock from excavation with borrow at no additional cost to the Department, unless such rock is excess to project embankment requirements. Finish the subgrade surface so it will not vary more than 0.10 foot when tested using a 10- foot straightedge nor vary more than 0.10 ft from the established grade. When embankment is to be placed over swampy or saturated ground, end dump an initial lift of material of sufficient depth to support hauling equipment, as directed. Repair damage to embankment caused by hauling equipment. Construct all embankments with moisture and density control unless the Engin eer determines that such controls are not feasible. Temporary surcharging consists of two methods:
1.Static Surcharge. Leave surcharge in place until the foundation material has reached stability or the required settlement has taken place.
2.Rolling Surcharge . Construct a surcharge on top of the embankment to the specified elevation and continually advance the surcharge as the embankment is constructed ahead. Use material removed from the temporary surcharge in areas indicated on the Plans. Do not dispose of temporary surcharge material without written approval. Compaction is not required for material placed in a temporary surcharge.
203-3.04 COMPACTION WITH MOISTURE AND DE NSITY CONTROL. The maximum density
and optimum moisture will be determined by ATM 207 or ATM 212. Adjust the moisture content of the embankment material to within 2 percent of the optimum moisture content and compact each layer to not less than 95 percent of the maximum density. Acceptance densities will be determined by ATM 213 and ATM 214.
203-3.05 COMPACTION WITHOUT MOISTURE AND DENSITY CONTROL. Except for rock fills
and the first layer of fills over swampy ground, deposit embankment materials in layers not exceeding 8 inches in thickness before compaction. Compact by routing constructi on equipment and/or rollers uniformly over the entire surface of each layer before the next layer is placed. Compact until embankment does not rut under the loaded hauling equipment. Keep dumping and rolling areas separate. Do not cover any lift by another until the required compaction has been completed. 99 ALASKA 2020 203-4.01 METHOD OF M EASUREMENT. See Section 109 and the following:
1.Items 203.0001.___ through 203.0004.____ and 23.0008.____. The volume measured in original position.
2.Item 203.0005.____. The volume meas ured in final position.
3.Item 203.0006.____. By weighing.
4.Item 203.0007.____. By vehicle measure.
5.Item 203.0009.____ and 203.0011.____. By the area measured before obliteration or blasting.
6.Item 203.0010.____. By adding the sum of the depths of line holes drilled and loaded.
7.Item 203.0012.____. By adding the sum of the depths of drain holes drilled.
8.Item 203.0016.____ By the length measured along the base of the fence.
9.Items 203.0015.____, 203.0017.____, and 203.0018.____. By the area covered, measured along the slope.
203-5.01 BASIS OF PA YMENT. When no pay item is shown in the bid schedule for “Stripping
Material Sources”, removal of overbur den and other unsuitable material from such Material Sources is subsidiary. The following work is subsidiary:
1.scarifyi ng material in place
2.hauling of material
3.excavating overbreak material
4.slope rounding excavation and benching of slopes
5.water for compaction
6.placing and removing of temporary surcharge material
7.work required to continually advance the heading on a rolling surcharge
8.test pits and explorations required to evaluate the acceptability of borrow
9.stage construction of cuts and stage excavation of material sources Removal of slides and associated work will be paid for at the contract unit price for excavation at the location of the slide or as extra work under Subsection 109- 1.05. 100 ALASKA 2020 Payment will be made under: PAY ITEM Item Number Item Description Unit 203.0001.____ Common Excavation CY 203.0002.____ Rock Excavation CY 203.0003.____ Unclassified Excavation CY 203.0004.____ Muck Excavation CY 203.0005.____ Borrow CY 203.0006.____ Borrow TON 203.0007.____ Borrow CYVM 203.0008.____ Stripping State -Furnished Material Sources CY 203.0009.____ Obliteration of Roadway SY 203.0010.____ Controlled Blasting LF 203.0011.____ Ditchline/Subgrade Blasting SY 203.0012.____ Drain Holes LF 203.0013.____ Stabilization - Rock Bolt EACH 203.0014.____ Stabilization - Rock Dowel EACH 203.0015.____ Stabilization - Shotcrete SY 203.0016.____ Rockfall Mitigation - Rock Fence LF 203.0017.____ Rockfall Mitigation - Wire Mesh SY 203.0018.____ Rockfall Mitigation - Cable Mesh SY 203.0019.____ Unclassified Excavation LS 203.0020.____ Borrow LS 203.0021.____ Obliteration of Roadway LS 101 ALASKA 2020 SECTION 204 STRUCTURE EXCAVATION FOR CONDUITS AND MINOR STRUCTURES
204-1.01 DESCRIPTION . Excavate and backfill for pipe culverts, storm drains, manholes, inlets
and other minor structures. Perform all pumping, bailing, draining, sheeting, bracing, and incidentals required for proper execution of the work.
204-2.01 MATERIALS . Use selected material, Type A (Subsection 703- 2.07) passing the 3- inch
sieve for bedding material, and for backfill material to 12 inches above the pipe. Use excavated native material for the remainder of the backfill if i t meets the requirements of Selected Material, Type C. Use bedding material, and backfill material within the pavement structure, meeting the requirements for the applicable lift of material. Use all suitable material from structure excavation for beddin g and backfill prior to using material from another source.
204-3.01 CONSTRUCTIO N REQUIREMENTS. Remove and dispose of unsuitable foundation
material below the designed elevation as directed. Replace with approved material. Remove rock or other unyielding material, when encountered, to the depth shown on the Plans or as directed and replace with approved material. Place bedding and backfill in uniform layers not more than 6 inches deep and compact to meet Subsection 203- 3.04. Ponding or jetting is not perm itted. Native material may be utilized for electrical conduit backfill outside the pavement structure if it meets the minimum requirements of Selected Material, Type C, as specified in Subsection 703- 2.07. Compaction may be as approved by the Engineer. Place backfill as uniformly as possible on all sides of structural units. Avoid unbalanced loading of backfill which could damage the structure. When placed against concrete, place backfill according to the requirements of Section 550. Support and protect exi sting conduits or utilities, which are not scheduled for removal or abandonment, when encountered in the excavation. Remove all sheeting and bracing used in structure excavation upon completion of the work.
204-4.01 METHOD OF M EASUREMENT. See Section 109 using neat line method as follows:
Structure excavation for:
1.Masonry culverts, headwalls, and drainage structures other than conduit . Between vertical planes 18 inches outside the base of the masonry sections shown on the Plans for the depth required.
2.Cond uit, including culverts, storm drains, underdrains, structural plate pipe and pipe arches . Between parallel vertical planes located 18 inches outside the horizontal projection of the outside diameter of the pipe and to the depth shown on the Plans. Structu re excavation will only be measured below the limits of other classes of excavation. When structures are to be placed in embankment sections, the natural ground line as cross -sectioned will be the uppermost level of computation.
Source: Alaska Standard Specifications for Highway Construction, 2020 Edition. Pages 122–128 of 584.