TREATMENT OF LIME SINKS
224.01 Description.
The work under this Section shall cover the treatment required to correct conditions occurring when lime sinks are found within or adjacent to construction limits of the work. The application and extent of the treatment will be in accordance with plan details or as directed.
224.02 Materials.
Material furnished for use under this Section shall be of the quality and character noted on the plans or ordered by the Engineer, suitable for the purpose intended, and consistent with the requirements for such materials as may be noted in other parts of these Specifications.
224.03 Construction Requirements.
a.General. Choice of equipment to perform the work required under this Section shall in general be that of the Contractor provided such will produce the desired results within the limits directed by the Engineer.
b.Sequence of Work. To properly evaluate the limits of the corrective treatment required to effectively bridge a lime sink, the work shall be performed in the following sequence: Exploration of the lime sink area to locate the sink hole will be as directed by the Engineer; the size of the exploratory excavation shall be kept to a minimum. The sink hole, once located, shall be enlarged to the size and depth as directed by the Engineer to expose the solution cavity. After exposing the solution cavity, it shall be plugged with a rock boulder or a plug of suitable material capable of sealing the cavity yet maintaining proper ground water drainage. After installation of the plug, a strata of selected material that will permit proper ground water drainage shall be placed to a depth of approximately one-half the excavated hole depth, but not in excess of 7 feet {2 m}. The material used for this "Special Backfill" shall be of the type shown on the plans or directed. This special backfill material shall be placed in approximately equal uniform layers, not to exceed 2 feet {600 mm} in thickness, for the depth specified or directed. No compaction or density tests will be required. The remainder of the backfill for the lime sink excavation shall then be constructed of Unclassified Excavation, Borrow, or other designated material in accordance with the requirements for Embankments as required in Section 210. In the event a sink hole occurs in the immediate vicinity of the finished subgrade elevation, the use of concrete seal may be directed. In such case, the same process noted before shall be used up to the bottom elevation designated for the concrete seal. The concrete shall be Class A concrete of the thickness shown on the plans or as directed. Steel reinforcement, if required, will be as provided by the plans or as directed.
224.04 Method of Measurement.
a.Lime Sink Excavation. Measurement for this item will be in cubic yards {cubic meters} computed from field measurements of the material actually removed as directed.
b.Special Backfill for Lime Sink. Special backfill material, furnished as directed, will be measured in cubic yards {cubic meters}, loose measurement, or per ton {metric ton} in the transporting vehicle. The boulder or plug will be measured for payment as an estimated number of cubic yards {cubic meters} or an estimated tonnage {metric tonnage}.
c.Concrete Seal. When the use of a concrete seal is ordered, measurement will be made in cubic yards {cubic meters} computed from field measurement of concrete actually placed. All reinforcement required will be measured in accordance with Section 502, Steel Reinforcement. SECTION 230 ROADBED PROCESSING
224.05 Basis of Payment.
a.Unit Price Coverage.
1.The accepted volume of Lime Sink Excavation, measured as provided above, will be paid for at the contract unit price bid which shall be payment in full for the removal and disposal of the excavated material in a manner satisfactory to the Engineer, and for all equipment, tools, labor, and incidentals necessary to complete the work in accordance with the plans and this Specification.
2.The accepted volume of Special Backfill material, including the plug, measured as noted above in accordance with the method provided in the contract (cubic yard {cubic meter} or ton {metric ton}), will be paid for at the contract unit price bid which shall be payment in full for the item complete in place and shall include all costs incidental to procurement, excavating, hauling, dumping, spreading, and formation of the embankment and for all equipment, tools, labor, and incidentals necessary to complete the work in accordance with the plans and these Specifications.
3.The accepted volume of concrete for the seal, measured as noted above, will be paid for at the contract unit price bid which shall be full compensation for the preparation of the concrete bed, furnishing of all materials, mixing, hauling and placing, and for all labor, tools, equipment, and incidentals necessary to complete the item. Steel reinforcement will be paid for under Item 502, Steel Reinforcement.
b.Payment will be made under Item No.: 224-A Lime Sink Excavation - per cubic yard {cubic meter} 224-B Special Backfill for Lime Sink, Type Material - per cubic yard {cubic meter} 224-C Special Backfill for Lime Sink, Type Material - per ton {metric ton} 224-D Concrete Seal for Lime Sink - per cubic yard {cubic meter} SECTION 230 ROADBED PROCESSING
230.01 Description.
This Section shall cover the operations required to provide a satisfactory roadbed for receiving a base or pavement structure layer. Roadbeds will be of two types: (1) Improved Roadbeds when designated on the plans or (2) Modified Roadbed whenever Improved Roadbed is not specified on the plans. This Section covers the additional work above that required for regular earthwork construction specified under Section 210. Improved Roadbed shall require the top layer, or layers, of the graded earth of both cuts and fills, with the upper surface at subgrade elevation, to be constructed of selected material from Unclassified Excavation or Borrow. Each layer of the plan designated thickness shall be processed and compacted as specified in Article 230.03. Modified Roadbed shall require that the existing top layer of the graded earth of both cuts and fills below subgrade elevation be processed and compacted as specified in Article 230.03. This procedure is to establish a proper subgrade before constructing an overlying layer.
230.02 Materials.
a.Improved Roadbed Materials from Unclassified Excavation. Materials for Improved Roadbed that are from Unclassified Excavation shall be the best available materials, as determined by the Engineer, meeting the requirements given in Item 210.02(c)2.
b.Improved Roadbed Materials from Borrow Excavation. Materials for Improved Roadbed that are from Borrow Excavation shall meet the requirements given in Item 210.02(c)2.
230.03 Construction Requirements.
a.General. Choice of equipment to perform the work required under this Section shall, in general, be that of the Contractor, provided such produces the desired results. Construction of the roadbed shall be conducted so that earth or other material does not prevent immediate drainage of water to the side ditches. SECTION 230 ROADBED PROCESSING
b.Improved Roadbed.
1.Preparation of Roadbed. Both cuts and fills shall be graded to the elevation designated on the plans, below subgrade elevation in accordance with the requirements of Section 210, and to the Typical Section shown on the plans or directed. No selected roadbed material shall be placed until the graded earth surface is satisfactory to grade, cross section, and density in accordance with Section 210. If a contract requires an improved roadbed to be placed on an earth surface constructed under a previous contract, the surface shall be repaired to the extent directed. Additional material required will be paid for under the proper classification of the material directed to be used.
2.Placement and Processing of Selected Roadbed Material. After preparation as noted above, the roadbed shall be brought up to subgrade elevation in maximum 6 inch {150 mm} layers using the designated selected materials. Each of these layers, except those specified in this Subarticle, shall be processed, utilizing the item Roadbed Processing, by thoroughly pulverizing, blending, and mixing until uniform in texture and appearance, insofar as practical, as determined by the Engineer. Each layer shall be compacted to the density noted in Subarticle 230.03(d) for improved roadbed layers. The section and density shall be maintained until placement of the next overlying improved roadbed, subbase, base, or other layer.
3.Special Conditions. In grading contracts which do not provide a subbase, base, or other overlying layer, the upper improved roadbed layer will not be processed as outlined above for Roadbed Processing, but shall be brought to the required elevation, typical section, and density, that specified in Subarticle 230.03(d). The required section shall be maintained until final acceptance; however, maintenance of the density will not be required.
c.Modified Roadbed.
1.Preparation of Roadbed. The graded earth shall have been constructed to subgrade elevation in accordance with Section 210 or may, by previous contract, have been constructed as an improved roadbed. No roadbed shall be processed, as outlined in this Subarticle, until the graded earth surface is satisfactory to elevation and typical section. If a contract requires roadbed processing on an earth surface constructed under a previous contract, the surface shall be repaired to the extent directed. Additional material required will be paid for under the proper classification of the material directed to be used.
2.Processing of the Roadbed Material. After preparation as noted above, at least the top six (6) inch {150 mm}layer, except for those layers specified in this Subarticle, of the entire width of both cuts and fills shall be processed, utilizing the item Roadbed Processing, by thoroughly pulverizing, blending, and mixing until uniform in texture and appearance, insofar as practical, as determined by the Engineer. Each layer shall be compacted to the density noted in Subarticle 230.03(d) for modified roadbed. The section and density shall be maintained until placement of the next overlying subbase, base, or other layer.
3.Special Conditions. The work described for a modified roadbed is for the establishment of a proper subgrade before constructing an overlying subbase, base, or pavement layer or temporary surfacing. In grading contracts which do not provide for one of the above, the upper 6 inch {150 mm} layer of subgrade will not be processed as outlined above for Roadbed Processing, but shall be brought to the required elevation, typical section, and density, that specified in Section 210. The required section shall be maintained until final acceptance; however, maintenance of the density will not be required. In addition to the above, Roadbed Processing will not be required for those roadbeds which are to be stabilized as specified in Section 231 or Section 232.
d.Density Requirements. Density for the layers of both improved and modified roadbed shall be as specified in Section 306 for each type layer. SECTION 230 ROADBED PROCESSING
e.Surface Requirements. The graded earth surface and the finished subgrade surface, after being properly compacted, shall be checked by the use of blue-tops, strings, and template and all portions not within the following tolerances shall be corrected: Variations from the designated grade up to plus 1/2 inch {13 mm} or minus 1 inch {25 mm} will be allowed provided the variation does not increase or decrease more than 1/2 inch {13 mm} in 100 feet {40 m}; however, at bridge structures a plus tolerance will require additional fine grading to prepare a suitable grade tie. The finished surface shall not vary at any point more than 1/2 inch {13 mm} in any 25 foot {7.5 m} section from a taut string applied parallel to the surface and the roadbed centerline, or more than 1/2 inch {13 mm} from a template placed at right angles to the roadbed centerline. The template shall be of a rigid frame, adjustable metal type, accurately set, and at least as long as the width of roadbed being checked up to 30 feet {9 m}. Additional widths may be checked by the use of string and level. The Contractor shall furnish template, string, and necessary personnel to handle same under the direction of the Engineer. No subbase or other layer shall be placed on the roadbed until it meets specified requirements for alignment, grades, cross section, and density. Where a Permeable Asphalt Treated Base (PATB) layer is to be placed (Pay Item 327-E), the finished subgrade elevations shall not vary from design by more than 0.03 feet {10mm} based on rod and level survey readings taken at a minimum of five locations across each lane (edge, outer wheel path, midlane, inner wheel path, and inside edge of lane) at longitudinal intervals not greater than 50 feet {15 m}. Surface irregularities shall not exceed 1/4 inch {7 mm} between two points longitudinally or transversely using a 10-foot {3 m} straightedge.
f.Protection and Maintenance of Roadbed. The Contractor shall be responsible for the protection and maintenance of any existing roadbed or any roadbed constructed during the contract. The roadbed shall be maintained free from ruts and other depressions, in a smooth and compacted condition, and true to lines and grades. Any of the Contractor's hauling and other equipment used in such a way as to cause excessive rutting or raveling of the roadbed material shall either be removed from the work or suitable runways shall be provided to prevent rutting. No payment will be made for the protection and maintenance of the roadbed, such being considered incidental to the work. However, if a contract requires an improved roadbed to be placed on an earth surface constructed under a previous contract, the surface shall be repaired to the extent directed under the requirements of Section 210.
230.04 Method of Measurement.
Measurement and payment for the materials used in the construction of improved roadbed and modified roadbed will be at the contract unit price for unclassified or Borrow Excavation as provided in the contract. No separate measurement will be made for reshaping of a roadbed constructed under a previous contract, such being considered incidental to the work covered by this Section; however, any additional material required to restore the roadbed to the typical section will be measured and paid for under the appropriate item of material ordered used.
a.Item 230-A. Measurement for the item of Roadbed Processing (which is the additional processing over and above that normally required by Section 210) will be in 100 foot {100 m} roadbed stations for each layer processed. The length of roadbed stationing will be in 100 foot {100 m} stations and fractions thereof to the nearest foot {meter} of any main roadbed in accordance with the following: on each roadbed separately for divided highways having more than one roadbed; on each half of a roadbed of a four lane facility constructed with a positive divider between opposing traffic; on ramps; on frontage, connecting, and crossing roads; and on widening work each roadbed as defined above whether widening is on one side or both sides. No measurement will be made for increased widths, lanes, turnouts, spurs, or crossovers when shown on the plans or for variations in widths due to changes in slopes. For additional areas over those shown on the plans, measurement will be allowed in the ratio of the increase in width to the standard width shown on the plans. The total measurement shall be the sum of the lengths measured along the center of the main roadbed or along each separate roadbed of divided highways, plus the measured ramps from where the ramp centerline crosses the edge of shoulders, plus (if any) the lengths of crossroads, connecting roads, and frontage roads. The length of modified roadbed or improved roadbed constructed under a previous contract and actually reprocessed will be measured for payment.
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Source: 2026 Standard Specifications for Highway Construction, 2026 Edition. Pages 149–152 of 826. View official source ↗