3-8 Section 303. Open-Graded Drainage Course
303.01. Description This work consists of constructing an OGDC on a surface approved by the Engineer. 303.02. Materials Provide materials in accordance with the following section : Open-Graded Aggregate 4G ................................................................. 902 303.03. Construction
A.Preparation. Provide and install the separation treatment, as specified on the plans, between the OGDC and the subbase or subgrade.
B.Placement and Compaction . Provide a ticket with each load stating the following information:
1.Project number ;
2.Aggregate source;
3.Aggregate series ;
4.Date;
5.Time ;
6.Truck identifier number ;
7.Supplier name; and
8.Type of aggregate approval . If the contract requires payment by weight, ensure the ticket includes gross weight, tare weight, and net weight to the nearest 100 pounds. Determine the truck tare weight at least once daily. If the contract does not require payment by weight, the Engineer may accept written documentation instead of tickets. Written documentation must identify the pay item of the material and include all of the information listed above except time and truck identifier number. Place OGDC in accordance with subsection 302.03. When additional thickness is being used for equipment travel, the layer must not exceed 10 inches. Provide a finished surface that is smooth and uniform in appearance and free of loose aggregate, holes, depressions, ruts , and ridges. Do not place OGDC on frozen, soft, unstable, or rutted subgrade, subbase, or aggregate base. Do not rut or distort the underlying layer during spreading. MDOT Standard Specifications for Construction Section 303
3-9 9. Control Strip . Construct a 600- to 1,000-foot -long control strip at the
start of the spreading operation to establish a construction method for placement and compaction that does not cause degradation or segregation detrimental to base stability and drainability. The Engineer will obtain an in-place sample from the control strip after compaction and final trimming and test for LBW and gradation (Table 902-1). In addition, the density will be verified to meet the minimum 95% of the maximum unit weight with the moisture content not greater than optimum. Do not place OGDC beyond the limits of the control strip until an acceptable placement method is determined and verified by test results. When contiguous plan quantities are less than 10,000 square yards, the Engineer may wai ve the control strip requirement , but the minimum density requirement would still apply.
C.Equipment Travel . Place at least 2 inches more than the finished thickness of the OGDC layer on the grade prior to use for equipment travel. All costs associated with placement of the additional aggregate and removal or trimming thereof will be borne by the Contractor. Stockpile and retest any removed OGDC aggregate to verify that the aggregate meets the grading requirements in Table 902-1 for the intended item of use on this or any Department project. Where no lateral space exists due to permanent physical obstructions, maint enance of traffic requirements , or other unavoidable conditions, deliver ing material to the paver by equipment traveling on the OGDC will be permit ted provided that:
1.The specified in-place OGDC gradation is maintained and no other damage to the OGDC, subbase, or subgrade occurs; and
2.Varied truck routes or paths are used to minimize the potential for damage to the OGDC. Correct all observed damage to the OGDC layer, subbase, or subgrade resulting from equipment travel according to subsection 303.03.B. Protect the underdrain system from damage at all times and locations.
D.Testing and Acceptance. The Engineer will determine the preferred sampling location and provide a written description to the Contractor at the pre-construction meeting and at the pre- bid meeting, if applicable. The Engineer may designate a revised preferred sampling location if circumstances change during construction. Provide mechanical methods to assist the Engineer with obtaining samples from the grade when layer thicknesses are greater than 4 inches. Make allowance for and be solely MDOT Standard Specifications for Construction Section 303
3-10 responsible for degradation and segregation during shipment, placement ,
and compaction of the OGDC material.
1.Daily Verification . The Engineer will verify compactive effort or stability by one of the following options :
a.Proof Roll . Complete a proof roll using equipment approved by the Engineer. The Engineer will witness and document the proof roll a nd determine the proper course of action to correct any observed rutting or displacement ; or
b.Density Control Testing . Perform in -place density control testing to verify that at least 95% of the maximum unit weight with a moisture content of not greater than optimum has been achieved for each individual layer. The Engineer may approve modifications to the construction method established during the construction of the control strip if the in-place gradation is not compromised and the compactive effort or stability can be verified. If the Engineer waives the control strip, in-place field testing is required to verify that placement and compaction methods are achieving at least 95% of the maximum unit weight with the moisture content not greater than optimum for each individual layer. In-place testing frequency will be the same as listed for a ggregate base courses in MDOT’s Density Testing and Inspection Manual .
2.Notification Require ments. Notify the Engineer if any of the following occur and construct a new 600- to 1,000-foot -long control strip:
a.Changes in placement procedures including layer thickness;
b.Equipment used in the placement of the previous control strip is removed from service or replaced; or
c.A switch in the material source or blending of multiple sources. The new control strip must be tested and approved by the Engineer prior to the resumption of OGDC placement.
3.Prior to Placement Acceptance Criteria. Material not meeting the requirements in Table 902-1 will not be permitted to be placed on the grade.
4.Compacted -In-Place Acceptance Criteria. The Engineer may sample and test the compacted-in -place OGDC for final acceptance. If segregation, contamination, or excessive degradation is observed, the Engineer will provide written notification of the need for in-place testing. The notification will also define the limits of the area subject to MDOT Standard Specifications for Construction Section 303
3-11 testing, not to exceed 500 feet in length for each occurrence.
Discon tinue OGDC placement upon receipt of the notification. Stop the paving operation at least 500 feet before the OGDC area subject to in-place acceptance testing. Do not resume OGDC placement and paving operations until directed by the Engineer. The Engineer may require the constructi on and testing of another 600- to 1,000-foot-long control strip in accordance with subsection 303.03.B.1. The Engineer will sample from within the defined area. Two additional samples will be obtained, one from each a djacent side of the defined area for in-place acceptance testing. Each test area will have a maximum length of 500 feet. All three acceptance tests will be completed within 48 hours of the time the samples were obtained from the project. The in-place aggre gate gradation for any test area, including control strips, must conform to the grading requirement in Table 902-1. Test results outside these gradation limits will be subject to pay adjustment or will be required to be removed and replaced in accordance w ith subsection 303.04. 303.04. Measurement and Payment Pay Item Pay Unit Open-Graded Dr Cse, __ inch ....................................................... Square Yard Open-Graded Dr Cse, CIP ............................................................... Cubic Yard Open-Graded Dr Cse, Shld ................................................... Square Yard, Ton
A.General . The unit prices for the OGDC pay items include furnishing the crushed aggregate; placing, spreading, shaping, compacting, trimming, protecting the underdrain system and all costs associated with constructing control strips, corrective actions necessary to rectify degradation and segregation. The open-graded drainage course pay items are subject to the pay adjustments described herein.
B.Open -Graded Dr Cse, __ inch . The Engineer will measure Open -Graded Dr Cse, __ inch by width and length for the specified depth as shown on the plans.
C.Open -Graded Dr Cse, CIP . The Engineer will measure Open -Graded Dr Cse, CIP based on plan quantity by volume in cubic yards. The plan quantity will include all of the OGDC below the paved shoulder and median to the top of the proposed subbase, as defined by the plan typical sections . If the Engineer determines that it is not feasible to determine quantities based on plan quantities, the measurement for Open -Graded Dr Cse, CIP will be based on the staked-section method as described for roadway earthwork volumes in subsection 205.04.A . MDOT Standard Specifications for Construction Section 303
3-12 D. Open -Graded Dr Cse, Shld . The Engineer will determine the moisture
content and pay weights as specified in section 109. If the contract requires weight measurement, the Engineer will measure Open -Graded Dr Cse, Shld by the scale weight, including additives, at a moisture content no greater than 8% . The Engineer will perform moisture tests at the start of weighing operations and when construction operations, weather conditions, or other causes may change the moisture content of the material. If tests indica te a moisture content greater than 8%, the Engineer will deduct the weight of the excess moisture from the scale weight of the aggregate until moisture tests indicate the moisture content is no greater than 8% . If the contract requires area measurement, t he Engineer will measure Open -Graded Dr Cse, Shld by width and length as shown on the plans.
E.Pay Adjustment Computation . Pay adjustments are not cumulative; only the largest of the computed sieve or LBW pay adjustments will be applied. All pay adjustments are negative. Pay adjustments are computed using the following formula: Pay Adjustment = Pay Factor Reduction × (quantity) × (base price) Where: Pay Factor Reduction = value shown in Table 303-1 or 303 -2 as applicable (expressed as a decimal) quantity = quantity subject to adjustment base price = unit price established by the Department and shown in the contract Apply computed pay adjustments using Tables 303-1 and 303-2 for material tested in-place according to subsection 303.03.D.4. Table 303- 1: Pay Factor Reduction for In -Place OGDC Exceeding Gradation Requirements on Any Sieve ( excludes LBW) Amount Exceeding Gradation Limit(a) Pay Factor Reduction 1% 0% 2–3% 10% 4–6% 30% >6% (b)
a.As shown in Table 902-1.
b.The Engineer will require removal and replacement of the material or will apply a 50% pay factor to the material. MDOT Standard Specifications for Construction Section 303
3-13 Table 303- 2:
Pay Factor Reduction for In -Place OGDC Exceeding Loss by Washing Requirements Amount Exceeding Gradation Limit(a) Pay Factor Reduction <0.5% 0% 0.5–1.0% 20% >1.0–1.5% 30% >1.5–2.0% 40% >2.0% (b)
a.As shown in Table 902-1.
b.Removal and replacement of the material is required.
Source: Michigan Standard Specifications for Construction, 2020 Edition. Pages 183–188 of 1,146.