Summary Sheet for Sec 720
Team Leader: / David Koenig
Team Members: / Mike Harms / Mike O’Malley / Kevin McLain
Keith Ferrell / Mathew Houser / Vicki Woods
Sec / Question #’s / Rationale
Title / NA / Questions don’t apply. This is the title block for the proposed specification.
720.1 / NA / This subsection is just a general description for the specification. The nine-question process does not apply.
720.2 / NA / Questions don’t apply. This is a title block for the subsection.
720.2.1 / NA / Questions don’t apply. The wording is a general reference to Division 1000 Materials. Table I lists the applicable Division 1000 sections.
720.2.2 / 1, 2, 4, 5 / Epoxy coating of concrete reinforcement on MSE Walls near roadways is recommended by AASHTO. The purpose is to protect concrete reinforcement from corrosion due to salt/water spray from adjacent roadways. Specifying this is necessary to achieve the desired result and to improve the long-term durability of the panels. Excluding this requirement for the soil reinforcement and corresponding attachments is essential for the overall safety and stability of the wall system.
720.2.3 / 1, 4 / Specifying this is necessary to achieve the desired result and to improve the long-term durability of the panels.
720.2.4 / 4 / Provides instruction for the contractor so as to achieve the desired result.
720.2.5 / 1, 4, 5 / Specifying the requirements for the unit fill ensures that the material functions with the desired purpose. Proper function of this material is essential for the long-term durability and safety of the wall system.
720.2.6 / 1, 4, 5 / Specifying concrete requirements for the coping, top cap units, and leveling pad ensures that a consistent quality is provided and contributes to the overall safety of these elements of the wall system.
720.3 / NA / Questions don’t apply. This is a title block for the subsection.
720.3.1 / 1, 5 / Having a prequalified products list assures MoDOT that we are getting a safe wall system that adheres to AAHSTO specifications along with helping to provide quality assurance of the wall system.
720.3.2 / 1, 5 / Limiting small block wall heights to 10 feet is a precautionary measure for both safety and quality control. This limit was put in place due to several construction problems and movements of these types of walls in the past when the height exceeded 10 feet.
720.3.3 / 3, 4, 5 / Gives instruction on the submittal of plans and the expected quality of the plans so work can be completed accurately and efficiently. Also, provides a means for MoDOT to review the quality of the product.
720.3.4 / 2, 3, 4 / Places responsibility for the proper completion of the design and plans according to specifications on the contractor. Absolves MoDOT of responsibility and liability for the design, detail and computations that are submitted by the contractor.
720.3.5 / 2 / State statute for signing and sealing. Chapter 327, RSMo.
720.3.6 / 1, 4, 5 / MSE walls shall be designed according to AASHTO specifications. The section provides the wall manufacturer with instruction along with providing assurance to MoDOT that the wall design is based on current accepted design practice.
720.3.7 / 1, 2, 4 / Distinguishes who is responsible for what part of the design. This is essential for safety and liability reasons. The sentence is already in AASHTO, but in this case, it should be reemphasized in the specification for the reasons as described above.
720.4 / NA / Questions don’t apply. This is a title block for the subsection.
720.4.1 / NA / Questions don’t apply. This is a title block for the subsection.
720.4.1.1 / 1, 4, 5 / The unit fill helps to provide proper drainage for the wall system and helps to provide resistance to lateral movement of the wall system. Proper placement of this material helps to contribute to the overall long-term stability and safety of the wall system.
720.4.1.2 / 1, 4, 5 / Instructions are provided to ensure that the proper result is achieved. These pre-cast units need to be properly secured to the wall facing panels to ensure that they do not fall off and cause safety problems and to secure the units against vandalism. Additionally, some manufacturers may treat the top courses as a grade-beam or bond-beam.
720.4.2 / NA / Questions don’t apply. This is a title block for the subsection.
720.4.2.1 / 4, 5 / Instructions are provided to achieve the desired results and for quality assurance. A filter cloth is needed to prevent fines from leaving the backfill.
720.4.2.2 / 4, 5 / Instructions are provided to achieve the desired results and for quality assurance. Coping is needed for structural integrity. Joints are needed to control cracking.
720.4.3 / 4, 5 / Instructions are provided to achieve the desired results and for quality assurance. Proper drainage is needed to provide structural integrity.
720.4.4 / 4, 5 / Instructions are provided to achieve the desired results and for quality assurance. A proper foundation is needed to provide structural integrity.
720.4.5 / 4, 5 / Instructions are provided to achieve the desired results and for quality assurance. A leveling pad is needed to ensure proper fit of wall panels.
720.4.6 / 4, 5 / Instructions are provided to achieve the desired results and for quality assurance. A proper batter is needed so that the wall system is vertical when completed.
720.4.7 / NA / Questions don’t apply. This is a title block for the subsection.
720.4.7.1 / 4, 5 / Method of placement for backfill must be included to prevent damage or misalignment of wall or wall facing materials. These procedures are necessary to achieve desired results.
720.4.7.2 / 4, 5 / Compaction requirements specified are necessary to prevent damage to wall and wall facing materials and achieve stability. Procedural specification for compaction of coarse graded material is necessary for desired results. Sheepsfoot rollers could cause damage to soil reinforcement and should not be used for quality assurance.
720.4.7.3 / 4 / Procedural specification necessary for proper placement of granular backfill to achieve desired results for stability.
720.4.8 / NA / Questions don’t apply. This is a title block for the subsection.
720.4.8.1 / 5 / The specification sets dimensional tolerances, which help to assure a quality product.
720.4.8.2 / 5 / The specification defines how alignment shall be measured, which is essential to quality assurance.
720.4.9 / 3 / The specification requirement to have a technical advisor is a convenience to MoDOT and the contractor, should questions arise.
720.5 / NA / Questions don’t apply. This is a title block for the subsection.
720.5.1 / 3, 7, 9 / The existing specification is vital to establish a benchmark for pay for all parties involved. It is possible to measure the final wall surface area to determine how much wall was built. The final measurement will be inexpensive.
720.5.2 / 3, 4, 7, 9 / This section is important to satisfy the contractor if significant additional work is required that was not in the bid documents.
720.5.3 / 3, 4, 7, 9 / This specification reduces the separate line items on a bid for both MoDOT’s and the contractor’s convenience. It is essential to reduce “double dipping” by the contractor on bidding the wall installation and the measurement will be cost efficient.
720.6 / 3 / This specification is essential for MoDOT’s convenience in determining the final pay amount.