Chapter 8 — Contracting Methods & Specifications¶
8.1 Policy development¶
An agency that intends to use MSE walls and reinforced slopes repeatedly needs a policy: which systems are approved, what design criteria apply, who designs the structure (the agency or the supplier), and how the work is specified and paid for. Without a policy, every project becomes a negotiation.
8.2 System or component approvals¶
Because many MSE systems are proprietary, agencies approve systems or components in advance, on the basis of the supplier's design methods, test data, and performance record. Approval transfers part of the design responsibility to the supplier and lets the agency specify a class of system rather than a single product.
8.3 Design and performance criteria¶
The agency states the criteria the structure must meet — geometry, loads, factors of safety, allowable deformation, design life, and durability — so that any approved system can be shown to comply.
8.4 Agency or supplier design¶
The manual distinguishes two design responsibilities:
Agency design — the agency designs the structure and specifies the reinforcement and facing explicitly. The design package includes:
- Plan and elevation sheets — geometry, limits, and layout.
- Facing/panel details — panel or block type, dimensions, and connections.
- Drainage facilities / special details — outlets, filters, and terminations.
- Design computations — the external, internal, and global stability checks.
- Geotechnical report — the soil parameters and the basis of design.
- Construction specifications — the material and workmanship requirements.
Supplier (end-result) design — the agency specifies the result (geometry, performance, and design criteria) and the supplier designs and warrants the system.
8.5 End-result design approach¶
In end-result (performance) contracting, the agency specifies:
- Geometric requirements — wall lines, heights, and limits.
- Geotechnical requirements — the design soil parameters and the fill specification.
- Structural and design requirements — the loads, factors of safety, and design-life/durability rules.
- Performance requirements — the allowable deformation, differential settlement, and any monitoring obligations.
The supplier then chooses a system and provides the design, with the agency reviewing and approving it.
8.6 Standard designs¶
MSEW standard designs. Pre-worked wall geometries and reinforcement layouts for common heights and conditions (from Chapter 4).
RSS standard designs. Equivalent pre-worked reinforced-slope designs (from Chapter 6).
Standard designs let routine structures be built without a bespoke design, and give the contractor a known quantity to price.
8.7 Review and approvals¶
The manual describes the review process: submittal requirements, the technical review of the supplier's design, and the approvals needed before construction.
8.8 Construction specifications and special provisions for MSEW and RSS¶
The manual provides model specification language — material requirements, construction procedures, tolerances, and measurement-and-payment provisions — that an agency can adapt.
8.9–8.12 Guide specifications¶
The manual's guide specifications cover:
- MSE walls with segmental precast concrete facings — panels, connections, bearing pads, and joint materials.
- Concrete modular block (MBW) facing and unit fill — block units, pins or connectors, and the unit fill behind the facing.
- Geosynthetic reinforcement materials — polymer type, strength, reduction factors, and testing requirements.
- Reinforced slope systems — RSS construction (agency design), erosion control mats or blankets, geosynthetic drainage composites, and geosynthetic reinforced soil slope systems.
8.13 Key takeaways¶
- Decide who designs — agency or supplier — before writing the contract; it determines the whole submittal and review process.
- Approve systems or components in advance so the contract can specify a class of system, not a single proprietary product.
- Standard designs convert routine walls and slopes into known quantities.
- The guide specifications are the manual's most directly reusable output — adapt them, do not rewrite them.