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RomanPisa - Installation Instructions

The following are the basic steps involved in constructing a conventional (non-geogrid reinforced) RomanPisa Segmental Retaining Wall. These steps are to be used in conjunction with all relevant details provided in the Details section of the Complete Installation Guide.


Step 1 - Plan:
With your final design in hand, begin to establish the wall location and proposed grades. Locate all utilities and contact local utility companies before digging. Mark a line where the front of the wall will be placed, keeping in mind the 3/4" (19 mm) setback per course.

Step 2 - Excavate:
Excavate a trench down to the foundation grades specified in the design. The front of the trench should be 6" (150mm) from the planned face of the block. The trench should be a minimum of 30" (750mm) wide (front to back) and 12" (304mm) deep. This depth assumes one unit is buried (unit height of 6" [152mm]) plus the compacted granular base minimum depth of 6" (150mm). As wall height increases, depth of embedment also increases, normally about 10% of the wall height. Greater embedment depths may be required to account for slopes more than 3H:1V in front of the wall, scour protection in water applications, global stability, or as specified in the design. The rear 6" (150mm) of the trench is excavated to account for the drainage layer. Excavations should be conducted in accordance with local codes under direction of the CE.

Step 3 - Verify Foundation Subgrade:
Once the foundation trench has been excavated to the specified elevations, the native foundation soil must be checked by the CE. The foundation soil must have the required allowable bearing capacity specified in the design.

Step 4 - Prepare the Compacted Granular Base:
Start the base at the lowest elevation of the wall. The base should be composed of well-graded, free-draining (less than 8% fines), angular granular material, and compacted to a minimum of 98% Standard Product Density (SPD). The minimum base thickness is 6" (150mm) or as required by the CE to reach competent founding soil. A layer of unreinforced concrete (2" [50mm] thick) may be placed on top of the of the granular material to provide a durable levelling surface for the base course. At the direction of the CE, geotextile might be required under the granular base. The minimum base dimensions are 24" (600mm) wide (front to back) and 6" (150mm) deep. The additional 6" (150mm) trench width allows for the placement of the drain.

Step 5 - Step the Base:
When the grade in front of the wall slopes up or down, the base must be stepped to compensate. Working out the stepped base as the wall steps up in elevation, the foundation steps must be located to ensure the minimum embedment is achieved. The height of each step is 6" (150mm) the height of 1 course. The 3/4" (19mm) offset must be accounted for at each step.

Step 6 - Place Filter Cloth:
Lay the approved filter fabric (geotextile) along the bottom of the rear of the trench and extend up the exposed excavation to the proposed wall height. Leave adequate material at the top to fold back towards the wall (completely containing the drainage material). Stake the filter cloth against the slope during construction.

Step 7 - Place the Drain:
Various options for drain placement may exist, depending on how the pipe is to be outlet (refer to Details Drainage in the Complete Installation Guide). The drain may be outlet through the wall face or connected to a positive outlet (sewer). The drainage system is extremely important and outlets must be planned prior to construction. In the case of connecting to a positive outlet, the drain should be placed at the lowest possible elevation and sloped at a minimum of 2%. At the rear of the base, allow the granular material to slope down on the sides towards the drain trench. In the 6" (150mm) area behind the base, place the approved drain tile (perforated drain with filter sock) on top of the filter cloth and minimal granular coverage.

Step 8 - Place the First Course:
Split units apart using a chisel and hammer if not already pre-split by manufacturer. Position a level string to mark location of the back of the first course (should be 12" [300mm] from the proposed wall face). Place the first course of Pisa2/RomanPisa units side-by-side (touching) on the granular base. Ensure units are level front to back and left to right. Extra care should be taken at this stage as it is critical for accurate alignment.

Step 9 - Stack Units:
Sweep top of underlying course and stack next course in a running bond pattern so that middle of the unit is above the joint between adjacent blocks below (4" [100mm] offset). Continue stacking courses to a maximum of 4 courses (24" [600mm]) before backfilling.

Step 10 - Backfill Drainage Material:
A free-draining, 3/4" (19mm) clear stone drainage material is placed immediately behind the wall facing and compacted with a light manual tamper. The drainage layer must be a minimum of 12" (300mm) thick and protected from the native material by the filter cloth.

Step 11 - Continue Stacking & Backfilling:
Continue stacking units and backfilling as described in Steps 10 & 11 until the desired height is reached, based on the design.

Step 12 - Place Coping Unit:
Either the Revers-a-Cap or the Coping Unit can be used to cap the wall, depending on the alignment of the wall and desired look. All coping units are 3" (75mm) in height. A layer of concrete adhesive must be applied to the top course in order to fix the coping units in place. Place the coping unit firmly on top of the adhesive, ensuring both surfaces are free of debris, and apply pressure to secure. Follow adhesive installation guidelines.

Step 13 - Encapsulate the Drainage Layer & Finish Grading:
Fold the excess filter fabric over the top of the drainage layer and extend up the back face of the coping unit. Ideally, place an impervious layer of soil on top of the filter fabric and compact manually, providing for the required grading and/or swales. For other treatments such as pavers, concrete, or asphalt, care must be taken to ensure that heavy compaction/paving equipment remains a minimum of 40" (1.0m) from the back of the coping unit. Slope the surface above and below the wall to ensure water will flow away from and not accumulate near the wall units. See the Details section of the Complete Installation Guide for ideas on tapering down and ending the wall.