Grouted Rock Grouted rock consists of rocks bound together by cement grout filled voids to form a greater mass that can resist pressures of water and prevent the rocks from being displaced. It permits the utilization of smaller rock and can reduce the quantity of rock required (US Department of Agriculture Soil Conservation Service, 1992). Grouting is generally used to reduce erosive leakage, excessive uplift pressure, and high water losses through the foundation rock. Proper drainage is critical to the long-term performance of grouted rock. Therefore, weep holes should be provided in the revetment to relieve hydrostatic pressure buildup behind the grout surface. (ODOT Hydraulic Manual, 2014).
Flows: Grouted rock prevents the rocks from being displaced so it can withstand high flow velocities and boundary shear stress.
Cost Benefit: Grouted rock is a good alternative for channel lining and is less expensive than reinforced concrete and gabion liners. This alternative would be expected to have a long-term beneficial effect on the hydrology of the river downstream of the diversion (URS, 2003).
Sediment Flow: Grouted rock offers resistance to erosion. During construction, a temporary increase in sediment would be expected in the stream channel and banks (URS, 2003). Sediment flow is at a disadvantage because a grouted structure will stop restrict the sediment's movement through the rocks in the way it currently moves through the pervious structures. This will cause sediment build up on the upstream side of the diversion and could cause cutting downstream. Overtime, sediment will need to flushed out so multiple sluice gates should be present on the structure. If a sluice gate in not provided or is not flushed regularly, sediment will have to be removed manually or it could cause a sediment plug.
Durability: Grouted rock is rigid but it is not extremely strong. Failure in a small portion of the diversion could lead to failure of a larger section. The application of grouted rock is not a long lasting solution. Due to forces from the water and expansive soils, the rocks could break apart after a few years. Cracking will be present and may enhance weathering.
Maintenance: Maintenance will be required if grouted rocks are undercut or fail.
FishPassage: Fish passage will be dependent on the slope. The general rule is a slope of 20:1 on the downstream end to allow for passage.