§ 11.3.4. Wall Location and Layout

A.

General

The city will assume maintenance responsibility only for those walls that support roadway embankment in street right of way or support channel slopes in drainage easements. Retaining walls that support private property must be built on private property and must be privately owned and maintained. Only in special cases approved by the Director will retaining walls that support private property be allowed in public right of way. License agreements will be required for all retaining walls in the right of way that support private property.

In street right of way, a minimum of 36 inches (1 meter) of protective soil or rock cover must be provided over the upper layer or row of external structural components such as geogrid, strips, bars, tie bars or buried pre-cast units.

Utility mains and service lines must not pass through or under a retaining wall unless the utility is installed in an encasement pipe meeting the approval of the affected Utility. The encasement pipe must extend beyond the retaining wall a sufficient distance to insure that future excavation to expose the ends of the casing will not endanger any external structural component of the wall, will not threaten the stability of the wall itself and will not encroach upon any components of the wall system. For utility services, the encasement pipe must extend from the main to the property line and must be large enough to pass valves, connections, couplings and other components that are integral parts of the service.

B.

In Streets and Utility Easements

Utilities, utility appurtenances, and pavements have priority over retaining walls in street right-of-way and utility easements. As a consequence, retaining wall layout must take into account utility assignments in addition to allowing for future utility installation and future excavation for utility maintenance and repair, including mains as well as services. No component of the retaining wall that is essential to the stability of the wall or wall system (such as footings, underdrains, strips, geogrid, bars, tie bars, or buried pre-cast units) can be within the excavation / backfill zone of any utility main or service regardless of the type of utility. The wall or wall system must be stable under any scenario involving utility excavation in the excavation / backfill zone. External components of the retaining wall, such as geogrid, anchors, strips, tie bars or buried pre-cast units, which are essential to stability of the wall, cannot extend beyond the back of curb, under the street, or into utility easements unless the external components are at least 10 feet (3 meters) below the street surface and at least 3 feet (1 meter) below the deepest utility.

The distance between the street-side face of the wall and the back of curb must be such that sidewalk and ramps can be accommodated, but in no case can this distance be less than 5 feet (1.5 meters), with provisions for pedestrian and vehicular railing, as needed