Street Use Shoring Review

Shoring is a means of supporting the earth in a trench or vertical cut for construction or other activity. There are many types of shoring techniques for earth reinforcement or support. The picture above shows a vertical cut wall using soldier piles, shotcrete and tiebacks. Properly installed shoring is critical for maintaining the structural integrity of the adjacent roadway and underground utility infrastructure.

The shoring review is one of the review locations for DPD. In order to become more customer friendly, DPD and SDOT combined the shoring review as part of the building permit review locations to allow for a one-stop permit.

The shoring review location is initiated at DPD. At the point of intake, the intake reviewer assigns all necessary review locations for a particular project. Street Use Shoring review is initiated for any proposed excavation that would be greater than three feet deep immediately adjacent to any given public right-of-way. Shoring review would also occur for any proposed excavation within an imaginary 1H:1V slope (a one-foot horizontal to one-foot vertical relationship, or a 45-degree line). This point is taken from the existing grade at the public/private property line and then descends down to within private property. (Please refer to Figure 1 below for clarity). Once Shoring is assigned as a review location, a plan is routed to Street Use for review. DPD will not issue a building permit until Shoring is signed off in the review location.

Figure 1

The shoring components may include cantilever soldier piles, soldier piles and tiebacks, soil nail walls, slope cuts or a combination of the aforementioned. The system that would be approved depends on site specific constraints and public need considerations. Our shoring reviewers always encourage and welcome pre-design meetings. To better facilitate the review process, a direct submittal to the shoring reviewer would be beneficial. The direct submittal shall include the following:

1. Soils report
2. Shoring plan
3. Building foundation plan
4. Site survey

The City of Seattle allows for components of the temporary shoring system to be placed in the public right of way. The city will allow temporary anchorage such as soil nails and tiebacks to be installed in the public right of way under an indemnity agreement. The soldier piles may be placed in the public right of way as long as they are temporary in function and the permanent building does not rely on their presence. The augur hole may extend 24" into the right of way and the steel soldier pile component, 21". (Please refer to Figure 2 below for clarity). Prior to the end of the project, the components of the temporary shoring system that are located in the public right of way will need to be removed as follows:

Tiebacks must be detensioned.

Soldier piles, lagging and any concrete encasement must be cut and removed to a point that is 4 feet below grade.

Figure 2

Typically a designer would size the tiebacks and soil nails to be fully contained within the width of any given public right of way. If the tiebacks or soil nails extend pass the public right of way and underneath a private property, an easement from the private property owner(s) is required prior to shoring sign off.