Decision Matrix

The following are the categories that each location was scored on and its associated weight for the decision matrix.

Stormwater mitigation potential - Weight: 5

Presence of existing infrastructure - Weight: 2

Presence of existing landscaping/vegetation - Weight: 2 

Ease of access for construction and maintenance - Weight: 1
Visibility - Weight: 1

Location Alternatives

The top 5 locations, whose decision matrix results can be seen below, were sent to the project client for review. With her input, location S-22 was selected due to the existance of flooding and erosion on site.

Final Design

Below are the plan and profile view details of the proposed design.

The team designed a vegetated swale that follows the path of the existing gully. The swale slows and spreads the stormwater, allowing it to infiltrate into the ground below. Gravel riprap will be utilized for upstream channel stabilization and energy dispersion, and a rock drop structure will be installed at the start on the swale to drop the channel elevation, allowing for a 1% slope downstream as required by the City of Flagstaff.

Vegetated Swale Detail - Cross Section

Cost of Construction

The anticipated cost to implement this project is $2,054.52.

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