water

South Euclid - Nine Mile Wetland / Langerdale Urban Marsh Project

A Stormwater Detention Basin Wetland Retrofit Project

Goals of project is to enhance water quality by: 1) Introducing naturally vegetated wetland areas and increasing storm water storage areas; 2) Restoring a channelized drainage way to a natural channel; and 3) Creating areas for aquatic habitat found in wetland environments.

Background:
Basin located in the Nine Mile Creek watershed that drains to Lake Erie. This watershed drainage area is 18 square miles. Located in the City of South Euclid, Ohio. The watershed has been heavily urbanized over the past century and impacted by urban runoff and habitat degradation.

The size of the site is 10.4 acres with wooded forest, four (4) small wetlands of category 1 (total 0.128 acres) and 787 lineal feet of stream (concrete channel). The basin was built in the early 1960s. The basin includes an overflow system that allows any overflow to flow directly down Langerdale Blvd. through a secondary spillway structure located inside the basin. The street itself is used as a spillway. The detention basin historically overflowed twice causing flooding on homes adjacent to the basin. The City has reports of at least 73 residents in the drainage basin that have experienced basement flooding during the two major storms in July of 1995 and July of 1999.

Solution:

- Retrofit the detention area to provide increased infiltration areas by:

  • introduction of naturally vegetated wetland areas and increased storage areas
  • restoration of a channelized drainage way to a natural channel
  • creation of areas for aquatic habitat found in wetland environments

- Increase storage of the basin to provide capacity for a five-year storm event before the secondary spillway comes into operation. Overall improvement will permit the basin to hold 50 to 100 year storm without the emergency spillway coming into operation.
The storm water retrofit includes important clean water functions.

Design Components Completed Summer 2008:

  • Removed concrete channel, modified basin inlet with plunge pool, and modified outlet structure with a trash rack. Most of the concrete was recycled offsite. The topsoil was stock piled and reused. The excavated soil was left on site and also removed offsite. An estimated 10,000 cubic yards of soil was excavated.
  • Installed 13 floodplain weirs with pools. Rock source is from Sandusky quarry. Each floodplain weir structure has a grade control rock and substrate material (angular). The grade control structure rock is boulder size limestone, roughly 2’ x 3’ x 3’ in size. The pools are mainly oblong in shape. The dimension are about 40 feet in width and 100 feet in length.

The planting materials are native to the region. Types of plants are herbaceous, shrubs, native seed and trees. Five zones were planted with a total of 13,000 native plants.

Zone 1 - Aquatic bed and open water wetland - 0.53 acre
Zone 2 - Scrub-Shrub Emergent Wetland - 0.71 acre
Zone 3 - Forested Wetland - 0.21 acre
Zone 4 - Riparian Deciduous Forest - 0.99 acre
Zone 5 - Native Mesic Meadow - 1.42 acres

Project cost/funding: South Euclid spent just under $800,000 on the project for the excavation, grading, floodweirs, and plantings. $320,000 was funded through the City and the remainder was paid for by Ohio Public Works Commission grants and loans.

Project Partners:
City of South Euclid, Biohabitats, Inc., Stephen Hovancsek and Associates, Inc., Mark Haynes Construction, Inc.