North Vernon retained Lochmueller Group (Lochgroup) to review options to address flooding in four areas of the city. Lochgroup prepared a Preliminary Engineering Report and then performed design and construction administration of the improvements that utilize Best Management Practices and incorporate green solutions to drainage issues in four areas:
- City Park: Three rain gardens, along with over 500 lf of vegetated swales were built to catch a large volume of runoff from park buildings, tennis and basketball courts, and a parking lot. To construct mowable swales, workers excavated approximately 4 feet deep and installed a perforated drainage pipe. Gravel was backfilled below the swale and topped with soil and plantings.
- Shull Park: Improvements to this residential area featured installation of a rain garden and 12,000 lf of vegetated swales along roadways with underground storage of the stormwater.
- College Street: Improvements to this residential area featured a rain garden and 200 lf of vegetated swales to capture and treat runoff.
- Lincoln Avenue: Improvements to this residential area featured 2 rain gardens and more than 1,400 lf of vegetated swales.
very time the southside of Indianapolis saw as little as one inch of rain, Frog Hollow, a small neighborhood of about 150 homes, would flood. Unfortunately there was no simple answer. Frog Hollow sits on low land with the White River to the west, Highland Creek to the east, and Germania Creek to the north. When heavy rains hit, the White River rises and both creeks experience backward flow.
The city asked Lochmueller Group (Lochgroup) to help find a sustainable solution. Lochgroup proposed an alternative that reduced costs significantly from initial estimates of $5 million or more to just $1.5 million. Lochgroup’s solution also avoided the relocation of existing fiber optic lines, and reduced the impact on the receiving stream by redirecting flow from Highland Creek to a nearby stormwater detention basin and a 1-acre constructed wetland. The design partially dammed Highland Creek to allow normal flow but divert stormwater to a box culvert then to a swale leading to the stormwater basin. The design redirects 75-95% of water away from the neighborhood during the majority of rain events, protecting the residential neighborhood from flooding.
The project not only reduced flooding but the wetland also filters pollutants from the runoff and provides a pleasant green space for the neighborhood.
“This fit our mission exactly. We were helping the residents of Frog Hollow, improving water quality, providing a sustainable green solution that incorporated wetlands and wildlife habitat considerations along with conserving taxpayer resources”
—Steve Nielsen, former Manager DPW’s Stormwater & Wastewater Programs
Lochgroup designed a hybrid ditch as a stormwater drainage system for a neighborhood that is very flat and prone to stormwater ponding and minor flooding. A traditional storm sewer would have been difficult to design and construct because of the existing side ditch infrastructure and flat topography.
A challenging aspect was to maintain the existing parking for the residents while creating areas for surface water infiltration. Design included hybrid ditches, which allow stormwater to seep through soil, sand, and stone layer to a perforated pipe. Parking areas are outlined in permeable parking pavers and then filled with open graded stone.