Comparison of stormwater management in a karst terrane in Springfield, Missouri—case histories

摘要

Control of stormwater in sinkhole areas ofSpringfield, MO has involved the utilization of several standardapproaches: concrete-lined channels draining into sinkholes;installation of drainage pipes into the sinkhole "eyes" (swallowholes); filling of sinkholes; elaborate drains or pumps to removestormwater from one sinkhole and discharging into anotherdrainage basin or sinkhole; and enlargement of swallow holes byexcavation to increase drainage capacity. Past planningconsiderations and standard engineering approaches have resultedin flooding of sinkholpes and drainage areas, including residential,industrial and commercial developments. Having recognized theinadequacy of existing designs to control flooding and the need toaccommodate increased runoff from future development, the Cityof Springfield adopted an ordinance (effective 19 June 1989 andmodified in 1990 and 1993) in response to public pressure andconcerns over flooding in sinkholes and sinkhole drainage areas.Three sites were analyzed to examine the effectiveness ofcontrasting design approaches to stormwater management. Thesesites differ in vegetation, on-site/off-site considerations, andtypes of development proposed. All three sites are located withinthe East Cherry Street Sinkhole Area. The first site, a woodedtract with unmodified sinkholes was cleared and developed forresidential use. Discharge of stormwater was directed intosinkholes, and erosion control consisted of hydro-mulching andsedimentation fences in sinkhole areas. East of this location aretwo parcels which differ in removal of vegetation and off-sitedrainage relationships. Stormwater design in these sites wasadapted for modifications made to sinkholes during railroad andhighway construction several decades earlier. Sediment fencing,hydro-mulching and detention berms segment infiltration, restricterosion, retard discharge to sinkholes, and incorporate off-site considerations.Ongoing observations of stormwater behavior indicateproblems of flooding and sediment control at the western site butminimal disruptions of existing drainage patterns at the easternsites. Design calculation for the western site show adequatevolume retention in sinkholes, but different design approacheswere implemented to "soften" the impact of stormwaterdischarging into these sinkholes, allowing for minimaldisruptions in the natural drainage network. The lack ofrecognition of sinkholes as integral parts of dynamic hydrologicsystems may result in problems with on-site/off-site drainage.Standard engineering designs for stormwater detention are notappropriate for the hydraulic characteristics of the shallow karstdrainage network. While runoff characteristics.