Using GIS to Inventory and Map Rapid City, South Dakota s Major Drainage Elements Jenifer Sorensen, PE, PhD FourFront Design, Inc. Dion Lowe, PE City of Rapid City Stormwater Program
Stormwater - Definition Precipitation runoff Drains into natural or manmade drainage ways In urban areas, drains into streets and storm sewers No water treatment before entering water bodies
Impacts of Changes in Runoff
Stormwater Issues Flooding risk Erosion Water Quality suspended solids, nutrients, chemicals, bugs Asset Management Environmental Impact point and nonpoint pollution sources
Ways to Manage Stormwater Traditional approach Move water through system as quickly as possible Does not control pollution Does not reduce runoff amounts Results in downstream flooding; poor water quality Integrated Systems Approach Combine preventive and control measures Minimize pollution and runoff through BMPs Manage pollution and runoff to minimize impacts Requires site planning, more natural drainage systems
Stormwater Control Control measures used to control volume and peak discharge Open channels swales Vegetative control Engineered vegetated channels Act as natural biofilter Detention cells Reduce peak discharge rates and pollution More land intensive and expensive
NPDES Phase II Stormwater Permit Rules Rapid City must comply because population > 10,000 Clean Water Act federal mandate 5 year permit up for renewal in January 2008 Permit covers: Public education and outreach Public involvement and participation Illicit discharge detection and elimination Construction site runoff control Post-construction stormwater management Pollution prevention for municipal operations
Need for GIS Project NPDES Phase II stormwater permit requirement Goal under illicit discharge detection and elimination to have storm sewer map in GIS City did not know how many elements there are and where they are located If/when funding available for construction/maintenance, can use GIS to prioritize projects HB 1125: cities now able to charge property owners storm sewer utility fees
Rapid City Drainage Basins
Rapid City Drainage Basins
Drainage Basin Design Plans Have 20 DBDPs written between 1989 and 2005 by different firms Based on hydraulic modeling Narrative descriptions of elements Schematic drawings not to scale Sub-basins of Haines Avenue DB
Map Detail Drainage Basin Design Plans
Project Tasks Read 20 Drainage Basin Design Plans Set up data fields Data creation/modification of elements Field assessment/data collection Photos of elements Data entry DBDPs Assessment
Data Fields
14 of 20 drainage basins completed Total elements in 20 plans: 909 705 channels 204 detention cells Channels: 86% (608) existing 14% (97) proposed Detention cells: 65% (133) existing 35% (71) proposed Project Status
Improvement Recommendations made in 20 DBDPs: 56%(393) Yes 44% (312) No Channel Elements
Improvement Recommendations made in 20 DBDPs: 81%(165) Yes 19% (39) No Detention Cell Elements
Outfalls for the 14 Drainage Basins Completed: Outfalls: 51 Yes 404 No
Details of Three Drainage Basins
Meade Hawthorne Drainage Basin
Meade Hawthorne Drainage Basin Existing Elements
Meade Hawthorne Drainage Basin MH241
Meade Hawthorne Drainage Basin MH49
Meade Hawthorne Drainage Basin MH41
Meade Hawthorne Drainage Basin MH13
County Heights Drainage Basin
County Heights Drainage Basin CH100
CH15 County Heights Drainage Basin
CH102 County Heights Drainage Basin
CH13 County Heights Drainage Basin
Arrowhead Drainage Basin
AH1 Arrowhead Drainage Basin
AH5 Arrowhead Drainage Basin
AH9 Arrowhead Drainage Basin
AH17 Arrowhead Drainage Basin
AH302 Arrowhead Drainage Basin
Arrowhead Drainage Basin AH23
Some Ways Rapid City Will Use the GIS Drainage Data: Review elements before going into the field Quantify elements and their characteristics Public education and involvement Maps Use by other city employees engineering/planning/public works/growth management Use with volunteers
Future Possibilities with GIS Drainage Data Asset management prioritize infrastructure maintenance Add construction costs as an attribute Maintenance records Track complaints Further assist with NPDES permit implementation Adapt to hydraulic model Assist with stormwater management master planning