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The Texas State University at San Marcos is located very near to one of Texas’ most pristine springs that flow out to create the San Marcos River. An effective method to treat the storm water on campus before it runs into the river would not only show responsible land stewardship, but if implemented properly could be the bench mark for the surrounding areas, and for future construction in sensitive watershed areas. The use of a GIS to locate the potential sites for storm water detention ponds on the campus of Texas State University, San Marcos, can model the best and most effective location of these ponds. The overall master plan of the campus will be factored in as well in order to maintain the goals of water quality during and after construction. This would greatly speed up the process of preliminary surveying and could potentially improve the effectiveness of the ponds.
The university’s current system of storm water runoff management is out of date. These detention ponds have not kept up with the construction on campus or the impact of the future construction planned over the next 10 years. With all the factors weighed in, the current system will not be adequate.
The problem of pollutants and sediment collecting in our streams and rivers through unrestricted storm water runoff should be of great concern to all of us. Over the past 20 years changes in land cover, grade changes from new construction, and especially an increase in impervious surfaces, such as streets and parking lots, has greatly increased the amounts pollutants reaching our surface water.
According to research by Gary Minton (2008), street pavement now constitutes 10 percent or more of an urban watershed; with parking lots, pavement constituting 20 to 40 percent of commercial areas. Pollutant loadings from pavement constitute a disproportionate fraction of the total urban loading for many pollutants, in particular metals and hydrocarbons. Pavement is also a significant source of pollutants not directly associated with transportation such as nutrients and pesticides, due to wash-on from landscapes and atmospheric deposition.
This has necessitated innovative and effective methods for controlling and collecting the pollutants before they reach our rivers. Referencing the EPA’s Best Management Practices (BMP), outlined in the Storm water Best Management Practice Design Guide Volume 3 (2004), one of the very best overall methods for collecting and reducing the pollutants and sediment is a storm water detention system. This analysis will focus on utilizing these Best Management Practices for the creation of an effective and well designed system for containing runoff pollutants produced on the campus of Texas State University, San Marcos.
The area covered for this analysis is the physical property owned by Texas State University, including all buildings, parking areas and sidewalks, as well as all the green spaces. The Roads around the campus are in the City of San Marcos’ jurisdiction. This analysis will utilize only the pertinent areas owned by the University including all storm water drains that discharge into the City’s drainage system.
The following data was provided by Bob Stafford and can be accessed via the Geography Department’s “W” drive at Texas State University.
Shapefiles:
60’ Storm- projection of impervious surfaces on campus that drain into the 60 inch storm drain on Concho Street. An attribute table with areas is included.
Blg07 - This map shows every building in San Marcos digitized with area attributes. Campus buildings have additions attributes.
Channelssp83sc - This layer shows existing drainage channels in and around campus including Sessoms creek.
Drainlinesp83 - This layer shows storm water drains and pipes in and around campus with dimension attributes.
Fieldsspsc83 - This layer shows Texas State owned playing fields and fairways around campus.
Greenzones - This layer projects all the spaces on campus not taken up by a building or impervious cover. It is divided into three categories: greenzone, redzone, and landzone.
Lakes - This layer shows a polygon projection of Spring Lake, the San Marcos River, and all the ponds on campus.
Manholesssp83 - This polyline layer shows the location and shape of all the manholes in and around campus.
Parkingsp - This layer is a polygon projection of all the parking lots on campus with area and zoning attributes.
Propertystsp - These polygons show the tracts of land and their boundaries that is Texas State University’s campus. It includes area attributes.
Right of way - This layer shows existing roads and rights of way in San Marcos. It includes no useful attribute data.
Sidewalkssp83 - This layer shows all sidewalks and cement walkways on campus.
Stormdrainmerge - This layer shows all storm drain inlets and outlets on campus.
Stormpipes - This polyline layer shows storm pipes on campus and where they drain.
Surfacefeatures - This layer is a digital drawing of campus.
SWTroads - This layer shows roads that are owned and maintained by Texas State University.
Topo06 - This layer shows one foot contour lines from n 2006 campus fly over.
Campus Master Plan Data:
Greenzones - This layer shows future green spaces on campus.
Masterplan1building1 - This layer shows polygons of future buildings on campus.
Masterplansurface6 - This layer is a polyline drawing of campus that contains no useful attribute data.
Metadata:
- All data is set to projection: Texas State Plane, South Central, NAD 83, feet.
- Buildings are combined city and campus shapefiles. Campus flyover 2006.
- Surface features were derived from campus flyover, converted from CAD into shapefiles. 2006
- Topographical data derived from campus flyover, then converted from CAD into shapefiles. 2006
- Underground utilities and storm drain inlets and outlets originated from campus CAD infrastructure layers. Updated regularly.
- Green areas, water areas, parking, streets, and sidewalks digitized in Arcview using background aerials and surface feature shapefile.
- Right of Way from City of San Marcos, 2002.
- Property shapefile compiled by way of COGO extension in Arcview. Reflects research performed to insure property line locations by meets and bounds. Updated regularly.
- 60 inch storm drain reflects study performed to locate the area of drainage that uses the 60 inch storm pipe that runs down Concho Street. The pipe is traced through campus and sizes are indicated in the tabular data of the shapefile. 2003.
- Aerial photography flown in January 2006 by Sanborn. 3 inch resolution normal color.
- All master plan shapefiles were digitized following Campus 2006 – 2015 Master Plan completed by Ayres/St. Gross, Boston, 2006. Updated as new designs are acquired.
Primary data:
GPS data points – points of current storm water detention facilities and possible future locations of ponds. (gathered using handheld GPS)
Software:
ESRI ArcGIS 9.2
The analysis of our data will include the following procedures:
- Formulate a watershed analysis model based on the Arc Hydro extension in ArcMap.
- Detailed slope analysis will be accomplished by utilizing the Texas State DEM model. This model will enable our team to best formulate slope calculations along with runoff frequency and speed in our predetermined runoff zones.
- Create a model of water flow for 2 inches of precipitation.
- Determine the size of all impervious surfaces located in each runoff zone.
- Determine the deposit of sedimentation from green zones and proposed construction sites into storm water network.
- Determine the adequate detention pond size for each runoff zone. Topographic map analysis along with spatial analysis of available land will be done to ensure correct placement of each proposed storm water detention pond.
- Analysis of the Texas State University underground storm drain network. This will determine the desired location of each storm detention pond in correspondence to the total water flow from the associated pipe network.
Implications
The ever expanding campus of Texas State University includes more and more impervious cover as well sediment runoff from construction sites. The university has an outdated storm water drainage system that hasn’t taken into account these changes. It lacks an effective filtration system that will improve the water quality of storm runoff. The preliminary research accomplished thus far has shown the need for storm water detention ponds, and therefore the ability to eliminate a large portion of pollutants that enter the San Marcos River during a storm. Once accomplished, the analysis of the stated procedures and system functions will enable Storm Water Solutions to formulate the best locations for future storm water detention ponds.
Data Collection
Analysts- (10 hrs/week * 2 weeks * 3 analyst) 60 hrs
Assistant Manager- (7 hrs/week * 2 weeks) 14 hrs
Manager- (5 hrs/week * 2 weeks) 10 hrs
Total Cost- (84 hrs * $25/hr) $2,100
Data Analysis
Analysts- (10 hrs/week * 6 weeks * 2 analysts) 120 hrs
Analyst/Web Developer- (10 hrs/week * 5 weeks) 50 hrs
Assistant Manager- (7 hrs/week * 6 weeks) 42 hrs
Manager- (5 hrs/week * 6 weeks) 30 hrs
Total Cost- (242 hrs * $35/hr) $8,470
System Management
Assistant Manger- (3 hrs/week * 10 weeks) 30 hrs
Manager- (5 hrs/week * 10 weeks) 50 hrs
Total Cost- (30 hrs * $30/hr) + (50 hrs * $35/hr) $2,650
Website Development
Web Developer- (10 hrs/week * 3 weeks) 30 hrs
Total Cost- (30 hrs * $20/hr) $600
Equipment
Workstations- (5 workstations * $300) $1,500
Maintenance- (5 workstations * $125) $625
Depreciation- ($2,150 [total value of workstations] / 36
[workstation life in months] * 2.5 months) $148
GPS Unit- $120
Digital Camera- $200
Supplies- $100
Total Cost- $2,693
Software
ESRI ArcView 9.2 for 10 weeks- ($25,000 yr / 12 * 2.5) $5,200
Total Project Cost- $21,713
Data Collection: Weeks 1 - 2
The team will gather primary data using hand held GPS units for prospective locations of storm water detention ponds. We will also use secondary data collected by Bob Stafford, the team will use the rest of the time to sort through and organize the data.
Analysis: Weeks 3 - 8
The analysis portion of our project will require six weeks to complete. During this time the team will create a watershed, a slope analysis, and a topographic map of campus. We will also determine the runoff from impervious surfaces, and loose sediment deposits during storms. The potential size for the detention ponds will be determined using runoff totals and available land. Analysis will be done on the underground drain network to help in locating the storm water detention ponds.
Web Design: Weeks 8 - 10
This portion of the project will overlap with the analysis so one team member will begin designing the company website while the remaining team members will continue and finalize the analysis. Web design will take place over the last three weeks of the project, to allot time for any unforeseen problems that may occur.
Final Deliverables: Weeks 9 – 10
The final two weeks will be focused on the final deliverables for the client. This will overlap with the web design aspect of the project so team members will be divided up to maximize work efficiency.
Timetable |
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Weeks |
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Tasks |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
10 |
Data Collection |
Two Weeks |
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Analysis |
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Six Weeks |
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Web Design |
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Three Weeks |
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Final Deliverables |
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Two Weeks |
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- Map showing proposed sites for storm water detention ponds
- Detailed Final Report
- Professional Poster
- CD (2 copies) containing:
- All data
- Metadata
- Report
- Poster
- PowerPoint Presentation
- Readme file (instructions on how to use the CD)
Storm water runoff can be a major source of pollution if left untreated. Chemicals, oils, and sediment embedded in impervious surfaces and construction zones get washed away with each storm event and can severely diminish the water quality in any given watershed. This study will analyze the storm water runoff on the Texas State University campus, with a strong focus on runoff from impervious surfaces. Impervious surface coverage, topography, amount of water flow, the existing drainage system, and future developments will be factors to consider when proposing sites for storm water detention ponds. The ponds must be strategically placed in order to compliment the existing drainage system and ensure that the storm water runoff from various areas throughout campus will not be left untreated.