Erosion Control June 2012 : Page 54
program almost daily, the decision to utilize SiteWorx for the park estimation was simple. “It cut our estimating time drastically, and it is a tremendous value for the money and has excellent technical support,” he says. Monitoring the Diff erence The Patton Creek Watershed Analysis project is taking place in hilly suburban Hoover, AL, where the land use is approx-imately 70% heavily wooded residential neighborhoods and approximately 30% commercial. In 2009, the city contracted Hydro-Engineering Solutions, which in turn contracted RainWave to use its monitoring software to collect data and issue reports at the site as the city sought to develop its stormwater management program (SWMP). “The city is required to develop a SWMP to maintain compli-ance with its NPDES [National Pollutant Discharge Elimination System] Phase I permit,” explains John Curry, a li-censed engineer and president of Hydro-Engineering Solutions based in Auburn, AL. He says one goal the city had was “to differentiate what was coming from them as opposed to what was affecting them from adjacent municipalities.” Rod Long, the city engineer for Hoover, explains that vegetation or de-composing vegetation had caused low dissolved oxygen levels. “We’re using in-stream monitors. One is in the northern part of the city attached to the bridge wing wall—a sonde with five sensors on it,” says Long. “Water-quality param-eters include dissolved oxygen, depth of water, pH, conductivity, and tempera-The RainWave system, in conjunction with the in-stream monitors, has helped the city identify potential water-quality problems in Patton Creek. 54 EROSION CONTROL WWW.EROSIONCONTROL.COM ture. Conductivity and pH changes can tell you something is in the water that shouldn’t be there.” He says the RainWave system, in con-junction with the in-stream monitors, has helped the city identify potential water-quality problems in Patton Creek. “RainWave gives us data we never had before,” says Long, noting that going out the day after an event and determin-ing 4.5 inches of rain had fallen doesn’t tell the complete story if, for example, that much rain fell over the course of just a few hours. “If you have an event, you can pick out a study area and actu-ally study an event after it happened,” he says. “This gives us an opportunity to have better con-trol of the rainfall data that we’re trying to analyze. They’ve got the data everywhere. You can go out on a construction zone, and after a three-quarter-inch event, stormwater alerts go out and you check all your erosion control. We get 50 to 55 inches a year here. Most of our rain is heaviest in the winter months.” Dewayne Smith, consultant for the city’s stormwater management pro-gram and senior engineer at Hydro-Engineering Solutions, says the NPDES permit required the city to collect grab samples on a quarterly basis for dry weather and wet-weather events for a laundry list of parameters. “It was quite expensive,” he says. “Patton Creek has a TMDL [total maxi-mum daily load] established for organic enrichment and dissolved oxygen. The TMDL attributes the source nutrients to be from leaking septic tanks and urban runoff. We requested that the state con-sider discontinuing the grab-sampling methodology and initiate continuous in-stream monitoring.” Set points in the basin are monitored continuously. Curry describes how the RainWave system has been used to help evaluate water quality at the site where 10 monitoring points are evenly distributed throughout the basin area: “It can send the rain distribution to the model. Now we’ve got better data to make better decisions. You can see how the stream reacts to the rainfall data. We definitely know this is a discharge without rainfall. We can track them up to whatever the source might be.” Long says that when a localized flood-ing event occurred within a 40-acre area, he was able to contact the company to pull up data in that specific area for that time period. Smith says that areas that are monitored could also be compared from year to year, allowing site managers to determine “are things getting better or are things getting worse. It is truly basin specific.” For example, Smith says the At this Virginia site, modeling helped in developing a mass grading plan to divert stormwater runoff. canopy at one location had heavily influ-enced a rain gauge, but using RainWave’s monitoring eliminates the potential for error in that regard. Smith says the innovative tools that the Hoover is using for its stormwater management program are being used as an example now for other municipal separate storm sewer systems (MS4s) in the state of Alabama. “It’s kind of a quality assurance for them,” he says, referring to the city of Hoover. “They can check on a developer to make sure it isn’t causing any harm to their MS4.” Curry describes the type of monitoring that RainWave does for construction areas and instances when an alert can be issued. “Say you’re going to clear a right of way for a road. We can monitor points along that linear project. It could be for a roadway or it could be power lines. We’ll monitor several points along the cleared area,” he RICHARD S. PHILLIPS
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