BROOKFIELD, CT, MARCH 24, 2017-- Minnesota is known as the "Land of 10,000 Lakes," but for one homeowner in the Crystal Spring neighborhood of Rochester, it was not a lake but nuisance ground water causing major headaches near his property. Crystal Spring was formerly farms and rural land when development occurred in the rural subdivision. The drainage area leading to the ditch located in the roadway right of way (ROW) drains approximately 9 acres of woods and yards. The ditch near a neighboring property has a Decorah Edge spring coming from an oak savanna hillside that contributes to the wet conditions. Approximately 3-5 gallons of water per minute flow through a culvert leading to the ditch along the road ROW. The amount of water increases after precipitation events. In 2015, the City of Rochester graded the ditch bottom, which provided only temporary relief, as the entire ditch section had very low grade (less than 1%). This past fall, the City of Rochester looked for a creative solution instead of trying to re-grade hundreds and potentially thousands of feet of ditch bottom and trying to re-set private driveway culverts.
Ryan Thesing, a Stormwater Compliance Specialist with the City of Rochester, took the lead on the project. Ryan and Coworker Mike Kraszewski researched infiltration alternatives, since the area had underlying sandy soils. Their goal was to get the water to infiltrate at the upper end of the ditch, potentially solving the water problems for the homeowner and the remaining neighbors downstream.
"The City is familiar with nuisance water in many rural and historic areas of town. The returning water here meant that we needed a different solution," Thesing says. "Typically, in a situation like this, the City could install a few hundred feet of precast drainage pipe for the whole neighborhood. This normally results in an assessment project and cost to the homeowners which can be expensive and not always what the adjoining property owners want. The underlying soil at this location is sand, so we were able to test and determine whether an infiltration system would be adequate. This kept the excavation localized to one property, working within the Roadway ROW and saved the City and homeowners from a larger, more expensive project."
His team reached out to Royal Enterprises, a local water control and utility infrastructure product supplier, for recommendations. Keeping in mind that the City was searching for cost-effective, dependable results that could be implemented throughout Rochester, Josh O'Neill at Royal recommended the CULTEC Recharger® 330XL stormwater management chambers.
"We've worked with CULTEC's products for many years, mostly on large commercial developments," says Josh O'Neill, Water Resource Engineer for Royal Enterprises. "Contractors appreciate that they can get nearly a whole project's worth of materials delivered on one truckload, and that they can maneuver the chambers in the trench without the use of heavy equipment. The ease-of-installation was very appealing to the Public Works department. They did not want to compound the eyesore caused by the wet condition by impacting the homeowner's property or work outside the ROW with the use of heavy equipment. We suggested the Recharger 330XLHD because it can store a lot of water in a small area and can be hand-carried into place. The chambers will allow the water to infiltrate within the footprint of the existing ditch while providing a more aesthetically pleasing and suitable underground alternative."
CULTEC's Recharger 330XLHD chambers are 30 1/2 inches high and 8 1/2 feet long; each unit is able to handle 390 gallons (52.21 cubic feet) of water without stone. The mid-sized Recharger 330XLHD chambers were able to maximize storage capability on site while managing the stormwater by spreading the water over a larger infiltration area of the ditch.
The Public Works team excavated the ditch to 54 feet long, 5 feet wide and 4 feet deep. After the excavation was complete, a non-woven geotextile was placed at the bottom and along the sides of the trench. Six inches of clean rock was laid down as a stable base for the chambers. A total of five Recharger 330XLHD chambers were interlocked end-to-end in the retrofitted trench which will now provide approximately 541 cubic feet of water storage. An inspection port was installed so the Rochester Water Resources staff can periodically check to make sure the system is working properly and has not become clogged with silt or leaves. The chambers were surrounded in embedment stone (1-2 inch diameter washed, crushed stone) consisting of a one foot stone border from the chamber side wall to an elevation of six inches above the chamber crown. A layer of geotextile was placed above the stone for the length of the trench, covering the entire chamber system and preventing soil intrusion into the stone. The ditch was then filled in with washed rock similar to river rock to final grade to promote infiltration over the entire ditch section.
Because of the new CULTEC stormwater management chambers, the ditch should be easier to maintain for the homeowner. A review of the site shortly after completion showed that the chambers are infiltrating properly and as expected, draining water from the spring and any precipitation events. Checking the inspection port located on the third chamber shows that the fall's precipitation had not filled the system, and water had only reached about the first 5-10 linear feet of the system. The true test will be the spring's snowmelt—Rochester averages around 48 inches of snow each winter—along with 32 inches of annual rainfall.
All parties involved, from the homeowner to the City of Rochester Water Resources Department, were pleased with the installation of the CULTEC chambers. The homeowner now has better conditions in front of his property, and the City now has an additional option for handling similar nuisance water issues where sandy underlying soils are present and the local geology allows.
"The continued success of the Crystal Spring project gives us a benchmark Best Practice moving forward where the right soils and topography are present., We could certainly utilize infiltration chamber systems on similar projects in the future," Says Thesing.
For more information about CULTEC and the company's stormwater chambers, call (203) 775-4416 or visit www.cultec.com.
CULTEC Inc., manufacturer of the Contactor® and Recharger® plastic septic and stormwater chambers, is a family-owned and operated company with experience in the drainage industry dating back to the 1950's. Introducing its Contactor and Recharger chambers to the industry in 1986, CULTEC helped begin a revolution toward using plastic construction products. Since then, several product developments and strategic alliances have made CULTEC a cutting-edge R&D-based manufacturer.