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HomeMy WebLinkAboutStormwaterManagementDesignReportIsolator™Row O&M Manual StormTech®Chamber System for Stormwater Management 1.1 INTRODUCTION An important component of any Stormwater Pollution Prevention Plan is inspection and maintenance. The StormTech Isolator Row is a patent pending technique to inexpensively enhance Total Suspended Solids (TSS) removal and provide easy access for inspection and maintenance. 1.2 THE ISOLATOR ™ROW The Isolator Row is a row of StormTech chambers, either SC-740 or SC-310 models, that is surrounded with filter fabric and connected to a closely located manhole for easy access. The fabric-wrapped chambers provide for settling and filtration of sediment as storm water rises in the Isolator Row and ultimately passes through the filter fabric. The open bottom chambers and perforated side- walls allow storm water to flow both vertically and horizon- tally out of the chambers. Sediments are captured in the Isolator Row protecting the storage areas of the adja- cent stone and chambers from sediment accumulation. Two different fabrics are used for the Isolator Row. A woven geotextile fabric is placed between the stone and the Isolator Row chambers. The tough geotextile provides a media for storm water filtration and provides a durable surface for maintenance operations. It is also designed to prevent scour of the underlying stone and remain intact during high pressure jetting. A non-woven fabric is placed over the chambers to provide a filter media for flows passing through the perforations in the sidewall of the chamber. 2 Call StormTech at 888.892.2694 or visit our website at www.stormtech.com for technical and product information. 1.0 The Isolator™Row The Isolator Row is typically designed to capture the “first flush” and offers the versatility to be sized on a vol- ume basis or flow rate basis. An upstream manhole not only provides access to the Isolator Row but typically includes a high flow weir such that storm water flowrates or volumes that exceed the capacity of the Isolator Row overtop the over flow weir and discharge through a manifold to the other chambers. The Isolator Row may also be part of a treatment train. By treating storm water prior to entry into the chamber system, the service life can be extended and pollutants such as hydrocarbons can be captured. Pre-treatment best management practices can be as simple as deep sump catch basins, oil-water separators or can be inno- vative storm water treatment devices. The design of the treatment train and selection of pretreatment devices by the design engineer is often driven by regulatory requirements. Whether pretreatment is used or not, the Isolator Row is recommended by StormTech as an effective means to minimize maintenance requirements and maintenance costs. Note: See the StormTech Design Manual for detailed information on designing inlets for a StormTech system, including the Isolator Row. ECCENTRIC HEADER MANHOLE WITH OVERFLOW WEIR STORMTECH ISOLATOR ROW OPTIONAL PRE-TREATMENT OPTIONAL ACCESS STORMTECH CHAMBERS StormTech Isolator Row with Overflow Spillway (not to scale) Looking down the Isolator Row from the manhole opening, woven geotextile is shown between the chamber and stone base. 2.0 Isolator Row Inspection/Maintenance Call StormTech at 888.892.2694 or visit our website at www.stormtech.com for technical and product information. 3 Maintenance is accomplished with the JetVac process. The JetVac process utilizes a high pressure water noz- zle to propel itself down the Isolator Row while scouring and suspending sediments. As the nozzle is retrieved, the captured pollutants are flushed back into the man- hole for vacuuming. Most sewer and pipe maintenance companies have vacuum/JetVac combination vehicles. Selection of an appropriate JetVac nozzle will improve maintenance efficiency. Fixed nozzles designed for cul- verts or large diameter pipe cleaning are preferable. Rear facing jets with an effective spread of at least 45” are best. Most JetVac reels have 400 feet of hose allow- ing maintenance of an Isolator Row up to 50 chambers long. The JetVac process shall only be performed on StormTech Isolator Rows that have AASHTO class 1 woven geotextile (as specified by StormTech) over their angular base stone. 2.1 INSPECTION The frequency of Inspection and Maintenance varies by location. A routine inspection schedule needs to be established for each individual location based upon site specific variables. The type of land use (i.e. industrial, commercial residential), anticipated pollutant load, per- cent imperviousness, climate, etc. all play a critical role in determining the actual frequency of inspection and maintenance practices. At a minimum, StormTech recommends annual inspec- tions. Initially, the Isolator Row should be inspected every 6 months for the first year of operation. For subsequent years, the inspection should be adjusted based upon previous observation of sediment deposition. The Isolator Row incorporates a combination of standard manhole(s) and strategically located inspection ports (as needed). The inspection ports allow for easy access to the system from the surface, eliminating the need to perform a confined space entry for inspection purposes. If upon visual inspection it is found that sediment has accumulated, a stadia rod should be inserted to deter- mine the depth of sediment. When the average depth of sediment exceeds 3 inches throughout the length of the Isolator Row, clean-out should be performed. 2.2 MAINTENANCE The Isolator Row was designed to reduce the cost of periodic maintenance. By “isolating” sediments to just one row, costs are dramatically reduced by eliminating the need to clean out each row of the entire storage bed. If inspection indicates the potential need for main- tenance, access is provided via a manhole(s) located on the end(s) of the row for cleanout. If entry into the manhole is required, please follow local and OSHA rules for a confined space entries. 2FT MIN. SUMP COVER ENTIRE ROW WITH AASHTO M288 CLASS 2 NON-WOVEN GEOTEXTILE SC-740 — 8' WIDE STRIP SC-310 — 5' WIDE STRIP STORMTECH ENDCAP INSPECTION PORT LOCATION PER ENGINEER'S DRAWING CATCH BASIN OR MANHOLE 12" MIN ID 25" MAX OD PIPE SET 1.5" FROM BOTTOM OF CHAMBER WOVEN GEOTEXTILE THAT MEETS AASHTO M288 CLASS 1 REQUIREMENTS, BETWEEN STONE BASE AND CHAMBERS SC-740 — 5'-6' WIDE STRIP SC-310 — 4' WIDE STRIP StormTech Isolator Row (not to scale) Examples of culvert cleaning nozzles appropriate for Isolator Row maintenance. (These are not StormTech products.) Step 1)Inspect Isolator Row for sediment A) Inspection ports (if present) i. Remove lid from floor box frame ii. Remove cap from inspection riser iii. Using a flashlight and stadia rod, measure depth of sediment and record results on maintenance log. iv. If sediment is at, or above, 3 inch depth proceed to Step 2. If not proceed to step 3. B) All Isolator Rows i. Remove cover from manhole at upstream end of Isolator Row ii. Using a flashlight, inspect down Isolator Row through outlet pipe 1.Mirrors on poles or cameras may be used to avoid a confined space entry 2.Follow OSHA regulations for confined space entry if entering manhole iii. If sediment is at or above the lower row of sidewall holes (approximately 3 inches) proceed to Step 2. If not proceed to Step 3. Step 2)Clean out Isolator Row using the JetVac process A) A fixed culvert cleaning nozzle with rear facing nozzle spread of 45 inches or more is preferable B) Apply multiple passes of JetVac until backflush water is clean C) Vacuum manhole sump as required Step 3) Replace all caps, lids and covers, record observations and actions Step 4)Inspect & clean catch basins and manholes upstream of the StormTech system StormTech products are covered by one or more of the following patents: U.S. Patents: 5,401,459; 5,511,903; 5,716,163; 5,588,778; 5,839,844; Canadian Patents: 2,158,418 Other U.S. and Foreign Patents PendingPrinted in U.S.A. © Copyright. All rights reserved. StormTech LLC, 2004 S090104-1 3.0 Isolator Row Step By Step Maintenance Procedures 4 21) B)1) A) StormTech Isolator Row (not to scale) Stadia Rod Readings Fixed point Fixed point Sediment Date to chamber to top of Depth Observations/Actions Inspector bottom (1) sediment (2) (1) - (2) 3/15/01 6.3 ft. none New installation. Fixed point is Cl frame at grade djm 9/24/01 6.2 0.1 ft. Some grit felt sm 6/20/03 5.8 0.5 ft. Mucky feel, debris visible in manhole and in rv Isolator row, maintenance due 7/7/03 6.3 ft. 0 System jetted and vacuumed djm Sample Maintenance Log 20 Beaver Road, Suite 104 Wethersfield Connecticut 06109 860.529.8188 888.892.2694 fax 866.328.8401 www.stormtech.com