Storm Chamber Design Manual

Design ManualStormWater retention, Detention, reuSe anD ConveyanCe• • • w w w . s t o r m c h a m b e r s . c o m • • •Thank you for your interest in StormChamber™. The StormChamber™ storm water management system provides an environmentally progressive and technologically advanced storage and pollutant removal solution that is more cost-effective and requires less maintenance than other types of underground systems.StormChamber™ was developed by biologists, ecologists, and engineers to improve upon older plastic storm water chambers that have been used in the marketplace for over 10 years. StormChamber™ utilizes the same basic corrugated arch shape for structural integrity and exceeds the AASHTO H20 wheel load rating. StormChamber™ significantly exceeds the storage capacity of existing plastic chambers, resulting in a need for fewer chambers, less stone, less filter fabric, less excavation, and approximately 40% less time to install. The side portal feeds eliminate the need for expensive header pipe systems currently used to manifold storm water effluent into rows of chamber systems. The ability to access any StormChamber™ in a system through the side portal feeds also provides great flexibility in engineering and hydraulic design, eliminating circuitous routing of feed pipes from inlet structures to the entry point of a header pipe.The combined designs of the side portal feeds and the perforated end walls with the provision for a 10” riser located near the end wall facilitates sediment maintenance. The open bottom of the StormChamber™ provides maximum infiltrative surface area, unlike the holes of a perforated pipe that easily become clogged. The open surface area functions similar to a septic drain field for nutrient and other pollutant degradation with formation of a bio-mat of micro-organisms over the substrate. Pollutants are further degraded as they pass through the soil column. The infiltration of storm water also helps to replicate pre-construction hydrology by recharging groundwater supplies, maintaining base flow to streams and wetlands, and in coastal areas, helping to retard salt water intrusion.StormChamber™ systems are not limited to areas with pervious soils. In non-pervious areas underground storage can also be provided with regulated outflow. Under these conditions, water quality is still enhanced more than with a pond due to the remediating effect of the bio-mat. Elimination of a pond leaves land available for other uses.StormChambers™ may also be used in place of concrete, corrugated metal, or HDPE pipe for storm water conveyance. They are less expensive, quicker and easier to install, and can be inserted directly into an inlet structure, similar to pipe. Significant water quality enhancement over pipe is also achieved with the associated infiltration benefits. When used in place of pipe for conveyance to ponds, algal blooms are minimized, sediment loading and maintenance are decreased, and pond level fluctuations are minimized by maintaining base flow. The StormChamber™, with its end walls removed, has a storm water conveyance capacity comparable to a 48” diameter pipe. Conveyance occurs through the StormChambers™ as well as the surrounding stone.Letter of Introductionw w w . s t o r m c h a m b e r s . c o m • • • ?General InformationProduct Information and BenefitsThe StormChamber™ was developed by HydroLogic Solutions as an infiltrative BMP to greatly enhance water quality and to surpass other storm water devices with the following design improvements:>> Greater phosphorous, nitrogen, and suspended sediment removal than other systems.>> 50% greater storage capacity over similar chambers.>> Reduced maintenance requirements.>> Sediment removal inside and outside the chamber, providing for longer chamber life.>> Functions in storm water hot-spot areas.>> Functions more effectively in soils with limited infiltrative capability.>> Filters certain pollutants with replaceable pollutant-absorbent materials.>> Exceeds national, state and local water quality standards.In order for municipalities to comply with the new EPA Phase II storm water and Total Maximum Daily Load (TMDL) regulations, HydroLogic Solutions has developed the StormChamber™ as a highly cost effective and environmentally sound alternative management tool for the control of storm water runoff, peak flow attenuation, sediment control, and nutrient and pollutant removal. It is designed to overcome the deficiencies of currently existing technologies.StormChamber™ was designed as an open bottom, high-density polyethylene infiltration chamber BMP which functions in both permeable and non-permeable soils for subsurface retention/detention of storm water runoff. It reduces nutrient and other pollutant loadings by taking advantage of the natural biological and physical properties of the soil, directly comparable to the functions of a septic drain field. It also recharges ground water drinking supplies, while concurrently helping to maintain base flow to streams, wetlands, lakes, and ponds, and counter salt-water intrusion. StormChamber™ provides approximately 50% greater storage capacity than similar chambers. It is significantly stronger than its competitors.? • • • w w w . s t o r m c h a m b e r s . c o mGeneral Information (continued)Company ProfileMission StatementThrough laboratory development and applied research it is the mission of StormChamber™ to provide innovative and environmentally sound solutions to storm water management and non-point source pollution problems. We are committed to provide solutions and address future storm water management challenges in a practical and cost effective manner. Company OverviewStormChamber™ is a multi-disciplinary environmental consulting and water resources research company founded and operated by experts in the fields of ecology, biology and land development. The company staff and its Advisory Board have several years of combined experience in the above disciplines as well as expert knowledge in the areas of stormwater management, engineering, and public health.In order to meet compliance with the new EPA Phase II storm water and Total Maximum Daily Load (TMDL) regulations, StormChamber™ was developed as a highly cost effective and environmentally sound alternative management tool for the control of storm water runoff, peak flow attenuation, sediment control, and nutrient and pollutant removal, designed to overcome the deficiencies of currently existing technologies.Company SupportDesign AssistanceStormChamber™ provides, free of charge, a CD ROM containing CAD-compatible drawings, design specifications, and other relevant information. This information can be copied directly onto engineering design plans. Drawings are provided showing different chamber views, cross-sectional storage capacities, inspection/clean out riser details, installation details, and example configurations.StormChamber™ also assists with the design of its systems. We frequently work in close association with engineering firms in creating a design that would be the most effective in light of local conditions and constraints. This assistance is provided in an advisory capacity only. The resulting design is the ultimate responsibility of the engineering firm to whom we provide the assistance. StormChamber™ does not provide engineering services; does not represent itself as engineers; and does not accept any responsibility for any design utilizing its StormChamber™. The design of StormChamber™ systems is the sole responsibility of the customer and/or its engineers.StormChamber™ always welcomes the opportunity to assist in the design of its products. It is in everyone’s best interests to do all that we can to help insure the effective utilization of our product.Plan ReviewSome engineers, particularly those with previous experience designing StormChamber™ systems, rely on us to review plans incorporating its StormChamber™. This service is provided at no charge to our customers. Simply fax or mail us the appropriate sections of your design for our review.InstallationStormChamber™ assists with installation guidance on the CD ROM provided with the design manual. We also provide an installation brochure to the contractor that will be installing the StormChamber™ system. This brochure can also be downloaded from our web site. A StormChamber™ representative can be on site, at the contractors request, when a StormChamber™ system is installed to assist with any installation problems that may be encountered.w w w . s t o r m c h a m b e r s . c o m • • • 3 ( )™ HydroLogic Solutions will warranty the structural integrity of each StormChamber unit in accordance with the installation instructions and is warranted to the original buyer against defective materials and workmanship for one year from the date of purchase. It is the responsibility of the buyer to inspect the StormChamber units prior to installation and to inform HydroLogic Solutions of any defect prior to installation. HydroLogic Solutions will only be respon-sible for supplying replacement units. HydroLogic Solution’s liability speci?cally excludes the cost of removal and/or installation of the units and shall not exceed the price or charge for its products.There are no other warranties with respect to the units, including no warranties of merchantability or ?tness for a particular purpose. This warranty does not extend to incidental, consequential, special or indirect damages. HydroLogic Solutions shall not be liable for penalties or liquidated damages, including loss of production and pro?ts, labor and materials, overhead costs, or other loss or expenses incurred by the buyer. Speci?cally, excluded from warranty coverage is damage to the units due to ordinary wear and tear, alteration, accident, misuse, abuse or neglect of the units, improper construction proto-cols, installation of the units not consistent with our installation instructions, placement by the buyer of improper materials into the system, damage due to crushing by heavy equipment weighing in excess of what is listed in the installation instructions, failure to maintain the minimum ground covers as set forth in the installation instructions or any other event not caused by HydroLogic Solutions.HydroLogic Solutions shall not be responsible for any loss or damage to the buyer, the units, or any third party resulting from its installation or shipment. The buyer shall be solely responsible for ensuring that the installation of the system is completed in according with the installation instructions, and will abide by all applicable laws, codes, rules and regulations.Inspection of shipment must occur within 5 days of receipt of StormChamber units and written notice of alleged defect must be provided in detail. Failure to advise us of defects within this allotted period will constitute acceptance of the shipment.This warranty shall not apply to any party other than the original buyer. Furthermore, no Company representative or employee has the authority to modify or change this warranty in any manner, nor does this warranty apply to shipping or in transit damage. maintain the minimum ground covers as set forth in the installation instructions or any other event not caused by HydroLogic Solutions.? • • • w w w . s t o r m c h a m b e r s . c o mProduct Specifications for StormChamber™Each unit will be 34” high, 60” wide and 8.5' long.Lay-up length is 8.1’ (start and end units) and 7.6’ (middle unit).Each chamber will be formed from high molecular weight/high density polyethylene.Use of filter fabric between the soil and stone backfill layer and lining the side walls of the excavated area is required to prevent intrusion of soil or silt into the chambers and surrounding stone.Each chamber has 14 ribs of approximately 3.6”in height, 3.8” wide at the top and tapering to 4.4” at the bottom. Spacing of the ribs at the bottom of the chamber is approximately 4.9” and approximately 3.2” at the top. One smaller rib sized dimensionally to effectively nest under and interlock to connect units is 2.9” high, 3.3” wide at the top of the rib, and 4.1” wide at the base.Overall height to the inside rib is 30.44”.Overall height to the outside rib is 34.04”.Invert height for 12” pipe is 16.49”.Invert height for 10” pipe is 17.49”.Invert height for 8” pipe is 18.49”.Each unit has the ability to accept up to 15” feed pipe in the unit’s side portal.Each unit is designed to handle 10 cubic feet of storage per lineal foot.Stone diameter will be 1.5”-2”.HydroLogic Solutions requires the use of a high quality filter fabric between the soil and crushed stone interface. The filter fabric minimizes the encroachment of soil particles into the stone voids and the chambers. Filter fabric meeting the following parameters is required.Fabric Interface Specifications TEST METHOD TEST RESULTS Grab Tensile Strength ASTM-D-4632 90 lbs. Grab Tensile Elongation ASTM-D-4632 50% Mullen Burst ASTM-D-3786 225 psi Puncture ASTM-D-4833 65 lbs. Trapezoid Tear ASTM-D-4533 45 lbs. UV Resistance ASTM-D-4355 70% Apparent Opening Size ASTM-D-4751 70 US Sieve Permitivity ASTM-D-4491 2.5 Sec.- 1 Flow Rate ASTM-D-4491 175 gal/min/ft2w w w . s t o r m c h a m b e r s . c o m • • • 5 ( )(8’ 7”)(8’ 2”)(8’ 2”)End Chamber Configuration6 • • • w w w . s t o r m c h a m b e r s . c o m (continued)Underdrain System for Marginal Soils‘w w w . s t o r m c h a m b e r s . c o m • • • ?Underdrain System for Marginal SoilsProduct Specifications (continued)8‘-6”4‘-8’ 5‘Cut out guide for 8” PVC riserCut Out Guide for 10” PVC Riser? • • • w w w . s t o r m c h a m b e r s . c o m?Example ConfigurationsExample Configuration 2w w w . s t o r m c h a m b e r s . c o m • • • ??Example Configurations (continued)? 0 • • • w w w . s t o r m c h a m b e r s . c o m? 0Example Configurations (continued)Example Configuration Direct Connectw w w . s t o r m c h a m b e r s . c o m • • • ? ?1. StormChambers™ will arrive either on a flat bed trailer or in an enclosed van. If in an enclosed van, we will try our best to have the driver load the pal-lets at the tail of the van. However, be prepared with a long chain, metal cable, or strong rope or straps to drag a pallet from the nose of the van. A forklift is the easiest way to unload pallets of StormChambers™. 2. A full pallet of StormChambers™ will weigh approximately 1,700 pounds, will be about 5’ wide, 8.5’ long, and approximately 8.5’ high. MATERIALS NEEDED1. Wire cutters to remove the metal bands that secure the StormChambers™ to their pallets.2. Two 6’-10’ lengths of 2x4 studs to use as levers to separate the palletized StormChambers™.3. 3” drywall screws to close in the bases of the StormChambers™ until the stone is placed around them.4. Light weight stabilization netting to go under the StormChambers™ to prevent movement of stone – shipped with the StormChambers™.5. Heavy weight stabilization netting, to be centered below each inspection/clean out riser to prevent removal of stone and soil when vacuum – cleaned with a vacuum truck. Also to be placed under each StormChamber™ to receive storm water from storm drain inlet pipes, to function as a “splash pan” to prevent erosion of underlying stone and soil – shipped with the StormChambers™. 6. 3/4”-2” crushed, washed, hard stone for the trench base and to backfill around the StormChambers™.7. 4 ounce non – woven filter fabric to be used at the interface between the stone and soil backfill and to cover trench side walls. Use Mirafi 140N, Mirafi 140NC, Synthetic Industries 401, or AMOCO 4545 or 4535 filter fabric.8. 4’ sections of 8” (unless otherwise specified), smooth walled Schedule 40 or SDR 35 or equiva-lent pipe for the interconnections between rows of StormChambers™ (check plans for number and location of interconnections).9. Unless otherwise specified, 10” smooth walled Schedule 40 or SDR 35 or equivalent pipe for inspection/clean out risers (check plans for number and location of risers).10. Three small angle irons and 0.5” screws for each inspection/clean out riser to support riser onto top portals of StormChambers™.11. Cleanout caps or tops for inspection/clean out risers.12. Unless otherwise specified, one casting for each inspection/clean out riser in pavement (East Jordan V – 8450 or equivalent).13. Unless otherwise specified, concrete and related materials to form 6’ x 9’ reinforced pads to hold castings for inspection/clean out risers.EQUIPMENT NEEDED1. Forklift or other type of equipment to unload StormChambers™ (see above).2. Excavator to dig the trench from the sides and to place stone and soil backfill.3. Two battery or power operated screw guns to con-nect bases of overlapping StormChambers™. 4. Saws – All, router bit on a drill, or key hole saw to cut open side and top portals in StormChambers™.5. Light weight, tracked dozer, not exceeding 1,100 lbs/sf to grade backfill.6. Hand – operated compactor, small roller, or tracked vehicle for fill compaction. Tracked vehicle must not exceed 1,100 lbs/sf; hand operated compactor or vibratory roller must not exceed a dynamic force of 20,000 lbs.7. Transit or laser.8. Stone bucket.Installation and MaintenancePlease note that all PhotograPhs and illustrations are for illustrative PurPoses only. Please rely on what the engineer sPecifies.? ? • • • w w w . s t o r m c h a m b e r s . c o mInstallation and Maintenance (continued)1. Do not excavate trench until dry weather is fore-cast long enough to allow at least coverage of the StormChamber™ system with filter fabric prior to raining to avoid soil filling void spaces in the stone.2. Excavate to a width and length sufficient to accom-modate the number of StormChambers™ plus a minimum one foot border around the entire bed. The bottom of the bed must be level, unless other-wise specified.3. If the StormChamber™ system was designed for infiltration and heavy clays are encountered, it is recommended that pea gravel and sharp concrete sand be tilled into the top one foot of trench bed prior to placing the stone base. 4. Do not use heavy equipment on the excavated trench bed in order to avoid soil compaction.5. If use of heavy equipment on the excavated trench bed can not be avoided, scarify the trench bottom and break up soil clumps before adding the stone base.Line trench walls, not trench bottom, with 4oz, non – woven filter fabric.6. Line trench walls with a 4 – ounce non – woven fil-ter fabric such as Mirafi 140N or 140NC, Synthetic Industries 401, or AMOCCO 4545 or 4535. Overlap adjacent filter fabric by at least 2’. Do not place filter fabric under the StormChambers™. The filter fabric will clog, restricting the infiltration capability of the StormChamber™ system. 7. Unless otherwise specified, place 6” of crushed, washed, 1” to 2” hard stone on the bottom of the level and zero grade trench. 8. If it becomes impractical to level the stone base by hand, use a low pressure, tracked dozer, not exceed-ing 1,100 lbs/sf, maintaining at least 6” of stone under the tracks at all times.9. Do not use excavated trench as a sedimentation trap or basin during construction. The fine soil parti-cles will accumulate at the soil boundary and restrict the infiltration capability of the system.1. Unloading – see “Before Your StormChambers™ Arrrive”, above. As a last resort, the pallets can be dragged off of the trailer and dropped on the ground. This will not injure the StormChambers™.2. Confirm the total number of StormChambers™ and contact HydroLogic Solutions immediately if the count is incorrect.3. Confirm the number of Start, Middle and End StormChambers™. Each pallet should be marked with the number of each.Trench Preparationw w w . s t o r m c h a m b e r s . c o m • • • ? ?Installation and Maintenance (continued)Place lightweight stabilization netting under StormChambers™.3. Roll out two rows of the light weight stabilization netting (provided with the StormChambers™) perpendicular to the rows of where the Start StormChambers™ will be placed. Overlap the rows by approximately 1’. Keep the netting flat; if moved, re – straighten and flatten out. Row placement begins at inflow end of chamber system with Start Model StormChambers™.2. Start building the StormChamber™ system with the Start Model StormChamber™ at the inflow end of the StormChamber™ system. The Start Models are completely closed at the end with the two side por-tals.You may need to use 2x4’s to separate chambers.1. You may need assistance in separating the StormChambers™. Based on weather and transit conditions, sometimes the StormChambers™ become tightly compacted. Separate StormChambers™ using two 2x4 studs along one of its sides for leverage. Do not use any damaged units – contact HydroLogic Solutions immediately. Place heavyweight stabilization netting under chambers receiving storm drain inflow.4. Place one piece of the heavy weight stabilization netting (provided with the StormChambers™) perpendicular to and under each StormChamber™ that will be receiving inlet storm drain pipes. Place on top of the light weight netting and place one edge of the netting under, and slightly extending beyond, the closed end wall of the StormChamber™. Have the netting extend equally beyond both sides of the StormChamber™. The purpose of the heavy weight stabilization netting is to function as a “splash pan,” preventing excavation of the underlying stone and soil, while allowing infiltra-tion to occur. ? ? • • • w w w . s t o r m c h a m b e r s . c o mInsert smooth wall PVC row connecting pipes.7. Mark the midpoints of 8” ID (unless otherwise speci-fied) smooth wall pipe and insert into the adjacent StormChambers™ where specified so that the marked midpoint is centered between the two adjacent StormChambers™. Pipe length should be sufficient to extend 6” – 12” into both adjacent StormChambers™. Space StormChambers™ at least 9” apart at the base at the end wall.5. Place the Start Model StormChambers™ (com-pletely closed at the end with the two side portals), spaced a minimum of 5’ 9” apart at the center line of the end walls (9” apart at the base at the end walls). Position the closed ends at least 1’ from the trench wall. Cut out side portals for smooth wall PVC inflow drainpipe and row connecting pipes. Cut out indentation guides are provided for 8", 10" and 12" pipes.6. Cut open the side portals for the inflow storm drain pipes (size and location specified on the plans) and lat-eral connecting pipes between StormChamber™ rows (8” ID Schedule 40 or SDR 35 smooth walled PVC, unless otherwise specified) with a reciprocating saw, router bit on a drill, or keyhole saw along the defined indented circle. If the cut extends more than 0.5” beyond the indented circle, place a piece of the filter fabric over the hole, cut an X just short of the width of the opening, and insert the pipe. The connection does not need to be water tight. 12” ID smooth walled pipe is the largest diameter pipe that can be inserted into the side portals. In order to facilitate placement, install the lateral con-necting pipes in the specified StormChambers™ before attaching the next StormChamber™ in the row. Example of typical StormChamber™ layout.8. If the locations of row – connecting pipes are not specified, add 8” pipes across all rows directly oppo-site where the inflow storm drain pipe(s) is inserted. This will typically connect at least all the Start Model StormChambers™ of each row. Additional connec-tions across all rows of StormChambers™ should be made so that the total diameter of pipe connections between any pair of rows is approximately equal to the total diameter of all inflow storm drain pipes. For example, a StormChamber™ system with one 12” inflow drain pipe would require 2, 8” pipes between each row of StormChambers™.Installation and Maintenance (continued)w w w . s t o r m c h a m b e r s . c o m • • • ? ?Place first rib of next chamber over last rib of previous chamber.9. Roll out additional light weight stabilization net-ting, over-laying the previous sheet by 1’ and place the first rib of a Middle Model (completely open at side portal end, partially open at top portal end) over the last rib of each of the Start Model StormChambers™. Screw StormChamber™ together to prevent stone inflow.10. You may have to screw the Middle Model StormChambers™ to the Start Models near their base on both sides with regular 3” dry wall screws. One screw on each side should be sufficient to temporarily hold the StormChambers™ together until the stone is placed. The gap between the two StormChambers™ near their base must be closed enough to prevent stone from migrating into them to prevent the potential for finished surface sub-sidence. End each row with and end model StormChamber™ which is closed at the top portal end and open at the side portal end.11. Continue placing and screwing the rest of the StormChambers™, one at a time, as necessary, inserting any additional lateral – connecting pipes as specified, leaving at least 1’ between the end of the End Model (completely open at the side portal end, completely closed at the top portal end) and the trench wall. Place heavyweight stabilization netting under chambers with cleanout risers.12. Place one piece of the heavy duty stabilization netting under the top portal end of each StormChamber™ that will be installed with a 10” PVC riser for access by a vacuum truck for clean out. Extend the netting equally beyond both sides of the StormChamber™ and extend about 1’ beyond the end wall of the StormChambers™. The purpose of the netting is to prevent the stone and soil from being sucked up by the vacuum truck. 13. For large StormChamber™ systems it may be neces-sary to install and backfill a few Stormchambers™ of all rows at a time.Installation and Maintenance (continued)1CR4'Heavyweight Stabilization Netting (Supplied)End Chamber Middle Chambers? ? • • • w w w . s t o r m c h a m b e r s . c o mInstall cleanout/inspection risers pipes.14. Cut a hole in the top portal for a 10” ID smooth walled SDR 35 or PVC Schedule 40 riser – along the larger of the two indented circles, unless an 8” pipe is specified. If the cut extends more than 0.5” beyond the cut out, place a piece of the filter fab-ric over the hole, cut an X slightly shorter than the width of the opening, and insert the pipe. Attach three small angle irons equally spaced approximate-ly 1’ up from the end of the pipe. Use 0.5” screws on riser pipe to prevent restricting insert of vacuum truck clean out tube. It is not necessary to screw the angle irons to the StormChamber™. The purpose of the angle irons is simply to support the pipe until the backfill is placed. Insert the bottom 1’ of pipe into the top portal and backfill. Attach top of riser pipe to a “Fernco Type” rubber cap, or to a cleanout cover assembly, as specified on the plans. Place an access casting in a concrete pad above, once all fill is placed, for risers in pavement. Deposit 3/4” – 2” crushed, washed, hard stone directly along the centerline of the StormChambers™.15. Deposit 3/4” – 2” crushed, washed, hard stone directly along the centerline of the StormChambers™ to even-ly flow down each side to keep the StormChambers™ in proper alignment. Do not place the stone directly against the closed end walls at the start and end of the rows. Let the stone fall in place at the StormChamber™ end from the top of the StormChamber™. Add stone to at least 6” above the StormChambers™. 16. Level the stone cover with a vibratory compactor, not to exceed a dynamic force of 10,000 lbs, or with a low pressure, tracked vehicle not exceeding 1,100 lbs/sf. IMPORTANT: If low pressure, tracked dozer is used, do not run dozer on anything less than 6” of stone above the StormChambers™. Spread stone in small piles to prevent movement of the StormChambers™. Caution must be exercised when placing stone on top of the StormChambers™ so that excessive pressure is not applied directly on the StormChambers™ by equipment “buckets”. 17. Cover the stone with 4 ounce non – woven filter fab-ric. Overlap adjacent sheets by at least 2’. 1. Backfill soil must be free from large stones and large organic material (e.g. tree limbs and root stumps), and must be capable of being compacted to at least 90% of the Standard Proctor Test (AASHTO Method T – 99). If not, crusher run or other suitable backfill material must be used. The same type of stone surrounding the StormChambers™ can also be extended up to the pavement sub grade, if desired. 2. Backfill and compaction of the soil backfill must be achieved in lifts 6” – 8” high. Grading of lifts should start in one corner of the system with a low pressure, tracked dozer, with a pressure not exceeding 1,100 lbs/sf, keeping at least 1’ of fill in front of the blade at all times. Compact lifts to 90% Standard Proctor with tracked vehicles not exceeding 1,100 lbs/sf, or with a hand operated compactor or vibratory roller not exceeding a dynamic force of 20,000 lbs. 3. Restrict wheeled vehicles to a maximum axle load of 8,000 pounds with 6” of fill over the StormChambers™ and 16,000 pounds with 12” of fill.4. Keep the StormChamber™ system closed or pro-tected from receiving sediment until the site is completely stabilized.IMPORTANT: After compaction of backfill and set-ting of final grade, avoid parking on or traversing over the StormChamber™ installation with heavily loaded trucks and heavy equipment until paved. IMPORTANT: These instructions assume accepted construction procedures and loaded trucks that do not exceed specified DOT load limits. Uncustomary loads or improper load distributions in vehicles may require additional cover. Contact HydroLogic Solutions for installation under abnormal conditions. Installations not in compliance with these instructions will void the war-BackfillingInstallation and Maintenance (continued)StormWater Management brought to you by Hydrologic SolutionsPhone 1.877.426.9128 email info@stormchambers.com.• • • w w w . s t o r m c h a m b e r s . c o m • • •