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HomeMy WebLinkAboutC405 - SWPP INFORMATIONProject Number: Drawing Number: Certified By: Checked ByDrawn ByIssue Date Revisions:PROJECT:Scope Drawings:CARMEL, INDIANAFORCARMEL CLAY SCHOOLSNEW ELEMENTARY SCHOOLSDrawing Title: 11-19-19 SO MK 19012L SWPP INFORMATION C405 CrA Crosby silt loam, 0 to 3 percent slopes This is a somewhat poorly drained soil with a seasonal high water table at 0.5 to 2.0 ft. This soil is located on rises on till plains; slopes are 0 to 3 percent. The native vegetation is hardwood forest. The surface layer is silt loam and has moderately low to moderate organic matter content (1.0 to 3.0 percent). Permeability is very slow (<0.06 in/hr) in the most restrictive layer above 60 inches. Available water capacity is moderate (6.2 inches in the upper 60 inches). The pH of the surface layer in non-limed areas is 5.1 to 6.5. Droughtiness and wetness are management concerns for crops production. This soil responds well to tile drainage; it is designated potentially highly erodible (class 2) in the Highly Erodible Land (HEL) classification system. MmB2 Miami silt loam, 2 to 6 percent slopes, eroded This is a moderately well drained soil with a seasonal water table at 2.0 to 3.5 ft. This soil is located rises on till plains; slopes are 2 to 6 percent. The native vegetation is hardwood forest. The surface layer is silt loam and has moderately low organic matter content (1.0 to 2.0 percent). Permeability is very slow (<0.06 in/hr) in the most restrictive layer above 60 inches. Available water capacity is moderate (6.1 inches in the upper 60 inches). The pH of the surface layer in non-limed areas is 5.1 to 6.5. Droughtiness and water erosion are management concerns for crop production. This soil is designated potential highly erodible (class 2) in the Highly Erodible Land (HEL) classification system. SOILS MAP BMP - Stormwater Quality Treatment Unit (AQUA-SWIRL AS-6 & AS-7) Basic Operation The Storm water Quality Treatment Unit ( SQTU ) is a hydrodynamic separator designed to enhance gravitational separation of floating and settling materials from storm water flows. Storm water flows enter the unit tangentially to the grit chamber, which promotes a gentle swirling motion. As polluted water circles within the grit chamber, pollutants migrate toward the center of the unit where velocities are the lowest. The majority of settleable solids are left behind as storm water exits the grit chamber through two apertures on the perimeter of the chamber. Next, buoyant debris and oil and grease are separated from water flowing under the baffle wall due to their relatively low specific gravity. As storm water exits the System through the flow control wall and ultimately through the outlet pipe, it is relatively free of floating and settling pollutants. Over time a conical pile tends to accumulate in the center of the unit containing sediment and associated metals, nutrients, hydrocarbons and other pollutants. Floating debris and oil and grease form a floating layer trapped in front of the baffle wall. Accumulation of these pollutants can easily be assessed through access manholes over each chamber. Maintenance is typically performed through the manhole over the grit chamber. Inspection of SQTU SQTU should be inspected at regular intervals and maintained when necessary to ensure optimum performance. The rate at which the System collects pollutants will depend more heavily on site activities than the size of the unit, e.g., unstable soils or heavy winter sanding will cause the grit chamber to fill more quickly but regular sweeping will slow accumulation. Inspection is the key to effective maintenance and is easily performed. Quarterly inspections of the accumulated sediment. Pollutant deposition and transport may vary from year to year and quarterly inspections will help insure that Systems are cleaned out at the appropriate time. Inspections should be performed more often in the winter months in climates where sanding operations may lead to rapid accumulations, or in equipment wash down areas. It is very useful to keep a record of each inspection. The SQTU system should be cleaned when inspection reveals that the sediment depth has accumulated to the determined elevation or depth. This determination can be made by taking 2 measurements with a stadia rod or similar measuring device. Cleaning of SQTU Structures Maintaining the SQTU is easiest when there is no flow entering the Systems. For this reason, it is a good idea to schedule the clean out during dry weather. Clean out of the SQTU with a vacuum truck is generally the most effective and convenient method of excavating pollutants from the System. If such a truck is not available, a "clamshell" grab may be used, but it is difficult to remove all accumulated pollutants with such devices. Oil or gasoline spills should be cleaned out immediately. Motor oil and other hydrocarbons that accumulate on a more routine basis should be removed when an appreciable layer has been captured. To remove these pollutants, it may be preferable to use adsorbent pads since they are usually cheaper to dispose of than the oil water emulsion that may be created by vacuuming the oily layer. Trash can be netted out if you wish to separate it from the other pollutants. Accumulated sediment is typically evacuated through the manhole over the grit chamber. Simply remove the cover and insert the vacuum hose into the grit chamber. As water is evacuated, the water level outside of the grit chamber will drop to the same level as the crest of the lower aperture of the grit chamber. It will not drop below this level due to the fact that the bottom and sides of the grit chamber are sealed to the tank floor and walls. This "Water Lock" feature prevents water from migrating into the grit chamber, exposing the bottom of the baffle wall. Floating pollutants will decant into the grit chamber as the water level there is drawn down. This allows most floating material to be withdrawn from the same access point above the grit chamber. If maintenance is not performed as recommended, sediment may accumulate outside the grit chamber. If this is the case, it may be necessary to pump out all chambers. It is a good idea to check for accumulation in all chambers during each maintenance event to prevent sediment build up there. Manhole covers should be securely seated following cleaning activities, to ensure that surface runoff does not leak into the unit from above. After a storm event, treated runoff is decanted out of the SQTU at a controlled rate, restoring the water level to a low dry-weather volume. This reveals a conical pile of accumulated sediment in the center of the grit chamber. Besides facilitating inspection and cleaning through the unobstructed access, the low water level significantly reduces maintenance costs by decreasing pump-out volume. Note: As the generator, the landowner is ultimately responsible for the proper disposal of material removed from water quality treatment structures. Quarterly inspections of the SQTU shall include observation of the accumulated sediment. Pollutant deposition and transport may vary from year to year and quarterly inspections will help insure that the systems are cleaned out at the appropriate time. Inspections should be performed more often in the winter months in climates where sanding operations may lead to rapid accumulations, or in equipment wash down areas. CONSTRUCTION SITE SWPPP CONTINUED 8. Continued: L. Monitoring and Maintenance Guidelines Continued. Monitoring and maintenance guidelines for each proposed storm water quality measure: Temporary gravel construction entrance maintenance requirements 1.Inspect entrance pad and sediment disposal area weekly and after storm events or heavy use. 2.Reshape as needed for drainage and runoff control. Maintain 150' driveway length. 3.Top dress with clean stone as needed. 4.Immediately remove mud and sediment tracked or washed onto streets by brushing or sweeping. Flushing should only be used if the water is conveyed into a sediment trap of basin. 5.Repair any broken road pavement immediately. Silt fence maintenance requirements 1.Inspect the silt fence periodically and after each storm event. 2.If fence fabric tears, starts to decompose or in any way becomes ineffective, replace the affected portion immediately. 3.Remove deposited sediment when it reaches half the height of the fence at its lowest point or is causing fabric to bulge. 4.Take care to avoid undermining the fence during cleanout. 5.After the contributing drainage area has been stabilized, remove the fence and sediment deposits, bring the disturbed area to grade and stabilize. Inlet Protection, and Drop Inlet barrier maintenance requirements. 1.Inspect after each storm event and repair if necessary. 2.Remove sediment, without flushing, when it reaches half the height of barrier. 3.Deposit removed sediment where it will not enter storm sewer drains. 4.Replace or repair if torn or damaged in other ways. 5.5.When contributing drainage area has been stabilized, remove and properly dispose of construction material and sediment, finish grade the disturbed area and stabilize.. Erosion control blanket (surface applied) maintenance requirements 1.During vegetative establishment, inspect after each storm event for any erosion below the blanket. 2.If any area(s) shows erosion, pull back that portion of the blanket covering it, reseed the area and relay and staple the blanket. 3.After vegetative establishment check the treated area periodically. Topsoil (Salvage and Utilization): 1.Inspect newly topsoiled areas frequently until vegetation is established 2.Repair eroded or damaged areas and re-vegetate. All erosion and sediment control measures must be properly maintained throughout construction. Temporary and permanent seeding should be watered as needed until established. See Plan Sheet C403. Implementation The following steps will help keep a clean site and reduce stormwater pollution: Select designated waste collection areas onsite. Inform trash-hauling contractors that you will accept only watertight dumpsters for onsite use. Inspect dumpsters for leaks and repair any dumpster that is not watertight. Provide an adequate number of containers with lids or covers that can be placed over the container to keep rain out or to prevent loss of wastes when it is windy. Plan for additional containers and more frequent pickup during the demolition phase of construction. Collect site trash daily, especially during rainy and windy conditions. Remove this solid waste promptly since erosion and sediment control devices tend to collect litter. Make sure that toxic liquid wastes (used oils, solvents, and paints) and chemicals (acids, pesticides, additives, curing compounds) are not disposed of in dumpsters designated for construction debris. Do not hose out dumpsters on the construction site. Leave dumpster cleaning to the trash hauling contractor. Arrange for regular waste collection before containers overflow. Clean up immediately if a container does spill. Make sure that construction waste is collected, removed, and disposed of only at authorized disposal areas. Collection, Storage, and Disposal Littering on the project site should be prohibited. To prevent clogging of the storm drainage system, litter and debris removal from drainage grates, trash racks, and ditch lines should be a priority. Trash receptacles should be provided in the contractor's yard, field trailer areas, and at locations where workers congregate for lunch and break periods. Litter from work areas within the construction limits of the project site should be collected and placed in watertight dumpsters at least weekly, regardless of whether the litter was generated by he contractor, the public, or others. Collected litter and debris should not be placed in or next to drain inlets, stormwater drainage systems, or watercourses. Dumpsters of sufficient size and number should be provided to contain the solid waste generated by the project. Full dumpsters should be removed from the project site and the contents should be disposed of by the trash hauling contractor. Construction debris and waste should be removed from the site biweekly or more frequently as needed. Construction material visible to the public should be stored or stacked in an orderly manner. Stormwater runoff should be prevented from contacting stored solid waste through the use of berms, dikes, or other temporary diversion structures or through the use of measures to elevate waste from site surfaces. Solid waste storage areas should be located at least 50 ft from drainage facilities and watercourses and should not be located in areas prone to flooding or ponding. Inspection and Maintenance Inspect and verify that activity-based BMPs are in place prior to the commencement of associated activities. While activities associated with the BMP are under way, inspect weekly to verify continued BMP implementation. Inspect BMPs subject to non-stormwater discharge daily while non-stormwater discharges occur Inspect construction waste area regularly. Arrange for regular waste collection. VEHICLE AND EQUIPMENT FUELING Description and Purpose Vehicle equipment fueling procedures and practices are designed to prevent fuel spills and leaks, and reduce or eliminate contamination of stormwater. This can be accomplished by using offsite facilities, fueling in designated areas only, enclosing or covering stored fuel, implementing spill controls, and training employees and subcontractors in proper fueling procedures. Limitations Onsite vehicle and equipment fueling should only be used where it is impractical to send vehicles and equipment offsite for fueling. Sending vehicles and equipment offsite should be done in conjunction with a Stabilized Construction Entrance/ Exit. Implementation Use offsite fueling stations as much as possible. These businesses are better equipped to handle fuel and spills properly. Performing this work offsite can also be economical by eliminating the need for a separate fueling area at a site. Discourage "topping-off" of fuel tanks. Absorbent spill cleanup materials and spill kits should be available in fueling areas and on fueling trucks, and should be disposed of properly after use. Drip pans or absorbent pads should be used during vehicle and equipment fueling, unless the fueling is performed over an impermeable surface in a dedicated fueling area. Use absorbent materials on small spills. Do not hose down or bury the spill. Remove the adsorbent materials promptly and dispose of properly. Avoid mobile fueling of mobile construction equipment around the site; rather, transport the equipment to designated fueling areas. Train employees and subcontractors in proper fueling and cleanup procedures. Dedicated fueling areas should be protected from stormwater runon and runoff, and should be located at least 50 ft away from downstream drainage facilities and watercourses. Fueling must be performed on level-grade areas. Protect fueling areas with berms and dikes to prevent runon, runoff, and to contain spills. Nozzles used in vehicle and equipment fueling should be equipped with an automatic shutoff to control drips. Fueling operations should not be left unattended. Federal, state, and local requirements should be observed for any stationary above ground storage tanks. Inspection and Maintenance Vehicles and equipment should be inspected each day of use for leaks. Leaks should be repaired immediately or problem vehicles or equipment should be removed from the project site. Keep ample supplies of spill cleanup materials onsite. Immediately clean up spills and properly dispose of contaminated soil and cleanup materials. SOLID WASTE MANAGEMENT Description and Purpose Solid waste management procedures and practices are designed to prevent or reduce the discharge of pollutants to stormwater from solid or construction waste by providing designated waste collection areas and containers, arranging for regular disposal, and training employees and subcontractors. Suitable Applications This BMP is suitable for construction sites where the following wastes are generated or stored: Solid waste generated from trees and shrubs removed during land clearing, demolition of existing structures (rubble), and building construction Packaging materials including wood, paper, and plastic Scrap or surplus building materials including scrap metals, rubber, plastic, glass pieces and masonry products Domestic wastes including food containers such as beverage cans, coffee cups, paper bags, plastic wrappers, and cigarettes Construction wastes including brick, mortar, timber, steel and metal scraps, pipe and electrical cuttings, nonhazardous equipment parts, styrofoam and other materials send transport and package construction materials SWPPP FOR POST CONSTRUCTION - CITY OF CARMEL 1.Post Construction SWPP: A.Potential Land Use Pollutants: Description of pollutants and their sources associated with the proposed land use include Silt and sediment from expose soils, leaves, mulch, vehicular sources such as leaking fuel or oil, brake fluid, brake dust, grease, antifreeze, metals, rubber fragments, road grit, salts and sands, construction trash and debris, fertilizers, household items including but not limited to cleaning agents, chemicals, paint, miscellaneous home improvement materials, toys, clothing and animal waste, elevated storm runoff temperatures, acid rains, pesticides and pathogens. B.Location, Dimensions, specifications and construction Details of Storm water Quality Measures. The hydronamic filters are located upstream of the detention basin. The detention basin is located at the NE property corner. C.Storm water Quality Implementation 1. Inspect and maintain all erosion control measures as detailed in the Storm Water Pollution Prevention Measures Maintenance Requirement beginning immediately after installation and continuing until vegetation has been sufficiently established and all construction activities completed. 2. Remove all individual inlet protection, coir fiber log check dams, silt fences, etc. only after seeding/sodding and sufficient vegetative growth has been established in each area to a point where sediment/pollutants will not enter the detention basin or storm sewer system. 3. Inspection and maintenance of all common area and infrastructure improvements is the responsibility of the owner/developer or his designee until improvements are accepted for maintenance by local agencies. 2.Description of proposed post-construction storm water quality measures: Site and facility design for storm water quality protection on this site employs a multi-level strategy consisting of: ·Controlling sources of pollutants. ·Filtering Runoff through a hydronamic filter then a wet pond with native banks. ·Permanent erosion control seeding/sodding and plantings. CONSTRUCTION SITE SWPPP CONTINUED 13. Material Handling and Spill Prevention Material handling and spill prevention plan: Purpose: The intention of this Spill Prevention, Control and Countermeasures (PCC) is to establish the procedures and equipment required to prevent the discharge of oil and hazardous substances in quantities that violate applicable water quality standards, cause a sheen upon or discoloration of the surface of Receiving water or adjoining shorelines, or cause sludge or emulsion to be deposited beneath the surface of the water or adjoining shorelines. The plan also establishes the activities required to mitigate such discharges (i.e. countermeasures) should they occur. Definitions: Pollutant: Means pollutant of any kind or in any form, including but not limited to sediment, paint, cleaning agents, concrete washout, pesticides, nutrients, trash, hydraulic fluids, fuel, oil, petroleum, fuel oil, sludge, oil refuse, and oil mixed with wastes other than dredged soil. Discharge: Includes, but is not limited to, any spilling, leaking, pumping, pouring, emitting, emptying or dumping. Receiving Navigable Waters: Means all waters of the United States that are connected with a Receiving stream, lake, or sea. [Note: this definition is usually interpreted to mean any wastewater even normally dry wash or storm sewer) that eventually drains into a Receiving stream. Plan Review Amendments:This plan shall be reviewed and/or amended, if necessary, whenever there is a change in the design of the site, construction, operation, or maintenance which materially affects the site's potential for the discharge of regulated material. Prediction of Potential Spills: 1. Nearest Receiving Water: Cool Creek . 2. Drainage System: In the pre-developed condition, storm runoff flows offsite to the east, south, southwest and north. The runoff is routed via storm sewers to Cool Creek. In post construction conditions, most onsite runoff with be routed to an underground detention basin. The detention basin will drain via storm sewer to Cool Creek. 3.Possible spill sources (during and post-construction): Vehicular sources such as leaking fuel or oil, brake fluid, grease, antifreeze; construction trash and debris, biological agents found in trash and debris, fertilizers, household items including but not limited cleaning agents, chemicals, paint, herbicides and pesticides. 4.Groundwater contamination: The facility maintains NO above ground oil & separator or underground storage tanks at this site. Therefore, it is felt that there is little or no possibility of post-construction groundwater contamination. The facility does have city sanitary sewer and city water. Alert Procedures for Spills: 1. Any personnel observing a spill will immediately initiate the following procedure: a. Notify the designated emergency coordinator for the project. 2. The Emergency Coordinator will then take the following actions: a. Barricade the area allowing no vehicles to enter or leave the spill zone. b. Notify the Indiana Department of Environmental Management, Office of Emergency Response by calling the appropriate telephone number. Office 317-233-7745 Toll Free 800-233-7745 Also the National Response Center at 800-424-8802 and provide the following information: - Time of observation of the spill - Location of the spill - Identity of material spilled - Probable source of the spill - Probable time of the spill - Volume of the spill and duration - Present and anticipated movement of the spill - Weather conditions - Personnel at the scene - Action initiated by personnel c. Notify the Carmel Fire Department : Phone 911 d. Notify the Carmel Police Department: Phone 911 e. Notify waste recovery contractor, maintenance personnel or other contractual personnel as necessary for clean up f. Coordinate and monitor clean up until the situation has been stabilized and all spills have been eliminated. g. Cooperate with the IDEM-OER on procedures and reports involved with the event. Cleanup Parameters: 1. The developer shall be continually kept informed, maintain lists of qualified contractors and available Vac-trucks, tank pumpers and other equipment readily accessible for clean-up operations. In addition, a continually updated list of available absorbent materials and clean up supplies should be kept on site. 2. All maintenance personnel will be made aware of techniques for prevention of spills. They will be kept abreast of current development or new information on the prevention of spills and/or necessary alteration to this plan. 3. When spills occur which could endanger human life and this becomes primary concern, the discharge of the life saving protection function will be carried out by the local police and fire departments. 4. Absorbent materials, which are used in cleaning up spilled materials, will be disposed of in a manner subject to the approval of the Indiana Department of Environmental Management. 5. Flushing of spilled material with water will not be permitted unless so authorized by the Indiana Department of Environmental Management. . 9.General Construction Sequencing: A. Pre-Construction Activities: 1.Schedule Pre-Con with City of Carmel Engineering Department before commencing work. 2.Call the Indiana Underground Plant Protection Systems, Inc. ("Holey Moley") at 1-800-382-5544 to check the location of any existing utilities. They should be notified two working days before construction takes place 3.Install silt fencing at the edges of the project site as indicated on plans. Preservation of existing grass strips upstream and downstream of silt fencing greatly reduces sediment transport offsite. 4.Maintain a 10' minimum grass filter strip along the site perimeter adjacent to public streets wherever possible. 5.Install inlet protection measures at all existing inlets as shown on the plans 6.A construction entrance shall be placed per the plan location. B. Construction Phase Activities: 1.Repair any silt fence, check dams or inlet protection damaged during Earthmoving or Construction activities. 2.Complete construction activities. 3.Designate the person responsible for complying with the on-site SWPPP inspections until site has reached 70 percent vegetative cover density. 4.If work or construction has stopped for 2 weeks or more before permanent seed is applied, install temporary seed and mulch as described on Sheet C403. Coordinate responsibility for completing the site review after each 12" rainfall and a minimum of one time a week. 5.Complete building, exterior paving and utilities 6.Perform final grading. 7.Place permanent seeding and plantings per Landscape Plan, and review final stabilization. 8.Maintain all inlet protection, check dams and silt fencing in the site project by cleaning out every week and after every rain event of 1/2" or greater depth. 9.Final stabilization is considered complete when al land disturbing activities have been completed and a uniform perennial vegetated having 70% density is achieved on all unpaved areas and areas not having a permanent structure. The contractor shall over-seed as required to obtain 70 percent vegetative density if required. 10.After site has 70% vegetative cover, contractor shall remove remaining temporary BMP structures and repair and re-seed any disturbed areas as required. 14.Once the construction activity is completed (by rule language, when final stabilization has occurred), a completed Rule 5 Notice of Termination (NOT) must be submitted to IDEM, with a copy being sent to the Carmel Engineering Department. . 10.Soil Stockpile Locations: A. Topsoil stockpile locations: See Sheet C401 and C402. 11.Temporary and Permanent Stabilization Measures: See Plan Sheets C401, C402 and C406. 12.Erosion Control Measure for Individual Building Lots: Not Applicable 14. Contact Information Project Name: Carmel Elementary Address: 101 4th Ave SE, Carmel, Indiana 46032 County: Hamilton Civil Township: Clay Quarter: SE Section: 21 Township: 18-N Range: 4-E Latitude: 86°07'89''N Longitude:39°58'70''W Project Location: 101 4th Ave SE, Carmel, Indiana 46032 Project Site Owner and Contact Information: Company Name (if applicable): Carmel Clay Schools Name (Individual): Ron Farrand Jr., RA Position: Director of Facilities and Transportation Address: 5201 East 131st Street City: Carmel State: IN Zip: 46033 Phone: (317) - 815 - 3962 Trained Individual Responsible for SWPPP Inspections: Company Name: Skillman Corporation Contact Person: Eli Miller Title/Position: Senior Project Manager Address: 3834 S. Emerson Ave. City: Indianapolisl State: IN Zip: 46203 Phone: (317) - 788-5149 Project Information: Project Narrative: New Elementary School with parking spaces, bus loading / unloading area, playgrounds and baseball fields. Storm Water utilities needed for operation of the development are also included with this project. SWPPP FOR CONSTRUCTION SITES - CITY OF CARMEL 1 14 Digit Hydrologic Code:05120201090030 2.Receiving Waters:Cool Creek-Grassy Branch/Little Cool Creek 3.Estimate of Peak Discharge for Post Construction: 10 year Pre-Construction Peak Discharge = 45.17 cfs 10 year Post-Construction Peak Discharge = 19.06 cfs 4.In the pre-developed condition, storm runoff flows offsite to the east, south, southwest and north. The runoff is routed via storm sewers to Cool Creek. In post construction conditions, most onsite runoff with be routed to an underground detention basin. The detention basin will drain via storm sewer to Cool Creek. 5.Identification of potential discharges to groundwater: Excavation pits can be potential sources of discharge into groundwater. There is a potential for discharges into groundwater from sediment resulting from exposed soils, leaves, mulch, and vehicular sources if a significant rain event occurs while excavations are open. 6.Soils Map: The grading generally slopes away from the center of the site. To accommodate this slope and prevent post construction pollutants from impervious areas from reaching the creek, impervious areas will drain to post construction storm water quality structures and elements. 7.Potential Construction Pollutants: Silt and sediment from exposed soils, leaves, mulch, vehicular sources such as leaking fuel or oil, brake fluid, brake dust, trash, debris, biological agents found in trash, fertilizers, herbicides, pesticides, acid rain, lime dust and concrete washout. 8. Temporary and Permanent Storm Water Quality Measures: A. Stable construction entrance location(s) and specifications: Located along Clay Center Road at middle of site. See Plan Sheet C401-C402, and C404. B. Sediment control measures for sheet flow areas: See Plan Sheets C401-C403. C. Sediment control measures for concentrated flow areas: See Plan Sheets C401- C403. D. Storm sewer inlet protection measures, locations and specifications: See Plan Sheets C401-C403. E. Runoff control measures: See Plan Sheets C401-C403. F. Storm water outlet protection specifications: See Plan Sheet C401-C403 & C405. G. Grade control structure locations and specifications: None. H. Location, dimensions, specifications and construction details of each storm water quality measure: See Plan Sheets C401-C405. I. Temporary Surface stabilization methods appropriate for each season: See Plan Sheets C401-C403 & C405. J. Permanent surface stabilization specifications: See Plan Sheet C405. K. Monitoring and Maintenance Guidelines. See Plan Sheet C406. CrA PROJECT SOIL LEGEND Crosby silt loam, fine-loamy subsoil, 0 to 2 percent slopes Mmb2 Miami silt loam, 2 to 6 percent slopes Underground Detention Basin: This site also incorporates an underground detention system which reduces the rate at which storm water runoff leaves the site. Control of the watershed basin maximum storm water runoff discharge rates serves to protect drainage channels downstream of the detention basin. The underground detention system includes a connected grid of 84‐inch CMP pipe set in porous stone where storm water runoff is stored. Discharge of the stored water is controlled by a downstream pipe. The restrictor structure shall be inspected monthly and after each major storm event to ensure that the orifices are not clogged and that the system is retaining and then draining storm water within 24‐48 hours of the storm event. ·Underground detention basins should be inspected quarterly to ensure that the structure operates in the manner originally intended. More frequent inspections should be performed during seasons in which high debris and sediment are expected (fall leaf drop). ·When possible, inspections should be conducted during wet weather to determine if the pond is properly reducing runoff discharge rates. ·Inspection is the key to effective maintenance and is easily performed. The underground detention system, which includes a connected grid of 84‐inch CMP pipe, can be accessed through access risers individually set near each of the four system perimeter corners. ·The downstream structure should be inspected monthly and after each rainfall event to ensure optimum performance and verify the orifices are not clogged. More frequent inspections should be performed during seasons in which high debris and sediment are expected (fall leaf drop). ·The underground detention pipe system should be inspected quarterly for sediment depth. If the depth of the sediment exceeds 6‐inches, in the 84‐inch CMP system the underground detention system should be cleaned. ·All appropriate precautions regarding confined space entry and OSHA regulations should be followed for inspections and maintenance. ·Maintaining an underground detention or retention system is easiest and safest when there is no flow entering the system. For this reason, it is imperative to conduct the cleanout during dry weather. ·If maintenance is not performed as recommended, sediment and trash may accumulate in front of the outlet orifice. ·Manhole covers should be securely seated following cleaning activities. ·A vactor truck is recommended for cleaning the pipes. Standard vactoring operations should be employed and disposal of material should be in accordance with the local municipality requirements. Disposal of the decant material to a POTW is recommended. ·Field decanting to the sanitary sewer is not permitted. Solids can be disposed similar to normal practices for materials collected from street sweeping and catch basin cleaning. ·Collected solids should be disposed in accordance with all Federal, State and Local regulations. ·Structural Repairs and/or Replacement: Eventually, the basin outlet structure or parts of the structure will deteriorate and must be replaced. The downstream outfall may deteriorate and need to be replaced in 20 or 30 years. ·Annual inspection reports for the underground detention system must been submitted to the City of Carmel Engineering Department. The first report is due one year after construction is completed, with subsequent reports due each year within the same month of the initial report. If there are any deficiencies found during the inspections, these should be addressed.