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HomeMy WebLinkAbout17--Stormwater OM PlanStormwater Operation and Maintenance Plan Bozeman Pilates Mixed Use Bozeman, MT 109 E. Main St. Suite B, Bozeman, MT 59715 I OFFICE 406.728.4611 I EMAIL wgm@wgmgroup.com BOZEMAN PILATES STORMWATER Operation and Maintenance Manual STORMWATER OPERATION & MAINTENANCE PLAN LOCATION The project location is Lot 5 of Block 16 of the Baxter Meadows Subdivision Phase 2A. The site is located on the northeast corner of Equestrian Ln and Vaquero Pkwy. PURPOSE Stormwater runoff is a significant source of water pollution in the City of Bozeman and in urban areas. In addition, increasing impervious area causes increased runoff flow rates and runoff volumes discharged to receiving drainageways. The proposed stormwater facilities help mitigate negative effects by providing treatment for pollutant removal as well as storage and infiltration functions to help control release rates downstream. Properly maintained stormwater facilities are effective at removing certain pollutants and providing necessary management of stormwater volumes during larger storm events. Improperly maintained facilities can increase the discharge of pollutants downstream, increase the risk of flooding downstream, increase the instability of downstream channels, and lead to aesthetic and nuisance problems. STORMWATER SYSTEM OVERVIEW The stormwater features used at this site include curb inlets, gutters, and underground storage and infiltration chambers located underneath the parking lot on the north portion of the site. The parking lot and surrounding sidewalk is graded to direct stormwater to the curb inlets, which then directs stormwater to the underground chambers. Landscaping throughout the site will encourage infiltration. In combination with each other, the site’s stormwater facilities have the following general objectives: • Efficient internal conveyance of stormwater runoff to final infiltration and treatment facilities. • Treatment and infiltration of runoff to improve water quality. • Protection of the downstream (i.e., offsite) drainage system through reduction of runoff peak flow rates and volumes via storage and infiltration. • Protection of groundwater and providing consideration to the relatively shallow and potentially fluctuating groundwater table. RESPOSIBILITY TO MAINTAIN Designation of a responsible party is important to assure proper operation of your stormwater detention and control features. In this instance it is a responsibility of the property owner(s) for the correct operation and proper maintenance of the facilities. The owner shall designate a qualified professional entity or individual to perform all monitoring and maintenance. The City of Bozeman Public Works Department is not responsible for the maintenance of the facilities located outside of the right-of-way including the water quality devices, flow control structures, and outlet pipes. Additionally, the City of Bozeman is not responsible for maintenance of the infiltration galleries within the right-of-way. However, the City of Bozeman Public Works Department does have the authority to inspect and review maintenance activities to ensure the viability of your facilities. The owner’s BOZEMAN PILATES STORMWATER Operation and Maintenance Manual representative shall be required to keep a log of all required inspections and maintenance required. The log shall be made available to the City of Bozeman Public Works Department for review as requested. INSPECTION & MAINTENANCE The onsite stormwater facilities have unique requirements for maintenance activities and intervals. The facility size, type and characteristics of the tributary area, and facility locations will all influence maintenance requirements. This section outlines maintenance activities, intervals, and procedures for the stormwater system. The site’s maintenance program should be adjusted as necessary to keep the stormwater system functioning properly. • Maintenance of the underground chambers should be per the manufacturer’s specifications. Accumulated sediment in the chambers should be cleaned whenever an inspection reveals sediment or trash is clogging the discharge orifice. Annual inspections are the best practice for all underground systems. • Regular maintenance activities should focus on the care of upstream pre-treatment facilities (i.e., catch basins and rain gardens) to protect the viability of larger downstream treatment features. This maintenance includes seasonal removal of any trash, debris, and sediment that accumulates within pipes, catch basins, curb and gutters, drywells, and infiltration galleries. Excessive accumulations of trash, debris, and sediment may cause clogging in the system and result in reduced lifespan of infiltration facilities, overflow and flooding, and damage risk to nearby structures. • Inlet grates should remain free of obstructions to flow from debris. Clogged inlets can lead to flooding risk and damage to onsite and offsite structures. Inlet grates are particularly prone to clogging from leaf litter in the fall and from road sanding/de-icing material in the spring. Inlets should be inspected four times per year and following large storm events and sumps should be cleaned annually or whenever basin sumps become filled with sediment to half of the depth. DO NOT ENTER confined spaces such as manholes and underground infiltration facilities for inspections. These facilities should be inspected from the surface. • Keeping underground infiltration facilities and drywells clear of accumulating sediment and debris is critical for their proper function and lifespan. If the underlying gravel pack and soils become clogged with fine sediments, the cobble galleries and drywells will not function as designed and may require complete replacement. Drywells should be inspected frequently and cleaned as necessary via hydraulic vacuum truck. • All piping should be inspected annually and following large storm events. Pipe should be cleaned and flushed as determined in the field. • All paved areas shall be swept twice a year, scheduled in the spring and fall. Routine Maintenance (seasonally to bi-annually): 1) Vegetation Management: When mowing, collect grass clippings and all other clippings/trimmings and take offsite for disposal or dispose in trash on site. Do not leave clippings in an area that will clog catch basin inlet grates, ponds, or pipes. Limit the use of BOZEMAN PILATES STORMWATER Operation and Maintenance Manual fertilizers and pesticides around channels and rain gardens to minimize entry into subsequent downstream waters. 2) Snow Storage Management: Snow shall be stockpiled in locations where accumulations won’t limit or restrict the ability of the infiltration facilities and storm structures to convey runoff. 3) Trash, Debris and Litter Removal: Removal of any trash, etc. causing any obstructions to the stormwater facilities during periodic inspections and especially after every significant runoff event. In general, pick up trash, etc. in and around the facilities during all inspections. Inspect all catch basins and drywell structures and clean floating debris as necessary. 4) Structural Component Check: Perform structural inspection of catch basins, drywells, inlets, grates, pipes, and culverts on a regular basis. 5) Structural Repair/Replacement: Eventually structural components may need to be repaired or replaced to ensure proper function. Monitor metal structures for excessive rust and corrosion. Monitor concrete structures for large cracking and/or spalling. Repair and replace as necessary. Underground stormwater detention and infiltration systems must be inspected and maintained at regular intervals for purposes of performance and longevity. Inspection Inspection is the key to effective maintenance of CMP detention systems and is easily performed. Contech recommends ongoing, quarterly inspections. The rate at which the system collects pollutants will depend more on site specific activities rather than the size or configuration of the system. Inspections should be performed more often in equipment washdown areas, in climates where sanding and/or salting operations take place, and in other various instances in which one would expect higher accumulations of sediment or abrasive/corrosive conditions. A record of each inspection is to be maintained for the life of the system. Maintenance CMP detention systems should be cleaned when an inspection reveals accumulated sediment or trash is clogging the discharge orifice. Accumulated sediment and trash can typically be evacuated through the manhole over the outlet orifice. 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. Contech suggests that all systems be designed with an access/inspection manhole situated at or near the inlet and the outlet orifice. Should it be necessary to get inside the system to perform maintenance activities, all appropriate precautions regarding confined space entry and OSHA regulations should be followed. Systems are to be rinsed, including above the spring line, annually soon after the spring thaw, and after any additional use of salting agents, as part of the maintenance program for all systems where salting agents may accumulate inside the pipe. Maintaining an underground detention or infiltration system is easiest when there is no flow entering the system. For this reason, it is a good idea to schedule the cleanout during dry weather. The foregoing inspection and maintenance efforts help ensure underground pipe systems used for stormwater storage continue to function as intended by identifying recommended regular inspection and maintenance practices. Inspection and maintenance related to the structural integrity of the pipe or the soundness of pipe joint connections is beyond the scope of this guide. Contech® CMP Detention Inspection and Maintenance Guide CMP MAINTENANCE GUIDE 2/17 PDF © 2017 Contech Engineered Solutions LLC All rights reserved. Printed in USA. ENGINEERED SOLUTIONS NOTHING IN THIS CATALOG SHOULD BE CONSTRUED AS A WARRANTY. APPLICATIONS SUGGESTED HEREIN ARE DESCRIBED ONLY TO HELP READERS MAKE THEIR OWN EVALUATIONS AND DECISIONS, AND ARE NEITHER GUARANTEES NOR WARRANTIES OF SUITABILITY FOR ANY APPLICATION. CONTECH MAKES NO WARRANTY WHATSOEVER, EXPRESS OR IMPLIED, RELATED TO THE APPLICATIONS, MATERIALS, COATINGS, OR PRODUCTS DISCUSSED HEREIN. ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND ALL IMPLIED WARRANTIES OF FITNESS FOR ANY PARTICULAR PURPOSE ARE DISCLAIMED BY CONTECH. SEE CONTECH’S CONDITIONS OF SALE (AVAILABLE AT WWW.CONTECHES.COM/COS) FOR MORE INFORMATION CMP DETENTION SYSTEMS Underground stormwater detention and infiltration systems must be inspected and maintained at regular intervals for purposes of performance and longevity. Inspection Inspection is the key to effective maintenance of CMP detention systems and is easily performed. Contech recommends ongoing, annual inspections. Sites with high trash load or small outlet control orifices may need more frequent inspections. The rate at which the system collects pollutants will depend more on- site specific activities rather than the size or configuration of the system. Inspections should be performed more often in equipment washdown areas, in climates where sanding and/or salting operations take place, and in other various instances in which one would expect higher accumulations of sediment or abrasive/ corrosive conditions. A record of each inspection is to be maintained for the life of the system. NOTHING IN THIS CATALOG SHOULD BE CONSTRUED AS A WARRANTY. APPLICATIONS SUGGESTED HEREIN ARE DESCRIBED ONLY TO HELP READERS MAKE THEIR OWN EVALUATIONS AND DECISIONS, AND ARE NEITHER GUARANTEES NOR WARRANTIES OF SUITABILITY FOR ANY APPLICATION. CONTECH MAKES NO WARRANTY WHATSOEVER, EXPRESS OR IMPLIED, RELATED TO THE APPLICATIONS, MATERIALS, COATINGS, OR PRODUCTS DISCUSSED HEREIN. ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND ALL IMPLIED WARRANTIES OF FITNESS FOR ANY PARTICULAR PURPOSE ARE DISCLAIMED BY CONTECH. SEE CONTECH’S CONDITIONS OF SALE (AVAILABLE AT WWW.CONTECHES.COM/COS) FOR MORE INFORMATION. CMP MAINTENANCE GUIDE 10/19 PDF © 2019 CONTECH ENGINEERED SOLUTIONS LLC, A QUIKRETE COMPANY ALL RIGHTS RESERVED. PRINTED IN USA. Maintenance CMP detention systems should be cleaned when an inspection reveals accumulated sediment or trash is clogging the discharge orifice. Accumulated sediment and trash can typically be evacuated through the manhole over the outlet orifice. 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. Contech suggests that all systems be designed with an access/inspection manhole situated at or near the inlet and the outlet orifice. Should it be necessary to get inside the system to perform maintenance activities, all appropriate precautions regarding confined space entry and OSHA regulations should be followed. Annual inspections are best practice for all underground systems. During this inspection if evidence of salting/de-icing agents is observed within the system, it is best practice for the system to be rinsed, including above the spring line soon after the spring thaw as part of the maintenance program for the system. Maintaining an underground detention or infiltration system is easiest when there is no flow entering the system. For this reason, it is a good idea to schedule the cleanout during dry weather. The foregoing inspection and maintenance efforts help ensure underground pipe systems used for stormwater storage continue to function as intended by identifying recommended regular inspection and maintenance practices. Inspection and maintenance related to the structural integrity of the pipe or the soundness of pipe joint connections is beyond the scope of this guide. Contech® CMP Detention Inspection and Maintenance Guide ENGINEERED SOLUTIONS CMP DETENTION SYSTEMS