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HomeMy WebLinkAbout06 1825 W Kagy_Storm System OI&M Plan JOB NO. B26-010 MONTANA | WASHINGTON | IDAHO | NORTH DAKOTA | PENNSYLVANIA MAY 2026 406.586.0277 tdhengineering.com 234 East Babcock Street Suite 3 Bozeman, MT 59715 CLIENT ENGINEER Reuter Walton Development 4450 Excelsior Boulevard, Suite 400 St. Louis Park, MN 55416 TD&H Engineering 234 East Babcock Street, Suite 3 Bozeman, MT 59715 Engineer: Cody Croskey, PE ON-SITE STORMWATER OPERATION, INSPECTION & MAINTENANCE PLAN 1825 W KAGY AFFORDABLE HOUSING BOZEMAN, MONTANA 1825 W KAGY AFFORDABLE HOUSING STORMWATER OI&M PLAN MAY 2026 The following is a Stormwater Operation, Inspection & Maintenance (OI&M) Plan for the 1825 W Kagy Affordable Housing project. The format of this plan follows the outline provided in the City of Bozeman Design and Construction Standards, Section 6.4.3. a. Responsible Party The designated responsible party for operation, inspection, maintenance, and replacement of all stormwater facilities is Drew Wojack of Reuter Walton Development on behalf of the property owner entity, 1825 W Kagy LLC. In the event of a change in ownership, this obligation transfers to the successor or assign of the property owner and will be disclosed as part of any ownership transfer. The landowner or responsibly party may delegate routine OI&M responsibilities to an on-site facility operations management team, or may hire a qualified professional entity or individual to perform certain OI&M tasks as necessary. b. Contact Information Drew Wojack Reuter Walton Development 4450 Excelsior Blvd, St. Louis Park, MN 55416 Phone: (612) 823-3489 Email: dwojack@reuterwalton.com c. Stormwater Management System Description and Map The on-site storm water management system at this site includes roof drains, curb & gutter, area inlets, curb inlets, conveyance piping and subsurface retention chambers. A map of the site with stormwater system components identified is included in the attached Appendix. d. Inspection & Maintenance Activities & Schedule General Stormwater System Maintenance: 1. Parking lot areas, curbs & gutters, drainage chases, and drainage paths should be cleared of leaves and other debris once after primary leaf drop in the fall and once after snow melt in early spring at a minimum. This will minimize the potential for debris to enter the system which could lead to premature clogging of structures, reduced storage capacity, and/or blockage of inlets. 2. Snow storage should be performed in designated areas during winter months and should not be allowed to be piled over storm inlets. Piled snow could block drainage paths preventing early snowmelt run-off from entering the system, possibly causing overflows and icy conditions. 3. Sanding of the parking lots and drive aisles should be done sparingly or avoided completely. Sand or other sediment on the parking lot will likely be washed into stormwater system components which can lead to buildup and reduced capacity or blockages over time. Stormwater System Components: 1. Routine Maintenance Activities (Every 3 Months): a. Inspect inlet grates, curb lines, and drainage chases, during a wet weather event if possible, for buildup of debris or blockages that may prevent ponding or runoff from reliably entering the subsurface retention system. b. Remove trash, gravel, debris, leaves, plant trimmings, etc. from drainage paths and inlet grates as necessary. c. Ensure inlets are not blocked by ice or snow storage during winter months. 2. Annual Maintenance Activities (Annually): a. Remove grates and covers to Inspect the insides of inlets and manholes for accumulated sediments and debris. b. Manually remove trapped trash or large debris to prevent blockages. Remove sediment if it has accumulated in the sump to within 1” of the lowest pipe invert. c. Open and observe the inspection ports on the subsurface retention chambers. If upon visual inspection it is found that sediment has accumulated, a stadia rod should be inserted to determine the depth of sediment. When the average depth of sediment exceeds 3" throughout the length of the chamber, a clean-out should be performed. 3. Long-Term Maintenance Activities (Every 5 Years): a. Access the provided cleanouts to jet roof drain piping. b. Use hydrovac equipment or other suitable methods to clean out storm manhole and inlet sumps. c. Disposal of accumulated sediment must be in accordance with all applicable local, state and federal regulations 4. Long-Term Maintenance Activities (Every 10 Years): a. Use jetting and hydrovac equipment or other suitable means to clean out the subsurface isolator row chambers (see attached manufacturer O&M guidance). b. Disposal of accumulated sediment must be in accordance with all applicable local, state and federal regulations e. Stormwater Facility Inspection Form The attached Stormwater Facility Inspection Form shall be duplicated and completed for all routine inspections and maintenance. Inspection and maintenance logs shall be made available to the City of Bozeman Stormwater Department for review as requested. f. Expected Design Life and Replacement Schedule The expected design life and replacement schedule for the stormwater system components are as follows: - ADS StormTech MC-7200 Chambers: 50-year design life (ADS documentation) - PVC Storm Drain Pipe: 50-year design life (industry standard) - Precast Concrete Manholes & Inlets: 50-year design life (industry standard) g. Cost Estimates for Routine Inspection, Maintenance, and Facility Replacement Itemized cost estimates for recurring operation, inspection, and maintenance activities and planned facility replacement: Inspection & Maintenance Activity Cost Estimate Quarterly – surface inspection and clean-up $500 / yr Annual – interior inspections and manual debris removal $500 / yr 5 year – vac manhole/inlet sumps and jet roof drains $250 / yr 10 year – jet/vac subsurface chambers $250 / yr Total Annual OI&M Estimate = $1,500 / yr Component Replacement Cost Estimate Qty. Unit Price Total Precast Manhole (50 Years) 4 ea. $6,500 /ea. $26,000 Precast Inlet (50 Years) 3 ea. $4,500 /ea. $13,500 PVC Drain Pipe (50 years) 530 lf $70 /lf $37,100 Stormwater Chambers (50 Years) 27,000 cf $15 /cf $405,000 Total Replacement Cost (50 years) = $481,600 Note: Assume 3% inflation per year to estimated costs. h. Financial Plan and Funding Recurring OI&M costs and planned facility replacement will be funded through operating reserves maintained by 1825 W Kagy LLC. We intend to establish and maintain a sinking fund beginning at project stabilization (estimated mid-2028), sized to cover the annual OI&M costs identified above plus a long-term replacement reserve, inflated at 3% per year over the life of each system component. APPENDIX Acknowledgement Form Stormwater System Map Stormwater Facility Inspection Form ADS StormTech Isolator Row Plus O&M Manual WSDSDWWWSSSSWWWSSQUALITY CHECK:DESIGNED BY:DRAWN BY:CAD NO.JOB NO.DATE:STORM MAINT MAPPRINTED 2026-05-04, BY CODY CROSKEY, I:\2026\BOZ\B26-010 KAGY LIHTC\06_CADD\CIVIL\FIGURES\STORM MAINT MAP.DWG1825 W KAGY AFFORDABLE HOUSINGBOZEMAN, MONTANASTORMWATER SYSTEM MAPCJC05.04.2026B26-010FIGURE1PAGE SETUP 2023_TDH_LETTER_LEngineering234 E. BABCOCK ST., SUITE 3 • BOZEMAN, MONTANA 59715406.586.0277 • tdhengineering.com0S C A L E80'120'40'W KAGY BLVD.S. 19TH AVE. HAWKS RIDGE DRIVE1825 W. KAGYPVC ROOF DRAINPVC ROOF DRAINMH-2INLET-2MH-1INLET-1PVC ROOF DRAINPVC STORM DRAINMH-3INLET-3MH-4STORM CHAMBERS-NORTHSTORM CHAMBERS-SOUTH Chapter 6 - Storm Drainage Design 6-44 City of Bozeman Design and Construction Standards Stormwater Facility Inspection Form Section 1: General Information Facility ID: Facility Type: Choose an item. Date/Time: Click or tap to enter a date. Owner: Contact: Inspector’s Name, contact info: Choose an item. Location/Access info: Type of Inspection: ☐ Routine, Dry Weather ☐ Routine, Wet Weather ☐ Complaint Driven ☐ Other: __________________ Section 2: Weather and Discharge Information Most recent precipitation or melt: Temperature: Is a stormwater discharge occurring? ☐ Yes ☐ No If yes, what is the source and quality of discharge? Is an illegal discharge occurring? ☐ Yes ☐ No If yes, what is the source and quality of discharge? Section 3: Facility Maintenance Priority ☐ Low: Stormwater facility appears to be functioning as designed. Continue scheduled maintenance. ☐ Medium: Stormwater facility requires minor to moderate sediment and vegetation maintenance to mitigate the risk of flooding, waterway pollution, and infrastructure failure. ☐ High: Stormwater facility requires significant sediment dredging, vegetation removal, and/or infrastructure repairs to restore function. Notes, Findings & Recommendations: Inspector’s Signature: ________________________________ Date: ___________________ 1825 W Kagy Blvd.Stormwater Retention Chambers 1825 W Kagy LLC Drew Wojack Parking Lot Chapter 6 - Storm Drainage Design 6-45 City of Bozeman Design and Construction Standards Section 4: Qualitative Analysis Components # Items Conditions Results Notes and Required Actions General Degraded, missing, or inadequate Yes 1.1 Accessibility maintenance access? No ☐☐ Trash, sediment, and waste within 1.2 Debris ☐Yes and around the facility? ☐ No Overgrown or dead cattails, Yes 1.3 Vegetation woody shrubs, weeds, grass, and ☐ trees? ☐ No Infrastructure Damaged inlet pipe, outlet pipe, Yes1.4 ☐ Condition outfall structure, or fencing? ☐ No Facility Condition Pretreatment Bay Clogged, obstructed, or filled 2.1 ☐ Yes or Facility pretreatment forebay or facility? ☐ No 2.2 Storage Bay Clogged or filled storage bay? ☐ Yes ☐ No Stagnant water with infiltration Groundwater or Yes 2.3 greater than 48 hours post-rain ☐ Standing Water event? ☐ No 2.4 Flow Path Clogged or obstructed flow path? ☐ Yes ☐ No Barren or exposed surfaces on Yes 2.5 Side Slopes ☐ Facility’s side slopes and bottom? ☐ No Maintenance Maintenance Plan Is there a written plan specific to ☐ Yes 3.1 or Agreement this facility? ☐ No Yes 3.2 Implementation Is there evidence of maintenance? ☐ ☐ No Chapter 6 - Storm Drainage Design 6-46 City of Bozeman Design and Construction Standards Section 5: Quantitative Analysis Vegetation Cover type % Within facility Notes Bare ground Aquatics Grasses/Herbaceou Trees >3” DBH Shrubs Total 100 Elevation Analysis Location Reading (ft) Elevation (ft) Notes SRV#CP Control Point SRV#1 Inlet SRV#2 Outlet SRV#3 Center SRV#4 North of Center SRV#5 East of Center SRV#6 South of Center SRV#7 West of center SRV#8 Berm or overflow SRV#9 Summary Chapter 6 - Storm Drainage Design 6-47 City of Bozeman Design and Construction Standards Section 6: Facility Maintenance Inspection Exhibit Chapter 6 - Storm Drainage Design 6-48 City of Bozeman Design and Construction Standards Photo 1 description Photo 2 description Section 7: Photo Log Isolator® Row Plus O&M Manual 2 Looking down the Isolator Row Plus from the manhole opening, ADS Plus Fabric is shown between the chamber and stone base. StormTech Isolator Row Plus with Overflow Structure (not to scale) The Isolator® Row Plus Introduction An important component of any Stormwater Pollution Prevention Plan is inspection and maintenance. The StormTech Isolator Row Plus is a technique to inexpensively enhance Total Suspended Solids (TSS), Total Phosphorus (TP), Total Petroluem Hydrocarbons (TPH) and Total Nitrogen (TN) removal with easy access for inspection and maintenance. The Isolator Row Plus The Isolator Row Plus is a row of StormTech chambers, either SC-160, SC- 310, DC-780, SC-800, MC-3500, MC-4500 or MC-7200 models, are lined with filter fabric and connected to a closely located manhole for easy access. The fabric lined chambers provide for sediment settling and filtration as stormwater rises in the Isolator Row Plus and passes through the filter fabric. The open bottom chambers allow stormwater to flow vertically out of the chambers. Sediments are captured in the Isolator Row Plus protecting the adjacent stone and chambers storage areas from sediment accumulation. ADS Isolator Row and Plus fabric are placed between the stone and the Isolator Row Plus chambers. The woven geotextile provides a media for stormwater filtration, a durable surface for maintenance, prevents scour of the underlying stone and remains intact during high pressure jetting. The Isolator Row Plus is designed to capture the “first flush” runoff and offers the versatility to be sized on a volume basis or a flow-rate basis. An upstream manhole provides access to the Isolator Row Plus and includes a high/low concept such that stormwater flow rates or volumes that exceed the capacity of the Isolator Row Plus bypass through a manifold to the other chambers. This is achieved with an elevated bypass manifold or a high-flow weir. This creates a differential between the Isolator Row Plus row of chambers and the manifold to the rest of the system, thus allowing for settlement time in the Isolator Row Plus. After Stormwater flows through the Isolator Row Plus and into the rest of the chamber system it is either exfiltrated into the soils below or passed at a controlled rate through an outlet manifold and outlet control structure. The Isolator Row Plus FlampTM is a flared end ramp apparatus attached to the inlet pipe on the inside of the chamber end cap. The FLAMP provides a smooth transition from pipe invert to fabric bottom. It is configured to improve chamber function performance by enhancing outflow of solid debris that would otherwise collect at the chamber's end, or more difficult to remove and require confined space entry into the chamber area. It also serves to improve the fluid and solid flow into the access pipe during maintenance and cleaning and to guide cleaning and inspection equipment back into the inlet pipe when complete. The Isolator Row Plus may be part of a treatment train system. The treatment train design and pretreatment device selection by the design engineer is often driven by regulatory requirements. Whether pretreatment is used or not, StormTech recommend using the Isolator Row Plus 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 Plus. 3 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, percent imperviousness, climate, etc. all play a critical role in determining the actual frequency of inspection and maintenance practices. At a minimum, StormTech recommends annual inspections. Initially, the Isolator Row Plus 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 Plus 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 determine the depth of sediment. When the average depth of sediment exceeds 3" (75 mm) throughout the length of the Isolator Row Plus, clean-out should be performed. Maintenance The Isolator Row Plus 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 maintenance, 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 entry. Maintenance is accomplished with the JetVac process. The JetVac process utilizes a high pressure water nozzle to propel itself down the Isolator Row Plus while scouring and suspending sediments. As the nozzle is retrieved, the captured pollutants are flushed back into the manhole 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 culverts or large diameter pipe cleaning are preferable. Rear facing jets with an effective spread of at least 45” are best. StormTech recommends a maximum nozzle pressure of 2000 psi be utilized during cleaning. JetVac reels can vary in length. For ease of maintenance, ADS recommends Isolator Row Plus lengths up to 200' (61 m). The JetVac process shall only be performed on StormTech Isolator Row Plus that have ADS Plus Fabric (as specified by StormTech) over their angular base stone. Isolator Row Plus Inspection/Maintenance StormTech Isolator Row Plus (not to scale) Isolator Row Plus Step By Step Maintenance Procedures Step 1 Inspect Isolator Row Plus 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 Row Plus i. Remove cover from manhole at upstream end of Isolator Row Plus ii. Using a flashlight, inspect down Isolator Row Plus 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 Plus using the JetVac process. A) A fixed floor 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. ADS “Terms and Conditions of Sale” are available on the ADS website, www.adspipe.com The ADS logo, StormTech®, the Isolator® Row Plus and the Green Stripe are registered trademarks of Advanced Drainage Systems, Inc. © 2025 Advanced Drainage Systems, Inc. #11081 5/25 CS 4 21) B)1) A) Sample Maintenance Log Date Stadia Rod Readings Sedi- ment Depth (1)–(2) Observations/Actions InspectorFixed point to chamber bottom (1) Fixed point to top of sediment (2) 3/15/11 6.3 ft none New installation. Fixed point is CI frame at grade DJM 9/24/11 6.2 0.1 ft Some grit felt SM 6/20/13 5.8 0.5 ft Mucky feel, debris visible in manhole and in Isolator Row Plus, maintenance due NV 7/7/13 6.3 ft 0 System jetted and vacuumed DJM adspipe.com 800-821-6710 StormTech Maintenance Log Project Name: Location: Stadia Rod Readings Date Fixed point to chamber bottom (1) Fixed point to top of sediment (2) Sediment Depth (1) - (2)Observations / Actions Inspector