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Home My Public Portal AboutP001174326_3/8/2024 2:37:30 PMPost-Construction Stormwater BMP Inspection and Maintenance Record Bayer Equip #:266291 MSD P Number:P001174326 Project:Technology Building Address:700 Chesterfield Parkway West 63017 Customer:Bayer Contact:Anna Tang Phone Number:314-694-3169 Email:anna.tang@bayer.com Inspector(s):Marianne Pott Company:Stormwater STL LLC Address:6514 Lansdowne Avenue 63109 Constr. Approval:September 26, 2018 Phone:(314) 229-8334 Record Start Date:June 21, 2018 E-mail:marianne@stormwater-stl.net Stormwater Treatment Facilities:Total Count: Count Type Description Count Type Description 2 BIOR BIORETENTION/RAINGARDEN (A)P-1 MICROPOOL EXTENDED DETENTION POND (A) BIOS BIORETENTION/RAINGARDEN (SMALL) (A)P-2 WET POND (A) GRWD GRAVEL WETLAND (A)P-3 WET EXTENDED DETENTION POND (A) CIST CISTERN/DRYWELL (U)P-5 POCKET POND (A) O-1 DRY SWALE - LARGE (A)W-2 ED SHALLOW WETLAND (A) O-2 DRY SWALE - SMALL (A)W-3 POND/WETLAND SYSTEM (A) O-3 WET SWALE - LARGE (A)SCDN STORM CREDIT - DISCONNECT NONROOFTOP (A) O-4 WET SWALE - SMALL (A)SCDR STORM CREDIT - DISCONNECT ROOFTOP (A) HDSP PROPRIETARY HYDRODYNAMIC SEPARATOR SCES STORM CREDIT - ENVIRONMENTALLY SENSTV(A) I-1 INFILTRATION TRENCH (A)SCNA STORM CREDIT - NATURAL AREA CONSERVA (A) I-2 INFILTRATION BASIN (A)SCOC STORM CREDIT - OPEN CHANNEL USE (A) AMDS AMENDED SOILS (A)SCSB STORM CREDIT - SHEET FLOW TO BUFFER (A) GRRF GREEN ROOF (A)F-1 SURFACE SAND FILTER (A) O-5 FILTER STRIPS - LARGE (A)F-3 PERIMETER SAND FILTER (A) O-6 FILTER STRIPS - SMALL (A)F-4 ORGANIC FILTER (A) PPAS PERMEABLE PAVEMENT - ASPHALT (A)F-5 POCKET SAND FILTER (A) PPBK PERMEABLE PAVEMENT - PAVER BLOCK (A)F-PR PROPRIETARY BMP FILTER (U) PPCO PERMEABLE PAVEMENT - CONCRETE (A)F-2 UNDERGROUND SAND FILTER (U) PPGR PERMEABLE PAVEMENT - GRAVEL (A) DET DETENTION WQS UNDERGROUND WATER QUALITY STORAGE 1 DET U UNDERGROUND FBAY PRETREATMENT FOREBAY Inspection, Maintenance and Annual Report Submission Record: Date Activity Date Activity 2018.06.21 Initial inspection 2018.09.10 Inspection 2018.12.11 Inspection 2019.03.11 Inspection 2019.06.13 Inspection 2019.09.17 Inspection 2019.12.11 Inspection 2020.03.05 Camera / Inspection 2020.03.05 Inspection 2020.06.22 2020.06.23 Inspection 2020.09.16 Inspection 2020.12.08 Inspection 2021.03.16 Inspection 2021.06.08 Inspection 2021.09.08 Inspection 2021.12.07 Inspection 2022.03.02 Inspection 2022.06.22 Inspection 2022.09.22 Inspection 2022.12.07 Inspection 2023.03.07 Inspection 2023.06.07 Inspection 2023.09.20 Inspection 2023.12.06 Inspection 3 Maintenance - Cleaning piping from ST E4 to ST E3 Post-Construction Stormwater BMP Inspection Report Bayer Equip #:266291 MSD P Number:P001174326 Project:Technology Building Address:700 Chesterfield Parkway West 63017 Inspection Date:December 6, 2023 Time:9:30 AM Weather:39°F; Sunny Last rain event:0.01" on December 5, 2023 Last one inch rainfall:1.62" on September 27, 2023 Inspector(s):Marianne Pott Bayer Company:Stormwater STL LLC Anna Tang Address:6514 Lansdowne Avenue 63109 314-694-3169 Phone:(314) 229-8334 anna.tang@bayer.com E-mail:marianne@stormwater-stl.net Last Inspection Date:September 20, 2023 Inspector's Summary: Status of Open Action Items Identified During This Reporting Year: Both Biodetention Basins Both Biodetention Basins Biodetention Basin 04B (GIS-BMP-9286) Biodetention Basin 04B (GIS-BMP-9286) Biodetention Basin 04B (GIS-BMP-9286) Biodetention Basin 04B (GIS-BMP-9286) Biodetention Basin 04B (GIS-BMP-9286)ADD mulch to bare soil along drive surface to west of basin to reduce erosion (Bayer) --- COMPLETED Biodetention Basin 04A (GIS-BMP-9141) Biodetention Basin 04A (GIS-BMP-9141) Action Items Identified During This Inspection: Biodetention Basin 04B (GIS-BMP-9286) Page 1 FILL hole on south embankment to west of ST A16 (Bayer) --- NOT COMPLETED FILL animal burrow at west end of basin (Bayer) --- NOT COMPLETED FILL animal burrow at east end of basin (Bayer) --- COMPLETED BUT NEEDED AGAIN ADD thick covering of mulch to all embankments (Bayer) --- COMPLETED CUT & REMOVE dead plant material before next growing season (Bayer) REFRESH mulch on bare west and southeast embankments (Bayer) --- COMPLETED This document has been prepared exclusively for the Customer noted above (Customer) by Stormwater STL LLC (Stormwater STL), based on a visual inspection conducted on the date(s) noted above. Unless specifically indicated, Stormwater STL did not undertake any forensic investigation at this location on the date(s) noted. The opinions expressed in this document relate only to the condition of the site and the Post-Construction Stormwater BMP(s) as observed by Stormwater STL on the date(s) noted. The content of this document reflects the opinion of Stormwater STL only and Stormwater STL makes no express or implied representation or warranty with respect to the conditions described or the functionality of the systems identified in this report. Other than Customer, third parties who rely upon this document do so solely at their own risk and Stormwater STL disclaims all liability, damages or loss with respect to such reliance. Neither Customer nor Stormwater STL, nor any person acting for and/or on behalf of those companies, assumes any responsibility, duty of care or liability to any person to update the contents of this document or to distribute any subsequently learned information to recipients of this document other than to Customer. This disclaimer must accompany every copy of this document, which is an integral document and must be read in its entirety. CUT & REMOVE dead plant material before next growing season (Bayer) --- COMPLETED 2022-2023 CONTROL for growth of invasive weeds (Bayer) --- COMPLETED Construction for the Technology Building was approved by MSD on September 26, 2018 and includes two biodetention basins and one StormTech underground detention system along with associated private inlets, manholes, and piping. The rainwater harvesting cistern associated with the project was a voluntary addition as part of the building's LEED certification, and is not treated as a MSD-regulated stormwater BMP. The configuration of basin 04A was revised by the Visitor Parking Project, MSD P001174333, in which the inlet ST C1 was eliminated and the stormwater was designed to enter through 7 curb cuts with rock swales (17 feet long by 2.5 feet wide by 6 inches deep) over filter fabric. MSD's GIS mapping and online annual reporting system actually include biodetention basin 04A and the entire existing Stormtech MC-4500 Underground Chamber System as being a part of MSD P001174333. The rock swales abruptly end at the bottom of the biodetention basin and appear to have been insufficiently lined with landscaping fabric, making the edges of all swales susceptible to erosion. After carefully reviewing each component of the system and finding only routine maintenance items to be addressed (see below), I can confirm: Based on what was observed, this stormwater treatment system appears to be functioning in accordance with the design intent. Customer: Contact: Phone Number: Email: ADD thick mulch to bottom half of south embankment (Bayer) --- NOT COMPLETED Post-Construction Stormwater BMP Inspection Report Field Observations: Biodetention Basin 04A at Southeast Corner of Building (GIS-BMP-9141) Assessment Comments Yellow Green Green Green Green Green Green Green Green Green Green Green Green Green Green Assessment Comments Green Green Green Green Green Green Control Structure in ST A10 Assessment Comments Green Green Green Green Biodetention Basin 04B to North of Building (GIS-BMP-9286) Attribute Assessment Comments Yellow Green Green Green Yellow Green Yellow Green Green Green Yellow Native plants on basin bottom Yellow Green Green Green Green Private Inlets/Manholes/Piping Attribute Assessment Comments Access Green Trash/deb Green Erosion/s ettlement Green System discharge Green Miscellaneous Attribute Assessment Comments Complaint Green Mosquito Green Encroach Green Public Hazard(s)Green Other (describe)Green Bayer Technology Building - December 6, 2023 Page 2 Crack in bottom of eastern Nyloplast drain but drains appear clear of obstructions, photo 2 Condition of filter media Filter media appears to be in good condition, photo 12 CUT & REMOVE dead plant material before next growing season (Bayer) Weeds Weeds were removed since the previous inspection Underdrain Underdrain is clear of obstructions and dry Structural components FILL animal burrow at west end of basin (Bayer) Mulch Mulch added at west end but remains mostly absent on bottom half of south slope; mulch on east part of south embankment is starting to wear thin Turf No turf adjacent to basin; mulched areas of native plantings Native plants on embankments CUT & REMOVE dead plant material before next growing season (Bayer) Erosion Slight scouring of surface below west rock blanket; minor erosion at north edge of rock blanket Erosion ADD thick mulch to bottom half of south embankment, photo 11 (Bayer) Sediment No silt observed on surface of basin Clogging No indications of clogging Water ponding on surface Some ponding water at foot of west rock blanket Odor FILL hole on south embankment to west of ST A16, photo 10 (Bayer) Access Trash/debris/leaves Some trash, leaves and debris present Structural components Foundation stone appears to be somewhat level; eccentric header pipe appears clear Structural components Concrete lids are showing signs of deterioration Trash/debris/leaves None Sediment buildup at low flow orifice Trash rack appears to be clear, photo 7 Attribute Access Attribute Underdrain Underdrain appears to be clear of obstructions and dry Structural components In good condition Measured sediment buildup Inspection port above isolator row has not been located Water ponding on bottom No ponding water in low spot on right side of row one third of the way back, photo 6 Condition of filter media Multiple probes confirm filter media is in good condition, photo 5 StormTech Underground Detention System (GIS-BMP-9142) Access Isolator row access is at the edge of crosswalk in the street Trash/debris/leaves Some mulch and organic debris apparent at back of isolator row Average sediment buildup Dusting at the front; Up to 0.5" estimated at back half / two thirds of row, photo 6 Weeds Weeds were removed since the previous inspection Erosion MONITOR for erosion within rock swales, photo 4 Sediment Up to 0.25" of silt is collecting on surface below rock swales 2 - 4 from west end Mulch Mulch remains on all embankments, some loss below 1st rock blanket from west Turf Turf on embankments is in good condition - susceptible to erosion at bottom edges Plants Excellent coverage of native plants; dead plant growth was cut down & removed, photo 1 Access FILL animal burrow reformed at east end of basin (Bayer) Trash/debris/leaves No trash, debris or leaves noted - basin was cleaned out for the winter Clogging No evidence of clogging Water ponding on surface No ponding water noted Erosion Interface of mulched beds and turf strips was covered with mulch Erosion Some scouring of mulch at west end below 1st curb opening & rock blanket, photo 3 Attribute Clear Post-Construction Stormwater BMP Inspection Report Photographs See attached sheet(s) Inspector's Notes Bayer Technology Building - December 6, 2023 Page 3 IMPORTANT NOTE ABOUT PLANT MATERIALS IN STORMWATER QUALITY SYSTEMS It's important for owners and property managers to understand that the use of native plants have a functional role in stormwater management facilities and are required by MSD. Care should be taken to retain them in the basin and replace them as needed. Routine maintenance includes removing weedy vegetation during the summer months and deadheading all vegetation when it has gone dormant during the winter. Please make sure that landscaping companies involved with the care of these basins understand the native plants are intentional and are skilled in identification of both native plants and weeds. Please let us know if you have questions about plant maintenance or would like to develop a stewardship program to protect your stormwater quality assets. ***On 9/20/2018, saturated hydraulic conductivity was measured in biodetention basin 04B at 3.3, 6.0, and 17.5 inches per hour. MSD requires saturated hydraulic conductivity to be at least 0.5 inches per hour, confirming that the infiltration rates exceed the minimum specification required by MSD. ***Inspection on 3/11/2019 occurred 48 hours after a 1.28" rain event, confirming that both biodetention basins drain as intended. March 16, 2021: Both basins continue to function well and as designed. Although silt is collecting on parts of the surface of basin 02A from erosion at the edges of the curb cuts, the basin continues to drain well within the standards. It was fully dry within only 12 hours of both a 0.44" and a 2.04" rain event in the week the inspections occurred. Basin 02B was mostly dry within 18 hours of the 2.04" rain event, with only a few wet spots where water drains down the west embankment. Dead tips should be removed from the tops of the rush plantings in basin 02A. The surface below the western most curb cut in basin 02A is native soil and not rain garden soil. Where mulch is consistently getting scoured out, the bare area should be covered with landscaping fabric and matching rock as a more stable way to convey stormwater. Erosion is occurring within four of the rock swales, resulting in silt collecting on the surface below no more than 0.25" deep. Mulch is looking very thin and nonexistent adjacent to the rock blanket at the west end of basin 02B and to the west of the rainwater harvesting overflow. June 8, 2021: A broken irrigation head on the west embankment of biodetention basin 04B is eroding the freshly mulched surface. The irrigation head should be replaced and the mulch regraded. The sumac shrubs are encroaching on the manholes of Control Structure ST A10. September 8, 2021: The broken irrigation head on the west embankment of biodetention basin 04B was repaired and the embankment was mulched. The eroding west embankment of biodetention basin 04A was also covered with landscaping fabric and rock. Some cattail growth was noted at the west end of basin 04B. The soil shows no signs of clogging; cattails are likely indicative of a very rainy summer. The middle cleanout in basin 02B needs a new 4" slip cap. It is missing and therefore functioning as an unintended overflow structure and preventing the designed ponding depth. December 7, 2021: All vegetation should be cut back to a few inches and removed from both basins. A large animal burrow has developed at the east end of basin 04A that needs to be filled back in. March 2, 2022: Basins were cleared out in preparation of next growing season. The base of the retaining wall in basin 04B was protected with rock and the standpipe was covered with a slip cap. June 22, 2022: Each area appears to be functioning as intended. Both biodetention basins need routine care to pull and remove weedy growth in and around that native plantings. September 22, 2022: Each area appears to be functioning as intended. Both biodetention basins need routine care to pull and remove weedy growth in and around that native plantings. Mulch will need to be added to the south embankment at the west and east ends following the winter cutdown. December 7, 2022: Animal burrows and holes need to be filled in and bare areas in the drainage area of each basin need to be mulched. March 7, 2023: Thick mulch was added to all embankments of biodetention basin 04A and to the west half of biodetention basin 04B. The animal burrow looks like it had been filled in at the east end of biodetention basin 04A. Biodetention basin 04B still has a few maintenance items needing to be addressed. Bare ground is present within the ponding elevation on the bottom half of the south embankment at the east end and also the edges of the drive to the west of the biodetention basin where the irrigation heads are located. The bare edge along the north side of the drive is the likely source of thin layer of silt collecting at the west end of the filter bed. June 7, 2023: Inspection of basins was done on 6/8, following a 0.20" rain event recorded on 6/7. The foot of the west rock blanket of basin 04B had some ponding water; the entire surface of basin 04A was dry. Invasive growth at the west end looks like it is being treated with herbicide. Weeds should continue to be managed. September 20, 2023: Edging and trap rock were added adjacent to the drive to the west of biodetention basin O4B. Invasive growth in basin 04B appears to show signs of being managed, but it seems like it is being trimmed back with a weed eater instead of hand-pulled. December 6, 2023: Invasive growth was removed in both basins. Dead plant debris was cut down and removed in basin 04A but still needs to be removed in basin 04B. Once dead growth comes out, it is suggested to fill in scour holes, animal burrows and add mulch. BAYER – Technology Building Stormwater BMP Photos December 6, 2023 1. VIEW OF BIODETENTION BASIN 04A (GIS-BMP- 9141) 2. CRACK NOTED IN BOTTOM OF EAST NYLOPLAST DRAIN BASIN IN BASIN 04B 3. SOME LOSS OF MULCH AT WEST EMBANKMENTS OF BASIN 04A 4. MONITOR FOR EROSION WITHIN ROCK SWALES OF BASIN 04A 5. FILTER MEDIA IS IN GOOD CONDITION & SHOWS NO SILT EXCEPT BELOW SWALES 6. UP TO 0.5” OF SEDIMENT IN HALF OF ISOLATOR ROW (GIS-BMP-9142) 7. CONTROL STRUCTURE IN ST A10 SHOWS THAT SYSTEM DISCHARGE IS CLEAR 8. VIEW OF BIODETENTION BASIN 04B (GIS-BMP- 9286) 9. EDGING & TRAP ROCK ADDED TO BARE SOIL ALONG DRIVE SURFACE TO WEST OF BASIN 04B 10. FILL HOLE ON SOUTH EMBANKMENT TO WEST OF ST A16 IN BASIN 04B 11. ADD MULCH TO BOTTOM OF SOUTH EMBANKMENT OF BIODETENTION BASIN 04B 12. FILTER MEDIA AROUND CATTAIL GROWTH SHOWS NO SIGNS OF SILT