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HomeMy Public PortalAboutP001174317_3/13/2024 5:20:11 PMPost-Construction Stormwater BMP Inspection and Maintenance Record Bayer Equip #:261387 MSD P Number:P001174317 Project:Bayer AA Parking Lot System Address:700 Chesterfield Parkway West Chesterfield, MO 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 Record Start Date:August 21, 2012 Phone:(314) 229-8334 E-mail:marianne@stormwater-stl.net Stormwater Treatment Facilities:Total Count: Count Type Description Count Type Description 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) 1 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)1 F-PR PROPRIETARY BMP FILTER (U) PPCO PERMEABLE PAVEMENT - CONCRETE (A)F-2 UNDERGROUND SAND FILTER (U) PPGR PERMEABLE PAVEMENT - GRAVEL (A) 1 DET DETENTION 1 WQS UNDERGROUND WATER QUALITY STORAGE DET U UNDERGROUND FBAY PRETREATMENT FOREBAY Inspection, Maintenance and Annual Report Submission Record: Date Activity Date Activity 2012.08.21 One-inch rainfall inspection by CBRE 2020.03.05 Inspection 2012.09.04 One-inch rainfall inspection by CBRE 2020.06.23 Inspection 2012.11.07 One-inch rainfall inspection by CBRE 2020.09.16 Inspection 2012.11.12 One-inch rainfall inspection by CBRE 2020.12.08 Inspection 2013.01.14 One-inch rainfall inspection by CBRE 2021.03.19 Inspection 2013.01.28 One-inch rainfall inspection by CBRE 2021.06.08 Inspection 2013.03.21 Inspection by Stormwater STL 2021.06.17 Maintenance - Storm Filter Vault 2013.04.01 2012 Annual Report submission to MSD 2021.09.08 Inspection 2014.03.28 Inspection 2021.12.07 Inspection 2014.03.29 2013 Annual Report submission to MSD 2022.03.02 Inspection 2014.09.05 Inspection 2022.06.22 Inspection 2014.12.08 Inspection 2022.09.22 Inspection 2015.03.11 Inspection 2022.11.09 Maintenance HDS Unit 2015.03.24 2014 Annual Report submission to MSD 2022.12.07 Inspection 2015.06.11 Inspection 2023.03.07 Inspection 2015.09.10 Inspection 2023.06.07 Inspection 2015.10.12 Maintenance - HDS 2023.09.20 Inspection 2015.10.13 Maintenance - StormFilter Vault 2023.12.06 Inspection 2015.12.09 Inspection 2016.02.23 Inspection 2016.06.20 Inspection 2016.09.14 Inspection 2016.09.21 Maintenance - StormFilter Vault 2016.12.06 Inspection 2017.03.02 Inspection 2017.06.19 Inspection 2017.09.13 Inspection 2017.12.12 Inspection 2018.02.07 Maintenance - Removal of leaves in HDS unit 2018.03.06 Inspection 2018.06.21 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 4 Post-Construction Stormwater BMP Inspection Report 261387 MSD P Number:P001174317 Project:Bayer AA Parking Lot System 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 Bayer Inspector(s):Marianne Pott Anna Tang Company:Stormwater STL LLC 314-694-3169 Address:6514 Lansdowne Avenue 63109 anna.tang@bayer.com Phone:(314) 229-8334 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: Curb Line to West of Double Curb Inlet A-1 Curb Line to West of Double Curb Inlet A-1 Action Items Identified During This Inspection: No new action items were identified during this inspection. ` Page 1 REMOVE heavy sediment at southwest edge of parking lot (Bayer) --- NOT COMPLETED SEAL curb line along southwest edge of parking lot (Bayer) --- NOT COMPLETED Bayer Equip #: Customer: Contact: Phone Number: Email: 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. This report covers the AA Building Parking Addition portion of the stormwater treatment system associated with P001174317. This portion of the project includes a Contech VortSentry HS48 Hydrodynamic Separator, a 48" RCP Water Quality Storage component, a Contech Storm filter Stormwater Quality component, a surface detention basin as well as associated private inlets, manholes and piping. All sediment was removed from the StormFilter Vault, the three spent filter cartridges were replaced in October 2015, September 2016, and June 2021. The HDS was vacuumed to remove all sediment in October 2015 and November 2022. After carefully reviewing each component of the system, I am pleased to report: Based on what was observed, this stormwater treatment system appears to be functioning in accordance with the design intent. Post-Construction Stormwater BMP Inspection Report Flow Splitter in Double Curb Inlet A-1 Comments Structural components Comments Access Clogging Water ponding on surface na Sheen on water surface Odor Sediment Mulch na Turf na Weeds na Underdrain na Structural components 10'-10.5" 10'-11" 0'-0.5" 2'-0" 48" RCP Water Quality Storage at MH A-3 and MH A-13 (GIS-BMP-7329) Comments Access Sediment buildup Sediment buildup Clogging Water ponding on bottom Structural components Comments Access Water ponding on surface Sheen on water surface na Odor Erosion na Sediment Mulch na Turf na Plants na Weeds na Underdrain Structural components South Surface Detention Basin (GIS-BMP-2886) Comments Access Clogging Water ponding on surface Sheen on water surface na Odor Sediment Mulch Turf Weeds Structural components Depth of sediment =0" - 2" Page 2 Minimal trash, debris or leaves noted, photo 2 No odor noted Some mulch, trash, leaves and debris noted, photo 4 Pretreatment - Contech VortSentry HS48 Hydrodynamic Separator in MH A-2 (GIS-BMP-4724) Erosion No sheen on water surface Trash/debris Trash/debris/sediment No trash or debris present Erosion/settlement around structures No further scouring in front and on sides of structure HDS unit was vacuumed and pressure washed in November 2022 HDS unit is at 2.08% of its capacity, photo 2 View into MH A-3 shows no sediment accumulation View into MH A-13 shows minimal sediment accumulation, photo 3 Minimal ponding - 0.5", photo 3 Contech StormFilter Stormwater Quality System at MH A-4 (GIS-BMP-5397) Max. sediment depth recommended by manufacturer = Distance from rim to sediment = Distance from rim to bottom = Depth of sediment = Field Observations - AA Building Parking Addition (MSD P001174317): Condition of filter media Trash/debris Clogging Depth of water/sediment on vault floor No indications of clogging In good condition 0.5" of sediment below ladder and around outlet module, photo 5 Dusting of sediment on cartridge tops, photo 4 Filter media is only slightly discolored by sediment and remains very porous, photo 6 Sediment was removed and cartridges were replaced in June 2021 Depth of silt on filter cartridge tops About 0.5" sediment around the perimeter, especially at ladder & outflow module Minimal ponding water Trash/debris Erosion Perforated standpipe is clear of blockages and debris, photo 10 MONITOR further erosion at west edge of rock blanket, photo 9 All vegetation is regularly managed including woody growth, photo 7 Flap valve has room to open and close, photo 8 No ponding water No trash, leaves or debris, photo 7 Increase of 0.5" since September 2023 inspection Bayer AA Parking Lot System - December 6, 2023 Up to 2" of sediment covering areas of seed netting Post-Construction Stormwater BMP Inspection Report Private Inlets/Manholes/Piping Comments Access System discharge - Overflow Structure A-5 Comments Other (describe)na Photographs Inspector's Notes Bayer AA Parking Lot System - December 6, 2023 Page 3 SEAL curb line along southwest edge of parking lot, photo 1 (Bayer) Settlement in front of double curb inlet A-1 was repaired Clear, photo 11 None of which I'm aware See attached sheet REMOVE heavy sediment at southwest edge of parking lot, photo 12 (Bayer) Miscellaneous Encroachment(s) on facility or easement Complaints Mosquitoes Trash/debris/sediment Erosion/settlement around structures Please note: Effective with the December 9, 2015 Inspection, what had been submitted as the NRB Building and Parking project on one report, is now being subdivided into two inspection reports: Bayer AA Building & Parking as well as Bayer CC Building & Parking. This reporting structure aligns to Bayer's internal project accounting process. March 19, 2021: A slight increase of sediment was measured in the HDS unit. A purchase order has been received to provide the needed maintenance on the StormFilter Vault. Maintenance will be scheduled in the future as the service provider is available. The upstream manhole A-13 of the RCP water quality storage was also opened this inspection. Some sediment is visible at this manhole, but no sediment is visible below the downstream manhole A-3. The surface detention basin continues to receive a high level of care and maintenance. It appears to remain structurally sound and needs no other work at this time. All structural components are free and clear to receive and discharge stormwater. June 8, 2021: A decrease of sediment was measured in the HDS unit. Maintenance is tentatively planned for June 17 & 18 to clean out the StormFilter Vault. September 8, 2021: The StormFilter vault was maintained since the previous inspection and remains in good condition. The HDS unit added 4.5 inches since June's visit. Conveyance into and out of the surface detention basin remains unobstructed and vegetation is being managed to keep any part of it from becoming overgrown. December 7, 2021: Sediment in the HDS unit decreased by 3.5 inches since September's visit. Conveyance into the surface detention basin was improved by removing some of the dirt around the flap valve. March 2, 2022: No changes noted. June 22, 2022: An increase of 1.5" sediment was measured in the HDS unit. Settlement in front of the curb inlet / flow splitter structure has worsened and should be repaired. The asphalt in front of the structure should be patched, and Aquablok (bentonite-coated pea gravel) should be added to fill scour at the southwest corner of the structure below the fencepost footing. September 22, 2022: Asphalt settlement in front of the curb inlet / flow splitter structure was patched. An increase of 3 inches of sediment was measured in the HDS unit. With the unit now above 75% of its capacity, it now needs to be pressure washed and vacuumed. December 7, 2022: The HDS unit was cleaned since September's inspection. Heavy sediment collecting along the southwest curb line of the parking lot shows scouring indicative of water draining out through the gap between the asphalt and the curb line. This needs to be sealed to prevent sinkhole development and to keep the stormwater going into the BMPs according to the design. Sediment should also be removed from along the curb line. March 7, 2023: The water quality storage unit was inspected with a QuickView Camera to confirm the pipe contains very little sediment through its entire length. The surface detention basin was inspected on 3/8/2023 during a light rain event, confirming that stormwater drains through the system effectively. June 7, 2023: No changes noted. Sediment collected along the curb line should be swept up and removed. It also shows scouring indicative of water draining out through the gap between the asphalt and the curb line. This needs to be sealed to prevent sinkhole development and to keep the stormwater going into the BMPs according to the design. September 20, 2023: No changes noted. December 6, 2023: No changes noted. BAYER – AA Building Parking Stormwater BMP Photos December 6, 2023 1. SEAL CURB LINE ALONG SOUTHWEST EDGE OF PARKING LOT 2. HDS UNIT IS AT 2.08% OF CAPACITY (GIS- BMP-4724) 3. MINIMAL SEDIMENT IN 48” RCP WATER QUALITY STORAGE (GIS-BMP-7329) 4. VIEW OF STORMFILTER VAULT IN MH 4-A (GIS-BMP-5397) 5. MINIMAL SEDIMENT ON VAULT FLOOR 6. FILTER MEDIA IS DISCOLORED BY SEDIMENT BUT REMAINS POROUS 7. VIEW OF SOUTH SURFACE DETENTION BASIN (GIS-BMP-2886) 8. FLAP VALVE HAS ROOM TO OPEN AND CLOSE 9. MONITOR FURTHER EROSION AT WEST EDGE OF ROCK BLANKET 10. PERFORATED STANDPIPE IS CLEAR OF BLOCKAGES AND DEBRIS (GIS-BMP-2886) 11. OVERFLOW STRUCTURE A-5 SHOWS SYSTEM DISCHARGE IS CLEAR 12. REMOVE HEAVY SEDIMENT AT THE SOUTHWEST EDGE OF THE PARKING LOT Post-Construction Stormwater BMP Inspection and Maintenance Record Bayer Equip #:261387 MSD P Number:P001174317 Project:Bayer AA Parking Lot System Address:700 Chesterfield Parkway West Chesterfield, MO 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 Record Start Date:August 21, 2012 Phone:(314) 229-8334 E-mail:marianne@stormwater-stl.net Stormwater Treatment Facilities:Total Count: Count Type Description Count Type Description 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) 1 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)1 F-PR PROPRIETARY BMP FILTER (U) PPCO PERMEABLE PAVEMENT - CONCRETE (A)F-2 UNDERGROUND SAND FILTER (U) PPGR PERMEABLE PAVEMENT - GRAVEL (A) 1 DET DETENTION 1 WQS UNDERGROUND WATER QUALITY STORAGE DET U UNDERGROUND FBAY PRETREATMENT FOREBAY Inspection, Maintenance and Annual Report Submission Record: Date Activity Date Activity 2012.08.21 One-inch rainfall inspection by CBRE 2020.03.05 Inspection 2012.09.04 One-inch rainfall inspection by CBRE 2020.06.23 Inspection 2012.11.07 One-inch rainfall inspection by CBRE 2020.09.16 Inspection 2012.11.12 One-inch rainfall inspection by CBRE 2020.12.08 Inspection 2013.01.14 One-inch rainfall inspection by CBRE 2021.03.19 Inspection 2013.01.28 One-inch rainfall inspection by CBRE 2021.06.08 Inspection 2013.03.21 Inspection by Stormwater STL 2021.06.17 Maintenance - Storm Filter Vault 2013.04.01 2012 Annual Report submission to MSD 2021.09.08 Inspection 2014.03.28 Inspection 2021.12.07 Inspection 2014.03.29 2013 Annual Report submission to MSD 2022.03.02 Inspection 2014.09.05 Inspection 2022.06.22 Inspection 2014.12.08 Inspection 2022.09.22 Inspection 2015.03.11 Inspection 2022.11.09 Maintenance HDS Unit 2015.03.24 2014 Annual Report submission to MSD 2022.12.07 Inspection 2015.06.11 Inspection 2023.03.07 Inspection 2015.09.10 Inspection 2023.06.07 Inspection 2015.10.12 Maintenance - HDS 2023.09.20 Inspection 2015.10.13 Maintenance - StormFilter Vault 2023.12.06 Inspection 2015.12.09 Inspection 2016.02.23 Inspection 2016.06.20 Inspection 2016.09.14 Inspection 2016.09.21 Maintenance - StormFilter Vault 2016.12.06 Inspection 2017.03.02 Inspection 2017.06.19 Inspection 2017.09.13 Inspection 2017.12.12 Inspection 2018.02.07 Maintenance - Removal of leaves in HDS unit 2018.03.06 Inspection 2018.06.21 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 4 Post-Construction Stormwater BMP Inspection Report 261387 MSD P Number:P001174317 Project:Bayer AA Parking Lot System 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 Bayer Inspector(s):Marianne Pott Anna Tang Company:Stormwater STL LLC 314-694-3169 Address:6514 Lansdowne Avenue 63109 anna.tang@bayer.com Phone:(314) 229-8334 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: Curb Line to West of Double Curb Inlet A-1 Curb Line to West of Double Curb Inlet A-1 Action Items Identified During This Inspection: No new action items were identified during this inspection. ` Page 1 REMOVE heavy sediment at southwest edge of parking lot (Bayer) --- NOT COMPLETED SEAL curb line along southwest edge of parking lot (Bayer) --- NOT COMPLETED Bayer Equip #: Customer: Contact: Phone Number: Email: 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. This report covers the AA Building Parking Addition portion of the stormwater treatment system associated with P001174317. This portion of the project includes a Contech VortSentry HS48 Hydrodynamic Separator, a 48" RCP Water Quality Storage component, a Contech Storm filter Stormwater Quality component, a surface detention basin as well as associated private inlets, manholes and piping. All sediment was removed from the StormFilter Vault, the three spent filter cartridges were replaced in October 2015, September 2016, and June 2021. The HDS was vacuumed to remove all sediment in October 2015 and November 2022. After carefully reviewing each component of the system, I am pleased to report: Based on what was observed, this stormwater treatment system appears to be functioning in accordance with the design intent. Post-Construction Stormwater BMP Inspection Report Flow Splitter in Double Curb Inlet A-1 Comments Structural components Comments Access Clogging Water ponding on surface na Sheen on water surface Odor Sediment Mulch na Turf na Weeds na Underdrain na Structural components 10'-10.5" 10'-11" 0'-0.5" 2'-0" 48" RCP Water Quality Storage at MH A-3 and MH A-13 (GIS-BMP-7329) Comments Access Sediment buildup Sediment buildup Clogging Water ponding on bottom Structural components Comments Access Water ponding on surface Sheen on water surface na Odor Erosion na Sediment Mulch na Turf na Plants na Weeds na Underdrain Structural components South Surface Detention Basin (GIS-BMP-2886) Comments Access Clogging Water ponding on surface Sheen on water surface na Odor Sediment Mulch Turf Weeds Structural components Depth of sediment =0" - 2" Page 2 Minimal trash, debris or leaves noted, photo 2 No odor noted Some mulch, trash, leaves and debris noted, photo 4 Pretreatment - Contech VortSentry HS48 Hydrodynamic Separator in MH A-2 (GIS-BMP-4724) Erosion No sheen on water surface Trash/debris Trash/debris/sediment No trash or debris present Erosion/settlement around structures No further scouring in front and on sides of structure HDS unit was vacuumed and pressure washed in November 2022 HDS unit is at 2.08% of its capacity, photo 2 View into MH A-3 shows no sediment accumulation View into MH A-13 shows minimal sediment accumulation, photo 3 Minimal ponding - 0.5", photo 3 Contech StormFilter Stormwater Quality System at MH A-4 (GIS-BMP-5397) Max. sediment depth recommended by manufacturer = Distance from rim to sediment = Distance from rim to bottom = Depth of sediment = Field Observations - AA Building Parking Addition (MSD P001174317): Condition of filter media Trash/debris Clogging Depth of water/sediment on vault floor No indications of clogging In good condition 0.5" of sediment below ladder and around outlet module, photo 5 Dusting of sediment on cartridge tops, photo 4 Filter media is only slightly discolored by sediment and remains very porous, photo 6 Sediment was removed and cartridges were replaced in June 2021 Depth of silt on filter cartridge tops About 0.5" sediment around the perimeter, especially at ladder & outflow module Minimal ponding water Trash/debris Erosion Perforated standpipe is clear of blockages and debris, photo 10 MONITOR further erosion at west edge of rock blanket, photo 9 All vegetation is regularly managed including woody growth, photo 7 Flap valve has room to open and close, photo 8 No ponding water No trash, leaves or debris, photo 7 Increase of 0.5" since September 2023 inspection Bayer AA Parking Lot System - December 6, 2023 Up to 2" of sediment covering areas of seed netting Post-Construction Stormwater BMP Inspection Report Private Inlets/Manholes/Piping Comments Access System discharge - Overflow Structure A-5 Comments Other (describe)na Photographs Inspector's Notes Bayer AA Parking Lot System - December 6, 2023 Page 3 SEAL curb line along southwest edge of parking lot, photo 1 (Bayer) Settlement in front of double curb inlet A-1 was repaired Clear, photo 11 None of which I'm aware See attached sheet REMOVE heavy sediment at southwest edge of parking lot, photo 12 (Bayer) Miscellaneous Encroachment(s) on facility or easement Complaints Mosquitoes Trash/debris/sediment Erosion/settlement around structures Please note: Effective with the December 9, 2015 Inspection, what had been submitted as the NRB Building and Parking project on one report, is now being subdivided into two inspection reports: Bayer AA Building & Parking as well as Bayer CC Building & Parking. This reporting structure aligns to Bayer's internal project accounting process. March 19, 2021: A slight increase of sediment was measured in the HDS unit. A purchase order has been received to provide the needed maintenance on the StormFilter Vault. Maintenance will be scheduled in the future as the service provider is available. The upstream manhole A-13 of the RCP water quality storage was also opened this inspection. Some sediment is visible at this manhole, but no sediment is visible below the downstream manhole A-3. The surface detention basin continues to receive a high level of care and maintenance. It appears to remain structurally sound and needs no other work at this time. All structural components are free and clear to receive and discharge stormwater. June 8, 2021: A decrease of sediment was measured in the HDS unit. Maintenance is tentatively planned for June 17 & 18 to clean out the StormFilter Vault. September 8, 2021: The StormFilter vault was maintained since the previous inspection and remains in good condition. The HDS unit added 4.5 inches since June's visit. Conveyance into and out of the surface detention basin remains unobstructed and vegetation is being managed to keep any part of it from becoming overgrown. December 7, 2021: Sediment in the HDS unit decreased by 3.5 inches since September's visit. Conveyance into the surface detention basin was improved by removing some of the dirt around the flap valve. March 2, 2022: No changes noted. June 22, 2022: An increase of 1.5" sediment was measured in the HDS unit. Settlement in front of the curb inlet / flow splitter structure has worsened and should be repaired. The asphalt in front of the structure should be patched, and Aquablok (bentonite-coated pea gravel) should be added to fill scour at the southwest corner of the structure below the fencepost footing. September 22, 2022: Asphalt settlement in front of the curb inlet / flow splitter structure was patched. An increase of 3 inches of sediment was measured in the HDS unit. With the unit now above 75% of its capacity, it now needs to be pressure washed and vacuumed. December 7, 2022: The HDS unit was cleaned since September's inspection. Heavy sediment collecting along the southwest curb line of the parking lot shows scouring indicative of water draining out through the gap between the asphalt and the curb line. This needs to be sealed to prevent sinkhole development and to keep the stormwater going into the BMPs according to the design. Sediment should also be removed from along the curb line. March 7, 2023: The water quality storage unit was inspected with a QuickView Camera to confirm the pipe contains very little sediment through its entire length. The surface detention basin was inspected on 3/8/2023 during a light rain event, confirming that stormwater drains through the system effectively. June 7, 2023: No changes noted. Sediment collected along the curb line should be swept up and removed. It also shows scouring indicative of water draining out through the gap between the asphalt and the curb line. This needs to be sealed to prevent sinkhole development and to keep the stormwater going into the BMPs according to the design. September 20, 2023: No changes noted. December 6, 2023: No changes noted. BAYER – AA Building Parking Stormwater BMP Photos December 6, 2023 1. SEAL CURB LINE ALONG SOUTHWEST EDGE OF PARKING LOT 2. HDS UNIT IS AT 2.08% OF CAPACITY (GIS- BMP-4724) 3. MINIMAL SEDIMENT IN 48” RCP WATER QUALITY STORAGE (GIS-BMP-7329) 4. VIEW OF STORMFILTER VAULT IN MH 4-A (GIS-BMP-5397) 5. MINIMAL SEDIMENT ON VAULT FLOOR 6. FILTER MEDIA IS DISCOLORED BY SEDIMENT BUT REMAINS POROUS 7. VIEW OF SOUTH SURFACE DETENTION BASIN (GIS-BMP-2886) 8. FLAP VALVE HAS ROOM TO OPEN AND CLOSE 9. MONITOR FURTHER EROSION AT WEST EDGE OF ROCK BLANKET 10. PERFORATED STANDPIPE IS CLEAR OF BLOCKAGES AND DEBRIS (GIS-BMP-2886) 11. OVERFLOW STRUCTURE A-5 SHOWS SYSTEM DISCHARGE IS CLEAR 12. REMOVE HEAVY SEDIMENT AT THE SOUTHWEST EDGE OF THE PARKING LOT Post-Construction Stormwater BMP Inspection and Maintenance Record Bayer Equip #:261387 MSD P Number:P001174317 Project:Bayer AA Parking Lot System Address:700 Chesterfield Parkway West Chesterfield, MO 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 Record Start Date:August 21, 2012 Phone:(314) 229-8334 E-mail:marianne@stormwater-stl.net Stormwater Treatment Facilities:Total Count: Count Type Description Count Type Description 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) 1 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)1 F-PR PROPRIETARY BMP FILTER (U) PPCO PERMEABLE PAVEMENT - CONCRETE (A)F-2 UNDERGROUND SAND FILTER (U) PPGR PERMEABLE PAVEMENT - GRAVEL (A) 1 DET DETENTION 1 WQS UNDERGROUND WATER QUALITY STORAGE DET U UNDERGROUND FBAY PRETREATMENT FOREBAY Inspection, Maintenance and Annual Report Submission Record: Date Activity Date Activity 2012.08.21 One-inch rainfall inspection by CBRE 2020.03.05 Inspection 2012.09.04 One-inch rainfall inspection by CBRE 2020.06.23 Inspection 2012.11.07 One-inch rainfall inspection by CBRE 2020.09.16 Inspection 2012.11.12 One-inch rainfall inspection by CBRE 2020.12.08 Inspection 2013.01.14 One-inch rainfall inspection by CBRE 2021.03.19 Inspection 2013.01.28 One-inch rainfall inspection by CBRE 2021.06.08 Inspection 2013.03.21 Inspection by Stormwater STL 2021.06.17 Maintenance - Storm Filter Vault 2013.04.01 2012 Annual Report submission to MSD 2021.09.08 Inspection 2014.03.28 Inspection 2021.12.07 Inspection 2014.03.29 2013 Annual Report submission to MSD 2022.03.02 Inspection 2014.09.05 Inspection 2022.06.22 Inspection 2014.12.08 Inspection 2022.09.22 Inspection 2015.03.11 Inspection 2022.11.09 Maintenance HDS Unit 2015.03.24 2014 Annual Report submission to MSD 2022.12.07 Inspection 2015.06.11 Inspection 2023.03.07 Inspection 2015.09.10 Inspection 2023.06.07 Inspection 2015.10.12 Maintenance - HDS 2023.09.20 Inspection 2015.10.13 Maintenance - StormFilter Vault 2023.12.06 Inspection 2015.12.09 Inspection 2016.02.23 Inspection 2016.06.20 Inspection 2016.09.14 Inspection 2016.09.21 Maintenance - StormFilter Vault 2016.12.06 Inspection 2017.03.02 Inspection 2017.06.19 Inspection 2017.09.13 Inspection 2017.12.12 Inspection 2018.02.07 Maintenance - Removal of leaves in HDS unit 2018.03.06 Inspection 2018.06.21 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 4 Post-Construction Stormwater BMP Inspection Report 261387 MSD P Number:P001174317 Project:Bayer AA Parking Lot System 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 Bayer Inspector(s):Marianne Pott Anna Tang Company:Stormwater STL LLC 314-694-3169 Address:6514 Lansdowne Avenue 63109 anna.tang@bayer.com Phone:(314) 229-8334 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: Curb Line to West of Double Curb Inlet A-1 Curb Line to West of Double Curb Inlet A-1 Action Items Identified During This Inspection: No new action items were identified during this inspection. ` Page 1 REMOVE heavy sediment at southwest edge of parking lot (Bayer) --- NOT COMPLETED SEAL curb line along southwest edge of parking lot (Bayer) --- NOT COMPLETED Bayer Equip #: Customer: Contact: Phone Number: Email: 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. This report covers the AA Building Parking Addition portion of the stormwater treatment system associated with P001174317. This portion of the project includes a Contech VortSentry HS48 Hydrodynamic Separator, a 48" RCP Water Quality Storage component, a Contech Storm filter Stormwater Quality component, a surface detention basin as well as associated private inlets, manholes and piping. All sediment was removed from the StormFilter Vault, the three spent filter cartridges were replaced in October 2015, September 2016, and June 2021. The HDS was vacuumed to remove all sediment in October 2015 and November 2022. After carefully reviewing each component of the system, I am pleased to report: Based on what was observed, this stormwater treatment system appears to be functioning in accordance with the design intent. Post-Construction Stormwater BMP Inspection Report Flow Splitter in Double Curb Inlet A-1 Comments Structural components Comments Access Clogging Water ponding on surface na Sheen on water surface Odor Sediment Mulch na Turf na Weeds na Underdrain na Structural components 10'-10.5" 10'-11" 0'-0.5" 2'-0" 48" RCP Water Quality Storage at MH A-3 and MH A-13 (GIS-BMP-7329) Comments Access Sediment buildup Sediment buildup Clogging Water ponding on bottom Structural components Comments Access Water ponding on surface Sheen on water surface na Odor Erosion na Sediment Mulch na Turf na Plants na Weeds na Underdrain Structural components South Surface Detention Basin (GIS-BMP-2886) Comments Access Clogging Water ponding on surface Sheen on water surface na Odor Sediment Mulch Turf Weeds Structural components Depth of sediment =0" - 2" Page 2 Minimal trash, debris or leaves noted, photo 2 No odor noted Some mulch, trash, leaves and debris noted, photo 4 Pretreatment - Contech VortSentry HS48 Hydrodynamic Separator in MH A-2 (GIS-BMP-4724) Erosion No sheen on water surface Trash/debris Trash/debris/sediment No trash or debris present Erosion/settlement around structures No further scouring in front and on sides of structure HDS unit was vacuumed and pressure washed in November 2022 HDS unit is at 2.08% of its capacity, photo 2 View into MH A-3 shows no sediment accumulation View into MH A-13 shows minimal sediment accumulation, photo 3 Minimal ponding - 0.5", photo 3 Contech StormFilter Stormwater Quality System at MH A-4 (GIS-BMP-5397) Max. sediment depth recommended by manufacturer = Distance from rim to sediment = Distance from rim to bottom = Depth of sediment = Field Observations - AA Building Parking Addition (MSD P001174317): Condition of filter media Trash/debris Clogging Depth of water/sediment on vault floor No indications of clogging In good condition 0.5" of sediment below ladder and around outlet module, photo 5 Dusting of sediment on cartridge tops, photo 4 Filter media is only slightly discolored by sediment and remains very porous, photo 6 Sediment was removed and cartridges were replaced in June 2021 Depth of silt on filter cartridge tops About 0.5" sediment around the perimeter, especially at ladder & outflow module Minimal ponding water Trash/debris Erosion Perforated standpipe is clear of blockages and debris, photo 10 MONITOR further erosion at west edge of rock blanket, photo 9 All vegetation is regularly managed including woody growth, photo 7 Flap valve has room to open and close, photo 8 No ponding water No trash, leaves or debris, photo 7 Increase of 0.5" since September 2023 inspection Bayer AA Parking Lot System - December 6, 2023 Up to 2" of sediment covering areas of seed netting Post-Construction Stormwater BMP Inspection Report Private Inlets/Manholes/Piping Comments Access System discharge - Overflow Structure A-5 Comments Other (describe)na Photographs Inspector's Notes Bayer AA Parking Lot System - December 6, 2023 Page 3 SEAL curb line along southwest edge of parking lot, photo 1 (Bayer) Settlement in front of double curb inlet A-1 was repaired Clear, photo 11 None of which I'm aware See attached sheet REMOVE heavy sediment at southwest edge of parking lot, photo 12 (Bayer) Miscellaneous Encroachment(s) on facility or easement Complaints Mosquitoes Trash/debris/sediment Erosion/settlement around structures Please note: Effective with the December 9, 2015 Inspection, what had been submitted as the NRB Building and Parking project on one report, is now being subdivided into two inspection reports: Bayer AA Building & Parking as well as Bayer CC Building & Parking. This reporting structure aligns to Bayer's internal project accounting process. March 19, 2021: A slight increase of sediment was measured in the HDS unit. A purchase order has been received to provide the needed maintenance on the StormFilter Vault. Maintenance will be scheduled in the future as the service provider is available. The upstream manhole A-13 of the RCP water quality storage was also opened this inspection. Some sediment is visible at this manhole, but no sediment is visible below the downstream manhole A-3. The surface detention basin continues to receive a high level of care and maintenance. It appears to remain structurally sound and needs no other work at this time. All structural components are free and clear to receive and discharge stormwater. June 8, 2021: A decrease of sediment was measured in the HDS unit. Maintenance is tentatively planned for June 17 & 18 to clean out the StormFilter Vault. September 8, 2021: The StormFilter vault was maintained since the previous inspection and remains in good condition. The HDS unit added 4.5 inches since June's visit. Conveyance into and out of the surface detention basin remains unobstructed and vegetation is being managed to keep any part of it from becoming overgrown. December 7, 2021: Sediment in the HDS unit decreased by 3.5 inches since September's visit. Conveyance into the surface detention basin was improved by removing some of the dirt around the flap valve. March 2, 2022: No changes noted. June 22, 2022: An increase of 1.5" sediment was measured in the HDS unit. Settlement in front of the curb inlet / flow splitter structure has worsened and should be repaired. The asphalt in front of the structure should be patched, and Aquablok (bentonite-coated pea gravel) should be added to fill scour at the southwest corner of the structure below the fencepost footing. September 22, 2022: Asphalt settlement in front of the curb inlet / flow splitter structure was patched. An increase of 3 inches of sediment was measured in the HDS unit. With the unit now above 75% of its capacity, it now needs to be pressure washed and vacuumed. December 7, 2022: The HDS unit was cleaned since September's inspection. Heavy sediment collecting along the southwest curb line of the parking lot shows scouring indicative of water draining out through the gap between the asphalt and the curb line. This needs to be sealed to prevent sinkhole development and to keep the stormwater going into the BMPs according to the design. Sediment should also be removed from along the curb line. March 7, 2023: The water quality storage unit was inspected with a QuickView Camera to confirm the pipe contains very little sediment through its entire length. The surface detention basin was inspected on 3/8/2023 during a light rain event, confirming that stormwater drains through the system effectively. June 7, 2023: No changes noted. Sediment collected along the curb line should be swept up and removed. It also shows scouring indicative of water draining out through the gap between the asphalt and the curb line. This needs to be sealed to prevent sinkhole development and to keep the stormwater going into the BMPs according to the design. September 20, 2023: No changes noted. December 6, 2023: No changes noted. BAYER – AA Building Parking Stormwater BMP Photos December 6, 2023 1. SEAL CURB LINE ALONG SOUTHWEST EDGE OF PARKING LOT 2. HDS UNIT IS AT 2.08% OF CAPACITY (GIS- BMP-4724) 3. MINIMAL SEDIMENT IN 48” RCP WATER QUALITY STORAGE (GIS-BMP-7329) 4. VIEW OF STORMFILTER VAULT IN MH 4-A (GIS-BMP-5397) 5. MINIMAL SEDIMENT ON VAULT FLOOR 6. FILTER MEDIA IS DISCOLORED BY SEDIMENT BUT REMAINS POROUS 7. VIEW OF SOUTH SURFACE DETENTION BASIN (GIS-BMP-2886) 8. FLAP VALVE HAS ROOM TO OPEN AND CLOSE 9. MONITOR FURTHER EROSION AT WEST EDGE OF ROCK BLANKET 10. PERFORATED STANDPIPE IS CLEAR OF BLOCKAGES AND DEBRIS (GIS-BMP-2886) 11. OVERFLOW STRUCTURE A-5 SHOWS SYSTEM DISCHARGE IS CLEAR 12. REMOVE HEAVY SEDIMENT AT THE SOUTHWEST EDGE OF THE PARKING LOT Post-Construction Stormwater BMP Inspection and Maintenance Record 263236 MSD P Number:P001174317 Project:Bayer CC Parking and Detention Address:700 Chesterfield Parkway West Chesterfield, MO 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 Record Start Date:August 21, 2012 Phone:(314) 229-8334 E-mail:marianne@stormwater-stl.net Stormwater Treatment Facilities:Total Count: Count Type Description Count Type Description 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)1 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)1 F-PR PROPRIETARY BMP FILTER (U) PPCO PERMEABLE PAVEMENT - CONCRETE (A)F-2 UNDERGROUND SAND FILTER (U) PPGR PERMEABLE PAVEMENT - GRAVEL (A) 1 DET DETENTION 1 WQS UNDERGROUND WATER QUALITY STORAGE DET U UNDERGROUND FBAY PRETREATMENT FOREBAY Inspection, Maintenance and Annual Report Submission Record: Date Activity Date Activity 2012.08.21 One-inch rainfall inspection by CBRE 2020.12.08 Inspection 2012.09.04 One-inch rainfall inspection by CBRE 2021.03.19 Inspection 2012.11.07 One-inch rainfall inspection by CBRE 2021.06.08 Inspection 2012.11.12 One-inch rainfall inspection by CBRE 2021.09.08 Inspection 2013.01.14 One-inch rainfall inspection by CBRE 2021.12.07 Inspection 2013.01.28 One-inch rainfall inspection by CBRE 2022.03.02 Inspection 2013.03.21 Inspection by Stormwater STL 2022.06.22 Inspection 2013.04.01 2012 Annual Report submission to MSD 2022.09.22 Inspection 2014.03.28 Inspection 2022.12.07 Inspection 2014.03.29 2013 Annual Report submission to MSD 2023.03.07 Inspection 2014.09.05 Inspection 2023.06.07 Inspection 2014.12.08 Inspection 2023.09.20 Inspection 2015.03.11 Inspection 2023.12.06 Inspection 2015.03.24 2014 Annual Report submission to MSD 2015.06.11 Inspection 2015.09.10 Inspection 2015.12.09 Inspection 2016.02.23 Inspection 2016.06.20 Inspection 2016.06.20 Inspection 2016.09.14 Inspection 2016.12.06 Inspection 2017.03.02 Inspection 2017.06.19 Inspection 2017.09.13 Inspection 2017.12.12 Inspection 2018.03.06 Inspection 2018.06.21 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 Inspection 2020.06.23 Inspection 2020.09.16 Inspection 4 Bayer Equip #: Post-Construction Stormwater BMP Inspection Report 263236 MSD P Number:P001174317 Project:Bayer CC Parking Lot System 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 Bayer Inspector(s):Marianne Pott Anna Tang Company:Stormwater STL LLC 314-694-3169 Address:6514 Lansdowne Avenue 63109 anna.tang@bayer.com Phone:(314) 229-8334 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: Surface Detention Basin (GIS-BMP-1660) Surface Detention Basin (GIS-BMP-1660) Surface Detention Basin (GIS-BMP-1660) Surface Detention Basin (GIS-BMP-1660) Surface Detention Basin (GIS-BMP-1660) Surface Sand Filter (GIS-BMP-6386) Surface Sand Filter (GIS-BMP-6386) Action Items Identified During This Inspection: Surface Detention Basin (GIS-BMP-1660) Page 1 CONTROL for sapling growth beginning in and around sand filter (Bayer) --- COMPLETED CUT AND REMOVE all plant growth and leaves from surface of basin (Bayer) REPAIR new hole at the bottom of retaining wall along northeast edge (Bayer) --- NOT COMPLETED CONTROL for growth of invasive weeds (Bayer) --- COMPLETED / ONGOING REPAIR new hole in bottom at west edge of swale below north inlet (Bayer) --- NOT COMPLETED Bayer Equip #: Customer: Contact: Phone Number: Email: 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. This report covers the CC Building Parking Addition portion of the stormwater treatment system associated with P001174317, including a surface sand filter, a 48" RCP Water Quality Storage component, a Contech Storm filter Stormwater Quality, and the surface detention basin to the north of the development. Further modifications of the surface detention basin include an underdrain system with cleanouts. The inspection in March 2017 showed that stormwater had eroded a hole in the center of the basin and the underlying legacy stormwater pipe underneath, bypassing the outflow structure to drain directly into the existing wetland to the northwest. Maintenance to repair this hole was completed by March 2018 and has restored the functionality of this system. The detention basin was further reconfigured to install three new inlets for the purposes of draining stormwater from the drive above and minimizing inundation and erosion at the substation. After a careful review of each component of the system and finding that each piece is stable and only the surface detention basin needs routine maintenance, I'm pleased to report: Based on what was observed, this stormwater treatment system appears to be functioning in accordance with the design intent. CUT AND REMOVE all plant growth and leaves from surface of basin (Bayer) --- COMPLETED REMOVE sediment from FES Inlet opposite of outflow structure (Bayer) --- COMPLETED REMOVE organic debris from east embankment (Bayer) --- COMPLETED Post-Construction Stormwater BMP Inspection Report Surface Sand Filter (GIS-BMP-6386) Comments Access Water ponding on surface Sheen on water surface na Odor Erosion Sediment Mulch Turf Plants na Weeds Underdrain Structural components Comments Access Trash/debris Sediment buildup Sediment buildup No more than 1" of sediment visible at Manhole B-6, photo 7 Water ponding on bottom Structural components Comments Access Water ponding on surface na Sheen on water surface na Odor Erosion na Sediment Mulch na Turf na Plants na Weeds na Underdrain Structural components 0.75 - 3.5" Minimal Porous Private Inlets/Manholes/Piping Comments Access System discharge Miscellaneous Comments Other (describe)n/a Photographs Page 2 Trash/debris No indications of clogging Trash, leaves, and organic debris collecting on the floor of the vault, photo 6 Condition of filter media 48" RCP Water Quality Storage (GIS-BMP-7328) No ponding water noted No sediment on surface of sand filter, but sediment has filled in river rock layer, photo 3 Area Inlet B-1 is clear of obstructions, photo 2 No turf adjacent to system Filter media inaccessible from depth of river rock approximately 8 inches deep Filter media is discolored by sediment but remains porous, photo 5 Sapling growth was removed since September's inspection, photo 1 Field Observations - CC Building Parking Addition (MSD P001174317): No erosion - embankments are composed of limestone revetment, photo 1 Condition of filter media observed during 12/2019 visit Clogging Clogging Depth of water/sediment on vault floor Depth of silt on filter cartridge tops Contech StormFilter Stormwater Quality System (GIS-BMP-5600) Trash/debris No trash, leaves or debris Minimal 3.5" sediment by overflow, 0.5" in middle, 1" under ladder, photo 6 Cartridge tops remain clean, photo 4 Floats appear functional and unimpeded by obstructions No vertical access to underdrain Trash/debris Erosion/settlement around structures Complaints Mosquitoes Encroachment(s) on facility or easement See attached sheet Bayer CC Building & Parking Lot - December 6, 2023 None of which I'm aware No erosion noted No trash, debris or leaves noted No standpipes to access underdrain No sediment visible at Manhole B-2 About 1" of ponding water visible through pipe No indications of clogging Post-Construction Stormwater BMP Inspection Report Field Observations - CC Building Addition Detention System (MSD P001174317 & P001174318): North Surface Detention Basin (GIS-BMP-1660) Comments Access Clogging Odor None Scour Sediment Turf Structural components Inlets Low flow orifice is clear of obstructions & draining stormwater, photo 12 Private Inlets/Manholes/Piping Comments Access System discharge Miscellaneous Comments Other (describe)na Photographs Inspector's Notes Page 3 Weeds Up to 6" of sediment was removed from throat of FES inlet across from outflow structure Up to 6" of sediment now covering all of rip rap swale across from outflow structure Erosion/settlement around structures New trench drains discharging to detention basin are collecting sediment & debris; turbid water in inlet piping opposite the outfall structure; up to 3" of silt, leaves & debris in one of the new inlets to the surface detention basin Trash/debris/leaves Erosion No clogging present - stormwater entering and leaving basin without obstructions Water ponding on surface REPAIR new hole in bottom at west edge of swale below north inlet, photo 9 (Bayer) Minimal trash, debris or leaves Previous hole in basin bottom / underlying legacy drain was repaired & remains stable South half of the basin contains up to 3" of water due to irregular surface, photos 8 & 11 REPAIR new hole at the bottom of retaining wall along northeast edge, photo 10 (Bayer) Low flow orifice & outflow structure are clear of obstructions, photo 12 Bayer CC Building & Parking Lot - December 6, 2023 See attached sheet Complaints Mosquitoes Encroachment(s) on facility or easement None of which I'm aware Please note: Effective with the December 9, 2015 Inspection, what had been submitted as the "NRB Building and Parking" project on one report, is now being subdivided into two inspection reports: "Bayer AA Building & Parking" as well as "Bayer CC Building & Parking." This reporting structure aligns to Bayer's internal project accounting process. Underdrain in Surface Detention Basin: The design of the detention basin included a 4" underdrain network, without any cleanouts or vertical access points, underneath 12" of engineered soil. While the detention basin was permitted and approved, it appears the underdrain system referred to as the SWM-1 Water Quality Filter was not. As such, the MSD Plan Reviewer for the project indicated it would be okay to abandon the underdrain system in a manner that would preserve all structural elements of the detention basin so that it continues to perform and function as such. A more complete abandonment of the underdrain system may be undertaken in an effort to resolve standing water issues in this facility. June 22, 2022: No changes were noted. September 22, 2022: Vegetation continues to be managed in the surface detention basin. Sediment continues to collect in the FES Inlet and rip rap swale opposite the outflow structure in the surface detention basin. Sediment measuring 6 inches deep was measured in the FES Inlet and up to 3 inches deep on the rip rap swale. December 7, 2022: New scouring was noted at the bottom of the retaining wall along the northeast edge of the surface detention basin. This needs to be filled in as well. Sediment continues to collecting in the surface detention basin, primarily washing in from the FES Inlet opposite of the outfall structure. This pipe holds about 6 inches of sediment inside. March 7, 2023: All BMPs remain functional. Underground treatment and storage BMPs were inspected on 3/7/2023. The surface detention basin was inspected on 3/8/2023 during a 0.15" rain event and stormwater was draining through the basin. Sediment is collecting within the inlet piping opposite the overflow structure and the southeast corner of the basin. June 7, 2023: Sediment in the piping of the FES Inlet added opposite of the outflow structure appears to have been cleaned out. Excessive sediment still remains in the rip rap swale, measured up to 5 inches. Surface sand filter, Contech StormFilter and water quality storage appear to remain very stable. September 20, 2023: Very few cattails have regrown in the surface detention basin. Saplings are starting to grow in and around the sand filter and should be removed. December 6, 2023: Maintenance is suggested on the surface detention basin to repair holes in its surface and routine maintenance to remove dead plant debris. Trenching work is being done in its drainage area and it seems that some turbid water and a small area of silt have gotten into the basin as a result. Underdrain Turf is established at north half of basin where surface dries out between rain events Outlets Trench work is being done in drainage area of basin No erosion around structures CUT AND REMOVE all plant growth and leaves from surface of basin, photo 11 (Bayer) Clear of obstructions, photo 12 Reconfigured with three new inlets to drain stormwater from drive above Trash/debris BAYER – CC Building Parking Stormwater BMP Photos December 6, 2023 1. VIEW OF SAND FILTER (GIS-BMP-6386)2. AI B-1 SHOWING SAND FILTER DISCHARGE IS CLEAR 3. TOP 8” OF RIVER ROCK IN SAND FILTER SHOWS HEAVY SILT ACCUMULATION 4. VIEW OF STORMFILTER VAULT (GIS-BMP- 5600) 5. FILTER MEDIA IS SLIGHTLY DISCOLORED BUT REMAINS VERY POROUS 6. MULCH & DEBRIS COLLECTING ON STORMFILTER VAULT FLOOR –UP TO 3.5” 7. MINIMAL SEDIMENT IN 48” RCP WATER QUALITY STORAGE (GIS-BMP-7328) 8. VIEW OF NORTH SURFACE DETENTION BASIN (GIS-BMP-1660) 9. REPAIR NEW HOLE IN BASIN BOTTOM AT WEST EDGE OF SWALE FROM NORTH INLET 10. REPAIR NEW HOLE AT THE BOOM OF RETAINING WALL ALONG NE EDGE 11.CUT AND REMOVE ALL PLANT GROWTH FROM SURFACE DETENTION BASIN 12. VIEW OF DISCHARGE INTO OUTFLOW STRUCTURE Post-Construction Stormwater BMP Inspection and Maintenance Record 263236 MSD P Number:P001174317 Project:Bayer CC Parking and Detention Address:700 Chesterfield Parkway West Chesterfield, MO 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 Record Start Date:August 21, 2012 Phone:(314) 229-8334 E-mail:marianne@stormwater-stl.net Stormwater Treatment Facilities:Total Count: Count Type Description Count Type Description 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)1 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)1 F-PR PROPRIETARY BMP FILTER (U) PPCO PERMEABLE PAVEMENT - CONCRETE (A)F-2 UNDERGROUND SAND FILTER (U) PPGR PERMEABLE PAVEMENT - GRAVEL (A) 1 DET DETENTION 1 WQS UNDERGROUND WATER QUALITY STORAGE DET U UNDERGROUND FBAY PRETREATMENT FOREBAY Inspection, Maintenance and Annual Report Submission Record: Date Activity Date Activity 2012.08.21 One-inch rainfall inspection by CBRE 2020.12.08 Inspection 2012.09.04 One-inch rainfall inspection by CBRE 2021.03.19 Inspection 2012.11.07 One-inch rainfall inspection by CBRE 2021.06.08 Inspection 2012.11.12 One-inch rainfall inspection by CBRE 2021.09.08 Inspection 2013.01.14 One-inch rainfall inspection by CBRE 2021.12.07 Inspection 2013.01.28 One-inch rainfall inspection by CBRE 2022.03.02 Inspection 2013.03.21 Inspection by Stormwater STL 2022.06.22 Inspection 2013.04.01 2012 Annual Report submission to MSD 2022.09.22 Inspection 2014.03.28 Inspection 2022.12.07 Inspection 2014.03.29 2013 Annual Report submission to MSD 2023.03.07 Inspection 2014.09.05 Inspection 2023.06.07 Inspection 2014.12.08 Inspection 2023.09.20 Inspection 2015.03.11 Inspection 2023.12.06 Inspection 2015.03.24 2014 Annual Report submission to MSD 2015.06.11 Inspection 2015.09.10 Inspection 2015.12.09 Inspection 2016.02.23 Inspection 2016.06.20 Inspection 2016.06.20 Inspection 2016.09.14 Inspection 2016.12.06 Inspection 2017.03.02 Inspection 2017.06.19 Inspection 2017.09.13 Inspection 2017.12.12 Inspection 2018.03.06 Inspection 2018.06.21 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 Inspection 2020.06.23 Inspection 2020.09.16 Inspection 4 Bayer Equip #: Post-Construction Stormwater BMP Inspection Report 263236 MSD P Number:P001174317 Project:Bayer CC Parking Lot System 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 Bayer Inspector(s):Marianne Pott Anna Tang Company:Stormwater STL LLC 314-694-3169 Address:6514 Lansdowne Avenue 63109 anna.tang@bayer.com Phone:(314) 229-8334 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: Surface Detention Basin (GIS-BMP-1660) Surface Detention Basin (GIS-BMP-1660) Surface Detention Basin (GIS-BMP-1660) Surface Detention Basin (GIS-BMP-1660) Surface Detention Basin (GIS-BMP-1660) Surface Sand Filter (GIS-BMP-6386) Surface Sand Filter (GIS-BMP-6386) Action Items Identified During This Inspection: Surface Detention Basin (GIS-BMP-1660) Page 1 CONTROL for sapling growth beginning in and around sand filter (Bayer) --- COMPLETED CUT AND REMOVE all plant growth and leaves from surface of basin (Bayer) REPAIR new hole at the bottom of retaining wall along northeast edge (Bayer) --- NOT COMPLETED CONTROL for growth of invasive weeds (Bayer) --- COMPLETED / ONGOING REPAIR new hole in bottom at west edge of swale below north inlet (Bayer) --- NOT COMPLETED Bayer Equip #: Customer: Contact: Phone Number: Email: 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. This report covers the CC Building Parking Addition portion of the stormwater treatment system associated with P001174317, including a surface sand filter, a 48" RCP Water Quality Storage component, a Contech Storm filter Stormwater Quality, and the surface detention basin to the north of the development. Further modifications of the surface detention basin include an underdrain system with cleanouts. The inspection in March 2017 showed that stormwater had eroded a hole in the center of the basin and the underlying legacy stormwater pipe underneath, bypassing the outflow structure to drain directly into the existing wetland to the northwest. Maintenance to repair this hole was completed by March 2018 and has restored the functionality of this system. The detention basin was further reconfigured to install three new inlets for the purposes of draining stormwater from the drive above and minimizing inundation and erosion at the substation. After a careful review of each component of the system and finding that each piece is stable and only the surface detention basin needs routine maintenance, I'm pleased to report: Based on what was observed, this stormwater treatment system appears to be functioning in accordance with the design intent. CUT AND REMOVE all plant growth and leaves from surface of basin (Bayer) --- COMPLETED REMOVE sediment from FES Inlet opposite of outflow structure (Bayer) --- COMPLETED REMOVE organic debris from east embankment (Bayer) --- COMPLETED Post-Construction Stormwater BMP Inspection Report Surface Sand Filter (GIS-BMP-6386) Comments Access Water ponding on surface Sheen on water surface na Odor Erosion Sediment Mulch Turf Plants na Weeds Underdrain Structural components Comments Access Trash/debris Sediment buildup Sediment buildup No more than 1" of sediment visible at Manhole B-6, photo 7 Water ponding on bottom Structural components Comments Access Water ponding on surface na Sheen on water surface na Odor Erosion na Sediment Mulch na Turf na Plants na Weeds na Underdrain Structural components 0.75 - 3.5" Minimal Porous Private Inlets/Manholes/Piping Comments Access System discharge Miscellaneous Comments Other (describe)n/a Photographs Page 2 Trash/debris No indications of clogging Trash, leaves, and organic debris collecting on the floor of the vault, photo 6 Condition of filter media 48" RCP Water Quality Storage (GIS-BMP-7328) No ponding water noted No sediment on surface of sand filter, but sediment has filled in river rock layer, photo 3 Area Inlet B-1 is clear of obstructions, photo 2 No turf adjacent to system Filter media inaccessible from depth of river rock approximately 8 inches deep Filter media is discolored by sediment but remains porous, photo 5 Sapling growth was removed since September's inspection, photo 1 Field Observations - CC Building Parking Addition (MSD P001174317): No erosion - embankments are composed of limestone revetment, photo 1 Condition of filter media observed during 12/2019 visit Clogging Clogging Depth of water/sediment on vault floor Depth of silt on filter cartridge tops Contech StormFilter Stormwater Quality System (GIS-BMP-5600) Trash/debris No trash, leaves or debris Minimal 3.5" sediment by overflow, 0.5" in middle, 1" under ladder, photo 6 Cartridge tops remain clean, photo 4 Floats appear functional and unimpeded by obstructions No vertical access to underdrain Trash/debris Erosion/settlement around structures Complaints Mosquitoes Encroachment(s) on facility or easement See attached sheet Bayer CC Building & Parking Lot - December 6, 2023 None of which I'm aware No erosion noted No trash, debris or leaves noted No standpipes to access underdrain No sediment visible at Manhole B-2 About 1" of ponding water visible through pipe No indications of clogging Post-Construction Stormwater BMP Inspection Report Field Observations - CC Building Addition Detention System (MSD P001174317 & P001174318): North Surface Detention Basin (GIS-BMP-1660) Comments Access Clogging Odor None Scour Sediment Turf Structural components Inlets Low flow orifice is clear of obstructions & draining stormwater, photo 12 Private Inlets/Manholes/Piping Comments Access System discharge Miscellaneous Comments Other (describe)na Photographs Inspector's Notes Page 3 Weeds Up to 6" of sediment was removed from throat of FES inlet across from outflow structure Up to 6" of sediment now covering all of rip rap swale across from outflow structure Erosion/settlement around structures New trench drains discharging to detention basin are collecting sediment & debris; turbid water in inlet piping opposite the outfall structure; up to 3" of silt, leaves & debris in one of the new inlets to the surface detention basin Trash/debris/leaves Erosion No clogging present - stormwater entering and leaving basin without obstructions Water ponding on surface REPAIR new hole in bottom at west edge of swale below north inlet, photo 9 (Bayer) Minimal trash, debris or leaves Previous hole in basin bottom / underlying legacy drain was repaired & remains stable South half of the basin contains up to 3" of water due to irregular surface, photos 8 & 11 REPAIR new hole at the bottom of retaining wall along northeast edge, photo 10 (Bayer) Low flow orifice & outflow structure are clear of obstructions, photo 12 Bayer CC Building & Parking Lot - December 6, 2023 See attached sheet Complaints Mosquitoes Encroachment(s) on facility or easement None of which I'm aware Please note: Effective with the December 9, 2015 Inspection, what had been submitted as the "NRB Building and Parking" project on one report, is now being subdivided into two inspection reports: "Bayer AA Building & Parking" as well as "Bayer CC Building & Parking." This reporting structure aligns to Bayer's internal project accounting process. Underdrain in Surface Detention Basin: The design of the detention basin included a 4" underdrain network, without any cleanouts or vertical access points, underneath 12" of engineered soil. While the detention basin was permitted and approved, it appears the underdrain system referred to as the SWM-1 Water Quality Filter was not. As such, the MSD Plan Reviewer for the project indicated it would be okay to abandon the underdrain system in a manner that would preserve all structural elements of the detention basin so that it continues to perform and function as such. A more complete abandonment of the underdrain system may be undertaken in an effort to resolve standing water issues in this facility. June 22, 2022: No changes were noted. September 22, 2022: Vegetation continues to be managed in the surface detention basin. Sediment continues to collect in the FES Inlet and rip rap swale opposite the outflow structure in the surface detention basin. Sediment measuring 6 inches deep was measured in the FES Inlet and up to 3 inches deep on the rip rap swale. December 7, 2022: New scouring was noted at the bottom of the retaining wall along the northeast edge of the surface detention basin. This needs to be filled in as well. Sediment continues to collecting in the surface detention basin, primarily washing in from the FES Inlet opposite of the outfall structure. This pipe holds about 6 inches of sediment inside. March 7, 2023: All BMPs remain functional. Underground treatment and storage BMPs were inspected on 3/7/2023. The surface detention basin was inspected on 3/8/2023 during a 0.15" rain event and stormwater was draining through the basin. Sediment is collecting within the inlet piping opposite the overflow structure and the southeast corner of the basin. June 7, 2023: Sediment in the piping of the FES Inlet added opposite of the outflow structure appears to have been cleaned out. Excessive sediment still remains in the rip rap swale, measured up to 5 inches. Surface sand filter, Contech StormFilter and water quality storage appear to remain very stable. September 20, 2023: Very few cattails have regrown in the surface detention basin. Saplings are starting to grow in and around the sand filter and should be removed. December 6, 2023: Maintenance is suggested on the surface detention basin to repair holes in its surface and routine maintenance to remove dead plant debris. Trenching work is being done in its drainage area and it seems that some turbid water and a small area of silt have gotten into the basin as a result. Underdrain Turf is established at north half of basin where surface dries out between rain events Outlets Trench work is being done in drainage area of basin No erosion around structures CUT AND REMOVE all plant growth and leaves from surface of basin, photo 11 (Bayer) Clear of obstructions, photo 12 Reconfigured with three new inlets to drain stormwater from drive above Trash/debris BAYER – CC Building Parking Stormwater BMP Photos December 6, 2023 1. VIEW OF SAND FILTER (GIS-BMP-6386)2. AI B-1 SHOWING SAND FILTER DISCHARGE IS CLEAR 3. TOP 8” OF RIVER ROCK IN SAND FILTER SHOWS HEAVY SILT ACCUMULATION 4. VIEW OF STORMFILTER VAULT (GIS-BMP- 5600) 5. FILTER MEDIA IS SLIGHTLY DISCOLORED BUT REMAINS VERY POROUS 6. MULCH & DEBRIS COLLECTING ON STORMFILTER VAULT FLOOR –UP TO 3.5” 7. MINIMAL SEDIMENT IN 48” RCP WATER QUALITY STORAGE (GIS-BMP-7328) 8. VIEW OF NORTH SURFACE DETENTION BASIN (GIS-BMP-1660) 9. REPAIR NEW HOLE IN BASIN BOTTOM AT WEST EDGE OF SWALE FROM NORTH INLET 10. REPAIR NEW HOLE AT THE BOOM OF RETAINING WALL ALONG NE EDGE 11.CUT AND REMOVE ALL PLANT GROWTH FROM SURFACE DETENTION BASIN 12. VIEW OF DISCHARGE INTO OUTFLOW STRUCTURE Post-Construction Stormwater BMP Inspection and Maintenance Record 263236 MSD P Number:P001174317 Project:Bayer CC Parking and Detention Address:700 Chesterfield Parkway West Chesterfield, MO 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 Record Start Date:August 21, 2012 Phone:(314) 229-8334 E-mail:marianne@stormwater-stl.net Stormwater Treatment Facilities:Total Count: Count Type Description Count Type Description 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)1 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)1 F-PR PROPRIETARY BMP FILTER (U) PPCO PERMEABLE PAVEMENT - CONCRETE (A)F-2 UNDERGROUND SAND FILTER (U) PPGR PERMEABLE PAVEMENT - GRAVEL (A) 1 DET DETENTION 1 WQS UNDERGROUND WATER QUALITY STORAGE DET U UNDERGROUND FBAY PRETREATMENT FOREBAY Inspection, Maintenance and Annual Report Submission Record: Date Activity Date Activity 2012.08.21 One-inch rainfall inspection by CBRE 2020.12.08 Inspection 2012.09.04 One-inch rainfall inspection by CBRE 2021.03.19 Inspection 2012.11.07 One-inch rainfall inspection by CBRE 2021.06.08 Inspection 2012.11.12 One-inch rainfall inspection by CBRE 2021.09.08 Inspection 2013.01.14 One-inch rainfall inspection by CBRE 2021.12.07 Inspection 2013.01.28 One-inch rainfall inspection by CBRE 2022.03.02 Inspection 2013.03.21 Inspection by Stormwater STL 2022.06.22 Inspection 2013.04.01 2012 Annual Report submission to MSD 2022.09.22 Inspection 2014.03.28 Inspection 2022.12.07 Inspection 2014.03.29 2013 Annual Report submission to MSD 2023.03.07 Inspection 2014.09.05 Inspection 2023.06.07 Inspection 2014.12.08 Inspection 2023.09.20 Inspection 2015.03.11 Inspection 2023.12.06 Inspection 2015.03.24 2014 Annual Report submission to MSD 2015.06.11 Inspection 2015.09.10 Inspection 2015.12.09 Inspection 2016.02.23 Inspection 2016.06.20 Inspection 2016.06.20 Inspection 2016.09.14 Inspection 2016.12.06 Inspection 2017.03.02 Inspection 2017.06.19 Inspection 2017.09.13 Inspection 2017.12.12 Inspection 2018.03.06 Inspection 2018.06.21 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 Inspection 2020.06.23 Inspection 2020.09.16 Inspection 4 Bayer Equip #: Post-Construction Stormwater BMP Inspection Report 263236 MSD P Number:P001174317 Project:Bayer CC Parking Lot System 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 Bayer Inspector(s):Marianne Pott Anna Tang Company:Stormwater STL LLC 314-694-3169 Address:6514 Lansdowne Avenue 63109 anna.tang@bayer.com Phone:(314) 229-8334 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: Surface Detention Basin (GIS-BMP-1660) Surface Detention Basin (GIS-BMP-1660) Surface Detention Basin (GIS-BMP-1660) Surface Detention Basin (GIS-BMP-1660) Surface Detention Basin (GIS-BMP-1660) Surface Sand Filter (GIS-BMP-6386) Surface Sand Filter (GIS-BMP-6386) Action Items Identified During This Inspection: Surface Detention Basin (GIS-BMP-1660) Page 1 CONTROL for sapling growth beginning in and around sand filter (Bayer) --- COMPLETED CUT AND REMOVE all plant growth and leaves from surface of basin (Bayer) REPAIR new hole at the bottom of retaining wall along northeast edge (Bayer) --- NOT COMPLETED CONTROL for growth of invasive weeds (Bayer) --- COMPLETED / ONGOING REPAIR new hole in bottom at west edge of swale below north inlet (Bayer) --- NOT COMPLETED Bayer Equip #: Customer: Contact: Phone Number: Email: 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. This report covers the CC Building Parking Addition portion of the stormwater treatment system associated with P001174317, including a surface sand filter, a 48" RCP Water Quality Storage component, a Contech Storm filter Stormwater Quality, and the surface detention basin to the north of the development. Further modifications of the surface detention basin include an underdrain system with cleanouts. The inspection in March 2017 showed that stormwater had eroded a hole in the center of the basin and the underlying legacy stormwater pipe underneath, bypassing the outflow structure to drain directly into the existing wetland to the northwest. Maintenance to repair this hole was completed by March 2018 and has restored the functionality of this system. The detention basin was further reconfigured to install three new inlets for the purposes of draining stormwater from the drive above and minimizing inundation and erosion at the substation. After a careful review of each component of the system and finding that each piece is stable and only the surface detention basin needs routine maintenance, I'm pleased to report: Based on what was observed, this stormwater treatment system appears to be functioning in accordance with the design intent. CUT AND REMOVE all plant growth and leaves from surface of basin (Bayer) --- COMPLETED REMOVE sediment from FES Inlet opposite of outflow structure (Bayer) --- COMPLETED REMOVE organic debris from east embankment (Bayer) --- COMPLETED Post-Construction Stormwater BMP Inspection Report Surface Sand Filter (GIS-BMP-6386) Comments Access Water ponding on surface Sheen on water surface na Odor Erosion Sediment Mulch Turf Plants na Weeds Underdrain Structural components Comments Access Trash/debris Sediment buildup Sediment buildup No more than 1" of sediment visible at Manhole B-6, photo 7 Water ponding on bottom Structural components Comments Access Water ponding on surface na Sheen on water surface na Odor Erosion na Sediment Mulch na Turf na Plants na Weeds na Underdrain Structural components 0.75 - 3.5" Minimal Porous Private Inlets/Manholes/Piping Comments Access System discharge Miscellaneous Comments Other (describe)n/a Photographs Page 2 Trash/debris No indications of clogging Trash, leaves, and organic debris collecting on the floor of the vault, photo 6 Condition of filter media 48" RCP Water Quality Storage (GIS-BMP-7328) No ponding water noted No sediment on surface of sand filter, but sediment has filled in river rock layer, photo 3 Area Inlet B-1 is clear of obstructions, photo 2 No turf adjacent to system Filter media inaccessible from depth of river rock approximately 8 inches deep Filter media is discolored by sediment but remains porous, photo 5 Sapling growth was removed since September's inspection, photo 1 Field Observations - CC Building Parking Addition (MSD P001174317): No erosion - embankments are composed of limestone revetment, photo 1 Condition of filter media observed during 12/2019 visit Clogging Clogging Depth of water/sediment on vault floor Depth of silt on filter cartridge tops Contech StormFilter Stormwater Quality System (GIS-BMP-5600) Trash/debris No trash, leaves or debris Minimal 3.5" sediment by overflow, 0.5" in middle, 1" under ladder, photo 6 Cartridge tops remain clean, photo 4 Floats appear functional and unimpeded by obstructions No vertical access to underdrain Trash/debris Erosion/settlement around structures Complaints Mosquitoes Encroachment(s) on facility or easement See attached sheet Bayer CC Building & Parking Lot - December 6, 2023 None of which I'm aware No erosion noted No trash, debris or leaves noted No standpipes to access underdrain No sediment visible at Manhole B-2 About 1" of ponding water visible through pipe No indications of clogging Post-Construction Stormwater BMP Inspection Report Field Observations - CC Building Addition Detention System (MSD P001174317 & P001174318): North Surface Detention Basin (GIS-BMP-1660) Comments Access Clogging Odor None Scour Sediment Turf Structural components Inlets Low flow orifice is clear of obstructions & draining stormwater, photo 12 Private Inlets/Manholes/Piping Comments Access System discharge Miscellaneous Comments Other (describe)na Photographs Inspector's Notes Page 3 Weeds Up to 6" of sediment was removed from throat of FES inlet across from outflow structure Up to 6" of sediment now covering all of rip rap swale across from outflow structure Erosion/settlement around structures New trench drains discharging to detention basin are collecting sediment & debris; turbid water in inlet piping opposite the outfall structure; up to 3" of silt, leaves & debris in one of the new inlets to the surface detention basin Trash/debris/leaves Erosion No clogging present - stormwater entering and leaving basin without obstructions Water ponding on surface REPAIR new hole in bottom at west edge of swale below north inlet, photo 9 (Bayer) Minimal trash, debris or leaves Previous hole in basin bottom / underlying legacy drain was repaired & remains stable South half of the basin contains up to 3" of water due to irregular surface, photos 8 & 11 REPAIR new hole at the bottom of retaining wall along northeast edge, photo 10 (Bayer) Low flow orifice & outflow structure are clear of obstructions, photo 12 Bayer CC Building & Parking Lot - December 6, 2023 See attached sheet Complaints Mosquitoes Encroachment(s) on facility or easement None of which I'm aware Please note: Effective with the December 9, 2015 Inspection, what had been submitted as the "NRB Building and Parking" project on one report, is now being subdivided into two inspection reports: "Bayer AA Building & Parking" as well as "Bayer CC Building & Parking." This reporting structure aligns to Bayer's internal project accounting process. Underdrain in Surface Detention Basin: The design of the detention basin included a 4" underdrain network, without any cleanouts or vertical access points, underneath 12" of engineered soil. While the detention basin was permitted and approved, it appears the underdrain system referred to as the SWM-1 Water Quality Filter was not. As such, the MSD Plan Reviewer for the project indicated it would be okay to abandon the underdrain system in a manner that would preserve all structural elements of the detention basin so that it continues to perform and function as such. A more complete abandonment of the underdrain system may be undertaken in an effort to resolve standing water issues in this facility. June 22, 2022: No changes were noted. September 22, 2022: Vegetation continues to be managed in the surface detention basin. Sediment continues to collect in the FES Inlet and rip rap swale opposite the outflow structure in the surface detention basin. Sediment measuring 6 inches deep was measured in the FES Inlet and up to 3 inches deep on the rip rap swale. December 7, 2022: New scouring was noted at the bottom of the retaining wall along the northeast edge of the surface detention basin. This needs to be filled in as well. Sediment continues to collecting in the surface detention basin, primarily washing in from the FES Inlet opposite of the outfall structure. This pipe holds about 6 inches of sediment inside. March 7, 2023: All BMPs remain functional. Underground treatment and storage BMPs were inspected on 3/7/2023. The surface detention basin was inspected on 3/8/2023 during a 0.15" rain event and stormwater was draining through the basin. Sediment is collecting within the inlet piping opposite the overflow structure and the southeast corner of the basin. June 7, 2023: Sediment in the piping of the FES Inlet added opposite of the outflow structure appears to have been cleaned out. Excessive sediment still remains in the rip rap swale, measured up to 5 inches. Surface sand filter, Contech StormFilter and water quality storage appear to remain very stable. September 20, 2023: Very few cattails have regrown in the surface detention basin. Saplings are starting to grow in and around the sand filter and should be removed. December 6, 2023: Maintenance is suggested on the surface detention basin to repair holes in its surface and routine maintenance to remove dead plant debris. Trenching work is being done in its drainage area and it seems that some turbid water and a small area of silt have gotten into the basin as a result. Underdrain Turf is established at north half of basin where surface dries out between rain events Outlets Trench work is being done in drainage area of basin No erosion around structures CUT AND REMOVE all plant growth and leaves from surface of basin, photo 11 (Bayer) Clear of obstructions, photo 12 Reconfigured with three new inlets to drain stormwater from drive above Trash/debris BAYER – CC Building Parking Stormwater BMP Photos December 6, 2023 1. VIEW OF SAND FILTER (GIS-BMP-6386)2. AI B-1 SHOWING SAND FILTER DISCHARGE IS CLEAR 3. TOP 8” OF RIVER ROCK IN SAND FILTER SHOWS HEAVY SILT ACCUMULATION 4. VIEW OF STORMFILTER VAULT (GIS-BMP- 5600) 5. FILTER MEDIA IS SLIGHTLY DISCOLORED BUT REMAINS VERY POROUS 6. MULCH & DEBRIS COLLECTING ON STORMFILTER VAULT FLOOR –UP TO 3.5” 7. MINIMAL SEDIMENT IN 48” RCP WATER QUALITY STORAGE (GIS-BMP-7328) 8. VIEW OF NORTH SURFACE DETENTION BASIN (GIS-BMP-1660) 9. REPAIR NEW HOLE IN BASIN BOTTOM AT WEST EDGE OF SWALE FROM NORTH INLET 10. REPAIR NEW HOLE AT THE BOOM OF RETAINING WALL ALONG NE EDGE 11.CUT AND REMOVE ALL PLANT GROWTH FROM SURFACE DETENTION BASIN 12. VIEW OF DISCHARGE INTO OUTFLOW STRUCTURE Post-Construction Stormwater BMP Inspection and Maintenance Record Bayer Equip #:261387 MSD P Number:P001174317 Project:Bayer AA Parking Lot System Address:700 Chesterfield Parkway West Chesterfield, MO 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 Record Start Date:August 21, 2012 Phone:(314) 229-8334 E-mail:marianne@stormwater-stl.net Stormwater Treatment Facilities:Total Count: Count Type Description Count Type Description 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) 1 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)1 F-PR PROPRIETARY BMP FILTER (U) PPCO PERMEABLE PAVEMENT - CONCRETE (A)F-2 UNDERGROUND SAND FILTER (U) PPGR PERMEABLE PAVEMENT - GRAVEL (A) 1 DET DETENTION 1 WQS UNDERGROUND WATER QUALITY STORAGE DET U UNDERGROUND FBAY PRETREATMENT FOREBAY Inspection, Maintenance and Annual Report Submission Record: Date Activity Date Activity 2012.08.21 One-inch rainfall inspection by CBRE 2020.03.05 Inspection 2012.09.04 One-inch rainfall inspection by CBRE 2020.06.23 Inspection 2012.11.07 One-inch rainfall inspection by CBRE 2020.09.16 Inspection 2012.11.12 One-inch rainfall inspection by CBRE 2020.12.08 Inspection 2013.01.14 One-inch rainfall inspection by CBRE 2021.03.19 Inspection 2013.01.28 One-inch rainfall inspection by CBRE 2021.06.08 Inspection 2013.03.21 Inspection by Stormwater STL 2021.06.17 Maintenance - Storm Filter Vault 2013.04.01 2012 Annual Report submission to MSD 2021.09.08 Inspection 2014.03.28 Inspection 2021.12.07 Inspection 2014.03.29 2013 Annual Report submission to MSD 2022.03.02 Inspection 2014.09.05 Inspection 2022.06.22 Inspection 2014.12.08 Inspection 2022.09.22 Inspection 2015.03.11 Inspection 2022.11.09 Maintenance HDS Unit 2015.03.24 2014 Annual Report submission to MSD 2022.12.07 Inspection 2015.06.11 Inspection 2023.03.07 Inspection 2015.09.10 Inspection 2023.06.07 Inspection 2015.10.12 Maintenance - HDS 2023.09.20 Inspection 2015.10.13 Maintenance - StormFilter Vault 2023.12.06 Inspection 2015.12.09 Inspection 2016.02.23 Inspection 2016.06.20 Inspection 2016.09.14 Inspection 2016.09.21 Maintenance - StormFilter Vault 2016.12.06 Inspection 2017.03.02 Inspection 2017.06.19 Inspection 2017.09.13 Inspection 2017.12.12 Inspection 2018.02.07 Maintenance - Removal of leaves in HDS unit 2018.03.06 Inspection 2018.06.21 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 4 Post-Construction Stormwater BMP Inspection Report 261387 MSD P Number:P001174317 Project:Bayer AA Parking Lot System 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 Bayer Inspector(s):Marianne Pott Anna Tang Company:Stormwater STL LLC 314-694-3169 Address:6514 Lansdowne Avenue 63109 anna.tang@bayer.com Phone:(314) 229-8334 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: Curb Line to West of Double Curb Inlet A-1 Curb Line to West of Double Curb Inlet A-1 Action Items Identified During This Inspection: No new action items were identified during this inspection. ` Page 1 REMOVE heavy sediment at southwest edge of parking lot (Bayer) --- NOT COMPLETED SEAL curb line along southwest edge of parking lot (Bayer) --- NOT COMPLETED Bayer Equip #: Customer: Contact: Phone Number: Email: 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. This report covers the AA Building Parking Addition portion of the stormwater treatment system associated with P001174317. This portion of the project includes a Contech VortSentry HS48 Hydrodynamic Separator, a 48" RCP Water Quality Storage component, a Contech Storm filter Stormwater Quality component, a surface detention basin as well as associated private inlets, manholes and piping. All sediment was removed from the StormFilter Vault, the three spent filter cartridges were replaced in October 2015, September 2016, and June 2021. The HDS was vacuumed to remove all sediment in October 2015 and November 2022. After carefully reviewing each component of the system, I am pleased to report: Based on what was observed, this stormwater treatment system appears to be functioning in accordance with the design intent. Post-Construction Stormwater BMP Inspection Report Flow Splitter in Double Curb Inlet A-1 Comments Structural components Comments Access Clogging Water ponding on surface na Sheen on water surface Odor Sediment Mulch na Turf na Weeds na Underdrain na Structural components 10'-10.5" 10'-11" 0'-0.5" 2'-0" 48" RCP Water Quality Storage at MH A-3 and MH A-13 (GIS-BMP-7329) Comments Access Sediment buildup Sediment buildup Clogging Water ponding on bottom Structural components Comments Access Water ponding on surface Sheen on water surface na Odor Erosion na Sediment Mulch na Turf na Plants na Weeds na Underdrain Structural components South Surface Detention Basin (GIS-BMP-2886) Comments Access Clogging Water ponding on surface Sheen on water surface na Odor Sediment Mulch Turf Weeds Structural components Depth of sediment =0" - 2" Page 2 Minimal trash, debris or leaves noted, photo 2 No odor noted Some mulch, trash, leaves and debris noted, photo 4 Pretreatment - Contech VortSentry HS48 Hydrodynamic Separator in MH A-2 (GIS-BMP-4724) Erosion No sheen on water surface Trash/debris Trash/debris/sediment No trash or debris present Erosion/settlement around structures No further scouring in front and on sides of structure HDS unit was vacuumed and pressure washed in November 2022 HDS unit is at 2.08% of its capacity, photo 2 View into MH A-3 shows no sediment accumulation View into MH A-13 shows minimal sediment accumulation, photo 3 Minimal ponding - 0.5", photo 3 Contech StormFilter Stormwater Quality System at MH A-4 (GIS-BMP-5397) Max. sediment depth recommended by manufacturer = Distance from rim to sediment = Distance from rim to bottom = Depth of sediment = Field Observations - AA Building Parking Addition (MSD P001174317): Condition of filter media Trash/debris Clogging Depth of water/sediment on vault floor No indications of clogging In good condition 0.5" of sediment below ladder and around outlet module, photo 5 Dusting of sediment on cartridge tops, photo 4 Filter media is only slightly discolored by sediment and remains very porous, photo 6 Sediment was removed and cartridges were replaced in June 2021 Depth of silt on filter cartridge tops About 0.5" sediment around the perimeter, especially at ladder & outflow module Minimal ponding water Trash/debris Erosion Perforated standpipe is clear of blockages and debris, photo 10 MONITOR further erosion at west edge of rock blanket, photo 9 All vegetation is regularly managed including woody growth, photo 7 Flap valve has room to open and close, photo 8 No ponding water No trash, leaves or debris, photo 7 Increase of 0.5" since September 2023 inspection Bayer AA Parking Lot System - December 6, 2023 Up to 2" of sediment covering areas of seed netting Post-Construction Stormwater BMP Inspection Report Private Inlets/Manholes/Piping Comments Access System discharge - Overflow Structure A-5 Comments Other (describe)na Photographs Inspector's Notes Bayer AA Parking Lot System - December 6, 2023 Page 3 SEAL curb line along southwest edge of parking lot, photo 1 (Bayer) Settlement in front of double curb inlet A-1 was repaired Clear, photo 11 None of which I'm aware See attached sheet REMOVE heavy sediment at southwest edge of parking lot, photo 12 (Bayer) Miscellaneous Encroachment(s) on facility or easement Complaints Mosquitoes Trash/debris/sediment Erosion/settlement around structures Please note: Effective with the December 9, 2015 Inspection, what had been submitted as the NRB Building and Parking project on one report, is now being subdivided into two inspection reports: Bayer AA Building & Parking as well as Bayer CC Building & Parking. This reporting structure aligns to Bayer's internal project accounting process. March 19, 2021: A slight increase of sediment was measured in the HDS unit. A purchase order has been received to provide the needed maintenance on the StormFilter Vault. Maintenance will be scheduled in the future as the service provider is available. The upstream manhole A-13 of the RCP water quality storage was also opened this inspection. Some sediment is visible at this manhole, but no sediment is visible below the downstream manhole A-3. The surface detention basin continues to receive a high level of care and maintenance. It appears to remain structurally sound and needs no other work at this time. All structural components are free and clear to receive and discharge stormwater. June 8, 2021: A decrease of sediment was measured in the HDS unit. Maintenance is tentatively planned for June 17 & 18 to clean out the StormFilter Vault. September 8, 2021: The StormFilter vault was maintained since the previous inspection and remains in good condition. The HDS unit added 4.5 inches since June's visit. Conveyance into and out of the surface detention basin remains unobstructed and vegetation is being managed to keep any part of it from becoming overgrown. December 7, 2021: Sediment in the HDS unit decreased by 3.5 inches since September's visit. Conveyance into the surface detention basin was improved by removing some of the dirt around the flap valve. March 2, 2022: No changes noted. June 22, 2022: An increase of 1.5" sediment was measured in the HDS unit. Settlement in front of the curb inlet / flow splitter structure has worsened and should be repaired. The asphalt in front of the structure should be patched, and Aquablok (bentonite-coated pea gravel) should be added to fill scour at the southwest corner of the structure below the fencepost footing. September 22, 2022: Asphalt settlement in front of the curb inlet / flow splitter structure was patched. An increase of 3 inches of sediment was measured in the HDS unit. With the unit now above 75% of its capacity, it now needs to be pressure washed and vacuumed. December 7, 2022: The HDS unit was cleaned since September's inspection. Heavy sediment collecting along the southwest curb line of the parking lot shows scouring indicative of water draining out through the gap between the asphalt and the curb line. This needs to be sealed to prevent sinkhole development and to keep the stormwater going into the BMPs according to the design. Sediment should also be removed from along the curb line. March 7, 2023: The water quality storage unit was inspected with a QuickView Camera to confirm the pipe contains very little sediment through its entire length. The surface detention basin was inspected on 3/8/2023 during a light rain event, confirming that stormwater drains through the system effectively. June 7, 2023: No changes noted. Sediment collected along the curb line should be swept up and removed. It also shows scouring indicative of water draining out through the gap between the asphalt and the curb line. This needs to be sealed to prevent sinkhole development and to keep the stormwater going into the BMPs according to the design. September 20, 2023: No changes noted. December 6, 2023: No changes noted. BAYER – AA Building Parking Stormwater BMP Photos December 6, 2023 1. SEAL CURB LINE ALONG SOUTHWEST EDGE OF PARKING LOT 2. HDS UNIT IS AT 2.08% OF CAPACITY (GIS- BMP-4724) 3. MINIMAL SEDIMENT IN 48” RCP WATER QUALITY STORAGE (GIS-BMP-7329) 4. VIEW OF STORMFILTER VAULT IN MH 4-A (GIS-BMP-5397) 5. MINIMAL SEDIMENT ON VAULT FLOOR 6. FILTER MEDIA IS DISCOLORED BY SEDIMENT BUT REMAINS POROUS 7. VIEW OF SOUTH SURFACE DETENTION BASIN (GIS-BMP-2886) 8. FLAP VALVE HAS ROOM TO OPEN AND CLOSE 9. MONITOR FURTHER EROSION AT WEST EDGE OF ROCK BLANKET 10. PERFORATED STANDPIPE IS CLEAR OF BLOCKAGES AND DEBRIS (GIS-BMP-2886) 11. OVERFLOW STRUCTURE A-5 SHOWS SYSTEM DISCHARGE IS CLEAR 12. REMOVE HEAVY SEDIMENT AT THE SOUTHWEST EDGE OF THE PARKING LOT