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