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HomeMy WebLinkAboutStormwater Management Plan 355 Research Parkway ▪ Meriden, CT 06450 ▪ T (203) 630-1406 ▪ F (203) 630-2615 ▪ www.blcompanies.com Stormwater Management Report For the: Proposed Retail Development Located at: 1967-1981 Norwich-New London Turnpike Town of Montville, Connecticut Prepared for Submission to: Town of Montville, Connecticut October 29, 2021 Prepared for: Garrett Homes, LLC 59 Field Street Torrington, Connecticut Prepared by: BL Companies 100 Constitution Plaza, 10th Floor Hartford, Connecticut 06103 Phone: (860) 249-2200 Fax: (860) 249-2400 BL Project Number: 2101750 355 Research Parkway ▪ Meriden, CT 06450 ▪ T (203) 630-1406 ▪ F (203) 630-2615 ▪ www.blcompanies.com 1 An Employee-Owned Company Contents Executive Summary ........................................................................................................ 1 Property Description ........................................................................................................ 2 Location ....................................................................................................................... 2 FEMA Flood Insurance Rate Map ................................................................................ 2 Hydrology Modeling and Methodology ............................................................................ 2 Hydrologic Modeling .................................................................................................... 2 Hydrologic Assumptions .............................................................................................. 3 Stormwater Analysis Summary .................................................................................... 3 Applicable Local and State Regulations ....................................................................... 4 Existing Site and Hydrology Conditions ........................................................................... 5 Existing Site Hydrology ................................................................................................ 5 Soil Description ............................................................................................................ 5 Existing Topography and Site Features ....................................................................... 5 Existing Drainage Areas .............................................................................................. 6 Existing Conditions Hydrologic Analysis Results ......................................................... 6 Proposed Site and Hydrology Conditions ........................................................................ 7 Proposed Site Hydrology ............................................................................................. 7 Proposed Topography and Site Features .................................................................... 8 Proposed Drainage Areas ............................................................................................ 8 Post-Development Hydrologic Analysis Results .......................................................... 9 Description of Proposed Stormwater Management System .......................................... 12 Proposed Permanent BMP’s and Water Quality ........................................................... 12 Summary ....................................................................................................................... 13 355 Research Parkway ▪ Meriden, CT 06450 ▪ T (203) 630-1406 ▪ F (203) 630-2615 ▪ www.blcompanies.com 1 An Employee-Owned Company Appendix A: Location Maps Figure 1: USGS Location Map Figure 2: Aerial Location Map Figure 3: FEMA Federal Insurance Rate Map Figure 4: NOAA Atlas 14 Storm Data (Depth, Inches) Appendix B: Existing Conditions Hydrology (2-, 10-, 25-, 100-year storms) Appendix C: Proposed Conditions Hydrology (2-, 10-, 25-, 100-year storms) Appendix D: Water Quality Calculations Appendix E: Drainage Maps ED-1 – Existing Drainage Map PD-1 – Proposed Drainage Map Appendix F: Soil Report Custom Soil Resource Report for State of Connecticut Appendix G: Stormwater System Operations and Maintenance Plan 355 Research Parkway ▪ Meriden, CT 06450 ▪ T (203) 630-1406 ▪ F (203) 630-2615 ▪ www.blcompanies.com An Employee-Owned Company Executive Summary This report shall support the Site Plan Application submitted to the Town of Montville by Garrett Homes, LLC for a proposed retail facility located on Norwich-New London Turnpike. The total area of the lot is approximately 80,244 SF or 1.84 Acres. The existing condition of the lot includes paved access drives, two residential properties with building numbers of 1967 and 1981, lawn areas, and woods. The subject parcel described above is bounded to the north by CVS Pharmacy, to the east by woods, to the south by McDonald’s, and to the west by Norwich-New London Turnpike (Route 32). The existing site does not provide water quality pretreatment nor detention prior to discharging to the woods northeast of the site. The proposed development includes the construction of a +/- 10,700 SF retail building. The development will include parking, landscaping, and additional site and utility improvements typical of commercial development. A series of catch basins and pipes collect and route the site’s runoff to each respective design point, matching or reducing hydrologic conditions to pre-development rates through a combined infiltration and detention system. The required water quality treatment for the site will be provided in an isolator row within the underground detention system prior to infiltration and discharge. The isolator row is further supplemented with other best management practices such as street sweeping and deep sump, hooded catch basins. A HydroCAD model, using TR-55 and SCS methodology, was developed to evaluate the existing and proposed drainage conditions for the property. The results of the analysis demonstrate a no net increase in the overall stormwater peak flow rates for the 2-, 10-, 25-, and 100-year storm events to the wooded area northeast of the site. The analysis as presented within this report complies with the Town of Montville Zoning Regulations, the 2002 Connecticut Guidelines for Soil Erosion, and the 2004 Connecticut Stormwater Quality Manual, latest editions. 355 Research Parkway ▪ Meriden, CT 06450 ▪ T (203) 630-1406 ▪ F (203) 630-2615 ▪ www.blcompanies.com An Employee-Owned Company Property Description Location The parcel included within this analysis is located on Norwich-New London Turnpike and includes a bounded area of approximately 80,244 SF or 1.84 Acres. The parcel is currently located within the Commercial District (C-1) with adjacent property’s being of the like. The existing conditions of the lot includes two residential properties with paved access, some grass, and some woods. The existing site does not provide water quality pretreatment nor detention prior to discharging towards the woods northeast of the site. The parcel described above is bounded to the north by CVS Pharmacy, to the east by woods, to the south by McDonald’s, and to the west by Norwich-New London Turnpike (Route 32). A copy of the project location map can be found within Appendix A of this report. FEMA Flood Insurance Rate Map Per the FEMA Flood Insurance Rate Map Number 09011C0351G for New London County, Connecticut effective July 18, 2011, the parcel resides entirely within Zone X, an area determined to be outside the 0.2% annual chance floodplain. A copy of the FEMA Flood Insurance Rate Map is included in Appendix A for reference. Hydrology Modeling and Methodology Hydrologic Modeling The SCS Runoff Curve Number and TR-55 Methods were utilized to determine the peak runoff for each drainage area impacted by the proposed development. All supporting calculations have been completed using the stormwater computer modeling program known as HydroCAD, version 10.00, developed by HydroCAD Software Solutions, LLC. Hydrographs for each area were developed using the SCS Synthetic Unit Hydrograph Method and rainfall depths per the NOAA Atlas 14 for Montville, CT and as shown in Table 1. The drainage areas, or sub-catchments as labeled by the program, are depicted by hexagons on the attached drainage diagrams in Appendices B and C. Reaches as identified by a rectangle shape within the program are included to clearly define the runoff 355 Research Parkway ▪ Meriden, CT 06450 ▪ T (203) 630-1406 ▪ F (203) 630-2615 ▪ www.blcompanies.com An Employee-Owned Company flow pattern logic to each design point. Existing Conditions HydroCAD results can be found in Appendix B and Proposed Conditions HydroCAD results can be found in Appendix C. Table 1 – 24-HR Rainfall Depths per NOAA Atlas 14 (Montville, CT) Return Period 24-hour Rainfall Depth 2-year 3.46 10-year 5.11 25-year 6.15 100-year 7.74 Hydrologic Assumptions For the purposes of this report and analysis, the following assumptions have been established: • The minimum time of concentration shall be 5.0 minutes for all impervious surfaces to comply with the Department of Transportation’s requirements. • The flow path used to calculate the time of concentration terminate at the design points. • The results noted at each design point are limited to the runoff generated by the development. • All tributary drainage areas upstream and outside of the site’s hydrology analysis of which are not affected by the proposed development have not been included in this analysis and report. • The results of this analysis do not imply or conclude the adequacy of the existing public storm sewer system and capacity. All pre-development conditions shall be maintained at each ultimate design point as noted at DP-1 and DP-2. Stormwater Analysis Summary A hydrologic analysis was performed to quantify the existing and proposed conditions of the site for the 2-, 10-, 25, and 100-year rainfall events. The methodology used is consistent with the SCS method, the TR-55 method, and general engineering principals typical of land development projects of this size. Due to the existing and proposed topography of the site, two (2) design points were selected for the purposes of this analysis and are noted as DP-1 and DP-2. 355 Research Parkway ▪ Meriden, CT 06450 ▪ T (203) 630-1406 ▪ F (203) 630-2615 ▪ www.blcompanies.com An Employee-Owned Company DP-1 is located along the northeastern corner of the site and estimates the combined runoff rates for the site’s overland flow to the northeast. DP-2 is located along the western property line at the Norwich-New London Turnpike right-of-way. This design point estimates the site’s overland flow prior to discharging into the public storm sewer system within Norwich-New London Turnpike. All pre-development runoff rates and drainage patterns shall be maintained to the greatest extent feasible. A copy of the drainage maps showing the design point is included within Appendix E of this report. Additional sections of this report describe and summarize the calculations supporting the design points noted above. Applicable Local and State Regulations The existing and proposed analyses presented within this report adhere to the following regulations: • 2004 Connecticut Stormwater Quality Manual • 2002 Connecticut Guidelines for Soil Erosion and Sediment Control • Town of Montville Zoning Regulations • CT DEEP General Stormwater Discharge Permit for Construction Activities 355 Research Parkway ▪ Meriden, CT 06450 ▪ T (203) 630-1406 ▪ F (203) 630-2615 ▪ www.blcompanies.com An Employee-Owned Company Existing Site and Hydrology Conditions Existing Site Hydrology The total existing drainage areas included within this analysis is approximately 1.273 acres with 21.4% being impervious. The site’s runoff consists of one drainage area. This drainage area includes the entire work area of the parcel extending to McDonald’s driveway and retaining wall to the south, Norwich-New London Turnpike to the west, a natural high point within the wooded area to the east, and to the southern property line. All runoff from the drainage area is released offsite untreated. The existing land coverages and soils assumed and supported by the Web Soil Survey are consistent with a rural area. They include the following: • Grass – >75% Grass cover, Good, HSG B • Woods – Good, HSG B • Gravel – Gravel Surface, HSG B • Pavement - Paved parking, HSG B • Roof, HSG B Soil Description The soils included within this stormwater analysis were identified using available online resources created by the United States Department of Agriculture (USDA) Natural Resource Conservation Services (NRCS). They are as follows: • Sutton fine sandy loam, 0-8% slopes, very stony – Type B soil • Udorthents-Urban land complex – Type B soil A copy of the USDA NRCS Hydrologic Soil Group map is located within Appendix F of this report. Existing Topography and Site Features The existing topography of the property varies from elevation 219 to 192, and generally slopes southwest to northeast. The existing site features are typical of residential properties consisting of single-family dwellings with paved driveways, grass, and some woods. 355 Research Parkway ▪ Meriden, CT 06450 ▪ T (203) 630-1406 ▪ F (203) 630-2615 ▪ www.blcompanies.com An Employee-Owned Company Existing Drainage Areas The existing drainage area as shown on the enclosed map titled Existing Drainage Map (ED-1) within Appendix E are as follows: Existing Drainage Area 100 (EDA-100): EDA-100 consists of the entire work area on the subject parcel. The drainage area EDA-100 consists of approximately 69,277 square feet and is approximately 21.4% impervious. This area is comprised of single-family dwellings with paved driveways, grass, and some woods. Runoff from this area is conveyed via sheet flow to the northeast prior to discharge to DP-1. Existing Conditions Hydrologic Analysis Results The results of the existing conditions hydrologic analysis are as follows and summarized in Table 2 and Table 3 below Table 2 –Existing Conditions Drainage Characteristics Drainage Area Total Area Composite Curve Number Imperviousness Cover Time of Concentration SF % Minutes EDA-100 69,277 68 21.4% 6.40 Table 3 – Existing Conditions Peak Flows Analysis Point Description Peak Flows (CFS) 2-YR 10-YR 25-YR 100- YR DP-1 Offsite Flow to North 1.50 3.75 5.35 7.97 355 Research Parkway ▪ Meriden, CT 06450 ▪ T (203) 630-1406 ▪ F (203) 630-2615 ▪ www.blcompanies.com An Employee-Owned Company Proposed Site and Hydrology Conditions Proposed Site Hydrology The proposed drainage area included within this analysis generally follows the same assumptions as described above. The total area analyzed is 71,003 square feet and is approximately 55.21% impervious. The proposed development includes an increase in impervious area of 24,411 SF. To mitigate the increase in runoff typical of new development, the following have been proposed for the subject property: • Addition of a swale along the east side of the development to collect discharge from the McDonald’s stormwater management system and convey it around the development to the low point at the northeast corner of the property. • Addition of an underground infiltration and detention facility to infiltrate stormwater and mitigate the increase in peak runoff rates. Infiltration and retention of the site’s water quality volume is provided within the underground infiltration and detention facility below the outlet elevation of the system. • Addition of primary water quality treatment in an isolator row within the underground infiltration and detention facility prior to infiltration. • Addition of secondary water quality treatment such as deep-sump, hooded catch basins, street sweeping, and a formalized O&M Plan. • Maintaining existing drainage patterns and design points where feasible to ensure that pre-development flow rates are maintained. • Maintain existing slopes and drainage patterns along property lines to maintain or increase overall flow travel times to discharge location. The proposed land coverages and soils assumed within previous sections of this report and supported by the Web Soil Survey have been maintained. They are as follows: • Grass – >75% Grass cover, Good, HSG • Woods – Good, HSG B • Gravel – Gravel Surface, HSG B • Pavement - Paved parking, HSG B • Roof, HSG B The proposed hydrologic analysis for this project maintains the methodologies, design points, and supporting assumptions described above. The intent of the proposed 355 Research Parkway ▪ Meriden, CT 06450 ▪ T (203) 630-1406 ▪ F (203) 630-2615 ▪ www.blcompanies.com An Employee-Owned Company stormwater design is to mimic the existing drainage patterns and runoff flowrates to the greatest extend practical while improving the stormwater quality for the site. Proposed Topography and Site Features The proposed topography of the site varies from elevation 219 to 192 and will generally follow the existing drainage patterns to the greatest extent feasible. A series of proposed catch basins and pipes will collect and route the site’s runoff to the respective design points. Primary water quality treatment will be provided in an isolator row within the underground infiltration and detention facility prior to infiltration. The results of the proposed analysis demonstrate a no net increase in the overall stormwater peak flow rates for the 2-, 10-, 25-, and 100-year storm events at the design point, DP-1. Design point DP-2 experiences a negligible increase in peak flow rates for all storms due to the addition of a street sidewalk. Proposed Drainage Areas The proposed drainage areas as shown on the enclosed map titled Proposed Drainage Map (PD-1) within Appendix E are as follows: Proposed Drainage Area 100 (PDA-100): PDA-100 consists of primarily of the grassed areas around the north, south, and east of the site that drain directly to DP-1. The drainage area PDA-100 consists of approximately 27,142 square feet and is approximately 9.2% impervious. This area is almost entirely comprised of grass, with minimal woods and sidewalk. Runoff from this area is conveyed via sheet flow into a swale prior to discharge to DP-1. Proposed Drainage Area 200 (PDA-200): PDA-200 includes the street sidewalk and is located along the western side of the site. It consists of approximately 2,191 SF and is 66.8% impervious. Land coverings associated with this area include paving and grass. Runoff from this drainage area sheet flows from the south to the northwest until reaching the street gutter line. Runoff from PDA-200 discharges to the municipal drainage system within the Norwich-New London Turnpike right-of-way. Proposed Drainage Area 310 (PDA-310): PDA-310 includes the paved parking and loading areas north of the building. It consists of approximately 9,649 SF and is 100% impervious. Land coverings associated with this area include the paved parking and loading areas as well as concrete sidewalk. Runoff generally flows north into a catch basin, into the isolator row for treatment, into the subsurface infiltration system, and 355 Research Parkway ▪ Meriden, CT 06450 ▪ T (203) 630-1406 ▪ F (203) 630-2615 ▪ www.blcompanies.com An Employee-Owned Company discharge to the grassed area east of the dumpster enclosure where stormwater will flow over land to DP-1. Proposed Drainage Area 320 (PDA-320): Located within the center of the site, drainage area PDA-320 consists of approximately 10,650 SF and is 100% impervious. Land coverings associated with this area include building roof. Runoff from the roof will be collected in gutters and downspouts, be piped into the subsurface infiltration system, and discharge to the grassed area east of the dumpster enclosure where stormwater will flow over land to DP-1. Proposed Drainage Area 330 (PDA-330): Located at the northwest side of the site, area PDA-330 consists of approximately 11,508 SF and is 74.1% impervious. Land coverings associated with this area include grass and paving. Runoff generally flows east into a catch basin, into the isolator row for treatment, into the subsurface infiltration system, and discharge to the grassed area east of the dumpster enclosure where stormwater will flow over land to DP-1. Proposed Drainage Area 340 (PDA-340): Located south of PDA-330, PDA-340 consists of approximately 9,863 SF and is 65.2% impervious. Land coverings associated with this area include grass and paving. Runoff generally flows east into a catch basin, into the isolator row for treatment, into the subsurface infiltration system, and discharge to the grassed area east of the dumpster enclosure where stormwater will flow over land to DP- 1. Post-Development Hydrologic Analysis Results The results of the post-development hydrologic analysis are as follows and summarized in Table 4 and Table 5 below: 355 Research Parkway ▪ Meriden, CT 06450 ▪ T (203) 630-1406 ▪ F (203) 630-2615 ▪ www.blcompanies.com An Employee-Owned Company Table 4 – Post Development Drainage Characteristics Drainage Area Total Area Composite Curve Number Imperviousness Cover Time of Concentration SF % Minutes PDA-100 27,142 64 9.2% 7.6 PDA-200 2,191 86 66.8% 6.6 PDA-310 9,649 98 100.0% 1.3 PDA-320 10,650 98 100.0% 1.0 PDA-330 11,508 88 74.1% 6.9 PDA-340 9,863 85 65.2% 5.4 Table 5 – Post-Development Conditions Peak Flows Analysis Point Description Peak Flows (CFS) 2-YR 10-YR 25-YR 100-YR DP-1 Offsite Flow to North 1.44 3.00 3.91 5.45 DP-2 Offsite Flow to Street 0.13 0.22 0.28 0.37 The results of the pre-development vs post-development hydrology analysis are presented below. The results of the analysis demonstrate a no net increase in the overall stormwater peak flow rates for the 2-, 10-, 25-, and 100-year storm events at the design point, DP-1. Design point DP-2 does result in a net increase because of adding the street sidewalk; however, the resulting flow rates are negligible. Although design point DP-2 does result in a light increase in peak flow rates, the total site runoff represents a net decrease for all design storm events. As a result, the proposed development will not adversely affect downstream infrastructure and properties located within the regional watershed. 355 Research Parkway ▪ Meriden, CT 06450 ▪ T (203) 630-1406 ▪ F (203) 630-2615 ▪ www.blcompanies.com An Employee-Owned Company Peak Flow (cfs) Design Storms Analysis Point 2-YR 10-YR 25-YR 100-YR DP-1 Existing 1.50 3.75 5.35 7.97 Proposed 1.44 3.00 3.91 5.45 Percent Change -4.00% -20.00% -26.92% -31.62% DP-2 Existing 0.00 0.00 0.00 0.00 Proposed 0.13 0.22 0.28 0.37 Percent Change 100.00% 100.00% 100.00% 100.00% 355 Research Parkway ▪ Meriden, CT 06450 ▪ T (203) 630-1406 ▪ F (203) 630-2615 ▪ www.blcompanies.com An Employee-Owned Company Description of Proposed Stormwater Management System The proposed stormwater management system will function to capture, route, treat, detain, and discharge the onsite runoff to the wooded area northeast of the site without adversely impacting the downstream conditions, to the greatest extent feasible. Offsite runoff will be routed around the proposed development to maintain existing drainage pathways. As noted within previous sections of this report, the existing conditions flow rate and drainage patterns shall be maintained at design point DP-1 within the proposed conditions. This will be accomplished by the following: 1. Balancing the site’s hydrologic drainage areas to match the existing conditions at the northeast corner of the property. 2. Installation of an underground infiltration and detention system to partially infiltrate and detain the required runoff to match the site’s existing conditions. 3. Implementing the use of an isolator row within the underground infiltration and detention system to treat the site’s runoff prior to being discharged. Proposed Permanent BMP’s and Water Quality The required water quality treatment for this site will be provided in an isolator row within the underground infiltration and detention system. The isolator row will provide the required treatment of the 1” storm for the entire site. To extend the life of the isolator row, secondary water quality treatment will be provided via street sweeping and deep sump, hooded catch basins. The proposed BMP’s will result in a TSS removal of 80 % or greater. Additional BMPs such as a formalized street sweeping program and the use of deep sump and hooded catch basins are included within the site’s stormwater management system and Stormwater Operation and Maintenance Plan. A copy of the site’s O&M Plan can be found in Appendix G of this report. A copy of this Plan shall be provided to the tenant after the completion of the project. Overall, the existing parcel’s water quality will be improved as neither detention nor water quality treatment measures exist today. The proposed development will thus bring each lot into conformance with today’s stormwater and water quality standards. 355 Research Parkway ▪ Meriden, CT 06450 ▪ T (203) 630-1406 ▪ F (203) 630-2615 ▪ www.blcompanies.com An Employee-Owned Company Summary The stormwater analysis presented within this report complies with the Town of Montville Zoning Regulations, the 2002 Connecticut Guidelines for Soil Erosion, and the 2004 Connecticut Stormwater Quality Manual, latest editions. The proposed stormwater management system has been designed to maintain the pre- development conditions at design point DP-1 for the 2-, 10-, 25-, and 100-year storm event while maintaining existing drainage patterns to the greatest extent feasible. All water quality treatment will be provided through an isolator row within the underground infiltration and detention system and further be supplemented by BMP’s such as street sweeping and deep sump and hooded catch basins. The proposed development and stormwater improvements described within this report generate an overall reduction in peak flowrates for the 2-, 10-, 25-, and 100-year rainfall events for the site, meeting the Town of Montville requirements. Thus, the proposed development will not adversely impact the downstream stormwater conditions due to the proposed activity and improvements included within this report. 355 Research Parkway ▪ Meriden, CT 06450 ▪ T (203) 630-1406 ▪ F (203) 630-2615 ▪ www.blcompanies.com An Employee-Owned Company APPENDIX A Location Maps Figure 1: USGS Location Map Figure 2: Aerial Location Map Figure 3: FEMA National Flood Hazard Layer FIRMette Figure 4: NOAA Atlas 14 Storm Data (Depth, Inches) LAND SURVEYING ENVIRONMENTAL ENGINEERING ARCHITECTURE LAND SURVEYING ENVIRONMENTAL ENGINEERING ARCHITECTURE NOAA Atlas 14, Volume 10, Version 3 Location name: Uncasville, Connecticut, USA* Latitude: 41.4784°, Longitude: -72.0991° Elevation: 216.09 ft** * source: ESRI Maps ** source: USGS POINT PRECIPITATION FREQUENCY ESTIMATES Sanja Perica, Sandra Pavlovic, Michael St. Laurent, Carl Trypaluk, Dale Unruh, Orlan Wilhite NOAA, National Weather Service, Silver Spring, Maryland PF_tabular | PF_graphical | Maps_&_aerials PF tabular PDS-based point precipitation frequency estimates with 90% confidence intervals (in inches)1 Duration Average recurrence interval (years) 1 2 5 10 25 50 100 200 500 1000 5-min 0.341 (0.267‑0.428) 0.407 (0.318‑0.511) 0.515 (0.401‑0.648) 0.605 (0.469‑0.764) 0.728 (0.546‑0.952) 0.821 (0.602‑1.09) 0.918 (0.654‑1.26) 1.03 (0.694‑1.43) 1.18 (0.769‑1.69) 1.31 (0.831‑1.90) 10-min 0.483 (0.378‑0.606) 0.577 (0.451‑0.724) 0.730 (0.569‑0.919) 0.857 (0.664‑1.08) 1.03 (0.773‑1.35) 1.16 (0.854‑1.55) 1.30 (0.927‑1.78) 1.46 (0.982‑2.02) 1.68 (1.09‑2.39) 1.86 (1.18‑2.70) 15-min 0.569 (0.445‑0.713) 0.679 (0.531‑0.852) 0.859 (0.669‑1.08) 1.01 (0.781‑1.27) 1.21 (0.910‑1.59) 1.37 (1.00‑1.82) 1.53 (1.09‑2.10) 1.71 (1.16‑2.38) 1.97 (1.28‑2.82) 2.19 (1.39‑3.17) 30-min 0.802 (0.627‑1.00) 0.956 (0.748‑1.20) 1.21 (0.942‑1.52) 1.42 (1.10‑1.79) 1.71 (1.28‑2.23) 1.93 (1.41‑2.56) 2.15 (1.54‑2.95) 2.41 (1.63‑3.35) 2.78 (1.80‑3.96) 3.08 (1.95‑4.46) 60-min 1.03 (0.810‑1.30) 1.23 (0.965‑1.55) 1.56 (1.22‑1.96) 1.83 (1.42‑2.31) 2.20 (1.65‑2.88) 2.48 (1.82‑3.30) 2.78 (1.98‑3.80) 3.11 (2.10‑4.31) 3.58 (2.32‑5.11) 3.97 (2.51‑5.75) 2-hr 1.36 (1.07‑1.69) 1.62 (1.27‑2.02) 2.04 (1.60‑2.55) 2.39 (1.87‑3.00) 2.88 (2.17‑3.74) 3.24 (2.40‑4.28) 3.63 (2.60‑4.93) 4.06 (2.75‑5.60) 4.70 (3.06‑6.65) 5.23 (3.32‑7.51) 3-hr 1.58 (1.25‑1.96) 1.88 (1.48‑2.33) 2.36 (1.86‑2.94) 2.77 (2.17‑3.46) 3.33 (2.52‑4.31) 3.75 (2.78‑4.93) 4.19 (3.02‑5.68) 4.70 (3.19‑6.44) 5.44 (3.55‑7.66) 6.06 (3.86‑8.66) 6-hr 2.00 (1.60‑2.47) 2.38 (1.89‑2.93) 2.99 (2.37‑3.69) 3.49 (2.75‑4.33) 4.19 (3.20‑5.38) 4.71 (3.52‑6.15) 5.26 (3.82‑7.08) 5.90 (4.03‑8.03) 6.83 (4.48‑9.54) 7.61 (4.87‑10.8) 12-hr 2.48 (1.99‑3.03) 2.93 (2.35‑3.59) 3.68 (2.94‑4.51) 4.30 (3.42‑5.29) 5.15 (3.96‑6.56) 5.79 (4.35‑7.50) 6.46 (4.71‑8.63) 7.24 (4.97‑9.78) 8.38 (5.52‑11.6) 9.32 (5.99‑13.1) 24-hr 2.91 (2.35‑3.53) 3.46 (2.80‑4.20) 4.36 (3.51‑5.31) 5.11 (4.09‑6.25) 6.15 (4.75‑7.78) 6.92 (5.24‑8.91) 7.74 (5.68‑10.3) 8.70 (6.00‑11.6) 10.1 (6.69‑13.9) 11.3 (7.28‑15.8) 2-day 3.26 (2.66‑3.93) 3.92 (3.19‑4.73) 5.00 (4.06‑6.04) 5.90 (4.75‑7.16) 7.13 (5.56‑8.97) 8.05 (6.14‑10.3) 9.03 (6.69‑11.9) 10.2 (7.07‑13.6) 12.0 (7.95‑16.3) 13.5 (8.73‑18.6) 3-day 3.54 (2.90‑4.25) 4.26 (3.48‑5.11) 5.43 (4.42‑6.54) 6.40 (5.18‑7.74) 7.74 (6.06‑9.70) 8.73 (6.69‑11.1) 9.80 (7.29‑12.9) 11.1 (7.70‑14.7) 13.0 (8.66‑17.7) 14.7 (9.51‑20.2) 4-day 3.81 (3.13‑4.55) 4.56 (3.74‑5.46) 5.79 (4.73‑6.95) 6.82 (5.54‑8.21) 8.23 (6.45‑10.3) 9.27 (7.12‑11.8) 10.4 (7.75‑13.6) 11.7 (8.18‑15.5) 13.8 (9.19‑18.6) 15.5 (10.1‑21.3) 7-day 4.55 (3.76‑5.40) 5.37 (4.43‑6.40) 6.73 (5.53‑8.03) 7.86 (6.42‑9.41) 9.40 (7.41‑11.7) 10.6 (8.14‑13.3) 11.8 (8.81‑15.3) 13.2 (9.26‑17.3) 15.4 (10.3‑20.7) 17.2 (11.2‑23.5) 10-day 5.27 (4.37‑6.25) 6.14 (5.09‑7.28) 7.56 (6.24‑8.99) 8.74 (7.17‑10.4) 10.4 (8.20‑12.8) 11.6 (8.95‑14.5) 12.9 (9.62‑16.6) 14.4 (10.1‑18.7) 16.5 (11.1‑22.1) 18.3 (12.0‑24.8) 20-day 7.50 (6.27‑8.82) 8.43 (7.03‑9.91) 9.94 (8.26‑11.7) 11.2 (9.25‑13.3) 12.9 (10.3‑15.7) 14.2 (11.0‑17.6) 15.6 (11.6‑19.7) 17.0 (12.0‑21.9) 18.9 (12.8‑25.0) 20.4 (13.4‑27.4) 30-day 9.35 (7.85‑10.9) 10.3 (8.65‑12.1) 11.9 (9.92‑13.9) 13.2 (10.9‑15.5) 15.0 (11.9‑18.1) 16.4 (12.7‑20.0) 17.7 (13.2‑22.1) 19.0 (13.5‑24.4) 20.7 (14.1‑27.3) 21.9 (14.4‑29.4) 45-day 11.6 (9.81‑13.6) 12.6 (10.6‑14.7) 14.3 (12.0‑16.7) 15.6 (13.0‑18.3) 17.5 (14.0‑21.0) 19.0 (14.8‑23.0) 20.4 (15.2‑25.2) 21.6 (15.4‑27.6) 23.1 (15.8‑30.3) 24.1 (15.9‑32.1) 60-day 13.5 (11.4‑15.7) 14.6 (12.3‑16.9) 16.3 (13.7‑19.0) 17.7 (14.8‑20.7) 19.7 (15.8‑23.5) 21.3 (16.6‑25.6) 22.7 (16.9‑27.9) 23.9 (17.1‑30.4) 25.3 (17.3‑33.0) 26.2 (17.4‑34.7) 1 Precipitation frequency (PF) estimates in this table are based on frequency analysis of partial duration series (PDS). Numbers in parenthesis are PF estimates at lower and upper bounds of the 90% confidence interval. The probability that precipitation frequency estimates (for a given duration and average recurrence interval) will be greater than the upper bound (or less than the lower bound) is 5%. Estimates at upperbounds are not checked against probable maximum precipitation (PMP) estimates and may be higher than currently valid PMP values. Please refer to NOAA Atlas 14 document for more information. Back to Top PF graphical Back to Top Maps & aerials Small scale terrain Large scale terrain Large scale map Large scale aerial + – 3km 2mi + – 100km 60mi + – 100km 60mi Back to Top US Department of Commerce National Oceanic and Atmospheric Administration National Weather Service National Water Center 1325 East West Highway Silver Spring, MD 20910 Questions?: HDSC.Questions@noaa.gov Disclaimer + – 100km 60mi 355 Research Parkway ▪ Meriden, CT 06450 ▪ T (203) 630-1406 ▪ F (203) 630-2615 ▪ www.blcompanies.com An Employee-Owned Company APPENDIX B Existing Conditions Hydrology (2-, 10-, 25-, and 100-year storms) EDA-100 Existing Site DP-1 Offsite Flow to North ˘ˇˆ˙ˇ˝˛˚˜˚˛ Prepared by BL Companies, Printed 10/27/2021 HydroCAD® 10.00-26 s/n 01334 © 2020 HydroCAD Software Solutions LLC Subcat Reach Pond Link CT-Montville 24-hr S1 2-yr Rainfall=3.46"˘ˇˆ˙ˇ˝˛˚˜˚˛ Printed 10/27/2021Prepared by BL Companies Page 2HydroCAD® 10.00-26 s/n 01334 © 2020 HydroCAD Software Solutions LLC Time span=0.00-48.00 hrs, dt=0.05 hrs, 961 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=69,277 sf 19.93% Impervious Runoff Depth=0.88"ˆ !!"#$%&'ˆ# Flow Length=368' Tc=6.4 min CN=68 Runoff=1.50 cfs 0.116 af Inflow=1.50 cfs 0.116 af#!"(%˚'#)*+˝" Outflow=1.50 cfs 0.116 af ˙*$#,-.!/*#,-0$1###2",-334 3-5(#1',-6!.-.65ˇ2#1',-6! CT-Montville 24-hr S1 2-yr Rainfall=3.46"˘ˇˆ˙ˇ˝˛˚˜˚˛ Printed 10/27/2021Prepared by BL Companies Page 3HydroCAD® 10.00-26 s/n 01334 © 2020 HydroCAD Software Solutions LLC ˆ7ˆ !!"#$%&'ˆ# Runoff = 1.50 cfs @ 12.06 hrs, Volume= 0.116 af, Depth= 0.88" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs CT-Montville 24-hr S1 2-yr Rainfall=3.46" Area (sf) CN Description 9,442 55 Woods, Good, HSG B 45,043 61 >75% Grass cover, Good, HSG B 9,880 98 Paved parking, HSG B 985 96 Gravel surface, HSG B 3,927 98 Roofs, HSG B 69,277 68 Weighted Average 55,470 80.07% Pervious Area 13,807 19.93% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 0.3 25 0.0400 1.43 ˆ"##)*+8 Smooth surfaces n= 0.011 P2= 3.46" 3.8 75 0.1067 0.33 ˆ"##)*+8 Grass: Short n= 0.150 P2= 3.46" 0.4 53 0.1226 2.45 ˆ"**+!##9)*+8 Short Grass Pasture Kv= 7.0 fps 0.2 60 0.0500 4.54 ˆ"**+!##9)*+8 Paved Kv= 20.3 fps 1.4 138 0.0543 1.63 ˆ"**+!##9)*+8 Short Grass Pasture Kv= 7.0 fps 0.3 17 0.0294 0.86 ˆ"**+!##9)*+8 Woodland Kv= 5.0 fps 6.4 368 Total ˆ7#!"(%˚'#)*+˝" Inflow Area = 1.590 ac, 19.93% Impervious, Inflow Depth = 0.88" for 2-yr event Inflow = 1.50 cfs @ 12.06 hrs, Volume= 0.116 af Outflow = 1.50 cfs @ 12.06 hrs, Volume= 0.116 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs CT-Montville 24-hr S1 10-yr Rainfall=5.11"˘ˇˆ˙ˇ˝˛˚˜˚˛ Printed 10/27/2021Prepared by BL Companies Page 4HydroCAD® 10.00-26 s/n 01334 © 2020 HydroCAD Software Solutions LLC Time span=0.00-48.00 hrs, dt=0.05 hrs, 961 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=69,277 sf 19.93% Impervious Runoff Depth=1.96"ˆ !!"#$%&'ˆ# Flow Length=368' Tc=6.4 min CN=68 Runoff=3.75 cfs 0.260 af Inflow=3.75 cfs 0.260 af#!"(%˚'#)*+˝" Outflow=3.75 cfs 0.260 af ˙*$#,-.!/*#,-0$1###2",-.04 3-5(#1',-6!.-.65ˇ2#1',-6! CT-Montville 24-hr S1 10-yr Rainfall=5.11"˘ˇˆ˙ˇ˝˛˚˜˚˛ Printed 10/27/2021Prepared by BL Companies Page 5HydroCAD® 10.00-26 s/n 01334 © 2020 HydroCAD Software Solutions LLC ˆ7ˆ !!"#$%&'ˆ# Runoff = 3.75 cfs @ 12.05 hrs, Volume= 0.260 af, Depth= 1.96" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs CT-Montville 24-hr S1 10-yr Rainfall=5.11" Area (sf) CN Description 9,442 55 Woods, Good, HSG B 45,043 61 >75% Grass cover, Good, HSG B 9,880 98 Paved parking, HSG B 985 96 Gravel surface, HSG B 3,927 98 Roofs, HSG B 69,277 68 Weighted Average 55,470 80.07% Pervious Area 13,807 19.93% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 0.3 25 0.0400 1.43 ˆ"##)*+8 Smooth surfaces n= 0.011 P2= 3.46" 3.8 75 0.1067 0.33 ˆ"##)*+8 Grass: Short n= 0.150 P2= 3.46" 0.4 53 0.1226 2.45 ˆ"**+!##9)*+8 Short Grass Pasture Kv= 7.0 fps 0.2 60 0.0500 4.54 ˆ"**+!##9)*+8 Paved Kv= 20.3 fps 1.4 138 0.0543 1.63 ˆ"**+!##9)*+8 Short Grass Pasture Kv= 7.0 fps 0.3 17 0.0294 0.86 ˆ"**+!##9)*+8 Woodland Kv= 5.0 fps 6.4 368 Total ˆ7#!"(%˚'#)*+˝" Inflow Area = 1.590 ac, 19.93% Impervious, Inflow Depth = 1.96" for 10-yr event Inflow = 3.75 cfs @ 12.05 hrs, Volume= 0.260 af Outflow = 3.75 cfs @ 12.05 hrs, Volume= 0.260 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs CT-Montville 24-hr S1 25-yr Rainfall=6.15"˘ˇˆ˙ˇ˝˛˚˜˚˛ Printed 10/27/2021Prepared by BL Companies Page 6HydroCAD® 10.00-26 s/n 01334 © 2020 HydroCAD Software Solutions LLC Time span=0.00-48.00 hrs, dt=0.05 hrs, 961 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=69,277 sf 19.93% Impervious Runoff Depth=2.74"ˆ !!"#$%&'ˆ# Flow Length=368' Tc=6.4 min CN=68 Runoff=5.35 cfs 0.363 af Inflow=5.35 cfs 0.363 af#!"(%˚'#)*+˝" Outflow=5.35 cfs 0.363 af ˙*$#,-.!/*#,-606$1###2",-:4 3-5(#1',-6!.-.65ˇ2#1',-6! CT-Montville 24-hr S1 25-yr Rainfall=6.15"˘ˇˆ˙ˇ˝˛˚˜˚˛ Printed 10/27/2021Prepared by BL Companies Page 7HydroCAD® 10.00-26 s/n 01334 © 2020 HydroCAD Software Solutions LLC ˆ7ˆ !!"#$%&'ˆ# Runoff = 5.35 cfs @ 12.05 hrs, Volume= 0.363 af, Depth= 2.74" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs CT-Montville 24-hr S1 25-yr Rainfall=6.15" Area (sf) CN Description 9,442 55 Woods, Good, HSG B 45,043 61 >75% Grass cover, Good, HSG B 9,880 98 Paved parking, HSG B 985 96 Gravel surface, HSG B 3,927 98 Roofs, HSG B 69,277 68 Weighted Average 55,470 80.07% Pervious Area 13,807 19.93% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 0.3 25 0.0400 1.43 ˆ"##)*+8 Smooth surfaces n= 0.011 P2= 3.46" 3.8 75 0.1067 0.33 ˆ"##)*+8 Grass: Short n= 0.150 P2= 3.46" 0.4 53 0.1226 2.45 ˆ"**+!##9)*+8 Short Grass Pasture Kv= 7.0 fps 0.2 60 0.0500 4.54 ˆ"**+!##9)*+8 Paved Kv= 20.3 fps 1.4 138 0.0543 1.63 ˆ"**+!##9)*+8 Short Grass Pasture Kv= 7.0 fps 0.3 17 0.0294 0.86 ˆ"**+!##9)*+8 Woodland Kv= 5.0 fps 6.4 368 Total ˆ7#!"(%˚'#)*+˝" Inflow Area = 1.590 ac, 19.93% Impervious, Inflow Depth = 2.74" for 25-yr event Inflow = 5.35 cfs @ 12.05 hrs, Volume= 0.363 af Outflow = 5.35 cfs @ 12.05 hrs, Volume= 0.363 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs CT-Montville 24-hr S1 100-yr Rainfall=7.74"˘ˇˆ˙ˇ˝˛˚˜˚˛ Printed 10/27/2021Prepared by BL Companies Page 8HydroCAD® 10.00-26 s/n 01334 © 2020 HydroCAD Software Solutions LLC Time span=0.00-48.00 hrs, dt=0.05 hrs, 961 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=69,277 sf 19.93% Impervious Runoff Depth=4.02"ˆ !!"#$%&'ˆ# Flow Length=368' Tc=6.4 min CN=68 Runoff=7.97 cfs 0.532 af Inflow=7.97 cfs 0.532 af#!"(%˚'#)*+˝" Outflow=7.97 cfs 0.532 af ˙*$#,-.!/*#,-6$1###2",:-4 3-5(#1',-6!.-.65ˇ2#1',-6! CT-Montville 24-hr S1 100-yr Rainfall=7.74"˘ˇˆ˙ˇ˝˛˚˜˚˛ Printed 10/27/2021Prepared by BL Companies Page 9HydroCAD® 10.00-26 s/n 01334 © 2020 HydroCAD Software Solutions LLC ˆ7ˆ !!"#$%&'ˆ# Runoff = 7.97 cfs @ 12.05 hrs, Volume= 0.532 af, Depth= 4.02" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs CT-Montville 24-hr S1 100-yr Rainfall=7.74" Area (sf) CN Description 9,442 55 Woods, Good, HSG B 45,043 61 >75% Grass cover, Good, HSG B 9,880 98 Paved parking, HSG B 985 96 Gravel surface, HSG B 3,927 98 Roofs, HSG B 69,277 68 Weighted Average 55,470 80.07% Pervious Area 13,807 19.93% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 0.3 25 0.0400 1.43 ˆ"##)*+8 Smooth surfaces n= 0.011 P2= 3.46" 3.8 75 0.1067 0.33 ˆ"##)*+8 Grass: Short n= 0.150 P2= 3.46" 0.4 53 0.1226 2.45 ˆ"**+!##9)*+8 Short Grass Pasture Kv= 7.0 fps 0.2 60 0.0500 4.54 ˆ"**+!##9)*+8 Paved Kv= 20.3 fps 1.4 138 0.0543 1.63 ˆ"**+!##9)*+8 Short Grass Pasture Kv= 7.0 fps 0.3 17 0.0294 0.86 ˆ"**+!##9)*+8 Woodland Kv= 5.0 fps 6.4 368 Total ˆ7#!"(%˚'#)*+˝" Inflow Area = 1.590 ac, 19.93% Impervious, Inflow Depth = 4.02" for 100-yr event Inflow = 7.97 cfs @ 12.05 hrs, Volume= 0.532 af Outflow = 7.97 cfs @ 12.05 hrs, Volume= 0.532 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs 355 Research Parkway ▪ Meriden, CT 06450 ▪ T (203) 630-1406 ▪ F (203) 630-2615 ▪ www.blcompanies.com An Employee-Owned Company APPENDIX C Proposed Conditions Hydrology (2-, 10-, 25-, and 100-year storms) PDA-100 Existing Site PDA-200 Street Sidewalk PDA-310 North Parking PDA-320 Building Roof PDA-330 Northwest Parking PDA-340 Southwest Parking DP-1 Offsite Flow to North DP-2 Offsite Flow to Street SUM Total Offsite Flow 1P Subsurface Infiltration System Routing Diagram for C-HYD-2101750-PROPOSED HYDROLOGY Prepared by BL Companies, Printed 10/27/2021 HydroCAD® 10.00-26 s/n 01334 © 2020 HydroCAD Software Solutions LLC Subcat Reach Pond Link C-HYD-2101750-PROPOSED HYDROLOGY Printed 10/27/2021Prepared by BL Companies Page 2HydroCAD® 10.00-26 s/n 01334 © 2020 HydroCAD Software Solutions LLC Project Notes Copied 7 events from CT-Montville 24-hr S1 storm CT-Montville 24-hr S1 2-yr Rainfall=3.46"C-HYD-2101750-PROPOSED HYDROLOGY Printed 10/27/2021Prepared by BL Companies Page 3HydroCAD® 10.00-26 s/n 01334 © 2020 HydroCAD Software Solutions LLC Time span=0.00-120.00 hrs, dt=0.05 hrs, 2401 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=27,142 sf 5.53% Impervious Runoff Depth=0.68"Subcatchment PDA-100: Existing Site Flow Length=350' Tc=7.6 min CN=64 Runoff=0.38 cfs 0.036 af Runoff Area=2,191 sf 66.77% Impervious Runoff Depth=2.06"Subcatchment PDA-200: Street Sidewalk Flow Length=177' Tc=6.6 min CN=86 Runoff=0.13 cfs 0.009 af Runoff Area=9,649 sf 100.00% Impervious Runoff Depth=3.23"Subcatchment PDA-310: North Parking Flow Length=113' Slope=0.0177 '/' Tc=5.0 min CN=98 Runoff=0.84 cfs 0.060 af Runoff Area=10,650 sf 100.00% Impervious Runoff Depth=3.23"Subcatchment PDA-320: Building Roof Flow Length=88' Slope=0.0208 '/' Tc=5.0 min CN=98 Runoff=0.93 cfs 0.066 af Runoff Area=11,508 sf 74.08% Impervious Runoff Depth=2.23"Subcatchment PDA-330: Northwest Flow Length=194' Tc=6.9 min CN=88 Runoff=0.72 cfs 0.049 af Runoff Area=9,863 sf 65.20% Impervious Runoff Depth=1.98"Subcatchment PDA-340: Southwest Parking Flow Length=91' Tc=5.4 min CN=85 Runoff=0.57 cfs 0.037 af Inflow=0.95 cfs 0.173 afReach DP-1: Offsite Flow to North Outflow=0.95 cfs 0.173 af Inflow=0.13 cfs 0.009 afReach DP-2: Offsite Flow to Street Outflow=0.13 cfs 0.009 af Inflow=1.01 cfs 0.182 afReach SUM: Total Offsite Flow Outflow=1.01 cfs 0.182 af Peak Elev=204.60' Storage=4,163 cf Inflow=3.00 cfs 0.212 afPond 1P: Subsurface Infiltration System Discarded=0.01 cfs 0.074 af Primary=0.75 cfs 0.137 af Secondary=0.00 cfs 0.000 af Outflow=0.76 cfs 0.212 af Total Runoff Area = 1.630 ac Runoff Volume = 0.256 af Average Runoff Depth = 1.88" 46.17% Pervious = 0.753 ac 53.83% Impervious = 0.877 ac CT-Montville 24-hr S1 2-yr Rainfall=3.46"C-HYD-2101750-PROPOSED HYDROLOGY Printed 10/27/2021Prepared by BL Companies Page 4HydroCAD® 10.00-26 s/n 01334 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment PDA-100: Existing Site Runoff = 0.38 cfs @ 12.07 hrs, Volume= 0.036 af, Depth= 0.68" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs CT-Montville 24-hr S1 2-yr Rainfall=3.46" Area (sf) CN Description 1,043 55 Woods, Good, HSG B 23,614 61 >75% Grass cover, Good, HSG B 1,500 98 Paved parking, HSG B 985 96 Gravel surface, HSG B 27,142 64 Weighted Average 25,642 94.47% Pervious Area 1,500 5.53% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.7 100 0.0700 0.29 Sheet Flow, Grass: Short n= 0.150 P2= 3.46" 0.9 52 0.0192 0.97 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 0.1 10 0.2000 3.13 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 0.1 15 0.2000 3.13 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 0.8 173 0.0566 3.57 Shallow Concentrated Flow, Grassed Waterway Kv= 15.0 fps 7.6 350 Total Summary for Subcatchment PDA-200: Street Sidewalk Runoff = 0.13 cfs @ 12.05 hrs, Volume= 0.009 af, Depth= 2.06" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs CT-Montville 24-hr S1 2-yr Rainfall=3.46" Area (sf) CN Description 728 61 >75% Grass cover, Good, HSG B 1,463 98 Paved parking, HSG B 2,191 86 Weighted Average 728 33.23% Pervious Area 1,463 66.77% Impervious Area CT-Montville 24-hr S1 2-yr Rainfall=3.46"C-HYD-2101750-PROPOSED HYDROLOGY Printed 10/27/2021Prepared by BL Companies Page 5HydroCAD® 10.00-26 s/n 01334 © 2020 HydroCAD Software Solutions LLC Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.9 100 0.0650 0.28 Sheet Flow, Grass: Short n= 0.150 P2= 3.46" 0.6 60 0.0583 1.69 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 0.1 17 0.0588 4.92 Shallow Concentrated Flow, Paved Kv= 20.3 fps 6.6 177 Total Summary for Subcatchment PDA-310: North Parking [49] Hint: Tc<2dt may require smaller dt Runoff = 0.84 cfs @ 12.02 hrs, Volume= 0.060 af, Depth= 3.23" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs CT-Montville 24-hr S1 2-yr Rainfall=3.46" Area (sf) CN Description 9,649 98 Paved parking, HSG B 9,649 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 1.2 100 0.0177 1.36 Sheet Flow, Smooth surfaces n= 0.011 P2= 3.46" 0.1 13 0.0177 2.70 Shallow Concentrated Flow, Paved Kv= 20.3 fps 1.3 113 Total, Increased to minimum Tc = 5.0 min Summary for Subcatchment PDA-320: Building Roof [49] Hint: Tc<2dt may require smaller dt Runoff = 0.93 cfs @ 12.02 hrs, Volume= 0.066 af, Depth= 3.23" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs CT-Montville 24-hr S1 2-yr Rainfall=3.46" Area (sf) CN Description 10,650 98 Roofs, HSG B 10,650 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 1.0 88 0.0208 1.42 Sheet Flow, Smooth surfaces n= 0.011 P2= 3.46" 1.0 88 Total, Increased to minimum Tc = 5.0 min CT-Montville 24-hr S1 2-yr Rainfall=3.46"C-HYD-2101750-PROPOSED HYDROLOGY Printed 10/27/2021Prepared by BL Companies Page 6HydroCAD® 10.00-26 s/n 01334 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment PDA-330: Northwest Parking Runoff = 0.72 cfs @ 12.05 hrs, Volume= 0.049 af, Depth= 2.23" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs CT-Montville 24-hr S1 2-yr Rainfall=3.46" Area (sf) CN Description 2,983 61 >75% Grass cover, Good, HSG B 8,525 98 Paved parking, HSG B 11,508 88 Weighted Average 2,983 25.92% Pervious Area 8,525 74.08% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 0.7 15 0.2667 0.34 Sheet Flow, Grass: Short n= 0.150 P2= 3.46" 5.4 85 0.0588 0.26 Sheet Flow, Grass: Short n= 0.150 P2= 3.46" 0.1 8 0.0625 1.75 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 0.7 86 0.0116 2.19 Shallow Concentrated Flow, Paved Kv= 20.3 fps 6.9 194 Total Summary for Subcatchment PDA-340: Southwest Parking [49] Hint: Tc<2dt may require smaller dt Runoff = 0.57 cfs @ 12.03 hrs, Volume= 0.037 af, Depth= 1.98" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs CT-Montville 24-hr S1 2-yr Rainfall=3.46" Area (sf) CN Description 3,432 61 >75% Grass cover, Good, HSG B 6,431 98 Paved parking, HSG B 9,863 85 Weighted Average 3,432 34.80% Pervious Area 6,431 65.20% Impervious Area CT-Montville 24-hr S1 2-yr Rainfall=3.46"C-HYD-2101750-PROPOSED HYDROLOGY Printed 10/27/2021Prepared by BL Companies Page 7HydroCAD® 10.00-26 s/n 01334 © 2020 HydroCAD Software Solutions LLC Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 2.2 40 0.1250 0.31 Sheet Flow, Grass: Short n= 0.150 P2= 3.46" 2.6 14 0.0100 0.09 Sheet Flow, Grass: Short n= 0.150 P2= 3.46" 0.6 37 0.0135 1.00 Sheet Flow, Smooth surfaces n= 0.011 P2= 3.46" 5.4 91 Total Summary for Reach DP-1: Offsite Flow to North [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 1.580 ac, 53.41% Impervious, Inflow Depth = 1.31" for 2-yr event Inflow = 0.95 cfs @ 12.20 hrs, Volume= 0.173 af Outflow = 0.95 cfs @ 12.20 hrs, Volume= 0.173 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs Summary for Reach DP-2: Offsite Flow to Street [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 0.050 ac, 66.77% Impervious, Inflow Depth = 2.06" for 2-yr event Inflow = 0.13 cfs @ 12.05 hrs, Volume= 0.009 af Outflow = 0.13 cfs @ 12.05 hrs, Volume= 0.009 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs Summary for Reach SUM: Total Offsite Flow [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 1.630 ac, 53.83% Impervious, Inflow Depth = 1.34" for 2-yr event Inflow = 1.01 cfs @ 12.16 hrs, Volume= 0.182 af Outflow = 1.01 cfs @ 12.16 hrs, Volume= 0.182 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs Summary for Pond 1P: Subsurface Infiltration System Inflow Area = 0.957 ac, 84.61% Impervious, Inflow Depth = 2.66" for 2-yr event Inflow = 3.00 cfs @ 12.03 hrs, Volume= 0.212 af Outflow = 0.76 cfs @ 12.30 hrs, Volume= 0.212 af, Atten= 75%, Lag= 15.8 min Discarded = 0.01 cfs @ 3.25 hrs, Volume= 0.074 af Primary = 0.75 cfs @ 12.30 hrs, Volume= 0.137 af Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af Routing by Stor-Ind method, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs CT-Montville 24-hr S1 2-yr Rainfall=3.46"C-HYD-2101750-PROPOSED HYDROLOGY Printed 10/27/2021Prepared by BL Companies Page 8HydroCAD® 10.00-26 s/n 01334 © 2020 HydroCAD Software Solutions LLC Peak Elev= 204.60' @ 12.30 hrs Surf.Area= 3,590 sf Storage= 4,163 cf Plug-Flow detention time= 999.5 min calculated for 0.212 af (100% of inflow) Center-of-Mass det. time= 999.5 min ( 1,787.3 - 787.9 ) Volume Invert Avail.Storage Storage Description #1A 202.90' 3,225 cf 34.75'W x 103.30'L x 3.50'H Field A 12,563 cf Overall - 4,502 cf Embedded = 8,061 cf x 40.0% Voids #2A 203.40' 4,502 cf ADS_StormTech SC-740 +Cap x 98 Inside #1 Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap 98 Chambers in 7 Rows 7,727 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Discarded 202.90'0.100 in/hr Exfiltration over Surface area #2 Primary 204.00'6.0" W x 12.0" H Vert. Orifice/Grate C= 0.600 #3 Secondary 206.00'4.0' long x 1.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31 3.30 3.31 3.32 Discarded OutFlow Max=0.01 cfs @ 3.25 hrs HW=202.94' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.01 cfs) Primary OutFlow Max=0.75 cfs @ 12.30 hrs HW=204.60' (Free Discharge) 2=Orifice/Grate (Orifice Controls 0.75 cfs @ 2.49 fps) Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=202.90' (Free Discharge) 3=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) CT-Montville 24-hr S1 10-yr Rainfall=5.11"C-HYD-2101750-PROPOSED HYDROLOGY Printed 10/27/2021Prepared by BL Companies Page 9HydroCAD® 10.00-26 s/n 01334 © 2020 HydroCAD Software Solutions LLC Time span=0.00-120.00 hrs, dt=0.05 hrs, 2401 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=27,142 sf 5.53% Impervious Runoff Depth=1.65"Subcatchment PDA-100: Existing Site Flow Length=350' Tc=7.6 min CN=64 Runoff=1.13 cfs 0.086 af Runoff Area=2,191 sf 66.77% Impervious Runoff Depth=3.57"Subcatchment PDA-200: Street Sidewalk Flow Length=177' Tc=6.6 min CN=86 Runoff=0.22 cfs 0.015 af Runoff Area=9,649 sf 100.00% Impervious Runoff Depth=4.87"Subcatchment PDA-310: North Parking Flow Length=113' Slope=0.0177 '/' Tc=5.0 min CN=98 Runoff=1.26 cfs 0.090 af Runoff Area=10,650 sf 100.00% Impervious Runoff Depth=4.87"Subcatchment PDA-320: Building Roof Flow Length=88' Slope=0.0208 '/' Tc=5.0 min CN=98 Runoff=1.39 cfs 0.099 af Runoff Area=11,508 sf 74.08% Impervious Runoff Depth=3.77"Subcatchment PDA-330: Northwest Flow Length=194' Tc=6.9 min CN=88 Runoff=1.20 cfs 0.083 af Runoff Area=9,863 sf 65.20% Impervious Runoff Depth=3.47"Subcatchment PDA-340: Southwest Parking Flow Length=91' Tc=5.4 min CN=85 Runoff=1.00 cfs 0.065 af Inflow=2.85 cfs 0.348 afReach DP-1: Offsite Flow to North Outflow=2.85 cfs 0.348 af Inflow=0.22 cfs 0.015 afReach DP-2: Offsite Flow to Street Outflow=0.22 cfs 0.015 af Inflow=3.01 cfs 0.363 afReach SUM: Total Offsite Flow Outflow=3.01 cfs 0.363 af Peak Elev=205.18' Storage=5,627 cf Inflow=4.75 cfs 0.338 afPond 1P: Subsurface Infiltration System Discarded=0.01 cfs 0.075 af Primary=1.94 cfs 0.262 af Secondary=0.00 cfs 0.000 af Outflow=1.94 cfs 0.338 af Total Runoff Area = 1.630 ac Runoff Volume = 0.439 af Average Runoff Depth = 3.23" 46.17% Pervious = 0.753 ac 53.83% Impervious = 0.877 ac CT-Montville 24-hr S1 10-yr Rainfall=5.11"C-HYD-2101750-PROPOSED HYDROLOGY Printed 10/27/2021Prepared by BL Companies Page 10HydroCAD® 10.00-26 s/n 01334 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment PDA-100: Existing Site Runoff = 1.13 cfs @ 12.07 hrs, Volume= 0.086 af, Depth= 1.65" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs CT-Montville 24-hr S1 10-yr Rainfall=5.11" Area (sf) CN Description 1,043 55 Woods, Good, HSG B 23,614 61 >75% Grass cover, Good, HSG B 1,500 98 Paved parking, HSG B 985 96 Gravel surface, HSG B 27,142 64 Weighted Average 25,642 94.47% Pervious Area 1,500 5.53% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.7 100 0.0700 0.29 Sheet Flow, Grass: Short n= 0.150 P2= 3.46" 0.9 52 0.0192 0.97 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 0.1 10 0.2000 3.13 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 0.1 15 0.2000 3.13 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 0.8 173 0.0566 3.57 Shallow Concentrated Flow, Grassed Waterway Kv= 15.0 fps 7.6 350 Total Summary for Subcatchment PDA-200: Street Sidewalk Runoff = 0.22 cfs @ 12.05 hrs, Volume= 0.015 af, Depth= 3.57" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs CT-Montville 24-hr S1 10-yr Rainfall=5.11" Area (sf) CN Description 728 61 >75% Grass cover, Good, HSG B 1,463 98 Paved parking, HSG B 2,191 86 Weighted Average 728 33.23% Pervious Area 1,463 66.77% Impervious Area CT-Montville 24-hr S1 10-yr Rainfall=5.11"C-HYD-2101750-PROPOSED HYDROLOGY Printed 10/27/2021Prepared by BL Companies Page 11HydroCAD® 10.00-26 s/n 01334 © 2020 HydroCAD Software Solutions LLC Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.9 100 0.0650 0.28 Sheet Flow, Grass: Short n= 0.150 P2= 3.46" 0.6 60 0.0583 1.69 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 0.1 17 0.0588 4.92 Shallow Concentrated Flow, Paved Kv= 20.3 fps 6.6 177 Total Summary for Subcatchment PDA-310: North Parking [49] Hint: Tc<2dt may require smaller dt Runoff = 1.26 cfs @ 12.02 hrs, Volume= 0.090 af, Depth= 4.87" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs CT-Montville 24-hr S1 10-yr Rainfall=5.11" Area (sf) CN Description 9,649 98 Paved parking, HSG B 9,649 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 1.2 100 0.0177 1.36 Sheet Flow, Smooth surfaces n= 0.011 P2= 3.46" 0.1 13 0.0177 2.70 Shallow Concentrated Flow, Paved Kv= 20.3 fps 1.3 113 Total, Increased to minimum Tc = 5.0 min Summary for Subcatchment PDA-320: Building Roof [49] Hint: Tc<2dt may require smaller dt Runoff = 1.39 cfs @ 12.02 hrs, Volume= 0.099 af, Depth= 4.87" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs CT-Montville 24-hr S1 10-yr Rainfall=5.11" Area (sf) CN Description 10,650 98 Roofs, HSG B 10,650 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 1.0 88 0.0208 1.42 Sheet Flow, Smooth surfaces n= 0.011 P2= 3.46" 1.0 88 Total, Increased to minimum Tc = 5.0 min CT-Montville 24-hr S1 10-yr Rainfall=5.11"C-HYD-2101750-PROPOSED HYDROLOGY Printed 10/27/2021Prepared by BL Companies Page 12HydroCAD® 10.00-26 s/n 01334 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment PDA-330: Northwest Parking Runoff = 1.20 cfs @ 12.05 hrs, Volume= 0.083 af, Depth= 3.77" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs CT-Montville 24-hr S1 10-yr Rainfall=5.11" Area (sf) CN Description 2,983 61 >75% Grass cover, Good, HSG B 8,525 98 Paved parking, HSG B 11,508 88 Weighted Average 2,983 25.92% Pervious Area 8,525 74.08% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 0.7 15 0.2667 0.34 Sheet Flow, Grass: Short n= 0.150 P2= 3.46" 5.4 85 0.0588 0.26 Sheet Flow, Grass: Short n= 0.150 P2= 3.46" 0.1 8 0.0625 1.75 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 0.7 86 0.0116 2.19 Shallow Concentrated Flow, Paved Kv= 20.3 fps 6.9 194 Total Summary for Subcatchment PDA-340: Southwest Parking [49] Hint: Tc<2dt may require smaller dt Runoff = 1.00 cfs @ 12.03 hrs, Volume= 0.065 af, Depth= 3.47" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs CT-Montville 24-hr S1 10-yr Rainfall=5.11" Area (sf) CN Description 3,432 61 >75% Grass cover, Good, HSG B 6,431 98 Paved parking, HSG B 9,863 85 Weighted Average 3,432 34.80% Pervious Area 6,431 65.20% Impervious Area CT-Montville 24-hr S1 10-yr Rainfall=5.11"C-HYD-2101750-PROPOSED HYDROLOGY Printed 10/27/2021Prepared by BL Companies Page 13HydroCAD® 10.00-26 s/n 01334 © 2020 HydroCAD Software Solutions LLC Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 2.2 40 0.1250 0.31 Sheet Flow, Grass: Short n= 0.150 P2= 3.46" 2.6 14 0.0100 0.09 Sheet Flow, Grass: Short n= 0.150 P2= 3.46" 0.6 37 0.0135 1.00 Sheet Flow, Smooth surfaces n= 0.011 P2= 3.46" 5.4 91 Total Summary for Reach DP-1: Offsite Flow to North [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 1.580 ac, 53.41% Impervious, Inflow Depth = 2.65" for 10-yr event Inflow = 2.85 cfs @ 12.11 hrs, Volume= 0.348 af Outflow = 2.85 cfs @ 12.11 hrs, Volume= 0.348 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs Summary for Reach DP-2: Offsite Flow to Street [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 0.050 ac, 66.77% Impervious, Inflow Depth = 3.57" for 10-yr event Inflow = 0.22 cfs @ 12.05 hrs, Volume= 0.015 af Outflow = 0.22 cfs @ 12.05 hrs, Volume= 0.015 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs Summary for Reach SUM: Total Offsite Flow [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 1.630 ac, 53.83% Impervious, Inflow Depth = 2.67" for 10-yr event Inflow = 3.01 cfs @ 12.10 hrs, Volume= 0.363 af Outflow = 3.01 cfs @ 12.10 hrs, Volume= 0.363 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs Summary for Pond 1P: Subsurface Infiltration System Inflow Area = 0.957 ac, 84.61% Impervious, Inflow Depth = 4.24" for 10-yr event Inflow = 4.75 cfs @ 12.03 hrs, Volume= 0.338 af Outflow = 1.94 cfs @ 12.18 hrs, Volume= 0.338 af, Atten= 59%, Lag= 8.7 min Discarded = 0.01 cfs @ 2.20 hrs, Volume= 0.075 af Primary = 1.94 cfs @ 12.18 hrs, Volume= 0.262 af Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af Routing by Stor-Ind method, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs CT-Montville 24-hr S1 10-yr Rainfall=5.11"C-HYD-2101750-PROPOSED HYDROLOGY Printed 10/27/2021Prepared by BL Companies Page 14HydroCAD® 10.00-26 s/n 01334 © 2020 HydroCAD Software Solutions LLC Peak Elev= 205.18' @ 12.18 hrs Surf.Area= 3,590 sf Storage= 5,627 cf Plug-Flow detention time= 661.4 min calculated for 0.338 af (100% of inflow) Center-of-Mass det. time= 661.4 min ( 1,438.3 - 777.0 ) Volume Invert Avail.Storage Storage Description #1A 202.90' 3,225 cf 34.75'W x 103.30'L x 3.50'H Field A 12,563 cf Overall - 4,502 cf Embedded = 8,061 cf x 40.0% Voids #2A 203.40' 4,502 cf ADS_StormTech SC-740 +Cap x 98 Inside #1 Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap 98 Chambers in 7 Rows 7,727 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Discarded 202.90'0.100 in/hr Exfiltration over Surface area #2 Primary 204.00'6.0" W x 12.0" H Vert. Orifice/Grate C= 0.600 #3 Secondary 206.00'4.0' long x 1.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31 3.30 3.31 3.32 Discarded OutFlow Max=0.01 cfs @ 2.20 hrs HW=202.94' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.01 cfs) Primary OutFlow Max=1.93 cfs @ 12.18 hrs HW=205.18' (Free Discharge) 2=Orifice/Grate (Orifice Controls 1.93 cfs @ 3.86 fps) Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=202.90' (Free Discharge) 3=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) CT-Montville 24-hr S1 25-yr Rainfall=6.15"C-HYD-2101750-PROPOSED HYDROLOGY Printed 10/27/2021Prepared by BL Companies Page 15HydroCAD® 10.00-26 s/n 01334 © 2020 HydroCAD Software Solutions LLC Time span=0.00-120.00 hrs, dt=0.05 hrs, 2401 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=27,142 sf 5.53% Impervious Runoff Depth=2.37"Subcatchment PDA-100: Existing Site Flow Length=350' Tc=7.6 min CN=64 Runoff=1.68 cfs 0.123 af Runoff Area=2,191 sf 66.77% Impervious Runoff Depth=4.55"Subcatchment PDA-200: Street Sidewalk Flow Length=177' Tc=6.6 min CN=86 Runoff=0.28 cfs 0.019 af Runoff Area=9,649 sf 100.00% Impervious Runoff Depth=5.91"Subcatchment PDA-310: North Parking Flow Length=113' Slope=0.0177 '/' Tc=5.0 min CN=98 Runoff=1.52 cfs 0.109 af Runoff Area=10,650 sf 100.00% Impervious Runoff Depth=5.91"Subcatchment PDA-320: Building Roof Flow Length=88' Slope=0.0208 '/' Tc=5.0 min CN=98 Runoff=1.68 cfs 0.120 af Runoff Area=11,508 sf 74.08% Impervious Runoff Depth=4.77"Subcatchment PDA-330: Northwest Flow Length=194' Tc=6.9 min CN=88 Runoff=1.50 cfs 0.105 af Runoff Area=9,863 sf 65.20% Impervious Runoff Depth=4.44"Subcatchment PDA-340: Southwest Parking Flow Length=91' Tc=5.4 min CN=85 Runoff=1.27 cfs 0.084 af Inflow=3.78 cfs 0.466 afReach DP-1: Offsite Flow to North Outflow=3.78 cfs 0.466 af Inflow=0.28 cfs 0.019 afReach DP-2: Offsite Flow to Street Outflow=0.28 cfs 0.019 af Inflow=4.00 cfs 0.485 afReach SUM: Total Offsite Flow Outflow=4.00 cfs 0.485 af Peak Elev=205.51' Storage=6,357 cf Inflow=5.85 cfs 0.418 afPond 1P: Subsurface Infiltration System Discarded=0.01 cfs 0.076 af Primary=2.40 cfs 0.343 af Secondary=0.00 cfs 0.000 af Outflow=2.41 cfs 0.418 af Total Runoff Area = 1.630 ac Runoff Volume = 0.561 af Average Runoff Depth = 4.13" 46.17% Pervious = 0.753 ac 53.83% Impervious = 0.877 ac CT-Montville 24-hr S1 25-yr Rainfall=6.15"C-HYD-2101750-PROPOSED HYDROLOGY Printed 10/27/2021Prepared by BL Companies Page 16HydroCAD® 10.00-26 s/n 01334 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment PDA-100: Existing Site Runoff = 1.68 cfs @ 12.06 hrs, Volume= 0.123 af, Depth= 2.37" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs CT-Montville 24-hr S1 25-yr Rainfall=6.15" Area (sf) CN Description 1,043 55 Woods, Good, HSG B 23,614 61 >75% Grass cover, Good, HSG B 1,500 98 Paved parking, HSG B 985 96 Gravel surface, HSG B 27,142 64 Weighted Average 25,642 94.47% Pervious Area 1,500 5.53% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.7 100 0.0700 0.29 Sheet Flow, Grass: Short n= 0.150 P2= 3.46" 0.9 52 0.0192 0.97 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 0.1 10 0.2000 3.13 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 0.1 15 0.2000 3.13 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 0.8 173 0.0566 3.57 Shallow Concentrated Flow, Grassed Waterway Kv= 15.0 fps 7.6 350 Total Summary for Subcatchment PDA-200: Street Sidewalk Runoff = 0.28 cfs @ 12.05 hrs, Volume= 0.019 af, Depth= 4.55" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs CT-Montville 24-hr S1 25-yr Rainfall=6.15" Area (sf) CN Description 728 61 >75% Grass cover, Good, HSG B 1,463 98 Paved parking, HSG B 2,191 86 Weighted Average 728 33.23% Pervious Area 1,463 66.77% Impervious Area CT-Montville 24-hr S1 25-yr Rainfall=6.15"C-HYD-2101750-PROPOSED HYDROLOGY Printed 10/27/2021Prepared by BL Companies Page 17HydroCAD® 10.00-26 s/n 01334 © 2020 HydroCAD Software Solutions LLC Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.9 100 0.0650 0.28 Sheet Flow, Grass: Short n= 0.150 P2= 3.46" 0.6 60 0.0583 1.69 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 0.1 17 0.0588 4.92 Shallow Concentrated Flow, Paved Kv= 20.3 fps 6.6 177 Total Summary for Subcatchment PDA-310: North Parking [49] Hint: Tc<2dt may require smaller dt Runoff = 1.52 cfs @ 12.02 hrs, Volume= 0.109 af, Depth= 5.91" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs CT-Montville 24-hr S1 25-yr Rainfall=6.15" Area (sf) CN Description 9,649 98 Paved parking, HSG B 9,649 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 1.2 100 0.0177 1.36 Sheet Flow, Smooth surfaces n= 0.011 P2= 3.46" 0.1 13 0.0177 2.70 Shallow Concentrated Flow, Paved Kv= 20.3 fps 1.3 113 Total, Increased to minimum Tc = 5.0 min Summary for Subcatchment PDA-320: Building Roof [49] Hint: Tc<2dt may require smaller dt Runoff = 1.68 cfs @ 12.02 hrs, Volume= 0.120 af, Depth= 5.91" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs CT-Montville 24-hr S1 25-yr Rainfall=6.15" Area (sf) CN Description 10,650 98 Roofs, HSG B 10,650 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 1.0 88 0.0208 1.42 Sheet Flow, Smooth surfaces n= 0.011 P2= 3.46" 1.0 88 Total, Increased to minimum Tc = 5.0 min CT-Montville 24-hr S1 25-yr Rainfall=6.15"C-HYD-2101750-PROPOSED HYDROLOGY Printed 10/27/2021Prepared by BL Companies Page 18HydroCAD® 10.00-26 s/n 01334 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment PDA-330: Northwest Parking Runoff = 1.50 cfs @ 12.05 hrs, Volume= 0.105 af, Depth= 4.77" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs CT-Montville 24-hr S1 25-yr Rainfall=6.15" Area (sf) CN Description 2,983 61 >75% Grass cover, Good, HSG B 8,525 98 Paved parking, HSG B 11,508 88 Weighted Average 2,983 25.92% Pervious Area 8,525 74.08% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 0.7 15 0.2667 0.34 Sheet Flow, Grass: Short n= 0.150 P2= 3.46" 5.4 85 0.0588 0.26 Sheet Flow, Grass: Short n= 0.150 P2= 3.46" 0.1 8 0.0625 1.75 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 0.7 86 0.0116 2.19 Shallow Concentrated Flow, Paved Kv= 20.3 fps 6.9 194 Total Summary for Subcatchment PDA-340: Southwest Parking [49] Hint: Tc<2dt may require smaller dt Runoff = 1.27 cfs @ 12.03 hrs, Volume= 0.084 af, Depth= 4.44" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs CT-Montville 24-hr S1 25-yr Rainfall=6.15" Area (sf) CN Description 3,432 61 >75% Grass cover, Good, HSG B 6,431 98 Paved parking, HSG B 9,863 85 Weighted Average 3,432 34.80% Pervious Area 6,431 65.20% Impervious Area CT-Montville 24-hr S1 25-yr Rainfall=6.15"C-HYD-2101750-PROPOSED HYDROLOGY Printed 10/27/2021Prepared by BL Companies Page 19HydroCAD® 10.00-26 s/n 01334 © 2020 HydroCAD Software Solutions LLC Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 2.2 40 0.1250 0.31 Sheet Flow, Grass: Short n= 0.150 P2= 3.46" 2.6 14 0.0100 0.09 Sheet Flow, Grass: Short n= 0.150 P2= 3.46" 0.6 37 0.0135 1.00 Sheet Flow, Smooth surfaces n= 0.011 P2= 3.46" 5.4 91 Total Summary for Reach DP-1: Offsite Flow to North [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 1.580 ac, 53.41% Impervious, Inflow Depth = 3.54" for 25-yr event Inflow = 3.78 cfs @ 12.09 hrs, Volume= 0.466 af Outflow = 3.78 cfs @ 12.09 hrs, Volume= 0.466 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs Summary for Reach DP-2: Offsite Flow to Street [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 0.050 ac, 66.77% Impervious, Inflow Depth = 4.55" for 25-yr event Inflow = 0.28 cfs @ 12.05 hrs, Volume= 0.019 af Outflow = 0.28 cfs @ 12.05 hrs, Volume= 0.019 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs Summary for Reach SUM: Total Offsite Flow [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 1.630 ac, 53.83% Impervious, Inflow Depth = 3.57" for 25-yr event Inflow = 4.00 cfs @ 12.08 hrs, Volume= 0.485 af Outflow = 4.00 cfs @ 12.08 hrs, Volume= 0.485 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs Summary for Pond 1P: Subsurface Infiltration System Inflow Area = 0.957 ac, 84.61% Impervious, Inflow Depth = 5.25" for 25-yr event Inflow = 5.85 cfs @ 12.03 hrs, Volume= 0.418 af Outflow = 2.41 cfs @ 12.17 hrs, Volume= 0.418 af, Atten= 59%, Lag= 8.6 min Discarded = 0.01 cfs @ 1.80 hrs, Volume= 0.076 af Primary = 2.40 cfs @ 12.17 hrs, Volume= 0.343 af Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af Routing by Stor-Ind method, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs CT-Montville 24-hr S1 25-yr Rainfall=6.15"C-HYD-2101750-PROPOSED HYDROLOGY Printed 10/27/2021Prepared by BL Companies Page 20HydroCAD® 10.00-26 s/n 01334 © 2020 HydroCAD Software Solutions LLC Peak Elev= 205.51' @ 12.17 hrs Surf.Area= 3,590 sf Storage= 6,357 cf Plug-Flow detention time= 547.8 min calculated for 0.418 af (100% of inflow) Center-of-Mass det. time= 549.8 min ( 1,322.0 - 772.2 ) Volume Invert Avail.Storage Storage Description #1A 202.90' 3,225 cf 34.75'W x 103.30'L x 3.50'H Field A 12,563 cf Overall - 4,502 cf Embedded = 8,061 cf x 40.0% Voids #2A 203.40' 4,502 cf ADS_StormTech SC-740 +Cap x 98 Inside #1 Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap 98 Chambers in 7 Rows 7,727 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Discarded 202.90'0.100 in/hr Exfiltration over Surface area #2 Primary 204.00'6.0" W x 12.0" H Vert. Orifice/Grate C= 0.600 #3 Secondary 206.00'4.0' long x 1.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31 3.30 3.31 3.32 Discarded OutFlow Max=0.01 cfs @ 1.80 hrs HW=202.94' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.01 cfs) Primary OutFlow Max=2.38 cfs @ 12.17 hrs HW=205.50' (Free Discharge) 2=Orifice/Grate (Orifice Controls 2.38 cfs @ 4.77 fps) Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=202.90' (Free Discharge) 3=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) CT-Montville 24-hr S1 100-yr Rainfall=7.74"C-HYD-2101750-PROPOSED HYDROLOGY Printed 10/27/2021Prepared by BL Companies Page 21HydroCAD® 10.00-26 s/n 01334 © 2020 HydroCAD Software Solutions LLC Time span=0.00-120.00 hrs, dt=0.05 hrs, 2401 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=27,142 sf 5.53% Impervious Runoff Depth=3.58"Subcatchment PDA-100: Existing Site Flow Length=350' Tc=7.6 min CN=64 Runoff=2.60 cfs 0.186 af Runoff Area=2,191 sf 66.77% Impervious Runoff Depth=6.08"Subcatchment PDA-200: Street Sidewalk Flow Length=177' Tc=6.6 min CN=86 Runoff=0.37 cfs 0.025 af Runoff Area=9,649 sf 100.00% Impervious Runoff Depth=7.50"Subcatchment PDA-310: North Parking Flow Length=113' Slope=0.0177 '/' Tc=5.0 min CN=98 Runoff=1.92 cfs 0.138 af Runoff Area=10,650 sf 100.00% Impervious Runoff Depth=7.50"Subcatchment PDA-320: Building Roof Flow Length=88' Slope=0.0208 '/' Tc=5.0 min CN=98 Runoff=2.12 cfs 0.153 af Runoff Area=11,508 sf 74.08% Impervious Runoff Depth=6.31"Subcatchment PDA-330: Northwest Flow Length=194' Tc=6.9 min CN=88 Runoff=1.96 cfs 0.139 af Runoff Area=9,863 sf 65.20% Impervious Runoff Depth=5.96"Subcatchment PDA-340: Southwest Parking Flow Length=91' Tc=5.4 min CN=85 Runoff=1.69 cfs 0.113 af Inflow=5.22 cfs 0.653 afReach DP-1: Offsite Flow to North Outflow=5.22 cfs 0.653 af Inflow=0.37 cfs 0.025 afReach DP-2: Offsite Flow to Street Outflow=0.37 cfs 0.025 af Inflow=5.49 cfs 0.678 afReach SUM: Total Offsite Flow Outflow=5.49 cfs 0.678 af Peak Elev=206.12' Storage=7,327 cf Inflow=7.54 cfs 0.543 afPond 1P: Subsurface Infiltration System Discarded=0.01 cfs 0.076 af Primary=3.05 cfs 0.464 af Secondary=0.43 cfs 0.003 af Outflow=3.49 cfs 0.543 af Total Runoff Area = 1.630 ac Runoff Volume = 0.754 af Average Runoff Depth = 5.55" 46.17% Pervious = 0.753 ac 53.83% Impervious = 0.877 ac CT-Montville 24-hr S1 100-yr Rainfall=7.74"C-HYD-2101750-PROPOSED HYDROLOGY Printed 10/27/2021Prepared by BL Companies Page 22HydroCAD® 10.00-26 s/n 01334 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment PDA-100: Existing Site Runoff = 2.60 cfs @ 12.06 hrs, Volume= 0.186 af, Depth= 3.58" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs CT-Montville 24-hr S1 100-yr Rainfall=7.74" Area (sf) CN Description 1,043 55 Woods, Good, HSG B 23,614 61 >75% Grass cover, Good, HSG B 1,500 98 Paved parking, HSG B 985 96 Gravel surface, HSG B 27,142 64 Weighted Average 25,642 94.47% Pervious Area 1,500 5.53% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.7 100 0.0700 0.29 Sheet Flow, Grass: Short n= 0.150 P2= 3.46" 0.9 52 0.0192 0.97 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 0.1 10 0.2000 3.13 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 0.1 15 0.2000 3.13 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 0.8 173 0.0566 3.57 Shallow Concentrated Flow, Grassed Waterway Kv= 15.0 fps 7.6 350 Total Summary for Subcatchment PDA-200: Street Sidewalk Runoff = 0.37 cfs @ 12.05 hrs, Volume= 0.025 af, Depth= 6.08" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs CT-Montville 24-hr S1 100-yr Rainfall=7.74" Area (sf) CN Description 728 61 >75% Grass cover, Good, HSG B 1,463 98 Paved parking, HSG B 2,191 86 Weighted Average 728 33.23% Pervious Area 1,463 66.77% Impervious Area CT-Montville 24-hr S1 100-yr Rainfall=7.74"C-HYD-2101750-PROPOSED HYDROLOGY Printed 10/27/2021Prepared by BL Companies Page 23HydroCAD® 10.00-26 s/n 01334 © 2020 HydroCAD Software Solutions LLC Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.9 100 0.0650 0.28 Sheet Flow, Grass: Short n= 0.150 P2= 3.46" 0.6 60 0.0583 1.69 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 0.1 17 0.0588 4.92 Shallow Concentrated Flow, Paved Kv= 20.3 fps 6.6 177 Total Summary for Subcatchment PDA-310: North Parking [49] Hint: Tc<2dt may require smaller dt Runoff = 1.92 cfs @ 12.02 hrs, Volume= 0.138 af, Depth= 7.50" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs CT-Montville 24-hr S1 100-yr Rainfall=7.74" Area (sf) CN Description 9,649 98 Paved parking, HSG B 9,649 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 1.2 100 0.0177 1.36 Sheet Flow, Smooth surfaces n= 0.011 P2= 3.46" 0.1 13 0.0177 2.70 Shallow Concentrated Flow, Paved Kv= 20.3 fps 1.3 113 Total, Increased to minimum Tc = 5.0 min Summary for Subcatchment PDA-320: Building Roof [49] Hint: Tc<2dt may require smaller dt Runoff = 2.12 cfs @ 12.02 hrs, Volume= 0.153 af, Depth= 7.50" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs CT-Montville 24-hr S1 100-yr Rainfall=7.74" Area (sf) CN Description 10,650 98 Roofs, HSG B 10,650 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 1.0 88 0.0208 1.42 Sheet Flow, Smooth surfaces n= 0.011 P2= 3.46" 1.0 88 Total, Increased to minimum Tc = 5.0 min CT-Montville 24-hr S1 100-yr Rainfall=7.74"C-HYD-2101750-PROPOSED HYDROLOGY Printed 10/27/2021Prepared by BL Companies Page 24HydroCAD® 10.00-26 s/n 01334 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment PDA-330: Northwest Parking Runoff = 1.96 cfs @ 12.05 hrs, Volume= 0.139 af, Depth= 6.31" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs CT-Montville 24-hr S1 100-yr Rainfall=7.74" Area (sf) CN Description 2,983 61 >75% Grass cover, Good, HSG B 8,525 98 Paved parking, HSG B 11,508 88 Weighted Average 2,983 25.92% Pervious Area 8,525 74.08% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 0.7 15 0.2667 0.34 Sheet Flow, Grass: Short n= 0.150 P2= 3.46" 5.4 85 0.0588 0.26 Sheet Flow, Grass: Short n= 0.150 P2= 3.46" 0.1 8 0.0625 1.75 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 0.7 86 0.0116 2.19 Shallow Concentrated Flow, Paved Kv= 20.3 fps 6.9 194 Total Summary for Subcatchment PDA-340: Southwest Parking [49] Hint: Tc<2dt may require smaller dt Runoff = 1.69 cfs @ 12.03 hrs, Volume= 0.113 af, Depth= 5.96" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs CT-Montville 24-hr S1 100-yr Rainfall=7.74" Area (sf) CN Description 3,432 61 >75% Grass cover, Good, HSG B 6,431 98 Paved parking, HSG B 9,863 85 Weighted Average 3,432 34.80% Pervious Area 6,431 65.20% Impervious Area CT-Montville 24-hr S1 100-yr Rainfall=7.74"C-HYD-2101750-PROPOSED HYDROLOGY Printed 10/27/2021Prepared by BL Companies Page 25HydroCAD® 10.00-26 s/n 01334 © 2020 HydroCAD Software Solutions LLC Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 2.2 40 0.1250 0.31 Sheet Flow, Grass: Short n= 0.150 P2= 3.46" 2.6 14 0.0100 0.09 Sheet Flow, Grass: Short n= 0.150 P2= 3.46" 0.6 37 0.0135 1.00 Sheet Flow, Smooth surfaces n= 0.011 P2= 3.46" 5.4 91 Total Summary for Reach DP-1: Offsite Flow to North [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 1.580 ac, 53.41% Impervious, Inflow Depth = 4.96" for 100-yr event Inflow = 5.22 cfs @ 12.12 hrs, Volume= 0.653 af Outflow = 5.22 cfs @ 12.12 hrs, Volume= 0.653 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs Summary for Reach DP-2: Offsite Flow to Street [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 0.050 ac, 66.77% Impervious, Inflow Depth = 6.08" for 100-yr event Inflow = 0.37 cfs @ 12.05 hrs, Volume= 0.025 af Outflow = 0.37 cfs @ 12.05 hrs, Volume= 0.025 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs Summary for Reach SUM: Total Offsite Flow [40] Hint: Not Described (Outflow=Inflow) Inflow Area = 1.630 ac, 53.83% Impervious, Inflow Depth = 4.99" for 100-yr event Inflow = 5.49 cfs @ 12.09 hrs, Volume= 0.678 af Outflow = 5.49 cfs @ 12.09 hrs, Volume= 0.678 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs Summary for Pond 1P: Subsurface Infiltration System Inflow Area = 0.957 ac, 84.61% Impervious, Inflow Depth = 6.81" for 100-yr event Inflow = 7.54 cfs @ 12.03 hrs, Volume= 0.543 af Outflow = 3.49 cfs @ 12.16 hrs, Volume= 0.543 af, Atten= 54%, Lag= 7.7 min Discarded = 0.01 cfs @ 1.45 hrs, Volume= 0.076 af Primary = 3.05 cfs @ 12.16 hrs, Volume= 0.464 af Secondary = 0.43 cfs @ 12.16 hrs, Volume= 0.003 af Routing by Stor-Ind method, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs CT-Montville 24-hr S1 100-yr Rainfall=7.74"C-HYD-2101750-PROPOSED HYDROLOGY Printed 10/27/2021Prepared by BL Companies Page 26HydroCAD® 10.00-26 s/n 01334 © 2020 HydroCAD Software Solutions LLC Peak Elev= 206.12' @ 12.16 hrs Surf.Area= 3,590 sf Storage= 7,327 cf Plug-Flow detention time= 440.0 min calculated for 0.543 af (100% of inflow) Center-of-Mass det. time= 439.9 min ( 1,206.4 - 766.5 ) Volume Invert Avail.Storage Storage Description #1A 202.90' 3,225 cf 34.75'W x 103.30'L x 3.50'H Field A 12,563 cf Overall - 4,502 cf Embedded = 8,061 cf x 40.0% Voids #2A 203.40' 4,502 cf ADS_StormTech SC-740 +Cap x 98 Inside #1 Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap 98 Chambers in 7 Rows 7,727 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Discarded 202.90'0.100 in/hr Exfiltration over Surface area #2 Primary 204.00'6.0" W x 12.0" H Vert. Orifice/Grate C= 0.600 #3 Secondary 206.00'4.0' long x 1.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 Coef. (English) 2.69 2.72 2.75 2.85 2.98 3.08 3.20 3.28 3.31 3.30 3.31 3.32 Discarded OutFlow Max=0.01 cfs @ 1.45 hrs HW=202.94' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.01 cfs) Primary OutFlow Max=3.04 cfs @ 12.16 hrs HW=206.10' (Free Discharge) 2=Orifice/Grate (Orifice Controls 3.04 cfs @ 6.07 fps) Secondary OutFlow Max=0.38 cfs @ 12.16 hrs HW=206.11' (Free Discharge) 3=Broad-Crested Rectangular Weir (Weir Controls 0.38 cfs @ 0.88 fps) 355 Research Parkway ▪ Meriden, CT 06450 ▪ T (203) 630-1406 ▪ F (203) 630-2615 ▪ www.blcompanies.com An Employee-Owned Company APPENDIX D Water Quality Calculations WQV Printed 10/27/2021 2:00 PM Water Quality Calculations Determine Water Quality Volume From CT 2004 Stormwater Quality Manual: WQV = water quality volume (ac-ft) R = volumetric runoff coefficient I = percent impervious cover A = site area in acres Area Impervious Cover Volumetric Runoff Coefficient Pretreatment Volume (10% of WQV) Sediment Forebay Volume ID ac ft2 ac ft2 % R acre-feet ft3 ft3 ft3 PDA-100 PDA-100 0.623 27,142 0.057 2,485 9.15 0.132 0.007 305 N/A N/A PDA-200 PDA-200 0.050 2,191 0.034 1,463 68.00 0.662 0.003 131 N/A N/A PDA-310 PDA-310 0.222 9,649 0.222 9,649 100.00 0.950 0.018 784 N/A N/A PDA-320 PDA-320 0.244 10,650 0.244 10,650 100.00 0.950 0.019 828 N/A N/A PDA-330 PDA-330 0.264 11,508 0.196 8,525 74.24 0.718 0.016 697 N/A N/A PDA-340 PDA-340 0.226 9,863 0.148 6,431 65.49 0.639 0.012 523 N/A N/A TOTAL 71,003 39,203 55%0.075 3,268 Proposed Stormwater Volument Retention Provided On-site DP-2 (COLLECTION TO ISOLATOR ROW) PDA-310, 320, 330, 340 0.734 41,670 0.588 35,255 80.11 0.771 0.047 2,047 N/A N/A 2,488 DP-2 (DIVERSION CHANNEL) PDA-100 0.623 27,142 0.057 2,485 9.15 0.132 0.007 305 N/A N/A 0 DP-2 OFFSITE FLOW TO STREET) PDA-200 0.050 2,191 0.034 1,463 68.00 0.662 0.003 131 N/A N/A 0 Total Area Impervious Area Water Quality Volume (WQV) (DRAINAGE AREA PDA-100 DOES NOT REQUIRE WQ TREATMENT DUE TO IMPERVOUS SURFACES BEING LOCATED WITHIN STREET ROW. ()()() 12 "1 ARWQV= ()IR009.005.0 += G:\JOBS20\06\2000696\ENG-TECH\CIVIL\WQ CALC\C-DAT-2000696-CTDEEP WQV Calcs.xlsm Page 1 of 1 WQF Printed 10/27/2021 2:06 PM Water Quality Calculations Determine Water Quality Flow From CT 2004 Stormwater Quality Manual: CN = Runoff Curve Number P = design preciptation, inches, (1" for water quality storm) Q = runoff depth (in watershed inches) Tc = time of concentration Ia = Initial abstraction, inches, from Table 4-1, Chapter 4, TR-55 qu = unit peak discharge, WQF = water quality flow (cfs) Facility Imp Cover R WQV Q P CN Ia Ia/P qu 1 WQF ID ft2 ac mi2 ft2 ac % - acre-feet in in - mins hours in -cfs/mi2/in cfs Isolator Row - 41,670 0.957 0.0015 35,255 0.809 84.54 0.811 0.065 0.82 1.00 98 6.9 0.12 0.041 0.041 400 0.49 1 From Exhibit 4-III: Unit peak discharge (qu) for SCS type III rainfall distribution, Urban Hydrology for Small Watersheds (TR-55), USDS< SCS, June 1986. TcTotal Area Imp Area WQ Treatment Device ( )  +-++ = 2 1 2 25.11010510 1000 QPQQP CN [][] )( )/(12)( acreseaDrainageAr footinchesfeetacreWQVQ´-= ()()()QAqWQFu= G:\JOBS20\06\2000696\ENG-TECH\CIVIL\WQ CALC\C-DAT-2000696-CTDEEP WQV Calcs.xlsm Page 1 of 1 GW Recharge Printed 10/27/2021 2:09 PM Groundwater Recharge Volume Calculations Groundwater Recharge Volume From CT 2004 Stormwater Quality Manual: GRV Groundwater Recharge Volume (ac-ft) D = Depth of Runoff to be Recharged (table 7-4) A = site area in acres I = impervious cover (decimal) A A B C D A B C D A B C D Existing 1.63 0.00 1.59 0.00 0.00 0.00 0.34 0.00 0.00 0.00 0.21 0.00 0.00 -0.007 - - Proposed 1.63 0.00 0.34 0.00 0.00 0.00 0.90 0.00 0.00 0.00 2.65 0.00 0.00 0.019 0.168 YES 0.0117 0.168 YES Total Site Area (AC) Provided Recharge Volume (ac-ft) (Undeground Detention Only) Site Area by NRCS Hydrologic Soil Group I Site Imperviousness (Decimel) by NRCS Hydrologic Soil GroupImpervious Cover by NRCS Hydrologic Soil Group GRV Required (ac-ft) Req. Meet 12 ))()((IADGVR= G:\JOBS19\02\1900245\ENG-TECH\CIVIL\HYDRO\C-DAT-1900245-CTDEEP WQV Calcs - ALT4.xlsm Page 1 of 1 Prepared for: Proposed Retail Development 1981 Norwich-New London Turnpike Montville, Connecticut Prepared by: BL Companies 100 Constitution Plaza, 10th Floor Hartford, CT Date prepared: October 27, 2021 BMP BMP Description Type pf Treatment Efficiency Rate %BMP Type pf Treatment TSS Removal Rate Starting TSS Load Amount Removed Remaining Load Et=[1-(1-E1)(1-E2)(1-E3)(1-E4)(1-E?)]*100 E1 Impervious Surface Sweeping*** secondary (conventional) 10 Impervious Surface Sweeping*** secondary (conventional) 0.10 1 0.10 0.9 E2 Deep Sump and Hooded Catch Basin secondary (conventional) 25 Deep Sump and Hooded Catch Basin secondary (conventional) 0.25 0.9 0.23 0.68 E3 Isolator Row**Primary 80 Isolator Row**Primary 0.8 0.68 0.54 0.14 Overall Treatment Train Efficiency (%)87 Overall Treatment Train Efficiency (Et)=87 % Total Suspended Solids (TSS) Removal * 80% required per CT DEEP ** Manufacturer Claims 80% TSS Removal *** Schueler 1996 & EPA 1993 TSS Removal Rates (adapted from Schueler, 1996, & EPA, 1993) Extended Detention Pond 70% 60-80% Wet Pond (a) 70% 60-80% Constructed Wetland (b) 80% 65-80% Water Quality Swale 70% 60-80% Infiltration Trench 80% 75-80% 75-80% (predicted) Sand Filter (c)80%80% Organic Filter (d)80%80%+ 15-35% w/ cleanout Sediment Trap (Forebay) 25% 25% w/ cleanout Drainage Channel 25% 25% Deep Sump and Hooded Catch Basin 25% 25% w/ cleanout Street Sweeping 10% 10% Best Management Practice (BMP) Treatment Train Efficiency Worksheet Overall Site Treatment Train Efficiency to Underground Stormwater Detention System BMP List Design Rate Range of Average TSS Removal Rates Brief Design Requirements Sediment forebay Sediment forebay Designed to infiltrate or retain Designed to infiltrate or retain Pretreatment critical Infiltration Basin 80% Pretreatment critical Dry Well 80% 80% (predicted) Rooftop runoff (uncontaminated only) Pretreatment Check dams; non-erosive for 2-yr. Deep sump general rule = 4 x pipe diameter or 4.0’ for pipes 18” or less Discretionary non-structural credit, must be part of approved plan Pretreatment Water Quality Inlet 25% Off-line only; 0.1” minimum Water Quality Volume (WQV) storage Storm flows for 2-year event must not cause erosion; 0.1” minimum WQV storage G:\JOBS21\16\2101750\ENG-TECH\CIVIL\C-DAT-2101750-Treatment Train.xlstreatment train USDS CT-Montville 24-hr S1 100-yr Rainfall=7.74"C-HYD-2101750-PROPOSED HYDROLOGY Printed 10/27/2021Prepared by BL Companies HydroCAD® 10.00-26 s/n 01334 © 2020 HydroCAD Software Solutions LLC Stage-Area-Storage for Pond 1P: Subsurface Infiltration System Elevation (feet) Surface (sq-ft) Storage (cubic-feet) 202.90 3,590 0 202.95 3,590 72 203.00 3,590 144 203.05 3,590 215 203.10 3,590 287 203.15 3,590 359 203.20 3,590 431 203.25 3,590 503 203.30 3,590 574 203.35 3,590 646 203.40 3,590 718 203.45 3,590 868 203.50 3,590 1,017 203.55 3,590 1,166 203.60 3,590 1,315 203.65 3,590 1,464 203.70 3,590 1,612 203.75 3,590 1,759 203.80 3,590 1,906 203.85 3,590 2,053 203.90 3,590 2,199 203.95 3,590 2,344 204.00 3,590 2,488 204.05 3,590 2,632 204.10 3,590 2,775 204.15 3,590 2,918 204.20 3,590 3,059 204.25 3,590 3,200 204.30 3,590 3,340 204.35 3,590 3,479 204.40 3,590 3,618 204.45 3,590 3,755 204.50 3,590 3,892 204.55 3,590 4,027 204.60 3,590 4,161 204.65 3,590 4,295 204.70 3,590 4,427 204.75 3,590 4,558 204.80 3,590 4,687 204.85 3,590 4,816 204.90 3,590 4,943 204.95 3,590 5,069 205.00 3,590 5,194 205.05 3,590 5,316 205.10 3,590 5,437 205.15 3,590 5,556 205.20 3,590 5,673 205.25 3,590 5,789 205.30 3,590 5,902 205.35 3,590 6,013 205.40 3,590 6,122 205.45 3,590 6,228 Elevation (feet) Surface (sq-ft) Storage (cubic-feet) 205.50 3,590 6,331 205.55 3,590 6,431 205.60 3,590 6,527 205.65 3,590 6,617 205.70 3,590 6,702 205.75 3,590 6,783 205.80 3,590 6,860 205.85 3,590 6,936 205.90 3,590 7,009 205.95 3,590 7,081 206.00 3,590 7,152 206.05 3,590 7,224 206.10 3,590 7,296 206.15 3,590 7,368 206.20 3,590 7,439 206.25 3,590 7,511 206.30 3,590 7,583 206.35 3,590 7,655 206.40 3,590 7,727 Underground detention system outlet control structure first orifice elevation 355 Research Parkway ▪ Meriden, CT 06450 ▪ T (203) 630-1406 ▪ F (203) 630-2615 ▪ www.blcompanies.com An Employee-Owned Company APPENDIX E Drainage Maps ED-1 – Existing Drainage Map PD-1 – Proposed Drainage Map EDA-100DP-1OFFSITEFLOW TONORTHNorwich-New London Turnpike(Connecticut Route 32)30651B51BDRAINAGEA AREATOTAL AREA (S.F.)IMPERVIOUS AREA (S.F.)PERVIOUS AREA (S.F.)PERCENT IMPERVIOUS(%)CNTIME OF CONCETRATIONS(MIN.)EDA-10069,27714,79254,48521.4%686.41"=20'EXISTINGDRAINAGEMAPT.A.H.T.A.H.ED-151B306DesignedReviewedProject No.ScaleDrawnDate210175010/29/2021Desc. REVISIONS DateNo.TitleMONTVILLE, NEW LONDON COUNTY, CONNECTICUT 1967-1981 ROUTE 32Sheet No.Xref (s): ; BD210175001 ; XY210175001 ; XC210175011 CAD File:ED21017500110/27/2021, THOULE, G:\JOBS21\16\2101750\DWG\ED210175001.DWG.ED-1 24X36 20SC.2021 BL COMPANIES, INC. THESE DRAWINGS SHALL NOT BE UTILIZED BY ANY PERSON, FIRM OR CORPORATION WITHOUT THE SPECIFIC WRITTEN PERMISSION OF BL COMPANIES.C100 Constitution Plaza, 10th Floor(860) 249-2200Hartford, CT 06103(860) 249-2400 FaxLand Surveying Environmental Engineering ArchitecturePROPOSED RETAIL DEVELOPMENTNOT FOR CONSTRUCTIONFOR PERMITTING PURPOSES ONLY Norwich-New London Turnpike(Connecticut Route 32)51B51B51B51B30651B51BPDA-100DP-1OFFSITEFLOW TONORTHPDA-320PDA-310PDA-340PDA-330DP-2OFFSITE FLOWTO STREETPDA-200DRAINAGEA AREATOTAL AREA (S.F.)IMPERVIOUS AREA (S.F.)PERVIOUS AREA (S.F.)PERCENT IMPERVIOUS(%)CNTIME OF CONCETRATIONS(MIN.)PDA-10027,1422,48524,6579.2%647.6PDA-2002,1911,46372866.8%866.6PDA-3109,6499,6490100.0%985.0PDA-32010,65010,6500100.0%985.0PDA-33011,5088,5252,98374.1%886.9PDA-3409,8636,4313,43265.2%855.41"=20'PROPOSEDDRAINAGEMAPT.A.H.T.A.H.PD-151B306DesignedReviewedProject No.ScaleDrawnDate210175010/29/2021Desc. REVISIONS DateNo.TitleMONTVILLE, NEW LONDON COUNTY, CONNECTICUT 1967-1981 ROUTE 32Sheet No.Xref (s): ; BD210175001 ; XY210175001 ; XC210175001 ; XC210175002 ; XC210175012 CAD File:PD21017500110/27/2021, THOULE, G:\JOBS21\16\2101750\DWG\PD210175001.DWG.PD-1 24X36 20SC.2021 BL COMPANIES, INC. THESE DRAWINGS SHALL NOT BE UTILIZED BY ANY PERSON, FIRM OR CORPORATION WITHOUT THE SPECIFIC WRITTEN PERMISSION OF BL COMPANIES.C100 Constitution Plaza, 10th Floor(860) 249-2200Hartford, CT 06103(860) 249-2400 FaxLand Surveying Environmental Engineering ArchitecturePROPOSED RETAIL DEVELOPMENTNOT FOR CONSTRUCTIONFOR PERMITTING PURPOSES ONLY 355 Research Parkway ▪ Meriden, CT 06450 ▪ T (203) 630-1406 ▪ F (203) 630-2615 ▪ www.blcompanies.com An Employee-Owned Company APPENDIX F Soil Report Custom Soil Resource Report For State Of Connecticut 355 Research Parkway ▪ Meriden, CT 06450 ▪ T (203) 630-1406 ▪ F (203) 630-2615 ▪ www.blcompanies.com An Employee-Owned Company APPENDIX G Stormwater System Operation and Maintenance Plan Stormwater System Operations and Maintenance Plan For the: Proposed Retail Facility Located at: 1967-1981 Norwich-New London Turnpike Town of Montville, Connecticut Prepared for Submission to: Town of Montville, Connecticut October 29, 2021 Prepared for: Garrett Homes, LLC 59 Field Street Torrington, Connecticut Prepared by: BL Companies 100 Constitution Plaza, 10th Floor Hartford, Connecticut 06103 Phone: (860) 249-2200 Fax: (860) 249-2400 BL Project Number: 2101750 An Employee-Owned Company Contents GENERAL OVERVIEW ............................................................................................................................................. 2 PURPOSE & GOALS .................................................................................................................................................. 2 RESPONSIBLE PARTIES ............................................................................................................................................ 3 LIST OF PERMITS & SPECIAL CONDITIONS .............................................................................................................. 3 MAINTENANCE LOGS AND CHECKLISTS ................................................................................................................... 3 FORMS ...................................................................................................................................................................... 4 EMPLOYEE TRAINING ................................................................................................................................................ 4 SPILL CONTROL ........................................................................................................................................................ 4 STORMWATER MANAGEMENT SYSTEM AND MAINTENANCE................................................................... 5 SYSTEM COMPONENTS ............................................................................................................................................ 5 CATCH BASINS .......................................................................................................................................................... 5 UNDERGROUND INFILTRATION SYSTEM ................................................................................................................... 5 REQUIRE MAINTENANCE........................................................................................................................................... 6 THE REQUIRED MAINTENANCE FOR EACH COMPONENT IS DESCRIBED BELOW: ...................................................... 6 CATCH BASINS AND MANHOLES ............................................................................................................................... 6 UNDERGROUND STORMWATER MANAGEMENT FACILITY ........................................................................................ 6 ADDITIONAL SITE MAINTENANCE ...................................................................................................................... 7 PARKING LOTS .......................................................................................................................................................... 7 LANDSCAPING ........................................................................................................................................................... 7 OUTDOOR STORAGE ................................................................................................................................................ 7 DE-ICING AND SNOW REMOVAL & STORAGE ........................................................................................................... 8 Operations & Maintenance Plan Proposed Retail Facility, Town of Montville, CT 355 Research Parkway ▪ Meriden, CT 06450 ▪ T (203) 630-1406 ▪ F (203) 630-2615 ▪ www.blcompanies.com 2 General Overview This Stormwater Operation and Maintenance Plan shall support the Site Plan Application submitted to the Town of Montville by Garrett Homes, LLC for a proposed retail facility located on Norwich-New London Turnpike. The purpose of this Plan is to establish the Operational and Maintenance requirements of the site during and after construction in order to comply with local and state requirements. The plan shall apply to the parcel, which has a total area of approximately 80,244 SF or 1.84 Acres. The subject parcel described above is bounded to the north by CVS Pharmacy, to the east by woods, to the south by McDonald’s, and to the west by Norwich-New London Turnpike. The proposed topography of the site varies from elevation 219 to 192 and will generally follow the existing drainage patterns to the greatest extent feasible. A series of proposed catch basins and pipes will collect and route the site’s runoff to the respective design points. Primary water quality treatment will be provided in an isolator row within the subsurface infiltration and detention system. The proposed development includes the construction of a +/- 10,700 SF retail building. The development will include parking, landscaping, and additional site and utility improvements typical of commercial development. The proposed development is located entirely within the FEMA Flood Zone X, an area determined to be outside the 0.2% annual chance floodplain. The proposed stormwater management system installed for the parcel complies with the Town of Montville Zoning Regulations, the 2002 Connecticut Guidelines for Soil Erosion, and the 2004 Connecticut Stormwater Quality Manual, latest editions. The following Operations and Maintenance Plan, hereby referred to as Plan, was prepared specifically for the development located within the Town of Montville, Connecticut. The Plan was developed to satisfy the requirements of the Connecticut Department of Energy and Environmental Protection’s 2002 Connecticut Guidelines for Soil Erosion and Sediment Control. Purpose & Goals The purpose of this Plan is to ensure that the stormwater management components are operated in accordance with all approvals and permits. The primary goal is to inform all Operations & Maintenance Plan Proposed Retail Facility, Town of Montville, CT 355 Research Parkway ▪ Meriden, CT 06450 ▪ T (203) 630-1406 ▪ F (203) 630-2615 ▪ www.blcompanies.com 3 property managers on how the system operates and what maintenance items are necessary to protect downstream wetlands and watercourses. The secondary goal is to provide a practical, efficient means of maintenance, planning, and record keeping, verifying permit compliance. Responsible Parties The Property Owner, and other parties as listed below, will be responsible for implementing the Plan for the subject property. Company: Garrett Homes, LLC Business Address: 59 Field Street Torrington, CT 06790 Maintenance inspections shall be performed by a qualified professional. Some utilities located on the site will be owned and maintained by various utility companies in accordance with their standards. The property owner may maintain the service connections and shall coordinate with the corresponding utility provider. List of Permits & Special Conditions The project will receive several permits, which may contain special conditions that require compliance by the property owner and maintenance contractors. This permit may include the following: • Town of Montville –Site Plan Approval, Zoning Permit, Building Permit • State of Connecticut Department of Transportation – Encroachment Permit Maintenance Logs and Checklists The property owner shall keep a record of all maintenance procedures performed, date of inspection/ cleanings, etc. Copies of inspection reports and maintenance records shall be kept on-site and readily available at the request of local municipalities or state authorities. Upon the request by the Town of Montville, all documented inspections, reports, or other supporting information pertaining to this plan shall be provided to the Town annually and submitted per their requirements. The responsibility party shall contact the Town of Montville for any pertinent information not specifically noted within this section. Operations & Maintenance Plan Proposed Retail Facility, Town of Montville, CT 355 Research Parkway ▪ Meriden, CT 06450 ▪ T (203) 630-1406 ▪ F (203) 630-2615 ▪ www.blcompanies.com 4 Forms The following forms shall be developed by the responsible party to record periodic maintenance and inspections. An example of a typical inspection and maintenance form for a catch basin is included within the appendices of this report for reference. All inspection and maintenance forms prepared by the responsible party shall be kept on- site as part of the Stormwater Management Plan. • Annual Checklist • Quarterly Checklist • Monthly Checklist Employee Training The property owner will have an employee-training program, with annual updates, to ensure that the qualified employees charged with maintaining the buildings and grounds do so in accordance with the approved permit conditions. All employees that have maintenance duties will be adequately informed of their responsibilities. Spill Control In addition to the good housekeeping and material management practices discussed in the previous sections of this plan, the following practices will be followed for spill prevention and clean-up: • Manufacturer’s recommended methods for spill clean-up will be clearly posted and site personnel will be made aware of the procedures and the location of the information and cleanup supplies. • Materials and equipment necessary for spill cleanup will be kept in the material storage area on-site. Equipment and materials will include but not be limited to: absorbent booms or mats, brooms, dust pans, mops, rags, gloves, goggles, sand, and plastic and metal trash containers specifically for this purpose. • All spills will be cleaned immediately after discovery. • The spill area will be kept well-ventilated and personnel will wear appropriate protective clothing to prevent injury from contact with hazardous substance. Operations & Maintenance Plan Proposed Retail Facility, Town of Montville, CT 355 Research Parkway ▪ Meriden, CT 06450 ▪ T (203) 630-1406 ▪ F (203) 630-2615 ▪ www.blcompanies.com 5 • Spills of toxic or hazardous material, regardless of size, will be reported to the appropriate State or local government agency. • If a spill occurs, this plan will be adjusted to include measures to prevent this type of spill from reoccurring and how to clean the spill if there is another one. A description of the spill, the cause, and the remediation measures shall also be included. A spill report shall be prepared by the property owner following each occurrence. The spill report shall present a description of the release, including quantity and type of material, date of spill, circumstances leading to the release, location of spill, response actions and personnel, documentation of notifications and corrective measures implemented to prevent reoccurrence. The property owner shall identify an appropriately qualified and trained site employee involved with day-to-day site operations to be the spill prevention and clean-up coordinator. The name(s) of responsible spill personnel shall be posted on-site. Each employee shall be instructed that all spills are to be reported to the spill prevention and clean-up coordinator. Stormwater Management System and Maintenance System Components The stormwater management system has several components that are shown on the Grading and Drainage Plan and perform various functions in capturing, routing, and treating stormwater runoff. A copy of the Grading and Drainage Plan can be found within the appendices of this Plan. Catch Basins Catch basins are stormwater inlets, which capture the site’s runoff and any road sand and floatable debris prior to draining through the storm sewer system. The proposed catch basins (CBs) are equipped with deep sumps with sump depths below the outlet pipe, and hoods over the outlet pipes. Isolator Row and Underground Infiltration System A subsurface infiltration system or underground infiltration system is a series of underground chambers or vaults that are used to infiltrate stormwater runoff. A secondary function is to retain stormwater runoff for a period of time to delay and reduce the peak discharged rates for various design storms. The isolator tow is a Operations & Maintenance Plan Proposed Retail Facility, Town of Montville, CT 355 Research Parkway ▪ Meriden, CT 06450 ▪ T (203) 630-1406 ▪ F (203) 630-2615 ▪ www.blcompanies.com 6 stormwater treatment device located in the first row of chambers within the system. Although difficult to identify from the surface, many systems will have one manhole with a series of orifices called an outlet structure. The infiltration system is typically attached upstream of this structure. An employee can also identify an underground infiltration system by identifying inspection ports at the surface and removing the lid for the required routine inspections. Require Maintenance The required maintenance for each component is described below: Catch Basins and Manholes The property owner is responsible for cleaning the catch basins and manholes on the property. A Connecticut Licensed hauler shall clean the sumps and remove and dispose of removed sediment and debris legally. The collected road sand may be reused for winter sanding but may not be stored on-site. The owner shall contact the local municipality for all requirements related to disposal and reuse of sediment. As part of the hauling contract, the hauler shall notify the property owner in writing where the material is being disposed. Each catch basin shall be inspected every four (4) months, with one (1) inspection occurring during the month of April. Any debris occurring within one foot from the bottom of each sump shall be removed by a Vacuum "Vactor" type, maintenance equipment. The deep sumps of each catch basin contribute to a portion of the required water quality treatment train. Ignoring the buildup of sediment and debris within each structure over time is a violation against State requirements. During the inspection of each catch basin sump, the hoods (where provided) on each of the outlet pipes shall also be inspected. In the event that a hood is damaged or off the hanger, it shall be reset or repaired. The inlet and outlet pipes shall be checked for blockages and shall be cleaned and repaired, as needed. All inlet grates at the surface shall be free of leaves and cleaned out each fall to permit proper flow into each basin and minimize the amount of leaf litter entering the system. Isolator Row and Underground Stormwater Management Facility The isolator row and subsurface infiltration system shall be inspected every six (6) months and in the months of April and October. Each of the inspection ports provided shall be opened and visually checked from the surface. Observation of grit inside of the infiltration system shall be noted and any deposits found to be 2 inches or more, as Operations & Maintenance Plan Proposed Retail Facility, Town of Montville, CT 355 Research Parkway ▪ Meriden, CT 06450 ▪ T (203) 630-1406 ▪ F (203) 630-2615 ▪ www.blcompanies.com 7 measured from the invert of pipe, shall be cleaned and removed. The underground infiltration system qualifies as a Confined Space under OSHA regulations, and any maintenance involving entry into the pipes should comply with OSHA Confined Space Entry Regulations. The chamber system will be visually inspected through the manholes. If deemed necessary, the chambers can be TV inspected. The outlet control structure shall be inspected during the inspection of the underground infiltration system. Each opening in the structure, including orifices and pipe openings, shall be free of debris. Any blockage in flow shall be remove immediately. The manufacture’s recommended inspection and maintenance guide has been included at within the Appendices of this Plan for reference. Additional Site Maintenance Parking Lots Parking lots and sidewalks shall be swept as necessary by the property owner to removed trash and other debris. The property owner will sweep parking lots on the property in the spring to remove winter accumulations of road sand and is requirement to maintain the functionality of the required stormwater quality treatment. Landscaping The management company retained by the property owner shall maintain all landscaped areas. Typical landscaping maintenance shall consist of pruning, mulching, planting, mowing lawns, raking leaves, etc. Use of fertilizers and pesticides will be controlled and limited to minimal amounts necessary for healthy landscape maintenance and as approved by the Town. Established lawn areas shall be maintained at a typical height of 3-1/2”. This will allow the grass to be maintained with minimal impact from weeds and/or pests. Topsoil, brush, leaves, clippings, woodchips, mulch, equipment, and other material shall be stored off site. Outdoor Storage There will be no outdoor storage of hazardous chemicals, de-icing agents, fertilizer, pesticides, or herbicides anywhere around the buildings. Operations & Maintenance Plan Proposed Retail Facility, Town of Montville, CT 355 Research Parkway ▪ Meriden, CT 06450 ▪ T (203) 630-1406 ▪ F (203) 630-2615 ▪ www.blcompanies.com 8 De-icing and Snow Removal & Storage The use of clean sand may be used to aid in traction. Snow shall be shoveled and plowed from sidewalk and parking areas within 24 hours of the storm’s conclusion. Sand accumulation shall be removed from the site at the end of the winter season or appropriate time when seasonal snow has melted. Alternative de-icing methods not specified within this section shall be submitted to the City of New Haven for approval prior to use. MAINTENANCE SCHEDULE During the First Year of Operation: Task: Completion Date: Manager’s Initials: JANUARY: Employee Training Program with Spill Program *Catch Basin Inspection *Isolator Row and Subsurface Stormwater Detention FEBRUARY: *Isolator Row and Subsurface Stormwater Detention MARCH: *Isolator Row and Subsurface Stormwater Detention APRIL: *Catch Basin Inspection *Isolator Row and Subsurface Stormwater Detention Sweeping of Paved Surfaces Shrub Fertilization Lawn Liming (if necessary) JUNE: *Catch Basin Inspection Sweeping of Paved Surfaces SEPTEMBER: *Isolator Row and Subsurface Stormwater Detention Sweeping of Paved Surfaces Tree and Lawn Fertilization DECEMBER: *Catch Basin Inspection *Isolator Row and Subsurface Stormwater Detention Sweeping of Paved Surfaces *NOTE: Use appropriate worksheet found in this plan to conduct the inspection. After the First Year of Operation: FOR YEAR___________________________ Task: Completion Date: Manager’s Initials: JANUARY: Employee Training Program with Spill Program APRIL: *Catch Basin Inspection *Isolator Row and Subsurface Stormwater Detention Sweeping of Paved Surfaces Shrub Fertilization Lawn Liming (if necessary) JUNE: *Catch Basin Inspection Sweeping of Paved Surfaces SEPTEMBER: *Isolator Row and Subsurface Stormwater Detention Sweeping of Paved Surfaces Tree and Lawn Fertilization DECEMBER: *Catch Basin Inspection Sweeping of Paved Surfaces *NOTE: Use appropriate worksheet found in this plan to conduct the inspection. CATCH BASIN / CATCH BASIN INSERT INSPECTION LOG Name of Inspector: Date: Catch Basin ID Condition (circle one) Debris above 1’ within sump? (If yes then catch basin is to be cleaned) Date of Catch Basin/Cleaning (if debris is greater than 1’) Condition of Hood (if applicable, remove trash/debris if necessary) Comments: Excellent Fair Poor Yes No Yes No Excellent Fair Poor Yes No Yes No Excellent Fair Poor Yes No Yes No Excellent Fair Poor Yes No Yes No Excellent Fair Poor Yes No Yes No Excellent Fair Poor Yes No Yes No Excellent Fair Poor Yes No Yes No Excellent Fair Poor Yes No Yes No Excellent On-site Procedures for Inspection and Maintenance of Catch Basin Inserts • Secure traffic and pedestrian traffic with cones, barrels, etc. • Clean surface area around each catch basin. • Remove grates and set aside • Clean grates, remove litter and debris that may be trapped within the grate • Visually inspect condition of outlet hood and remove trash and debris from hood if necessary. • Remove by vactor hose the debris that has been trapped in the trough area. Dispose of in accordance with local, state and federal regulatory agency requirements. Most debris that is captured in the trough or sump area will fall into the non-hazardous waste category. • Visually inspect and check the condition of the trough area. • Replace grate and lockdown as needed. • Un-secure traffic control area. • Complete service report and submit to facility owner. SUBSURFACE STROWMATER DETENTION SYSTEM AND ISOLATOR ROW INSPECTION LOG Name of Inspector: Date: Basin ID Overall condition of Inlet Pipe (circle one) Condition of Facility (circle one) Debris and Sediment Removed from Basin?1 Inlets and Outlets are Clear and Functioning? Date of Cleaning Performed Comments Excellent Fair Poor Excellent Fair Poor Yes No Yes No Excellent Fair Poor Excellent Fair Poor Yes No Yes No Excellent Fair Poor Excellent Fair Poor Yes No Yes No Excellent Fair Poor Excellent Fair Poor Yes No Yes No Excellent Fair Poor Excellent Fair Poor Yes No Yes No Excellent Fair Poor Excellent Fair Poor Yes No Yes No Excellent Fair Poor Excellent Fair Poor Yes No Yes No Excellent Fair Poor Excellent Fair Poor Yes No Yes No Excellent Fair Poor Excellent Fair Poor Yes No Yes No Excellent Fair Poor Excellent Fair Poor Yes No Yes No Excellent Fair Poor Excellent Fair Poor Yes No Yes No Excellent Fair Poor Excellent Fair Poor Yes No Yes No Excellent Fair Poor Excellent Fair Poor Yes No Yes No Excellent Fair Poor Excellent Fair Poor Yes No Yes No Excellent Fair Poor Excellent Fair Poor Yes No Yes No Excellent Fair Poor Excellent Fair Poor Yes No Yes No Excellent Fair Poor Excellent Fair Poor Yes No Yes No Excellent Fair Poor Excellent Fair Poor Yes No Yes No Excellent Fair Poor Excellent Fair Poor Yes No Yes No Excellent Fair Poor Excellent Fair Poor Yes No Yes No Excellent Fair Poor Excellent Fair Poor Yes No Yes No Excellent Fair Poor Excellent Fair Poor Yes No Yes No Excellent Fair Poor Excellent Fair Poor Yes No Yes No Excellent Fair Poor Excellent Fair Poor Yes No Yes No Excellent Fair Poor Excellent Fair Poor Yes No Yes No Excellent Fair Poor Excellent Fair Poor Yes No Yes No 1 – Sediment deposits shall be removed from the subsurface detention basin when the deposited material reaches a height of 2” measured from the top of the stone bedding. 2 Call StormTech at 888.892.2694 for technical and product information or visit www.stormtech.com Isolator Row Field Verification Testing at the University of New Hampshire Stormwater Center StormTech’s patented IsolatorTM Row is a row of chambers wrapped in a geotextile which filters the stormwater trapping pollutants in the row. The Isolator Row provides a way to inspect and maintain the system. Isolator Row Detail StormTech and Stormwater Quality This system achieves a removal efficiency of 80% for TSS which meets most municipal recommended levels for water quality treatment. •Field testing (TARP tier II protocol) of the Isolator Row has been ongoing since December 2006. •Removal efficiencies for TSS have improved as the filter cake has built up on the bottom fabric of the Isolator Row. •Current data shows a TSS removal efficiency which exceeds 80%. Removal Efficiency Results: •Total Suspended Solids = 80% •Phosphorous = 49% •Total Petroleum Hydrocarbons = 90% •Zinc = 53% Inspection and Maintenance The Isolator Row can be inspected through the upstream manhole or optional inspection port. Maintenance is easily accomplished with the JetVac process. The frequency of inspection and maintenance varies by location. Contact StormTech for assistance with inspection and maintenance scheduling. Note:For many applications, the non-woven geotextile over the DC-780, MC-3500 and MC-4500 Isolator Row chambers can be eliminated or substituted with the AASHTO Class 1 woven geotextile. Contact your StormTech representative for assistance. THE MOST ADVANCED NAME IN WATER MANAGEMENT SOLUTIONS™ Isolator ® Row O&M Manual An company SC-740 MC-4500 MC-3500 2 THE MOST ADVANCED NAME IN WATER MANAGEMENT SOLUTIONS TM Looking down the Isolator Row from the manhole opening, woven geotextile is shown between the chamber and stone base. StormTech Isolator Row with Overflow Spillway (not to scale) THE ISOLATOR® ROW INTRODUCTION An important component of any Stormwater Pollution Prevention Plan is inspection and maintenance. The StormTech Isolator Row is a technique to inexpensively enhance Total Suspended Solids (TSS) and Total Phosphorus (TP) removal with easy access for inspection and maintenance. THE ISOLATOR ROW The Isolator Row is a row of StormTech chambers, either SC-160, SC- 310, SC-310-3, SC-740, DC-780, MC-3500 or MC-4500 models, that is surrounded with filter fabric and connected to a closely located manhole for easy access. The fabric-wrapped chambers provide for settling and filtration of sediment as storm water rises in the Isolator Row and ultimately passes through the filter fabric. The open bottom chambers and perforated sidewalls (SC-310, SC- 310-3 and SC-740 models) allow storm water to flow both vertically and horizontally out of the chambers. Sediments are captured in the Isolator Row protecting the storage areas of the adjacent stone and chambers from sediment accumulation. A woven geotextile fabric is placed between the stone and the Isolator Row chambers. The woven geotextile provides a media for stormwater filtration, a durable surface for maintenance, prevents scour of the underlying stone and remains intact during high pressure jetting. A non-woven fabric is placed over the chambers to provide a filter media for flows passing through the perforations in the sidewall of the chamber. The non-woven fabric is not required over the SC-160, DC-780, MC-3500 or MC-4500 models as these chambers do not have perforated side walls. The Isolator Row is typically designed to capture the “first flush” and offers the versatility to be sized on a volume basis or flow rate basis. An upstream manhole provides access to the Isolator Row and typically includes a high flow weir. When flow rates or volumes exceed the Isolator Row weir capacity the water will flow over the weir and discharge through a manifold to the other chambers. Another acceptable design uses one open grate inlet structure. Using a “high/low” design (low invert elevation on the Isolator Row and a higher invert elevation on the manifold) an open grate structure can provide the advantages of the Isolator Row by creating a differential between the Isolator Row and manifold thus allowing for settlement in the Isolator Row. The Isolator Row may be part of a treatment train system. The design of the treatment train and selection of pretreatment devices by the design engineer is often driven by regulatory requirements. Whether pretreatment is used or not, the Isolator Row is recommended by StormTech as an effective means to minimize maintenance requirements and maintenance costs. Note: See the StormTech Design Manual for detailed information on designing inlets for a StormTech system, including the Isolator Row. ECCENTRICHEADER MANHOLEWITHOVERFLOWWEIR STORMTECHISOLATOR ROW OPTIONAL PRE-TREATMENT OPTIONAL ACCESS STORMTECH CHAMBERS INSPECTION The frequency of inspection and maintenance varies by location. A routine inspection schedule needs to be established for each individual location based upon site specific variables. The type of land use (i.e. industrial, commercial, residential), anticipated pollutant load, percent imperviousness, climate, etc. all play a critical role in determining the actual frequency of inspection and maintenance practices. At a minimum, StormTech recommends annual inspections. Initially, the Isolator Row should be inspected every 6 months for the first year of operation. For subsequent years, the inspection should be adjusted based upon previous observation of sediment deposition. The Isolator Row incorporates a combination of standard manhole(s) and strategically located inspection ports (as needed). The inspection ports allow for easy access to the system from the surface, eliminating the need to perform a confined space entry for inspection purposes. If upon visual inspection it is found that sediment has accumulated, a stadia rod should be inserted to determine the depth of sediment. When the average depth of sediment exceeds 3 inches throughout the length of the Isolator Row, clean-out should be performed. MAINTENANCE The Isolator Row was designed to reduce the cost of periodic maintenance. By “isolating” sediments to just one row, costs are dramatically reduced by eliminating the need to clean out each row of the entire storage bed. If inspection indicates the potential need for maintenance, access is provided via a manhole(s) located on the end(s) of the row for cleanout. If entry into the manhole is required, please follow local and OSHA rules for a confined space entries. Maintenance is accomplished with the JetVac process. The JetVac process utilizes a high pressure water nozzle to propel itself down the Isolator Row while scouring and suspending sediments. As the nozzle is retrieved, the captured pollutants are flushed back into the manhole for vacuuming. Most sewer and pipe maintenance companies have vacuum/JetVac combination vehicles. Selection of an appropriate JetVac nozzle will improve maintenance efficiency. Fixed nozzles designed for culverts or large diameter pipe cleaning are preferable. Rear facing jets with an effective spread of at least 45” are best. Most JetVac reels have 400 feet of hose allowing maintenance of an Isolator Row up to 50 chambers long. The JetVac process shall only be performed on StormTech Isolator Rows that have AASHTO class 1 woven geotextile (as specified by StormTech) over their angular base stone. StormTech Isolator Row (not to scale) ISOLATOR ROW INSPECTION/MAINTENANCE Note: Non-woven fabric is only required over the inlet pipe connection into the end cap for SC-160LP, DC-780, MC-3500 and MC-4500 chamber models and is not required over the entire Isolator Row. ISOLATOR ROW STEP BY STEP MAINTENANCE PROCEDURES STEP 1Inspect Isolator Row for sediment. A) Inspection ports (if present) i. Remove lid from floor box frame ii. Remove cap from inspection riser iii. Using a flashlight and stadia rod,measure depth of sediment and record results on maintenance log. iv. If sediment is at or above 3 inch depth, proceed to Step 2. If not, proceed to Step 3. B) All Isolator Rows i. Remove cover from manhole at upstream end of Isolator Row ii. Using a flashlight, inspect down Isolator Row through outlet pipe 1. Mirrors on poles or cameras may be used to avoid a confined space entry 2. Follow OSHA regulations for confined space entry if entering manhole iii. If sediment is at or above the lower row of sidewall holes (approximately 3 inches), proceed to Step 2. If not, proceed to Step 3. STEP 2Clean out Isolator Row using the JetVac process. A) A fixed floor cleaning nozzle with rear facing nozzle spread of 45 inches or more is preferable B) Apply multiple passes of JetVac until backflush water is clean C) Vacuum manhole sump as required STEP 3 Replace all caps, lids and covers, record observations and actions. STEP 4Inspect & clean catch basins and manholes upstream of the StormTech system. ADS “Terms and Conditions of Sale” are available on the ADS website, www.ads-pipe.com The ADS logo and the Green Stripe are registered trademarks of Advanced Drainage Systems, Inc. Stormtech® and the Isolator® Row are registered trademarks of StormTech, Inc. © 2018 Advanced Drainage Systems, Inc. #11011 08/18 CS An company Advanced Drainage Systems, Inc. 4640 Trueman Blvd., Hilliard, OH 43026 1-800-821-6710 www.ads-pipe.com SAMPLE MAINTENANCE LOG Date Stadia Rod Readings Sediment Depth (1)–(2)Observations/Actions InspectorFixed point to chamber bottom (1)Fixed point to top of sediment (2) 3/15/11 6.3 ft none New installation. Fixed point is CI frame at grade DJM 9/24/11 6.2 0.1 ft Some grit felt SM 6/20/13 5.8 0.5 ft Mucky feel, debris visible in manhole and in Isolator Row, maintenance due NV 7/7/13 6.3 ft 0 System jetted and vacuumed DJM