STORMWATER MANAGEMENT PLAN

Transcription

1 STORMWATER MANAGEMENT PLAN GLEN LAKE APARTMENTS Minnetonka, MN DATE: PREPARED FOR: Campion Engineering Services, Inc Pioneer Creek Center Maple Plain, MN PREPARED BY: Civil Methods, Inc Livingston Avenue, Ste. 104 West St. Paul, MN ENGINEER CERTIFICATION: I hereby certify that this plan, specification, or report was prepared by me or under my direct supervision and that I am a duly licensed Professional Engineer under the laws of the State of Minnesota. Name: David Poggi, PE Signed: Date: Registration: MN No

2 Table of Contents 1. INTRODUCTION SITE DESCRIPTION STORMWATER QUANTITY & QUALITY VOLUME CONTROL & WATER QUALITY RATE CONTROL... 2 APPENDIX A SOILS INFORMATION APPENDIX B DRAINAGE DIAGRAMS APPENDIX C SUBCATCHMENT DATA APPENDIX D HYDROCAD OUTPUT Glen Lake Apts - SWMP October, 2018 Page i

3 1. INTRODUCTION The Glen Lake Apartments development is proposed to be located at the existing residential property at Excelsior Blvd., Minnetonka, MN. The development will include removal of the existing home for construction of a 60-unit, 3-story apartment complex. In addition to the new building, construction will include improved entrances to the north and south, parking lot pavements, stormwater management infrastructure, and other associated appurtenances. The project will include disturbance of approximately 1.2 acres and will increase impervious area to 0.69 acres. This level of construction activity must meet the stormwater management requirements of the City of Minnetonka and the Nine Mile Creek Watershed District (NMCWD). The specific requirements addressed herein: 1) Rate control: Existing flow rates must not be exceeded for the 2-year (2.9 ), 10-year (4.3 ) and 100-year (7.3 ) rainfall events. [City & NMCWD] 2) Abstraction of 1.0 of runoff from the site impervious area, provided soils are suitable for infiltration. [City]. 1.1 abstraction required by NMCWD 3) Water quality: Removal of 60% TP and 90% TSS, annually. [City & NMCWD] 4) Infiltration / filtration practices require pretreatment. 5) Infiltration / filtration practices must draw down within 48 hours. 6) Minimum of 3.0 of separation from bottom of infiltration practice and seasonal high groundwater table. 2. SITE DESCRIPTION The existing parcel contains a house, driveways and open space with lawn and trees. The property includes approximately 7,940 ft 2 of hard surface, while the soils are generally classified as fill material with a mix of organics and silt / clay-sands, underlain by well-draining sand (See Geotechnical Report in Appendix A). The surface soils consist of hydrologic soil group Type B/C, while the underlying soils are high-infiltrating Type A. In the existing condition, stormwater runoff is split to the north and south, with the majority draining to the south (Appendix B). Storm sewer in Excelsior Blvd and Stewart Lane convey water to the northeast and south, respectively. In the proposed condition, the site will be almost entirely disturbed (except for the northeast corner, where trees are being saved) to accommodate the new apartment structure and necessary parking. While drainage patterns will remain generally unchanged, the new building, Glen Lake Apts - SWMP Page 1 October, 2018

4 drive and parking areas will increase impervious area on the property by 29,876 ft 2, to a total of 37,816 ft 2. Stormwater BMPs will be added to the site to meet quality and quantity standards of the City and Watershed District. 3. STORMWATER QUANTITY & QUALITY 3.1 VOLUME CONTROL & WATER QUALITY While much of the property is not suitable for infiltration due to the presence of tight soils at the surface, an underground arch chamber system is proposed to store and infiltrate water into the suitable soils available at depth. If the required volume equal to 1.1 over the site impervious area is abstracted through infiltration practices, then the required treatment goal (60% TP and 90% TSS reduction) is inherently met. The required abstraction volume calculation is summarized in the Subcatchment Data table in Appendix C, resulting from the following calculation: 1.1 x Impervious Area = (1/12) ft x 37,816 ft 2 = 3,466 ft 3 required The amount of storage provided in the StormTech MC-3500 chamber system is designed to infiltrate this volume, as well as detain higher flows to mitigate discharge rates from the site. The chamber gallery will consist of 3 rows of arch chambers encased in rock, roughly 141 long, with a bed elevation of and outlet pipe elevation of The volume stored for infiltration below the chamber outlet elevation (within rock voids and bottom portion of chambers) is 3,796 ft 3, exceeding the water quality / abstraction volume required for the site. Pretreatment will be provided in the form of a sumped manhole or an isolator row to provide a maintainable area for sediment accumulation and pretreatment. The isolator row can be easily jetted and vacuumed to restore the infiltration and pretreatment capacity. 3.2 RATE CONTROL The configuration and outlet works associated with the proposed arch chamber gallery discussed above will mitigate stormwater discharge rate from the site. Remaining small areas of the property on the north and south sides will drain directly offsite; these areas are also factored into the H&H calculations. The existing and proposed site conditions have been modeled with the HydroCAD modeling software using the TR-20 methodology and Atlas 14 design rainfall amounts. Glen Lake Apts - SWMP Page 2 October, 2018

5 The stormwater BMP as designed will mitigate the increased runoff flow rates associated with the new impervious area, for the 2-, 10-, and 100-year, 24-hour design storms. Model results are shown in Table 1: Node, ID Existing (cfs) Table 1: Flow Rate Comparison 2-Year, 2.9" 10-Year, 4.3" 100-Year, 7.3" Proposed (cfs) Existing (cfs) Proposed (cfs) Existing (cfs) Proposed (cfs) 1R R Glen Lake Apts - SWMP Page 3 October, 2018

6 Appendix A Soils Information

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8 L O G O F B O R I N G (See Descriptive Terminology sheet for explanation of abbreviations) Braun Project B GEOTECHNICAL EVALUATION Glen Lake Condo - GEO Excelsior Boulevard Minnetonka, Minnesota DRILLER: Elev. feet Depth feet 0.0 J. Tatro Symbol FILL FILL SP METHOD: 3 1/4" HSA, Autohammer Description of Materials (Soil-ASTM D2488 or D2487, Rock-USACE EM ) FILL: Silty Sand, fine- to medium-grained, with roots, dark brown, moist. (Topsoil Fill) FILL: Poorly Graded Sand with Silt, fine- to medium-grained, trace Gravel and fibers, brown, moist. POORLY GRADED SAND, fine- to coarse-grained, with Gravel, brown, moist, loose to medium dense. (Glacial Outwash) BORING: LOCATION: N: ; E: See attached sketch. DATE: 7/16/18 SCALE: 1" = 4' BPF WL MC % 2 ST-1 P200 % 4 Tests or Notes / / / / / / / / / / / / / Proposed Lowest Level Elevation=937 See attached Grain-Size Accumulation Curve. 14 LOG OF BORING N:\GINT\PROJECTS\AX PROJECTS\2018\06821.GPJ BRAUN_V8_CURRENT.GDT 8/1/18 15: B SP POORLY GRADED SAND, fine-grained, brown, moist, medium dense. (Glacial Outwash) END OF BORING. Water not observed while drilling. Boring then grouted. Braun Intertec Corporation ST-1 page 1 of 1

9 L O G O F B O R I N G (See Descriptive Terminology sheet for explanation of abbreviations) Braun Project B GEOTECHNICAL EVALUATION Glen Lake Condo - GEO Excelsior Boulevard Minnetonka, Minnesota DRILLER: Elev. feet Depth feet 0.0 J. Tatro Symbol FILL FILL FILL FILL SP METHOD: 3 1/4" HSA, Autohammer Description of Materials (Soil-ASTM D2488 or D2487, Rock-USACE EM ) FILL: Silty Sand, fine- to medium-grained, with roots, dark brown, moist. (Topsoil Fill) FILL: Poorly Graded Sand with Silt, fine- to medium-grained, trace Gravel, brown, moist. FILL: Silty Sand, fine- to medium-grained, trace organics and Gravel, black to dark brown, moist. FILL: Poorly Graded Sand with Silt, fine- to medium-grained, trace Gravel, brown, moist. POORLY GRADED SAND, fine- to coarse-grained, with Gravel, brown, moist, loose to medium dense. (Glacial Outwash) BORING: LOCATION: N: ; E: See attached sketch. DATE: 7/16/18 SCALE: 1" = 4' BPF WL MC % 7 ST-2 / / / / / / / / / / / / / Proposed Lowest Level Elevation=937 OC=2% Tests or Notes 15 LOG OF BORING N:\GINT\PROJECTS\AX PROJECTS\2018\06821.GPJ BRAUN_V8_CURRENT.GDT 8/1/18 15: B END OF BORING. Water not observed while drilling. Boring then grouted. Braun Intertec Corporation ST-2 page 1 of 1

10 L O G O F B O R I N G (See Descriptive Terminology sheet for explanation of abbreviations) Braun Project B GEOTECHNICAL EVALUATION Glen Lake Condo - GEO Excelsior Boulevard Minnetonka, Minnesota DRILLER: Elev. feet Depth feet 0.0 J. Tatro Symbol FILL FILL FILL METHOD: 3 1/4" HSA, Autohammer Description of Materials (Soil-ASTM D2488 or D2487, Rock-USACE EM ) FILL: Clayey Sand, with roots, dark brown, moist. (Topsoil Fill) FILL: Poorly Graded Sand with Silt, fine- to medium-grained, trace Gravel, mixed with occasional Silty Sand and Sandy Lean Clay layers, brown, moist. FILL: Silty Sand, fine- to medium-grained, with organics, trace Gravel, brown, moist. BORING: LOCATION: N: ; E: See attached sketch. DATE: 7/16/18 SCALE: 1" = 4' BPF WL MC % 6 ST-3 P200 % 9 Tests or Notes / / / / / / / / / / / / / Proposed Lowest Level Elevation= FILL FILL: Clayey Sand, trace fibers, dark brown, moist LOG OF BORING N:\GINT\PROJECTS\AX PROJECTS\2018\06821.GPJ BRAUN_V8_CURRENT.GDT 8/1/18 15: B SC SP CLAYEY SAND, brown, moist, stiff. (Glacial Till) POORLY GRADED SAND, fine- to medium-grained, tan, moist, medium dense. (Glacial Outwash) END OF BORING. Water not observed while drilling. Boring then grouted. Braun Intertec Corporation ST-3 page 1 of 1

11 L O G O F B O R I N G (See Descriptive Terminology sheet for explanation of abbreviations) Braun Project B GEOTECHNICAL EVALUATION Glen Lake Condo - GEO Excelsior Boulevard Minnetonka, Minnesota DRILLER: Elev. feet Depth feet 0.0 J. Tatro Symbol FILL FILL SP METHOD: 3 1/4" HSA, Autohammer Description of Materials BORING: DATE: (Soil-ASTM D2488 or D2487, Rock-USACE EM ) FILL: Silty Sand, fine- to medium-grained, with roots, dark brown, moist. (Topsoil Fill) FILL: Silty Sand, fine- to medium-grained, mixed with Clayey Sand, brown, moist. POORLY GRADED SAND, fine- to coarse-grained, with Gravel, light brown, moist, loose to medium dense. (Glacial Outwash) LOCATION: N: ; E: See attached sketch. 7/16/18 SCALE: 1" = 4' BPF 13* 8 12 WL ST-4 Tests or Notes *No recovery. Sampled from auger cuttings. / / / / / / / / / / / / / Proposed Lowest Level Elevation= LOG OF BORING N:\GINT\PROJECTS\AX PROJECTS\2018\06821.GPJ BRAUN_V8_CURRENT.GDT 8/1/18 15: B END OF BORING. Water not observed while drilling. Boring then grouted. Braun Intertec Corporation ST-4 page 1 of 1

12 L O G O F B O R I N G (See Descriptive Terminology sheet for explanation of abbreviations) Braun Project B GEOTECHNICAL EVALUATION Glen Lake Condo - GEO Excelsior Boulevard Minnetonka, Minnesota DRILLER: Elev. feet Depth feet 0.0 J. Tatro Symbol FILL FILL FILL SP- SM METHOD: 3 1/4" HSA, Autohammer Description of Materials (Soil-ASTM D2488 or D2487, Rock-USACE EM ) FILL: Clayey Sand, with roots, dark brown, moist. (Topsoil Fill) FILL: Silty Sand, fine- to medium-grained, mixed with Sandy Lean Clay, brown, moist. FILL: Silty Sand, fine- to medium-grained, trace organics, black, moist. POORLY GRADED SAND with SILT, fine- to coarse-grained, with Gravel, brown, moist, loose. (Glacial Outwash) BORING: LOCATION: N: ; E: See attached sketch. DATE: 7/16/18 SCALE: 1" = 4' BPF WL MC % ST-5 P200 % Tests or Notes / / / / / / / / / / / / / Proposed Lowest Level Elevation=937 OC=3% 4 9 LOG OF BORING N:\GINT\PROJECTS\AX PROJECTS\2018\06821.GPJ BRAUN_V8_CURRENT.GDT 8/1/18 15: B SP POORLY GRADED SAND, fine- to coarse-grained, with Gravel, light brown, moist, loose to medium dense. (Glacial Outwash) END OF BORING. Water not observed while drilling. Boring then grouted. Braun Intertec Corporation ST-5 page 1 of 1

13 L O G O F B O R I N G (See Descriptive Terminology sheet for explanation of abbreviations) Braun Project B GEOTECHNICAL EVALUATION Glen Lake Condo - GEO Excelsior Boulevard Minnetonka, Minnesota DRILLER: Elev. feet Depth feet 0.0 J. Tatro Symbol PAV FILL FILL SP METHOD: 3 1/4" HSA, Autohammer Description of Materials (Soil-ASTM D2488 or D2487, Rock-USACE EM ) 4 1/2 inches of bituminous over 3 1/2 inches of aggregate base. FILL: Sandy Lean Clay, with Gravel, brown, moist. FILL: Silty Sand, fine- to medium-grained, dark brown to brown, moist. With black seam at approximately 5 feet. POORLY GRADED SAND, fine- to coarse-grained, with Gravel, light brown, moist, medium dense. (Glacial Outwash) BORING: LOCATION: N: ; E: See attached sketch. DATE: 7/16/18 SCALE: 1" = 4' BPF WL MC % 8 ST-6 P200 % 17 Tests or Notes / / / / / / / / / / / / / Proposed Lowest Level Elevation= END OF BORING. 17 Water not observed while drilling. Boring then backfilled. LOG OF BORING N:\GINT\PROJECTS\AX PROJECTS\2018\06821.GPJ BRAUN_V8_CURRENT.GDT 8/1/18 15:48 B Braun Intertec Corporation ST-6 page 1 of 1

14 Descriptive Terminology of Soil Based on Standards ASTM D / a (Unified Soil Classification System) Coarse-grained Soils (more than 50% retained on No. 200 sieve) Fine-grained Soils (50% or more passes the No. 200 sieve) Gravels (More than 50% of coarse fraction retained on No. 4 sieve) Sands (50% or more coarse fraction passes No. 4 sieve) Silts and Clays (Liquid limit less than 50) Silts and Clays (Liquid limit 50 or more) Highly Organic Soils Criteria for Assigning Group Symbols and Group Names Using Laboratory Tests A Clean Gravels (Less than 5% fines C ) Gravels with Fines (More than 12% fines C ) Clean Sands (Less than 5% fines H ) Sands with Fines (More than 12% fines H ) Inorganic Organic Inorganic Organic Soil Classification Group Symbol Group Name B C u 4 and 1 C c 3 D GW Well-graded gravel E C u < 4 and/or (C c < 1 or C c > 3) D GP Poorly graded gravel E Fines classify as ML or MH GM Silty gravel E F G Fines Classify as CL or CH GC Clayey gravel E F G C u 6 and 1 C c 3 D SW Well-graded sand I C u < 6 and/or (C c < 1 or C c > 3) D SP Poorly graded sand I Fines classify as ML or MH SM Silty sand F G I Fines classify as CL or CH SC Clayey sand F G I PI > 7 and plots on or above "A" line J CL Lean clay K L M PI < 4 or plots below "A" line J ML Silt K L M Liquid Limit oven dried Liquid Limit not dried PI plots on or above "A" line PI plots below "A" line Liquid Limit oven dried Liquid Limit not dried <0.75 <0.75 Primarily organic matter, dark in color, and organic odor OL CH Fat clay K L M MH Elastic silt K L M OH PT Peat Organic clay K L M N Organic silt K L M O Organic clay K L M P Organic silt K L M Q A. Based on the material passing the 3-inch (75-mm) sieve. B. If field sample contained cobbles or boulders, or both, add "with cobbles or boulders, or both" to group name. C. Gravels with 5 to 12% fines require dual symbols: GW-GM well-graded gravel with silt GW-GC well-graded gravel with clay GP-GM poorly graded gravel with silt GP-GC poorly graded gravel with clay D. C u = D 60 / D 10 C c = D 2 30 / (D 10 x D 60 ) E. If soil contains 15% sand, add "with sand" to group name. F. If fines classify as CL-ML, use dual symbol GC-GM or SC-SM. G. If fines are organic, add "with organic fines" to group name. H. Sands with 5 to 12% fines require dual symbols: SW-SM well-graded sand with silt SW-SC well-graded sand with clay SP-SM poorly graded sand with silt SP-SC poorly graded sand with clay I. If soil contains 15% gravel, add "with gravel" to group name. J. If Atterberg limits plot in hatched area, soil is CL-ML, silty clay. K. If soil contains 15 to < 30% plus No. 200, add "with sand" or "with gravel", whichever is predominant. L. If soil contains 30% plus No. 200, predominantly sand, add sandy to group name. M. If soil contains 30% plus No. 200 predominantly gravel, add gravelly to group name. N. PI 4 and plots on or above A line. O. PI < 4 or plots below A line. P. PI plots on or above A line. Q. PI plots below A line. Particle Size Identification Boulders... over 12" Cobbles... 3" to 12" Gravel Coarse... 3/4" to 3" (19.00 mm to mm) Fine... No. 4 to 3/4" (4.75 mm to mm) Sand Coarse... No. 10 to No. 4 (2.00 mm to 4.75 mm) Medium... No. 40 to No. 10 (0.425 mm to 2.00 mm) Fine... No. 200 to No. 40 (0.075 mm to mm) Silt... No. 200 (0.075 mm) to.005 mm Clay... <.005 mm Relative Proportions L, M trace... 0 to 5% little... 6 to 14% with... 15% Inclusion Thicknesses lens... 0 to 1/8" seam... 1/8" to 1" layer... over 1" Apparent Relative Density of Cohesionless Soils Very loose... 0 to 4 BPF Loose... 5 to 10 BPF Medium dense to 30 BPF Dense to 50 BPF Very dense... over 50 BPF Consistency of Blows Approximate Unconfined Cohesive Soils Per Foot Compressive Strength Very soft... 0 to 1 BPF... < 1/4 tsf Soft... 2 to 4 BPF... 1/4 to 1/2 tsf Medium... 5 to 8 BPF... 1/2 to 1 tsf Stiff... 9 to 15 BPF... 1 to 2 tsf Very Stiff to 30 BPF... 2 to 4 tsf Hard... over 30 BPF... > 4 tsf Moisture Content: Dry: Absence of moisture, dusty, dry to the touch. Moist: Damp but no visible water. Wet: Visible free water, usually soil is below water table. Drilling Notes: BPF: Numbers indicate blows per foot recorded in standard penetration test, also known as N value. The sampler was set 6 inches into undisturbed soil below the hollow-stem auger. Driving resistances were then counted for second and third 6-inch increments, and added to get BPF. Partial Penetration: If the sampler cannot be driven the full 12 inches beyond the initial 6-inch set, the number of blows for that partial penetration is shown as "No./X" (i.e., 50/2"). If the sampler cannot be advanced beyond the initial 6-inch set, the depth of penetration will be recorded in the Notes column as "No. to set X" (i.e., 50 to set 4"). WH: WH indicates the sampler penetrated soil under weight of hammer and rods alone; driving not required. WR: WR indicates the sampler penetrated soil under weight of rods alone; hammer weight and driving not required. WL: WL indicates the water level measured by the drillers either while drilling or following drilling. Laboratory Tests DD Dry Density, pcf OC Organic content, % PL Plastic limit WD Wet Density, pcf q p Pocket penetrometer strength, tsf LL Liquid limit P200 % Passing #200 sieve MC Moisture conent, % PI Plasticity Index 1/2018

15 Appendix B Drainage Diagrams

16 Print Date: 10/26/ :55 PM File Loc: C:\CM\Civil Methods, Inc\CMI - Documents\7. Projects\0448_CES Glen Lake Apartments SWM\08_DRAWINGS AND SPECIFICATIONS\C3D\0448_WR.dwg R 1R 1a 1P 1 2R 2 1R N31 58'09"W N31 10'55"W S89 48'46"W 1.01 CIVIL METHODS, INC Livingston Avenue, Suite 104 West St. Paul, MN o: EXCELSIOR BLVD. N31 58'09"W STEWART LANE STEWART LANE S54 36'05"W S54 36'05"W N31 10'55"W S60 54'07"W S35 23'55"E STEWART LANE STEWART LANE EXCELSIOR BLVD. LEGEND X SUBCATCHMENT NODE ID X BASIN NODE ID X Feet REACH NODE ID SUBCATCHMENT DELINEATION DRAINAGE DIRECTION S89 48'46"W 1.01 EXISTING CONDITION PROPOSED CONDITION TITLE: SHEET NO: DRAINAGE DIAGRAM GLEN LAKE APARTMENTS - SWMP MINNETONKA, MN FIG1 S60 54'07"W S35 23'55"E

17 Appendix C Subcatchment Data

18 Subcatchment Data Hydrology Parameter Summary Project: Glen Lake Apartments Date: 10/24/2018 CN: Pre-Dev Pre-Dev Location: Minnetonka, MN Watershed: Nine Mile Creek Watershed EXISTING CONDITIONS Area / Region ID Total (sq ft) Total (acre) Imperv. (sq ft) (acre) Imperv. (%) Perv 1 (sq ft) (acre) Perv 1 CN Perv 2 (sq ft) (acre) Perv 2 CN Perv 3 (sq ft) 1, to N % , to S % (acre) Perv 3 CN Total: PROPOSED CONDITIONS Area / Region ID Total (sq ft) Total (acre) Imperv. (sq ft) (acre) Imperv. (%) Perv 1 (sq ft) (acre) Perv 1 CN Perv 2 (sq ft) (acre) Perv 2 CN Perv 3 (sq ft) (acre) Perv 3 CN Rainfall (inches) Infiltration Vol. Req'd Gross Imperv. Infilt. Vol Credit (cu ft) Area, SF 1, to N % a, to N % , to S % Final Net Infilt Vol (cu ft) TOTAL: TOTAL: Civil Methods, Inc. File: _Hydrology and Hydraulics.xlsx

19 Appendix D HydroCAD Output

20 1R To Offsite North 1 Existing to North 2 Existing to South 2R To Offsite South Subcat Reach Pond Link Routing Diagram for _0448 Glen Apt_Exist Prepared by Civil Methods, Inc., Printed 10/26/2018 HydroCAD s/n HydroCAD Software Solutions LLC

21 181025_0448 Glen Apt_Exist MSE 24-hr 3 2-Year Rainfall=2.86" Prepared by Civil Methods, Inc. Printed 10/26/2018 HydroCAD s/n HydroCAD Software Solutions LLC Page 2 Summary for Subcatchment 1: Existing to North Runoff = hrs, Volume= af, Depth= 0.31" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= hrs, dt= 0.01 hrs MSE 24-hr 3 2-Year Rainfall=2.86" Area (sf) CN Description 3, >75% Grass cover, Good, HSG B 3, % Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 2: Existing to South Runoff = hrs, Volume= af, Depth= 0.52" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= hrs, dt= 0.01 hrs MSE 24-hr 3 2-Year Rainfall=2.86" Area (sf) CN Description * 7, Impervious 43, >75% Grass cover, Good, HSG B 51, Weighted Average 43, % Pervious Area 7, % Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 12.0 Direct Entry, Summary for Reach 1R: To Offsite North Inflow Area = ac, 0.00% Impervious, Inflow Depth = 0.31" for 2-Year event Inflow = hrs, Volume= af Outflow = hrs, Volume= af, Atten= 0%, Lag= 0.0 min Routing by Dyn-Stor-Ind method, Time Span= hrs, dt= 0.01 hrs Summary for Reach 2R: To Offsite South Inflow Area = ac, 15.49% Impervious, Inflow Depth = 0.52" for 2-Year event Inflow = hrs, Volume= af Outflow = hrs, Volume= af, Atten= 0%, Lag= 0.0 min

22 181025_0448 Glen Apt_Exist MSE 24-hr 3 2-Year Rainfall=2.86" Prepared by Civil Methods, Inc. Printed 10/26/2018 HydroCAD s/n HydroCAD Software Solutions LLC Page 3 Routing by Dyn-Stor-Ind method, Time Span= hrs, dt= 0.01 hrs

23 181025_0448 Glen Apt_Exist MSE 24-hr 3 10-Year Rainfall=4.26" Prepared by Civil Methods, Inc. Printed 10/26/2018 HydroCAD s/n HydroCAD Software Solutions LLC Page 4 Summary for Subcatchment 1: Existing to North Runoff = hrs, Volume= af, Depth= 0.95" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= hrs, dt= 0.01 hrs MSE 24-hr 3 10-Year Rainfall=4.26" Area (sf) CN Description 3, >75% Grass cover, Good, HSG B 3, % Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 2: Existing to South Runoff = hrs, Volume= af, Depth= 1.31" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= hrs, dt= 0.01 hrs MSE 24-hr 3 10-Year Rainfall=4.26" Area (sf) CN Description * 7, Impervious 43, >75% Grass cover, Good, HSG B 51, Weighted Average 43, % Pervious Area 7, % Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 12.0 Direct Entry, Summary for Reach 1R: To Offsite North Inflow Area = ac, 0.00% Impervious, Inflow Depth = 0.95" for 10-Year event Inflow = hrs, Volume= af Outflow = hrs, Volume= af, Atten= 0%, Lag= 0.0 min Routing by Dyn-Stor-Ind method, Time Span= hrs, dt= 0.01 hrs Summary for Reach 2R: To Offsite South Inflow Area = ac, 15.49% Impervious, Inflow Depth = 1.31" for 10-Year event Inflow = hrs, Volume= af Outflow = hrs, Volume= af, Atten= 0%, Lag= 0.0 min

24 181025_0448 Glen Apt_Exist MSE 24-hr 3 10-Year Rainfall=4.26" Prepared by Civil Methods, Inc. Printed 10/26/2018 HydroCAD s/n HydroCAD Software Solutions LLC Page 5 Routing by Dyn-Stor-Ind method, Time Span= hrs, dt= 0.01 hrs

25 181025_0448 Glen Apt_Exist MSE 24-hr Year Rainfall=7.32" Prepared by Civil Methods, Inc. Printed 10/26/2018 HydroCAD s/n HydroCAD Software Solutions LLC Page 6 Summary for Subcatchment 1: Existing to North Runoff = hrs, Volume= af, Depth= 2.94" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= hrs, dt= 0.01 hrs MSE 24-hr Year Rainfall=7.32" Area (sf) CN Description 3, >75% Grass cover, Good, HSG B 3, % Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 2: Existing to South Runoff = hrs, Volume= af, Depth= 3.56" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= hrs, dt= 0.01 hrs MSE 24-hr Year Rainfall=7.32" Area (sf) CN Description * 7, Impervious 43, >75% Grass cover, Good, HSG B 51, Weighted Average 43, % Pervious Area 7, % Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 12.0 Direct Entry, Summary for Reach 1R: To Offsite North Inflow Area = ac, 0.00% Impervious, Inflow Depth = 2.94" for 100-Year event Inflow = hrs, Volume= af Outflow = hrs, Volume= af, Atten= 0%, Lag= 0.0 min Routing by Dyn-Stor-Ind method, Time Span= hrs, dt= 0.01 hrs Summary for Reach 2R: To Offsite South Inflow Area = ac, 15.49% Impervious, Inflow Depth = 3.56" for 100-Year event Inflow = hrs, Volume= af Outflow = hrs, Volume= af, Atten= 0%, Lag= 0.0 min

26 181025_0448 Glen Apt_Exist MSE 24-hr Year Rainfall=7.32" Prepared by Civil Methods, Inc. Printed 10/26/2018 HydroCAD s/n HydroCAD Software Solutions LLC Page 7 Routing by Dyn-Stor-Ind method, Time Span= hrs, dt= 0.01 hrs

27 1R 1a To Offsite North Proposed Direct to North 1P 1 Underground BMP Proposed to Underground 2 Proposed Direct to South 2R To Offsite South Subcat Reach Pond Link Routing Diagram for _0448 Glen Apt_Prop Prepared by Civil Methods, Inc., Printed 10/26/2018 HydroCAD s/n HydroCAD Software Solutions LLC

28 181025_0448 Glen Apt_Prop MSE 24-hr 3 2-Year Rainfall=2.86" Prepared by Civil Methods, Inc. Printed 10/26/2018 HydroCAD s/n HydroCAD Software Solutions LLC Page 2 Summary for Subcatchment 1: Proposed to Underground Runoff = hrs, Volume= af, Depth= 2.03" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= hrs, dt= 0.01 hrs MSE 24-hr 3 2-Year Rainfall=2.86" Area (sf) CN Description * 31, Impervious 6, >75% Grass cover, Good, HSG B 37, Weighted Average 6, % Pervious Area 31, % Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 1a: Proposed Direct to North Runoff = hrs, Volume= af, Depth= 0.31" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= hrs, dt= 0.01 hrs MSE 24-hr 3 2-Year Rainfall=2.86" Area (sf) CN Description 3, >75% Grass cover, Good, HSG B 3, % Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 2: Proposed Direct to South Runoff = hrs, Volume= af, Depth= 1.03" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= hrs, dt= 0.01 hrs MSE 24-hr 3 2-Year Rainfall=2.86" Area (sf) CN Description 7, >75% Grass cover, Good, HSG B * 6, Roof Direct 14, Weighted Average 7, % Pervious Area 6, % Impervious Area

29 181025_0448 Glen Apt_Prop MSE 24-hr 3 2-Year Rainfall=2.86" Prepared by Civil Methods, Inc. Printed 10/26/2018 HydroCAD s/n HydroCAD Software Solutions LLC Page 3 Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Reach 1R: To Offsite North Inflow Area = ac, 0.00% Impervious, Inflow Depth = 0.31" for 2-Year event Inflow = hrs, Volume= af Outflow = hrs, Volume= af, Atten= 0%, Lag= 0.0 min Routing by Dyn-Stor-Ind method, Time Span= hrs, dt= 0.01 hrs Summary for Reach 2R: To Offsite South Inflow Area = ac, 73.02% Impervious, Inflow Depth = 0.47" for 2-Year event Inflow = hrs, Volume= af Outflow = hrs, Volume= af, Atten= 0%, Lag= 0.0 min Routing by Dyn-Stor-Ind method, Time Span= hrs, dt= 0.01 hrs Summary for Pond 1P: Underground BMP Inflow Area = ac, 82.90% Impervious, Inflow Depth = 2.03" for 2-Year event Inflow = hrs, Volume= af Outflow = hrs, Volume= af, Atten= 96%, Lag= 85.6 min Discarded = hrs, Volume= af Primary = hrs, Volume= af Secondary = hrs, Volume= af Routing by Dyn-Stor-Ind method, Time Span= hrs, dt= 0.01 hrs Peak Elev= hrs Surf.Area= 3,229 sf Storage= 4,252 cf Plug-Flow detention time= (not calculated: outflow precedes inflow) Center-of-Mass det. time= min ( 1, ) Volume Invert Avail.Storage Storage Description #1A ' 4,561 cf 22.75'W x 'L x 5.50'H Field A 17,759 cf Overall - 6,357 cf Embedded = 11,402 cf x 40.0% Voids #2A ' 6,357 cf ADS_StormTech MC-3500 d +Cap x 57 Inside #1 Effective Size= 70.4"W x 45.0"H => sf x 7.17'L = cf Overall Size= 77.0"W x 45.0"H x 7.50'L with 0.33' Overlap 3 Rows of 19 Chambers Cap Storage= cf x 2 x 3 rows = 89.4 cf 10,918 cf Total Available Storage Storage Group A created with Chamber Wizard

30 181025_0448 Glen Apt_Prop MSE 24-hr 3 2-Year Rainfall=2.86" Prepared by Civil Methods, Inc. Printed 10/26/2018 HydroCAD s/n HydroCAD Software Solutions LLC Page 4 Device Routing Invert Outlet Devices #1 Primary ' 10.0" Round Culvert L= 50.0' Ke= Inlet / Outlet Invert= ' / ' S= '/' Cc= n= 0.011, Flow Area= 0.55 sf #2 Discarded ' in/hr Exfiltration over Surface area #3 Secondary ' 27.0" Horiz. Orifice/Grate C= Limited to weir flow at low heads Discarded OutFlow Max= hrs HW=935.57' (Free Discharge) 2=Exfiltration (Exfiltration Controls 0.04 cfs) Primary OutFlow Max= hrs HW=937.47' TW=0.00' (Dynamic Tailwater) 1=Culvert (Barrel Controls fps) Secondary OutFlow Max= hrs HW=935.50' TW=0.00' (Dynamic Tailwater) 3=Orifice/Grate ( Controls 0.00 cfs)

31 181025_0448 Glen Apt_Prop MSE 24-hr 3 10-Year Rainfall=4.26" Prepared by Civil Methods, Inc. Printed 10/26/2018 HydroCAD s/n HydroCAD Software Solutions LLC Page 5 Summary for Subcatchment 1: Proposed to Underground Runoff = hrs, Volume= af, Depth= 3.37" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= hrs, dt= 0.01 hrs MSE 24-hr 3 10-Year Rainfall=4.26" Area (sf) CN Description * 31, Impervious 6, >75% Grass cover, Good, HSG B 37, Weighted Average 6, % Pervious Area 31, % Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 1a: Proposed Direct to North Runoff = hrs, Volume= af, Depth= 0.95" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= hrs, dt= 0.01 hrs MSE 24-hr 3 10-Year Rainfall=4.26" Area (sf) CN Description 3, >75% Grass cover, Good, HSG B 3, % Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 2: Proposed Direct to South Runoff = hrs, Volume= af, Depth= 2.10" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= hrs, dt= 0.01 hrs MSE 24-hr 3 10-Year Rainfall=4.26" Area (sf) CN Description 7, >75% Grass cover, Good, HSG B * 6, Roof Direct 14, Weighted Average 7, % Pervious Area 6, % Impervious Area

32 181025_0448 Glen Apt_Prop MSE 24-hr 3 10-Year Rainfall=4.26" Prepared by Civil Methods, Inc. Printed 10/26/2018 HydroCAD s/n HydroCAD Software Solutions LLC Page 6 Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Reach 1R: To Offsite North Inflow Area = ac, 0.00% Impervious, Inflow Depth = 0.95" for 10-Year event Inflow = hrs, Volume= af Outflow = hrs, Volume= af, Atten= 0%, Lag= 0.0 min Routing by Dyn-Stor-Ind method, Time Span= hrs, dt= 0.01 hrs Summary for Reach 2R: To Offsite South Inflow Area = ac, 73.02% Impervious, Inflow Depth = 1.64" for 10-Year event Inflow = hrs, Volume= af Outflow = hrs, Volume= af, Atten= 0%, Lag= 0.0 min Routing by Dyn-Stor-Ind method, Time Span= hrs, dt= 0.01 hrs Summary for Pond 1P: Underground BMP Inflow Area = ac, 82.90% Impervious, Inflow Depth = 3.37" for 10-Year event Inflow = hrs, Volume= af Outflow = hrs, Volume= af, Atten= 80%, Lag= 15.0 min Discarded = hrs, Volume= af Primary = hrs, Volume= af Secondary = hrs, Volume= af Routing by Dyn-Stor-Ind method, Time Span= hrs, dt= 0.01 hrs Peak Elev= hrs Surf.Area= 3,229 sf Storage= 5,485 cf Plug-Flow detention time= (not calculated: outflow precedes inflow) Center-of-Mass det. time= min ( 1, ) Volume Invert Avail.Storage Storage Description #1A ' 4,561 cf 22.75'W x 'L x 5.50'H Field A 17,759 cf Overall - 6,357 cf Embedded = 11,402 cf x 40.0% Voids #2A ' 6,357 cf ADS_StormTech MC-3500 d +Cap x 57 Inside #1 Effective Size= 70.4"W x 45.0"H => sf x 7.17'L = cf Overall Size= 77.0"W x 45.0"H x 7.50'L with 0.33' Overlap 3 Rows of 19 Chambers Cap Storage= cf x 2 x 3 rows = 89.4 cf 10,918 cf Total Available Storage Storage Group A created with Chamber Wizard

33 181025_0448 Glen Apt_Prop MSE 24-hr 3 10-Year Rainfall=4.26" Prepared by Civil Methods, Inc. Printed 10/26/2018 HydroCAD s/n HydroCAD Software Solutions LLC Page 7 Device Routing Invert Outlet Devices #1 Primary ' 10.0" Round Culvert L= 50.0' Ke= Inlet / Outlet Invert= ' / ' S= '/' Cc= n= 0.011, Flow Area= 0.55 sf #2 Discarded ' in/hr Exfiltration over Surface area #3 Secondary ' 27.0" Horiz. Orifice/Grate C= Limited to weir flow at low heads Discarded OutFlow Max= hrs HW=935.57' (Free Discharge) 2=Exfiltration (Exfiltration Controls 0.04 cfs) Primary OutFlow Max= hrs HW=937.96' TW=0.00' (Dynamic Tailwater) 1=Culvert (Barrel Controls fps) Secondary OutFlow Max= hrs HW=935.50' TW=0.00' (Dynamic Tailwater) 3=Orifice/Grate ( Controls 0.00 cfs)

34 181025_0448 Glen Apt_Prop MSE 24-hr Year Rainfall=7.32" Prepared by Civil Methods, Inc. Printed 10/26/2018 HydroCAD s/n HydroCAD Software Solutions LLC Page 8 Summary for Subcatchment 1: Proposed to Underground Runoff = hrs, Volume= af, Depth= 6.37" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= hrs, dt= 0.01 hrs MSE 24-hr Year Rainfall=7.32" Area (sf) CN Description * 31, Impervious 6, >75% Grass cover, Good, HSG B 37, Weighted Average 6, % Pervious Area 31, % Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 1a: Proposed Direct to North Runoff = hrs, Volume= af, Depth= 2.94" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= hrs, dt= 0.01 hrs MSE 24-hr Year Rainfall=7.32" Area (sf) CN Description 3, >75% Grass cover, Good, HSG B 3, % Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 2: Proposed Direct to South Runoff = hrs, Volume= af, Depth= 4.77" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= hrs, dt= 0.01 hrs MSE 24-hr Year Rainfall=7.32" Area (sf) CN Description 7, >75% Grass cover, Good, HSG B * 6, Roof Direct 14, Weighted Average 7, % Pervious Area 6, % Impervious Area

35 181025_0448 Glen Apt_Prop MSE 24-hr Year Rainfall=7.32" Prepared by Civil Methods, Inc. Printed 10/26/2018 HydroCAD s/n HydroCAD Software Solutions LLC Page 9 Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Reach 1R: To Offsite North Inflow Area = ac, 0.00% Impervious, Inflow Depth = 2.94" for 100-Year event Inflow = hrs, Volume= af Outflow = hrs, Volume= af, Atten= 0%, Lag= 0.0 min Routing by Dyn-Stor-Ind method, Time Span= hrs, dt= 0.01 hrs Summary for Reach 2R: To Offsite South Inflow Area = ac, 73.02% Impervious, Inflow Depth = 4.44" for 100-Year event Inflow = hrs, Volume= af Outflow = hrs, Volume= af, Atten= 0%, Lag= 0.0 min Routing by Dyn-Stor-Ind method, Time Span= hrs, dt= 0.01 hrs Summary for Pond 1P: Underground BMP Inflow Area = ac, 82.90% Impervious, Inflow Depth = 6.37" for 100-Year event Inflow = hrs, Volume= af Outflow = hrs, Volume= af, Atten= 65%, Lag= 7.2 min Discarded = hrs, Volume= af Primary = hrs, Volume= af Secondary = hrs, Volume= af Routing by Dyn-Stor-Ind method, Time Span= hrs, dt= 0.01 hrs Peak Elev= hrs Surf.Area= 3,229 sf Storage= 8,997 cf Plug-Flow detention time= (not calculated: outflow precedes inflow) Center-of-Mass det. time= min ( 1, ) Volume Invert Avail.Storage Storage Description #1A ' 4,561 cf 22.75'W x 'L x 5.50'H Field A 17,759 cf Overall - 6,357 cf Embedded = 11,402 cf x 40.0% Voids #2A ' 6,357 cf ADS_StormTech MC-3500 d +Cap x 57 Inside #1 Effective Size= 70.4"W x 45.0"H => sf x 7.17'L = cf Overall Size= 77.0"W x 45.0"H x 7.50'L with 0.33' Overlap 3 Rows of 19 Chambers Cap Storage= cf x 2 x 3 rows = 89.4 cf 10,918 cf Total Available Storage Storage Group A created with Chamber Wizard

36 181025_0448 Glen Apt_Prop MSE 24-hr Year Rainfall=7.32" Prepared by Civil Methods, Inc. Printed 10/26/2018 HydroCAD s/n HydroCAD Software Solutions LLC Page 10 Device Routing Invert Outlet Devices #1 Primary ' 10.0" Round Culvert L= 50.0' Ke= Inlet / Outlet Invert= ' / ' S= '/' Cc= n= 0.011, Flow Area= 0.55 sf #2 Discarded ' in/hr Exfiltration over Surface area #3 Secondary ' 27.0" Horiz. Orifice/Grate C= Limited to weir flow at low heads Discarded OutFlow Max= hrs HW=935.57' (Free Discharge) 2=Exfiltration (Exfiltration Controls 0.04 cfs) Primary OutFlow Max= hrs HW=939.56' TW=0.00' (Dynamic Tailwater) 1=Culvert (Barrel Controls fps) Secondary OutFlow Max= hrs HW=935.50' TW=0.00' (Dynamic Tailwater) 3=Orifice/Grate ( Controls 0.00 cfs)

37 181025_0448 Glen Apt_Prop MSE 24-hr Year Rainfall=7.32" Prepared by Civil Methods, Inc. Printed 10/26/2018 HydroCAD s/n HydroCAD Software Solutions LLC Page 1 Stage-Area-Storage for Pond 1P: Underground BMP Elevation (feet) Surface (sq-ft) Storage (cubic-feet) , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , ,229 1, ,229 1, ,229 1, ,229 1, ,229 1, ,229 1, ,229 1, ,229 1, ,229 1, ,229 1, ,229 1, ,229 1, ,229 1, ,229 1, ,229 1,817 Elevation (feet) Surface (sq-ft) Storage (cubic-feet) ,229 1, ,229 1, ,229 1, ,229 2, ,229 2, ,229 2, ,229 2, ,229 2, ,229 2, ,229 2, ,229 2, ,229 2, ,229 2, ,229 2, ,229 2, ,229 2, ,229 2, ,229 2, ,229 2, ,229 2, ,229 2, ,229 3, ,229 3, ,229 3, ,229 3, ,229 3, ,229 3, ,229 3, ,229 3, ,229 3, ,229 3, ,229 3, ,229 3, ,229 3, ,229 3, ,229 3, ,229 3, ,229 3, ,229 3, ,229 3, ,229 4, ,229 4, ,229 4, ,229 4, ,229 4, ,229 4, ,229 4, ,229 4, ,229 4, ,229 4, ,229 4, ,229 4, ,229 4, ,229 4,678

38 STORM SEWER DESIGN GLEN LAKE APARTMENTS OCTOBER 26, 2018 CES PROJECT NO DESIGNED BY: YEAR STORM: MANNINGS "N": MPC STRUCTURE NO. LENGTH AREA (ACRES) TIME OF CONC. "C" OF NEW "I" RUNOFF SLOPE PIPE DESIGN VALUES UPSTREAM STRUCT. DOWNSTREAM STRUCT. UPSTRM DWNSTRM (FEET) INCR. TOTAL TO INLET IN PIPE INCREASE "C" (IN/HR) (CFS) (%) DIA. (IN) Q (CFS) V (FT/SEC) RIM INVERT RIM INVERT CB1 CBMH CB 2 CBMH CBMH 3 CBMH CBMH 2 CBMH CBMH 1 STORMCEPTO