BROADSTONE VANTAGE POINT APARTMENTS NE corner of S. Parker Road, and E. Cottonwood Drive Parker, Colorado

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1 BROADSTONE VANTAGE POINT APARTMENTS NE corner of S. Parker Road, and E. Cottonwood Drive Parker, Colorado PRELIMINARY DRAINAGE REPORT Strategic Land Solutions, Inc. JN: Report Date/History: July Prepared for: ATTN: Mr. Harsh Parikh - Principal harsh@parikhstevens.com ATTN: Mr. Andy Clay Managing Director (Mountain Region) 44 Cook Street, Suite 400, Denver, CO Denver, Colorado Phone: (303) Fax: (303) aclay@allresco.com Prepared by: Robert J. Palmer, P.E., as President Strategic Land Solutions, Inc Ponderosa Road Franktown, CO Phone (720) rpalmer@strategicls.net

2 Copyright by Strategic Land Solutions, Inc. All rights reserved. This report or parts thereof may not be reproduced in any form, stored in a retrieval system, or transmitted in any form by any means electronic, mechanical, photocopy, recording, or otherwise without prior written permission of Strategic Land Solutions, Inc., except as provided by United States of America copyright law. Published by Strategic Land Solutions, Inc. (2595 Ponderosa Road, Franktown, CO 80116, phone)

3 Vantage Point (S. Parker Rd. & E. Cottonwood Dr. Parker, CO) DRAINAGE REPORT Tuesday July 14, 2015 Page i TABLE OF CONTENTS TABLE OF CONTENTS... i DEVELOPER S CERTIFICATION... ii 1. GENERAL LOCATION AND DESCRIPTION LOCATION DESCRIPTION OF PROPERTY DRAINAGE BASINS AND SUB-BASINS MAJOR BASIN DESCRIPTION SUB-BASIN DESCRIPTION DRAINAGE DESIGN CRITERIA REGULATIONS DEVELOPMENT RESTRAINTS... 4 HYDROLOGIC CRITERIA HYDRAULIC CRITERIA WATER QUALITY REQUIREMENTS... 4 WAIVERS FROM CRITERIA DRAINAGE FACILITY DESIGN GENERAL CONCEPT... 4 SPECIFIC DETAILS MAINTENANCE PLAN CONCLUSIONS COMPLIANCE WITH STANDARDS DESIGN REFERENCES... 7 LIST OF FIGURES Figure 1 - SITE LOCATION MAP... 1 Figure 2 - SITE LOCATION ENLARGEMENT... 1 APPENDIX A: HYDROLOGIC COMPUTATIONS APPENDIX B: HYDRAULIC COMPUTATIONS APPENDIX C: MAP POCKET APPENDICES

4 Vantage Point (S. Parker Rd. & E. Cottonwood Dr. Parker, CO) DRAINAGE REPORT Tuesday July 14, 2015 Page ii ENGINEER S CERTIFICATION This STORMWATER MANAGEMENT REPORT was prepared by me or under my direct supervision in accordance with the provisions of the Town of Parker Storm Drain and Environmental Manual for the owners thereof. It is understood that the Town of Parker does not and will not assume liability for the drainage facilities designed by others. SIGNATURE: Robert J. Palmer, PE CO PE #36320 DEVELOPER S CERTIFICATION THE PROPERTY OWNER (hereinafter DEVELOPER) hereby certifies that the drainage facilities for the project detailed within this Report will be constructed according to the design presented. It is understood that the Town of Parker does not and will not assume liability for the drainage facilities designed and/or certified by my engineer and that the Town of Parker reviews drainage plans pursuant to Colorado Revised Statutes, Title 24, Article 28; but cannot, on behalf of DEVELOPER, guarantee that final drainage design review will absolve DEVELOPER and/or their successor and/or assigns of future liability for improper design. SIGNATURE: Printed Name Title

5 Vantage Point (S. Parker Rd. & E. Cottonwood Dr. Parker, CO) DRAINAGE REPORT Tuesday July 14, 2015 Page 1 1. GENERAL LOCATION AND DESCRIPTION 1.1. LOCATION The planned Apartment Building will consist of 400-apartment units located at NE corner of S. Parker Road and E. Cottonwood Drive within the northeast ¼ of Section 4, Township 6 South, Range 66 West of the 6 th Principal Meridian, Town of Parker, State of Colorado. The site is bounded on the north by rural residential property, on the West by S. Parker Road, south by E. Cottonwood Drive, and east by a vacant land. Figure 1 - SITE LOCATION MAP Figure 2 - SITE LOCATION ENLARGEMENT 1.2. DESCRIPTION OF PROPERTY The site is approximately 16.5 acres total (to be developed with phase 1) and consists of vacant land. The site specific development improvements will consist of 400-apartment units located in multiple buildings, a club house, swimming pool / deck area, with associated parking, drives, landscaping, water quality, and detention facilities. 2. DRAINAGE BASINS AND SUB-BASINS 2.1. MAJOR BASIN DESCRIPTION The site lies within the Cherry Creek Drainage Basin. Runoff from the existing site generally flows overland north to south at approximately 5% slope. Runoff from the project sheet flows to a swale along E. Cottonwood Drive, where it is conveyed to a culvert under S. Parker Road, and ultimately to Cherry Creek. The project is located within Flood Zone X, as shown on the National Flood Insurance Program s Flood Insurance Rate Map (FIRM), Douglas County, Panel 67 of 495, Community Panel Number 08035C0067F, with an Effective Date of September 30, According the National Resource Council Soil (NRCS) web site, the onsite soil consists of Bresser sandy loam (0.2%), Bresser-Truckton sandy loam(66.9%), and Sampson loam (32.9%), all of which have a hydraulic soils classification type B. According to the site Geotechnical Report prepared by PSI Consulting, groundwater was encountered at 19-feet to 24-feet below the existing ground. As such, no dewatering is expected as part of the storm drain improvements. There are no major drainage ways crossing the site. There is an existing drainage swale along E. Cottonwood Drive which will be routed through the proposed detention pond.

6 Vantage Point (S. Parker Rd. & E. Cottonwood Dr. Parker, CO) DRAINAGE REPORT Tuesday July 14, 2015 Page SUB-BASIN DESCRIPTION Under proposed conditions, the site is roughly divided into 28 drainage sub-basins. All runoff from the project, except for a small area between the buildings and the streets, will be by roof drains, and catch basins, where it will be conveyed underground to the full spectrum detention pond located at the corner of E. Cottonwood Drive, and S. Parker Road. The following is a description of the 28 proposed sub-basins: Basin A contains approximately 0.62 acre, and is comprised of the club house and adjacent drives and parking. Runoff from this area is captured by roof drains and a catch basin, where it will be conveyed underground to the detention pond. Basin B contains approximately 0.59 acre, and is comprised of building roof tops, drive aisles, parking, and landscaping. Runoff from this area is captured by roof drains and a catch basin, where it will be conveyed underground to the detention pond. Basin C contains approximately 0.39 acre, and is comprised of building roof tops, drive aisles, parking, and landscaping. Runoff from this area is captured by roof drains and a catch basin, where it will be conveyed underground to the detention pond. Basin D contains approximately 0.32 acre, and is comprised of the main road leading into the site. Runoff from this area is captured by a catch basin, where it will be conveyed underground to the detention pond. Basin E contains approximately 0.42 acre, and is comprised of the main road leading into the site. Runoff from this area is captured by a catch basin, where it will be conveyed underground to the detention pond. Basin F contains approximately 0.31 acre, and is comprised of the main road leading into the site. Runoff from this area is captured by a catch basin, where it will be conveyed underground to the detention pond. Basin G contains approximately 0.61 acre, and is comprised of the main road leading into the site. Runoff from this area is captured by a catch basin, where it will be conveyed underground to the detention pond. Basin H contains approximately 0.80 acre, and is comprised of the pool deck area. runoff from this area will be collected in area inlets and grate inlets, where it will be conveyed underground to the detention pond. Basin I contains approximately 0.90 acre, and is comprised of building roof tops, drive aisles, parking, and landscaping. Runoff from this area is captured by roof drains and a catch basin, where it will be conveyed underground to the detention pond. Basin J contains approximately 0.14 acre, and is comprised of drive aisles, parking, and landscaping. Runoff from this area is captured by a catch basin, where it will be conveyed underground to the detention pond. Basin K contains approximately 0.09 acre, and is comprised of drive aisles, parking, and landscaping. Runoff from this area is captured by a catch basin, where it will be conveyed underground to the detention pond. Basin L contains approximately 0.18 acre, and is comprised of drive aisles, parking, and landscaping. Runoff from this area is captured by a catch basin, where it will be conveyed underground to the detention pond. Basin M contains approximately 0.28 acre, and is comprised of drive aisles, parking, and landscaping. Runoff from this area is captured by a catch basin, where it will be conveyed underground to the detention pond. Basin N contains approximately 0.68 acre, and is comprised of building roof tops, drive aisles, parking, and landscaping. Runoff from this area is captured by roof drains and a catch basin, where it will be conveyed underground to the detention pond.

7 Vantage Point (S. Parker Rd. & E. Cottonwood Dr. Parker, CO) DRAINAGE REPORT Tuesday July 14, 2015 Page 3 Basin O contains approximately 0.08 acre, and is comprised of drive aisles, parking, and landscaping. Runoff from this area is captured by a catch basin, where it will be conveyed underground to the detention pond. Basin P contains approximately 0.27 acre, and is comprised of drive aisles, parking, and landscaping. Runoff from this area is captured by a catch basin, where it will be conveyed underground to the detention pond. Basin Q contains approximately 0.53 acre, and is comprised of drive aisles, parking, and landscaping. Runoff from this area is captured by a catch basin, where it will be conveyed underground to the detention pond. Basin R contains approximately 0.26 acre, and is comprised of building roof tops, drive aisles, parking, and landscaping. Runoff from this area is captured by roof drains and a catch basin, where it will be conveyed underground to the detention pond. Basin S contains approximately 0.55 acre, and is comprised of building roof tops, drive aisles, parking, and landscaping. Runoff from this area is captured by roof drains and a catch basin, where it will be conveyed underground to the detention pond. Basin T contains approximately 0.58 acre, and is comprised of building roof tops, drive aisles, parking, and landscaping. Runoff from this area is captured by roof drains and a catch basin, where it will be conveyed underground to the detention pond. Basin U contains approximately 1.05 acre, and is comprised of building roof tops, drive aisles, parking, and landscaping. Runoff from this area is captured by roof drains and a catch basin, where it will be conveyed underground to the detention pond. Basin V contains approximately 0.65 acre, and is comprised of building roof tops, drive aisles, parking, and landscaping. Runoff from this area is captured by roof drains and a catch basin, where it will be conveyed underground to the detention pond. Basin W contains approximately 0.48 acre, and is comprised of building roof tops, drive aisles, parking, and landscaping. Runoff from this area is captured by roof drains and a catch basin, where it will be conveyed underground to the detention pond. Basin X contains approximately 0.77 acre, and is comprised of building roof tops, drive aisles, parking, and landscaping. Runoff from this area is captured by roof drains and a catch basin, where it will be conveyed underground to the detention pond. Basin Y contains approximately 1.64 acres, and is comprised of building roof tops, drive aisles, parking, and landscaping. Runoff from this area is captured by roof drains and a catch basin, where it will be conveyed underground to the detention pond. Basin Z contains approximately 1.32 acres, and is comprised of building roof tops, drive aisles, parking, and landscaping. Runoff from this area is captured by roof drains and a catch basin, where it will be conveyed underground to the detention pond. Basin AA contains approximately 1.28 acres, and is comprised of building roof tops, drive aisles, parking, and landscaping. Runoff from this area is captured by roof drains and a catch basin, where it will be conveyed underground to the detention pond. Basin BB contains approximately 1.32 acres, and is comprised of building roof tops, drive aisles, parking, and landscaping. Runoff from this area is captured by roof drains and a catch basin, where it will be conveyed underground to the detention pond. For this report, inlet capacity was evaluated for a 5 Type R Catch Basin, and a 10 Type R Catch Basin. Most of the basins utilize a similar longitudinal slope and similar cross-slope. Future drainage submittals will contain sizing sheets for each catch basins design point. 3. DRAINAGE DESIGN CRITERIA 3.1. REGULATIONS This drainage report was prepared in compliance with the following criteria: Town of Parker Storm Drain and Environmental Manual Urban Drainage and Flood Control District (UDFCD) Urban Storm Drainage Criteria Manual

8 Vantage Point (S. Parker Rd. & E. Cottonwood Dr. Parker, CO) DRAINAGE REPORT Tuesday July 14, 2015 Page 4 During construction, disturbed areas will be stabilized for erosion and sediment control in accordance with Town of Parker and UDFCD Criteria. The methods used to control erosion and sediment during construction of this project will comply with the non-structural and structural Best Management Practices (BMPs) described within the Town of Parker and UDFCD manuals. Erosion Control plans are included in the construction plan set. No deviation from the Town of Parker Criteria is being requested 3.2. DEVELOPMENT RESTRAINTS Because the site is confined on all sides, runoff from a small area will be released, undetained, into the adjacent streets. However, runoff from the remainder of the project will be directed to the underground detention system, where it will be detained for the 10-year and 100-year storms, and released at reduced empirically allowed release rates for the entire project HYDROLOGIC CRITERIA Runoff was calculated per the Town of Parker Criteria. Rainfall intensity was taken from Figure 5.1 of the Town of Parker Criteria, and runoff coefficients were taken from UDFCD Table RO-3 utilizing soil type B. The rational method was used to calculate runoff from the proposed development. The following formula was used to determine the runoff values: Q=CIA Where Q = Storm runoff, cubic feet per second (CFS) C = Runoff coefficient I = Storm intensity, inches per hour A = Drainage area, acres Detention and water quality volumes for this development were calculated using the UDFCD Full Spectrum Detention Basins spread sheet. The outlet control structure was design per Volume 3 Full Spectrum Design details HYDRAULIC CRITERIA The pipe hydraulics will be modeled on our next submittal using LDD Pipe using a friction coefficient of for concrete and 0.10 for PVC. The hydraulic grade lines will be shown on the pipe profiles located in the appendix of the report. Inlet and exit losses are calculated as part of the pipe program. A printout of the program output will be located in the appendix of the report. The hydraulic design has been done in accordance with the Town of Parker Criteria WATER QUALITY REQUIREMENTS Stormwater quality will be provided using Full Spectrum / EURV detention. The proposed pond will utilize a permanent water quality pool WAIVERS FROM CRITERIA No deviation from the Town of Parker Criteria is being requested. 4. DRAINAGE FACILITY DESIGN 4.1. GENERAL CONCEPT Runoff from the project will drain to swales, yard inlets, catch basins, and rood drains, where it will be conveyed by a proposed underground storm drain system, to the proposed Full Spectrum detention Pons located near the corner of S. Parker Road, and E. Cottonwood Drive. Runoff from the site will be detained and released per the Full Spectrum / EURV design worksheet. A permanent water quality pool is part of the detention pond. The runoff in the existing drainage swale will be routed through the pond. Strategic Land Solutions, will work with the Town of Parker staff to determine the expected runoff in the swale, as well as the exact method of routing the runoff through the pond. All developed areas of the project are tributary to the detention pond, except very small area at the two entrances from E. Cottonwood Drive.

9 Vantage Point (S. Parker Rd. & E. Cottonwood Dr. Parker, CO) DRAINAGE REPORT Tuesday July 14, 2015 Page 5 Water quality will be provided using a permanent pool surface in the pond as part of the Full Spectrum / EURV design. Runoff from adjacent land will be conveyed around the site using a drainage swale at the top of the wall. All of the tributary land is native, except a single family residences, so runoff from adjacent site is minimal. The proposed storm drain facilities maintain a minimum horizontal clearance of 10-feet from adjacent sanitary sewer and waterlines, and a minimum 18-inch vertical clearance at utility crossings. Runoff from the site will be detained, treated for water quality and excessive runoff, before being released at 90% of the historic flows, as defined in the Full Spectrum / EURV design criteria. The outlet pipe is designed to convey 120% of the expected 100-year peak runoff SPECIFIC DETAILS DESCRIPTION Developed ACRES PERCENT IMPERVIOUS WATER QUALITY CONTROL VOLUME EURV-YEAR DETENTION VOLUME 10-YEAR DETENTION VOLUME 100-DETENTION VOLUME EURV RELEASE RATE 100-YEAR RELEASE RATE POND OVERFLOW VALUE REQUIRED/PROVIDED total site 71.76% (onsite Basins) 17,816 CUBIC FEET/ 17,186 CUBIC FEET 60,505 CUBIC FEET/60,505 CUBIC FEET 80,760 CUBIC FEET/80,760 CUBIC FEET 152,329 CUBIC FEET/152,329 CUBIC FEET 0.3 CFS 0.9 CFS To E. Cottonwood Drive A Permanent Easement will be recorded with the Town of Parker over all drainage facilities MAINTENANCE PLAN The detention pond will be visually inspected bi-annually to ensure proper operations. Visible trash will be removed regularly in an effort to keep solids out of the water quality areas. Sedimentation will be removed annually, or as determined by visual inspections to maintain proper function of the detention facilities. Temporary stormwater quality will be provided during construction. Detailed erosion control report and plans will be submitted as part of the construction drawings. Permanent stormwater quality will be provided by the features described in this report. 5. CONCLUSIONS 5.1. COMPLIANCE WITH STANDARDS This stormwater Management Report was prepared in compliance with the Town of Parker Storm Drain and Environmental Manual and the UDFCD Urban Storm Drainage Criteria Manual. No variances will be requested, except to allow a reduction in the release rates to offset the offsite basins DESIGN This project meets the requirements shown in the Town of Parker Storm Drain and Environmental Manual and the UDFCD Urban Storm Drainage Criteria Manual. Additionally, the proposed drainage design will reduce the intensity of runoff to the existing drainage facilities in the surrounding streets due to the minor and major storms, The proposed improvements will

10 Vantage Point (S. Parker Rd. & E. Cottonwood Dr. Parker, CO) DRAINAGE REPORT Tuesday July 14, 2015 Page 6 enhance runoff water quality. As such, this project should not have a negative impact on the surrounding developments and existing drainage facilities.

11 Vantage Point (S. Parker Rd. & E. Cottonwood Dr. Parker, CO) DRAINAGE REPORT Tuesday July 14, 2015 Page 7 6. REFERENCES 1. Town of Parker, Storm Drainage Design and Technical Criteria, November, Flood Insurance Rate Map Town of Parker, Colorado, Panel 88 of 300, Map # H, Revised November 20, Urban Storm Drainage Criteria Manual (Volumes 1, 2, and 3); Urban Drainage and Flood Control District, 2001 (latest revision).

12 APPENDIX A Hydrologic Computations Appendix A Hydrologic Computations

13 Broadstone Vantage Point - Parker, CO - Drainage Calculations LAND USAGE FOR EACH SUB-BASIN LAND USAGE PERCENT 5-YR 100-YR SUM IMPERVIOUS RUNOFF RUNOFF OF COEFF. COEFF. AREA AREA (%) C 5 C100 A B C D E F G H I J K L M N O P Q R S T U V (ACRE) LANDSCAPE ROOF DRIVES AND WALKS (IMPERVIOUS) Total LAND USAGE PERCENT 5-YR 100-YR SUM IMPERVIOUS RUNOFF RUNOFF OF COEFF. COEFF. AREA AREA (%) C 5 C100 W X Y Z AA BB CC T U V (ACRE) LANDSCAPE ROOF DRIVES AND WALKS (IMPERVIOUS) Total COMPOSITE % IMPERVIOUSNESS AND RUNOFF COEFFICIENTS SUB-BASIN EFFECTIVE COMPOSITE COMPOSITECOMPOSITE AREA % IMPERVIOUS C 2 C5 C100 acres A B C D E F G DP8 (Basins A-G) H I J K L M N O P Q R S T U V W X DP 26 (Basins H-O) DP 27 (Basins H-X) Y Z AA BB DP 32 (Basins Y-BB) DP 33 Total Developed Site (A-BB)

14 SUBDIVISION: Broadstone Vantage Point-Parker, CO STANDARD FORM SF-2 TIME OF CONCENTRATION YEAR CALCULATED BY: Robert Palmer DATE: 07/15/15 t c = t i + t t SUB-BASIN INITIAL / OVERLAND TRAVEL TIME t c CHECK FINAL REMARKS DATA TIME (t i ) (t i ) (URBANIZED BASINS) DESIGN AREA C 5 LENGTH SLOPE t i LENGTH SLOPE VEL t t COMP TOTAL t c =(L/180)+10 Ac Ft % Min Ft % FPS Min t c LENGTH Min Min (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) MAIN DETENTION POND A use 5 minute min. B C D E F G use 10 min. max DP use 10 min. max H use 10 min. max I use 5 minute min. J K use 5 minute min. L use 5 minute min. M N O use 5 minute min. P Q R S T U V W use 5 minute min. X use 5 minute min. STORM DRAINGE DESIGN AND TECHNICAL CRITERIA t c

15 SUBDIVISION: Broadstone Vantage Point-Parker, CO STANDARD FORM SF-2 TIME OF CONCENTRATION YEAR CALCULATED BY: Robert Palmer DATE: 07/15/15 t c = t i + t t SUB-BASIN INITIAL / OVERLAND TRAVEL TIME t c CHECK FINAL REMARKS DATA TIME (t i ) (t i ) (URBANIZED BASINS) DESIGN AREA C 5 LENGTH SLOPE t i LENGTH SLOPE VEL t t COMP TOTAL t c =(L/180)+10 Ac Ft % Min Ft % FPS Min t c LENGTH Min Min (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) MAIN DETENTION POND DP use 10 min. max DP use 10 min. max Y use 10 min. max Z AA BB DP use 10 min. max DP use 10 min. max t c STORM DRAINGE DESIGN AND TECHNICAL CRITERIA

16 STANDARD FORM SF-3 STORM DRAINAGE SYSTEM DESIGN (Rational Method Procedure) SUBDIVISION: Broadstone Vantage Point - Parker, CO CALCULATED BY: Robert Palmer DATE: 07/15/15 DESIGN STORM: 2-Yr DESIGN POINT AREA DESIGN AREA (AC) RUNOFF COEFF t c (MIN) C*A (AC) i (IN/HR) Q (CFS) t c (MIN) (C*A) (AC) i (IN/HR) Q (CFS) SLOPE (%) STREET FLOW (CFS) DESIGN FLOW (CFS) SLOPE (%) PIPE SIZE LENGTH (FT) VELOCITY (FPS) STREET DIRECT RUNOFF TOTAL RUNOFF STREET PIPE TRAVEL TIME t t (MIN) (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) (17) (18) (19) (20) (21) (22) REMARKS 1 Basin A 1 A Basin B 2 B Basin C 3 C Basin D 4 D Basin E 5 E Basin F 6 F Basin G 7 G DP 8 8 A-G Basin H 9 H Basin I 10 I Basin J 11 J Basin K 12 K Basin L 13 L Basin M 14 M

17 STANDARD FORM SF-3 STORM DRAINAGE SYSTEM DESIGN (Rational Method Procedure) SUBDIVISION: Broadstone Vantage Point - Parker, CO CALCULATED BY: Robert Palmer DATE: 07/15/15 DESIGN STORM: 2-Yr AREA DESIGN AREA (AC) RUNOFF COEFF t c (MIN) C*A (AC) i (IN/HR) Q (CFS) t c (MIN) (C*A) (AC) i (IN/HR) Q (CFS) SLOPE (%) STREET FLOW (CFS) DESIGN FLOW (CFS) SLOPE (%) PIPE SIZE LENGTH (FT) VELOCITY (FPS) STREET DIRECT RUNOFF TOTAL RUNOFF STREET PIPE TRAVEL TIME t t (MIN) (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) (17) (18) (19) (20) (21) (22) REMARKS DESIGN POINT 15 Basin N 15 N Basin O 16 O Basin P 17 P Basin Q 18 Q Basin R 19 R Basin S 20 S Basin T 21 T Basin U 22 U Basin V 23 V Basin W 24 W M ##### ##### 25 Basin X 25 X DP H-O DP H-X Basin Y 28 Y

18 STANDARD FORM SF-3 STORM DRAINAGE SYSTEM DESIGN (Rational Method Procedure) SUBDIVISION: Broadstone Vantage Point - Parker, CO CALCULATED BY: Robert Palmer DATE: 07/15/15 DESIGN STORM: 2-Yr AREA DESIGN AREA (AC) RUNOFF COEFF t c (MIN) C*A (AC) i (IN/HR) Q (CFS) t c (MIN) (C*A) (AC) i (IN/HR) Q (CFS) SLOPE (%) STREET FLOW (CFS) DESIGN FLOW (CFS) SLOPE (%) PIPE SIZE LENGTH (FT) VELOCITY (FPS) STREET DIRECT RUNOFF TOTAL RUNOFF STREET PIPE TRAVEL TIME t t (MIN) (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) (17) (18) (19) (20) (21) (22) REMARKS DESIGN POINT 29 Basin Z 15 Z Basin AA 16 AA Basin BB 17 BB DP Y-BB DP A-BB

19 STANDARD FORM SF-3 STORM DRAINAGE SYSTEM DESIGN (Rational Method Procedure) SUBDIVISION: Broadstone Vantage Point - Parker, CO CALCULATED BY: Robert Palmer DATE: 07/15/15 DESIGN STORM: 100-Yr AREA DESIGN AREA (AC) RUNOFF COEFF t c (MIN) C*A (AC) i (IN/HR) Q (CFS) t c (MIN) (C*A) (AC) i (IN/HR) Q (CFS) SLOPE (%) STREET FLOW (CFS) DESIGN FLOW (CFS) SLOPE (%) PIPE SIZE LENGTH (FT) VELOCITY (FPS) STREET DIRECT RUNOFF TOTAL RUNOFF STREET PIPE TRAVEL TIME t t (MIN) (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) (17) (18) (19) (20) (21) (22) REMARKS DESIGN POINT 1 Basin A 1 A Basin B 2 B Basin C 3 C Basin D 4 D Basin E 5 E Basin F 6 F Basin G 7 G DP 8 8 A-G Basin H 9 H Basin I 10 I Basin J 11 J Basin K 12 K Basin L 13 L Basin M 14 M

20 STANDARD FORM SF-3 STORM DRAINAGE SYSTEM DESIGN (Rational Method Procedure) SUBDIVISION: Broadstone Vantage Point - Parker, CO CALCULATED BY: Robert Palmer DATE: 07/15/15 DESIGN STORM: 100-Yr AREA DESIGN AREA (AC) RUNOFF COEFF t c (MIN) C*A (AC) i (IN/HR) Q (CFS) t c (MIN) (C*A) (AC) i (IN/HR) Q (CFS) SLOPE (%) STREET FLOW (CFS) DESIGN FLOW (CFS) SLOPE (%) PIPE SIZE LENGTH (FT) VELOCITY (FPS) STREET DIRECT RUNOFF TOTAL RUNOFF STREET PIPE TRAVEL TIME t t (MIN) (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) (17) (18) (19) (20) (21) (22) REMARKS DESIGN POINT 15 Basin N 15 N Basin O 16 O Basin P 17 P Basin Q 18 Q Basin R 19 R Basin S 20 S Basin T 21 T Basin U 22 U Basin V 23 V Basin W 24 W Basin X 25 X DP H-O DP H-X Basin Y 28 Y

21 STANDARD FORM SF-3 STORM DRAINAGE SYSTEM DESIGN (Rational Method Procedure) SUBDIVISION: Broadstone Vantage Point - Parker, CO CALCULATED BY: Robert Palmer DATE: 07/15/15 DESIGN STORM: 2-Yr AREA DESIGN AREA (AC) RUNOFF COEFF tc (MIN) C*A (AC) i (IN/HR) Q (CFS) tc (MIN) (C*A) (AC) i (IN/HR) Q (CFS) SLOPE (%) STREET FLOW (CFS) DESIGN FLOW (CFS) SLOPE (%) PIPE SIZE LENGTH (FT) VELOCITY (FPS) STREET DIRECT RUNOFF TOTAL RUNOFF STREET PIPE TRAVEL TIME tt (MIN) (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) (17) (18) (19) (20) (21) (22) REMARKS DESIGN POINT 29 Basin Z 15 Z Basin AA 16 AA Basin BB 17 BB DP Y-BB DP A-BB

22 DRAINAGE CRITERIA MANUAL (V. 1) RUNOFF Table RO-5 Runoff Coefficients, C Percentage Imperviousness Type C and D NRCS Hydrologic Soil Groups 2-yr 5-yr 10-yr 25-yr 50-yr 100-yr 0% % % % % % % % % % % % % % % % % % % % % TYPE B NRCS HYDROLOGIC SOILS GROUP 0% % % % % % % % % % % % % % % % % % % % % RO-11 Urban Drainage and Flood Control District

23 DRAINAGE CRITERIA MANUAL (V. 1) RUNOFF Figure RO-1 Estimate of Average Overland Flow Velocity for Use With the Rational Formula RO-13 Urban Drainage and Flood Control District

24 TOWN OF PARKER STORM DRAINAGE AND ENVIRONMENTAL CRITERIA MANUAL Intensity, Duration, Frequency Parker, Colorado Intensity (inches per hour) year 50 year 25 year 10 year 5 year 2 year Time of Concentration (minutes) FIGURE 5.1 RAINFALL INTENSITY VERSUS DURATION CURVES FOR PARKER, COLORADO SECTION 5. HYDROLOGIC CRITERIA

25 Initial Design for Full Spectrum Detention Basins Project: Broadstone Vantage Point Basin ID: total developed site Worksheet Protected User Input: Watershed Parameters Calculated Watershed Parameters Watershed Area = acres Required EURV = 62,308 ft 3 Watershed Imperviousness = 70.3% percent Routed EURV = acre ft Percentage Hydrologic Soil Group A = percent Routed EURV = 62,801 ft 3 Percentage Hydrologic Soil Group B = 100% percent Calc. vs. Req Volume % Diff = 0.8% Percentage Hydrologic Soil Groups C/D = percent EURV Drain Time = >120 hrs Location for 1 hr Rainfall Depths = UDFCD Default Calculated Detention Basin Parameters User Input: Detention Basin Parameters Surface Area of Initial Surcharge Volume = 170 ft 2 Depth of Initial Surcharge Volume = 0.33 ft Maximum EURV Ponding Depth = 4.52 ft Trickle Channel Slope = ft/ft Depth Where Basin Floor Meets Side Slopes = 1.08 ft Detention Basin Length to Width Ratio = 5.94 L:W Basin Side Slope (Above Basin Floor) = 5.00 H:V Available EURV Ponding Depth = 4.62 ft (relative to lowest WQ orifice) Desired WQCV Drain Time = 40 hours Calculated Overflow Grate Parameters Height of Grate Upper Edge H t = 5.6 ft User Input: Outlet Structure Parameters Grate Open Area / 100 yr Orifice Area = should be > 4 Overflow Weir Front Edge Height, H o = 4.6 ft (relative to lowest WQ orifice) Overflow Weir Slope Length = 5.1 ft Overflow Weir Front Edge Length = 5.0 ft Overflow Grate Open Area w/o Debris = 18 ft 2 Overflow Weir Slope = 5 H:V (enter zero for flat grate) Horizontal Length of the Overflow Weir Sides = 5.0 ft Calculated WQ Plate Parameters Overflow Grate Open Area % = 70% %, grate open area / total area WQ Orifice Area per Row = 1.175E 02 ft 2 Debris Clogging % = 50% % of open area clogged w/ debris Elliptical Half Width = N/A ft Water Quality Plate Type = WQ Orifice Plate Elliptical Slot Centroid = N/A ft WQ Orifice Plate: Orifice Vertical Spacing = 18.5 in Elliptical Slot Area = N/A ft 2 WQ Orifice Plate: Orifice Area per Row = 1.69 sq. inch (diameter = 1 7/16 inches) User Input: 100 Year Orifice Parameters Calculated 100 yr Orifice Parameters 100 Year Restrictor Type = Circular Pipe w/ Plate 100 Year Orifice Area = 0.04 ft Year Orifice Invert Depth = 1.0 ft (below the lowest WQ orifice) 100 Year Orifice Centroid = 0.05 ft 100 Year Outlet Pipe Diameter = 24.0 in Half Central Angle of Plate on Pipe = 0.41 radians 100 Year Restrictor Plate Height = 1.0 in Calculated Spillway Parameters User Input: Emergency Spillway Parameters Depth of Flow through Spillway = 0.9 ft Spillway Crest Stage = 7.8 ft (relative to lowest WQ orifice) Stage at Top of Freeboard = 9.2 ft Spillway Crest Length = 85 ft Detention Basin Area at Top of Freeboard = 0.94 acres Spillway End Slopes = 4.00 H:V Freeboard above Spillway = 0.50 ft Routed Hydrograph Results For 5.94:1 L:W Rectangular Basin with ft/ft Slope Trickle Channel Design Storm Return Period WQCV 2 Year EURV 5 Year 10 Year 25 Year 50 Year 100 Year One Hour Rainfall Depth in Calculated Runoff Volume acre ft OPTIONAL Override Runoff Volume acre ft Inflow Hydrograph Volume acre ft Historic Peak Flow Rate Per Acre (q) cfs/acre Historic Peak Q cfs Peak Inflow Q cfs Peak Outflow Q cfs Ratio Peak Outflow to Historic Q N/A N/A N/A Ratio Structure Controlling Flow WQ Plate WQ Plate WQ Plate Grate 100yr Outlet 100yr Outlet 100yr Outlet 100yr Outlet Max Velocity through Grate N/A N/A N/A fps Time to Drain Detention Basin >120 >120 >120 >120 >120 >120 hours Maximum Ponding Depth ft Maximum Volume Stored ac ft Copy of UD FSD_v1.08, Initial Design 7/15/2015, 1:05 PM

26 Initial Design for Full Spectrum Detention Basins FLOW [cfs] PONDING DEPTH [ft] YR IN 100YR OUT 100 Year Dropdown WQ Plate Dropdown 50YR IN 4Type 2Type 50YR OUT YR IN 25YR OUT 4 Circular Pipe w/ Plate 2 Circular Orifice 2 WQ Orifice Plate 3 Rectangular Orifice 3 WQ Elliptical Slot 10YR IN 50 10YR OUT Ao Dia 5YR IN eter = 3/8 inch) 40 5YR OUT Start/Stop Parameters COUNTA for User Defined Rainfall Depths ter = 7/16 inch) Doing Basin Sizing Only= No eter = 1/2 inch) EURV IN JSS = 1 0 Msgbox for COUNTA_UserDe ter = 9/16 inch) 30 EURV OUT COUNTA for Soil Sum= eter = 5/8 inch) COUNTA for WQ Plate = 2YR IN er = 11/16 inch) COUNTA for 100 Year Orifice Type = eter = 3/4 inch) 20 2YR OUT CountA= er = 13/16 inch) WQCV IN QuickCountA= eter = 7/8 inch) 10 Doing Quick Start= No er = 15/16 inch) WQCV OUT Doing Clear Formatting= No ameter = 1 inch) Doing Plate Formatting= No = 1 1/16 inches) 0 InitialRun= Yes = 1 1/8 inches) 0.1 Hidden Program Calculations = 1 3/16 inches) 10 OPTIONAL Override EURV = ac ft TIME [hr] = 1 1/4 inches) Overflow Weir Angle = = 1 5/16 inches) 9 C dw = = 1 3/8 inches) 100YR C do = = 1 7/16 inches) 8 CLOG = = 1 1/2 inches) 50YR WQ Plate Flow at 100yr depth = = 1 9/16 inches) 25YR MaxPondDepth_Error? FALSE = 1 5/8 inches) 7 10YR WQ Ao First Estimate = /16 inches) 5YR = 1 3/4 inches) /16 inches) 6 EURV = 1 7/8 inches) 2YR /16 inches) 5 WQCV eter = 2 inches) gular openings) ISV 56 L FLOOR L_MAIN A_ISV W_FLOOR 49.2 W_MAIN 84.6 L_ISV 13.0 A_FLOOR 11,399 A_MAIN 22,588 W_ISV 13.0 V_FLOOR 3,249 V_MAIN 59,003 H_FLOOR H_MAIN 3.54 EURVCALC 62, DRAIN TIME [hr] , ,000 Volume [ft^3] 300,000 Area [ft^2] 2000 AREA [ft^2], VOLUME[ft^3] 250, , ,000 Outflow [cfs] OUTFLOW [cfs] 100, , PONDING DEPTH [ft] Copy of UD FSD_v1.08, Initial Design 7/15/2015, 1:05 PM

27 Initial Design for Full Spectrum Detention Basins Storm Inflow Hydrograph WORKBOOK SOURCE WORKBOOK WORKBOOK WORKBOOK WORKBOOK WORKBOOK WORKBOOK WORKBOOK WORKBOOK EURV (CFS) TIME WQCV [cfs] 2 Year [cfs] EURV [cfs] 5 Year [cfs] 10 Year [cfs] 25 Year [cfs] 50 Year [cfs] 100 Year [cfs] 0: : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : Copy of UD FSD_v1.08, Initial Design 7/15/2015, 1:05 PM

28 B. Hydraulic Computations Appendix B Hydraulic Computations

29 Outlet Structure Design DETENTION POND SIZING EURV Elev. Area H Volume FT 3 WQ SWEL , , , , , , , ,754 EURV WSEL= Orifice Sizing , , , ,588 Q=C o A(2gH o ) , , YEAR WSEL= Q = Discharge cfs C o = orifice coefficient = 0.65 A o = area ft 2 g = gravitational constant = 32.2 ft/sec 2 H o = head above centerline of orifice H o10 = H o100 = H o10 at 100-year wsel =

30 INLET IN A SUMP OR SAG LOCATION Project = Inlet ID = Broadstone Vantage Point 5' Type R Capacity H-Curb W W P H-Vert Lo (C) Wo Lo (G) Design Information (Input) MINOR MAJOR Type of Inlet Inlet Type = CDOT Type R Curb Opening Local Depression (additional to continuous gutter depression 'a' from 'Q-Allow') a local = inches Number of Unit Inlets (Grate or Curb Opening) No = 1 1 Water Depth at Flowline (outside of local depression) Ponding Depth = inches Grate Information MINOR MAJOR Override Depths Length of a Unit Grate L o (G) = N/A N/A feet Width of a Unit Grate W o = N/A N/A feet Area Opening Ratio for a Grate (typical values ) A ratio = N/A N/A Clogging Factor for a Single Grate (typical value ) C f (G) = N/A N/A Grate Weir Coefficient (typical value ) C w (G) = N/A N/A Grate Orifice Coefficient (typical value ) C o (G) = N/A N/A Curb Opening Information MINOR MAJOR Length of a Unit Curb Opening L o (C) = feet Height of Vertical Curb Opening in Inches H vert = inches Height of Curb Orifice Throat in Inches H throat = inches Angle of Throat (see USDCM Figure ST-5) Theta = degrees Side Width for Depression Pan (typically the gutter width of 2 feet) W p = feet Clogging Factor for a Single Curb Opening (typical value 0.10) C f (C) = Curb Opening Weir Coefficient (typical value ) C w (C) = Curb Opening Orifice Coefficient (typical value ) C o (C) = MINOR MAJOR Total Inlet Interception Capacity (assumes clogged condition) Q a = cfs Inlet Capacity IS GOOD for Minor and Major Storms (>Q PEAK) Q PEAK REQUIRED = cfs UD-Inlet_v3.14, Inlet In Sump 7/13/2015, 5:00 PM

31 INLET IN A SUMP OR SAG LOCATION Project = Inlet ID = Broadstone Vantage Point 5' Type R Capacity H-Curb W W P H-Vert Lo (C) Wo Lo (G) Design Information (Input) MINOR MAJOR Type of Inlet Inlet Type = CDOT Type R Curb Opening Local Depression (additional to continuous gutter depression 'a' from 'Q-Allow') a local = inches Number of Unit Inlets (Grate or Curb Opening) No = 2 2 Water Depth at Flowline (outside of local depression) Ponding Depth = inches Grate Information MINOR MAJOR Override Depths Length of a Unit Grate L o (G) = N/A N/A feet Width of a Unit Grate W o = N/A N/A feet Area Opening Ratio for a Grate (typical values ) A ratio = N/A N/A Clogging Factor for a Single Grate (typical value ) C f (G) = N/A N/A Grate Weir Coefficient (typical value ) C w (G) = N/A N/A Grate Orifice Coefficient (typical value ) C o (G) = N/A N/A Curb Opening Information MINOR MAJOR Length of a Unit Curb Opening L o (C) = feet Height of Vertical Curb Opening in Inches H vert = inches Height of Curb Orifice Throat in Inches H throat = inches Angle of Throat (see USDCM Figure ST-5) Theta = degrees Side Width for Depression Pan (typically the gutter width of 2 feet) W p = feet Clogging Factor for a Single Curb Opening (typical value 0.10) C f (C) = Curb Opening Weir Coefficient (typical value ) C w (C) = Curb Opening Orifice Coefficient (typical value ) C o (C) = MINOR MAJOR Total Inlet Interception Capacity (assumes clogged condition) Q a = cfs WARNING: Inlet Capacity less than Q Peak for Minor and Major Storms Q PEAK REQUIRED = cfs 10' type r capacity, Inlet In Sump 7/13/2015, 5:03 PM

32 C. Map Pocket Appendix C Map Pocket

33 Web Soil Survey 1 of 2 7/10/2015 9:23 AM Contact Us Subscribe Archived Soil Surveys Soil Survey Status Glossary Preferences Link Logout Help A A A Area of Interest (AOI) Soil Map Soil Data Explorer Download Soils Data Shopping Cart (Free) View Soil Information By Use: Printable Version Add to Shopping Cart Intro to Soils Suitabilities and Limitations for Use Soil Properties and Qualities Ecological Site Assessment Soil Reports Search Map Hydrologic Soil Group Properties and Qualities Ratings Scale (not to scale) Open All Close All Soil Chemical Properties Soil Erosion Factors Soil Physical Properties Available Water Capacity Available Water Storage Available Water Supply, 0 to 100 cm Available Water Supply, 0 to 150 cm Available Water Supply, 0 to 25 cm Available Water Supply, 0 to 50 cm Bulk Density, 15 Bar Bulk Density, One-Tenth Bar Bulk Density, One-Third Bar Linear Extensibility Liquid Limit Organic Matter Percent Clay Percent Sand Percent Silt Plasticity Index Saturated Hydraulic Conductivity (Ksat) Saturated Hydraulic Conductivity (Ksat), Standard Classes Surface Texture Water Content, 15 Bar Water Content, One-Third Bar Soil Qualities and Features AASHTO Group Classification (Surface) Depth to a Selected Soil Restrictive Layer Depth to Any Soil Restrictive Layer Drainage Class Frost Action Frost-Free Days Hydrologic Soil Group View Options Map Table Description of Rating Rating Options View Description View Rating Warning: Soil Ratings Map may not be valid at this scale. You have zoomed in beyond the scale at which the soil map for this area is intended to be used. Mapping of soils is done at a particular scale. The soil surveys that comprise your AOI were mapped at 1:20,000. The design of map units and the level of detail shown in the resulting soil map are dependent on that map scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Tables Hydrologic Soil Group Summary By Map Unit Summary by Map Unit Castle Rock Area, Colorado (CO622) Map unit symbol Map unit name Rating Acres in AOI Percent of AOI BrB Bresser sandy loam, 1 to 3 percent slopes B % BtE Bresser-Truckton sandy loams, 5 to 25 percent slopes B % Sa Sampson loam B % Totals for Area of Interest % Description Hydrologic Soil Group Hydrologic soil groups are based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long-duration storms. The soils in the United States are assigned to four groups (A, B, C, and D) and three dual classes (A/D, B/D, and C/D). The groups are defined as follows: Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission. Advanced Options Aggregation Method Component Percent Cutoff Detailed Description Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission. Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission. Tie-break Rule Lower Higher View Description View Rating Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink-swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission. Map Unit Name Parent Material Name Representative Slope Unified Soil Classification (Surface) Water Features If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is for drained areas and the second is for undrained areas. Only the soils that in their natural condition are in group D are assigned to dual classes. Rating Options Hydrologic Soil Group Aggregation Method: Dominant Condition Component Percent Cutoff: None Specified

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