final drainage report eastcreek farms - thornton co

solutions. partnerships. success.

t 303.561.3333 | f 303.561.3339 | 45 West 2nd Avenue, Denver, Colorado 80223 | www.jansenstrawn.com

FINAL DRAINAGE REPORT

Eastcreek Farms Thornton, CO

October 28, 2016

JN: 13049

Prepared for:

Carlson Associates, Inc. 12460 1st Street

Eastelake, CO 80614 P:303.457.2966

Prepared by:

Jansen Strawn Consulting Engineers 45 W. 2nd Avenue Denver, CO 80223 P: 303.561.3333 F: 303.561.3339

Thomas C. Jansen, PE No. 35942

Principal

Eastcreek Farm 10/28/2016

t 303.561.3333 | f 303.561.3339 | 45 West 2nd Avenue, Denver, Colorado 80223 | www.waremalcomb.com

Carlson Associates hereby certifies that the drainage facilities for the Eastcreek Farms Subdivision shall be constructed according to the design presented in this report. I understand that the City of Thornton does not and will not assume liability for the drainage facilities designed and/or certified by my engineer and that the City of Thornton reviews drainage plans pursuant to Colorado Revised Statutes Title 30, Article 28; but cannot, on behalf of the Eastcreek subdivision, guarantee that final drainage design review will absolve the Carlson Associates and/or their successors and/or assigns of future liability for improper design. I further understand that approval of the Final Plat, Final Development Plan, and/or Subdivision Development Plan does not imply approval of my engineer’s drainage design. __________________________________ Printed Name for and on behalf of Carlson Associates _________________________________ Authorized Signature CERTIFICATION I hereby affirm that this report and plan for the final drainage design of the Eastcreek Farms Subdivision was prepared by me, or under my direct supervision, for the owners thereof, in accordance with the provisions of City of Thornton Standards and Specifications for the Design and Construction of Public and Private Improvements and the Urban Drainage and Flood Control District Criteria Manual, and approved variances and exceptions thereto. I understand that the City of Thornton does not and will not assume liability for drainage facilities designed by others. Thomas C. Jansen, PE Date State of Colorado Registration No. 35942 For and on behalf of Jansen Strawn Consulting Engineers, Inc.



T A B L E O F C O N T E N T S

I. GENERAL LOCATION AND DESCRIPTION .............................................................................................. 5

II. DRAINAGE BASINS AND SUB-BASINS .................................................................................................... 6

III. DRAINAGE FACILITY DESIGN AND CRITERIA ......................................................................................... 7

IV. STORMWATER MANAGEMENT FACILITY DESIGN ................................................................................. 9

V. CONCLUSION ....................................................................................................................................... 13

VI. REFERENCES ........................................................................................................................................ 14



A P P E N D I C E S

APPENDIX A – Reference Materials FEMA Flood Insurance Rate Map NRCS Soil Information Related Drainage Reports

APPENDIX B – Site Hydrology and Hydraulics % Impervious Calculations “C” Value Calculations SF2 & SF3 Rational Method Calculations Street Capacity Calculations Inlet Calculations Storm Sewer Design

APPENDIX C – Pond Design & Outlet Structure Stage-Storage Sizing WQCV Outlet Design Restrictor Plate Design Outlet Design & Culvert Design Emergency Spillway Design

APPENDIX D - Maps Historical Basin Map Developed Basin Map



I. GENERAL LOCATION AND DESCRIPTION

The purpose of this report is to define and analyze developed runoff quantities and conveyance through the Eastcreek Farm development. Runoff will generally drain toward one of the proposed Full Spectrum EURV and 100-year detention pond prior to being discharged from the site. Development constraints that are presented in the Outfall Systems Planning Update of Big Dry Creek Northern Tributaries Conceptual Preliminary Design Report (March 2007) and have been evaluated against the proposed development and the proposed drainage plan. Local restrictions due to existing and future drainage improvements surrounding the site are also evaluated within this report.

A. Site Location

The Eastcreek Farm development (site) is located in the south ½ of Section 12, Township 1 South, Range 68 West of the Sixth Principal Meridian, City of Thornton, county of Adams, Colorado. The site lies to the north of East 152nd Avenue and to the east of York Street. The site is bounded on the north by E-470 and to the west by the Fairfield Subdivision which is currently under construction. The site is bounded on the south by the Silver Creek Elementary School and the Haven At York Street Filing No. 4 subdivision. See the enclosed vicinity map and the Final Drainage Map in Appendix F for exact locations.

B. Description of Property The entire Site is approximately 96 acres, which includes parks and 276 residential lots. The development will include improvements to adjacent portions of East 152nd Avenue and York Street, internal streets and utilities that are required to support the proposed homes. The existing site is undeveloped farmland that has experienced limited oil and gas development. Generally, half the site slopes north and northwest. The existing German Ditch irrigation ditch runs through the property from the lower middle edge of the site to the northeast corner. Existing runoff flows enter the German Ditch from the eastern edge of the site. The Wadley North Creek crosses the site on the southwest corner via an engineered channel where it is received by an existing culvert, eventually outfalling to Big Dry Creek. The Short Run drainage way runs adjacent to the northeast corner of the site. The USCS Soils Survey indicates that the site is generally underlain by Platner loam (PIB and PIC) hydrological groups C and D, as well as Ulm loam (UIC and UID) hydrologic soil groups C and D, as well as a very small portion of Ascolon Sandy Loam (AsD and AsC) hydraulic soil group B. See the soil map located in Appendix A. Platner and Ulm soils are described as having slow permeability on nearly level to mildly sloping areas.



Hydrologic soil group C soils are identified as soils having a slow infiltration rate when thoroughly wetted and consisting chiefly of soils with a layer that impedes downward movement of water or soils with moderately-fine to fine texture. Hydrologic soil group D soils are identified as soils having high runoff potential when thoroughly wet. Water movement through Type D soils is restricted to very restricted.

II. DRAINAGE BASINS AND SUB-BASINS

A. Major Drainage Basins This site lies within the Big Dry Creek major drainage basin. Development within the Big Dry Creek major drainage basin is controlled by the Outfall Systems Planning Update of Big Dry Creek Northern Tributaries Conceptual Preliminary Design Report (March 2007), prepared by Wright Engineers Inc (OSP). Generally, the OSP describes the historic runoff entering either the Wadley Creek North or Short Run drainageway. According to the Flood Insurance Rate Map Number 08001C0302J, the site is mostly within Zone X, with a small portion of the site identified as being within Zone A where Wadley North Creek lies at the southwest corner of the site. Refer to Appendix A for the Flood Insurance Rate Map information. Proposed improvements will not alter the Zona A floodplain.

B. Sub-Basin Description

The entire site lies within the Big Dry Creek major drainage basin and historically drains towards the existing Short Run drainage way, Wadley Creek North, and existing inlets at low points near the E-470 onramp. The Wadley Creek North and Short Run drainage ways both flow to the Big Dry Creek. The proposed site basins have been evaluated in this report as “Basin A”, “Basin B” and “Basin C”. Ultimately all flows within Basin A, B and C will be conveyed to the proposed detention and WQCV pond A, B, and C (respectively) by way of overland flows which will be captured by the proposed storm drainage system. There will be some offsite flows in the proposed development which will generally follow historic runoff patterns. Some of the offsite flows will enter the existing German Ditch irrigation ditch, which agrees with historic drainage patterns for the site.



III. DRAINAGE DESIGN AND CRITERIA

A. Regulations The regulations, guidelines, and drainage design criteria used for this report are those contained within the City of Thornton Standards and Specifications for the Design and Constriction of Public and the Urban Drainage Criteria Manual, Volume 1, 2, and 3. The pond and pond release have been designed in accordance with UDFCD criteria. Onsite inlets have been sized and designed utilizing both UDFCD and City of Thornton Criteria, with street capacities and storm sewer being designed in accordance with City of Thornton Criteria.

B. Drainage Studies, Outfall Systems Plans, Site Constraints The site is within the Big Dry Creek major drainage basin. Outfall Systems Planning Update of Big Dry Creek Northern Tributaries Conceptual Preliminary Design Report (March 2007). There are no irregular site constraints that come by way of any streets, utilities, structures or other potential conflicts to the overall drainage design.

C. Hydrology

For the purpose of this report, the onsite flows routed to the stormsewer were calculated using the rational method calculations. These calculations have been included in Appendix B. The pond sizing has been sized using the full spectrum method utilizing UDFCD spreadsheets. The minor and major storm frequencies for design are the 5-year and 100-year storm events, respectively. The one hour point rainfall for the 5-year event is 1.38 inches and 2.69 inches for the 100-year event. The peak discharge for sizing the onsite storm sewer and for the street capacity calculations was calculated using the following Rational Method formula: Q=CIA

Where: Q = peak discharge (cfs) C = runoff coefficient from Table RO-5 of the UDSCM I = rainfall intensity (inches/hour) A = drainage area (acres)



These flows were routed through the site using the UDFCD SF-3 form to determine the total flow at respective design points. See Appendix B for routing spreadsheets. Stormwater quality and detention for the water quality and detention basin will be located in the southeast corner of the site for Basin A, the northeast corner for Basin B, and across E. 152nd Ave. for Basin C. The ponds will be designed using full spectrum detention and in accordance with Urban Drainage and City of Thornton criteria. This includes providing storage for the Excess Urban Runoff Volume (EURV) and releasing that volume over a period of 72 hours. Storage for the 100-year detention volume is provided within the onsite pond. The 100-year developed release rate from the proposed UDFCD detention pond will be restricted to a maximum of 1.0 cfs per acre. In accordance with current UDFCD recommendations, additional water quality volume will not be added to the 100-year detention volume for the proposed onsite ponds. Please refer to Appendix C for the storage calculations.

D. Hydraulics

Allowable street capacities for the proposed improvements are in accordance with City of Thornton Standards. In the minor storm event, runoff in the streets is not allowed to overtop the crown and is not allowed to flow beyond the back of attached walks or over top the curb. In the major storm event runoff cannot flow at a depth greater than 12 inches or extend beyond the right-of-way. Flows will not encroach upon residential lots in accordance with City of Thornton Criteria. Street capacities were checked for the proposed 34 foot flowline-to-flowline street section with mountable 4 inch curbing, except for E. 152nd Ave. which used a 6 inch curb. Completed street capacity worksheets have been supplied in Appendix B for the proposed street section street capacities which were calculated using the Q-Allow sheet of the UDFCD UD-Inlet spreadsheet. Inlets have been designed throughout the site to capture runoff from the streets before maximum allowable street capacities are exceeded and at sump locations. Inlet calculations have been prepared for the site using the Urban Drainage and Flood Control District UD-Inlet_V4.03.xls spreadsheet. Inlet capture calculations are provided in Appendix B. All inlets have also been analyzed to ensure there is an emergency overflow route which keeps runoff away from residential lots. All inlets will have a 6-inch throat height as shown on the City of Thornton and CDOT M Standard drawings.



Proposed storm sewers have been designed in accordance with the City of Thornton Standards. During the minor storm event, flows within the storm sewer remain within the pipe, that is, the storm sewer system does not become pressurized. City of Thornton criteria allows the 100-year storm to be controlled in the overall drainage system, which includes in most cases the street and the proposed storm sewer. Hydraflow Storm Sewers Extension for AutoCAD Civil 3D software was utilized to perform hydraulic computations on the proposed storm sewer, including the calculation of hydraulic grade lines. Hydraflow output for the proposed storm sewer, including profiles with hydraulic grade lines, is included in Appendix B.

E. Variances from Criteria

There are no variances from the required criteria.

IV. STORMWATER MANAGEMENT FACILITY DESIGN

A. General Concept

Stormwater within the developed residential portions of the site will have the following runoff characteristics: rainfall within the individual lots will be conveyed through roofs, downspouts, shallow swales, and sheet flow to adjacent sheets or tracts. Once runoff is within the street it will be conveyed within the street section to proposed storm sewer inlets. Runoff captured in proposed inlets will be conveyed through proposed storm sewer to designated outfall locations into the proposed EURV and Detention Ponds. Runoff rates will be attenuated to allowable release rates based of UDFCD criteria and existing downstream offsite conditions for full spectrum detention and released offsite.

B. Specific Details The residential density for the site is computed based on the area of the site that will be developed for residential purposes. This gives the site a density of 2.8 dwelling units per acre for hydrologic calculations. The average home size is anticipated to be roughly 2400 S.F. with 75 percent Single Family two-story homes, and 25 percent ranch style homes. In accordance with UDFCD USDCM Figures RO-3 through RO-5, the residential portions of the site are anticipated to be 35.5 percent impervious. Proposed drainage basins for the site will generally follow historic patterns. See historical drainage map in Appendix D for more information. Basin A



Basin A accounts for the runoff being directed to Pond A. To the greatest extent possible, runoff from developed portions of Basin A is conveyed to this proposed EURV and 100-year detention pond located at the southwest corner of the site. Sub-basins A-01 (1.36 AC.), A-02 (1.68 AC.), and A-03 (1.35 AC.) consist of residential lots that will be graded with the highpoint in the middle (Type ‘B’) or at the back of the lot (Type ‘A’). Runoff from these basins are directed via the street curb and gutter to design point 1 and 2. At these design points, 2 sump inlets receive the runoff and convey it to the detention pond (Pond A) via underground storm pipe. Sub-basins A-04 (1.45 AC.), A-05 (1.81 AC.), A-06 (0.75 AC.), A-07 (1.53 AC.), A-7.1 (0.33 AC.), A-08 (1.97 AC.), A-09 (1.13 AC.), A-10 (0.29 AC.) also consist of standard residential Type ‘A’ and Type ‘B’ lots. Runoff from theses sub-basins are directed via curb and gutter to design points 6, 7.1, 8 and 10. These design points are located next to the speed table and are in the low point of the street. Four sump inlets receive the flow at this point and direct the runoff to Pond A via underground storm pipe. An on-grade inlet at design point 7 helps reduce flow in the curb and gutter in order to keep the minor flow from overtopping the curb. Sub-basins A-11 (1.49 AC.), A-12 (0.55 AC.), A-13 (0.60 AC.), A-14 (2.11 AC.) also consist of standard residential Type ‘A’ and Type ‘B’ lots. Runoff from these basins are directed to design point 11 via curb and gutter. A sump inlet at this design point receives the flow and directs it to Pond A via underground storm pipe. Sub-basin A-15 consists mostly of detention pond A. A portion of this basin consists of rear lot runoff from Type ‘B’ lots. Runoff sheet flows overland until it reaches the trickle channel at the pond bottom, where it is directed with rest of the flows from Basin A, and then into the Pond A outlet structure. Basin B Basin B accounts for the runoff being directed to Pond B. To the greatest extent possible, runoff from developed portions of Basin B is conveyed to this proposed EURV and 100-year detention pond located at the northeast corner of the site. Sub-basins B-01 (0.66 AC.), B-02 (1.41 AC.), B-03 (3.08 AC.), B-04 (2.13 AC.), B-05 (0.72 AC.), B-4.1 (0.41 AC.), B-06 (2.34 AC.), B-07 (0.51 AC.) and B-08 (0.70 AC.) also consist of standard residential Type ‘A’ and Type ‘B’ lots with some park area. Runoff from these basins are directed to design points 17 and 18 via curb and gutter. Two sump inlets at these design points receive the flow and directs it to Pond B via underground storm pipe running along the northern boundary of the site. An on-grade inlet at design point 16



helps reduce flow in the curb and gutter in order to keep the minor flow from overtopping the curb. Sub-basins B-10 (1.42 AC.), B-20 (2.34 AC.), B-16 (4.20 AC.), B-15 (0.49 AC.), B-18 (1.00 AC.) and B-19 (1.25 AC.) also consist of standard residential Type ‘A’ and Type ‘B’ lots. Flows from B-15 and B-16 are mostly captured at sump inlets located at design points 33 and 34 next to the speed table. The major storm will overtop the speed table and be directed toward design point 24 via curb and gutter. Runoff from basins B-10, B-20, B-18 and B-19 are also directed to design point 24 via curb and gutter. A sump inlet at this design point receives the flow and directs it to Pond B via underground storm pipe. An on-grade inlet at design point 28 helps reduce flow in the curb and gutter in order to keep the minor flow from overtopping the curb before reaching the sump inlet at design point 24. Sub-basins B-09 (2.18 AC.), B-11 (1.66 AC.), B-12 (1.53 AC.), B-13 (0.48 AC.), B-21 (0.98 AC.) and B-22 (1.52 AC.) also consists of standard residential Type ‘A’ and Type ‘B’ lots with some park area. Runoff from these basins being directed to design point 32 via curb and gutter. A sump inlet at this design point receives the flow and directs it to Pond B via underground storm pipe running along the northern boundary of the site. An on-grade inlet at design point 29 helps reduce flow in the curb and gutter in order to keep the minor flow from overtopping the curb. Sub-basins B-23 (2.88 AC.), B-24.1 (0.25 AC.), B-24 (1.49 AC.), B-25 (2.65 AC.) also consist of standard residential Type ‘A’ and Type ‘B’ lots. Runoff from these basins are directed to design point 27 via curb and gutter. A sump inlet at this design point receives the flow and directs it to Pond B via underground storm pipe running along the northern boundary of the site. An on-grade inlet at design point 26 helps reduce flow in the curb and gutter in order to keep the minor flow from overtopping the curb. Sub-basins B-27 (2.48 AC.) and B-26 (2.17 AC.) consists mostly of detention pond B. A portion of these basins consist of rear lot runoff from Type ‘B’ lots. Runoff sheet flows overland until it reaches the trickle channel at the pond bottom, where it is directed with rest of the flows from Basin B, and then into the Pond B outlet structure. Basin C Basin C accounts for the runoff being directed to Pond A. To the greatest extent possible, runoff from developed portions of Basin A is conveyed to this proposed EURV and 100-year detention pond located south of E. 152nd Ave. on the southern portion of the site. Sub-basins C-01 (0.80 AC.), C-02 (0.86 AC.) and C-03 (2.61 AC.) consists of standard residential Type ‘A’ and Type ‘B’ lots. Runoff from these basins are directed to design



point 39 via curb and gutter. A sump inlet at this design point receives the flow and directs it to Pond C via underground storm pipe. Sub-basin C-04 (2.72 AC.) consists of Type ‘B’ lots and E. 152nd Ave. Runoff from this basin is directed to design point 40 via curb and gutter. A sump inlet at this design point receives the flow and directs it to Pond C via underground storm. Sub-basins C-05 (1.28 AC.) and C-06 (2.27 AC.) consists mostly of standard residential Type ‘A’ and Type ‘B’ lots. Runoff from these basins are directed to design point 42 via curb and gutter. A sump inlet at this design point receives the flow and directs it to Pond C via underground storm pipe. Sub-basins C-07 (1.42 AC.) and C-08 (0.91 AC.) consists mostly of York Street, with some standard residential Type ‘B’ lots. Runoff from these basins are directed to design points 36 and 37 via curb and gutter. A sump inlet at this design point receives the flow and directs it to Pond C via underground storm pipe. Sub-basins C-09 (1.02 AC.) and C-10 (0.83 AC.) consists mostly of detention pond C. Runoff sheet flows overland until it reaches the trickle channel at the pond bottom, where it is directed with rest of the flows from Basin C, and then into the Pond C outlet structure.

German Ditch German Ditch is an irrigation ditch that runs through the eastern side of the site. This irrigation ditch will be left undisturbed, except where proposed roads will cross the ditch. In these areas, a proposed 48” RCP has been placed to convey irrigation flows under the road.

Sump Inlet Overflow Design Overflow channels have been designed and graded in at drainage points 6,7,8,10,11,18,17,27,32,39,42,43 and 40. These overflow channels have been designed to convey flows away from potentially clogged inlets and lead them directly to the appropriate driangeways. The overflow channels have each been designed to convey the flows in the 100-year storm event. See Appendix B of this report for more information on emergency overflow design. Offsite Basin Conveyance The offsite basins within this project are referred to as Basin OS-1 through OS-14. These basins represent property which generally drains in its historic fashion onto the proposed site.



Riprap Design Riprap has been designed in accordance with Urban Drainage Criteria. All rundowns have also been designed in accordance with Urban Drainage criteria. Details of these designs have been included within Appendix B of this report. All flow characteristics and velocities were taken from the Hydraflow storm sewer design which can also be found in Appendix B. Any type L riprap has been upsized to type M soil riprap.

V. CONCLUSION

This drainage report has been prepared in conformity with the City of Thornton Standards and Specifications for the Design and Construction of Public and Improvements, and Urban Drainage Criteria Manuals. The proposed drainage plan is also in conformance with assumptions made within the OSP study that was prepared for the Big Dry Creek major drainage basin. The proposed drainage facilities shall safely and effectively convey significant storm events to adequate outfall locations.



VI. REFERENCES

1. Urban Storm Drainage Criteria Manual, volumes 1, 2, and 3, Urban Drainage and Flood Control District, January 2016.

2. Natural Resources Conservation Center Web Soil Survey, United States Department of Agriculture, site visited October 2016.

3. Federal Emergency Management Agency Flood Insurance Rate Map, Community-Panel Number 08001C0302J, Map Revised January 20, 2016.

4. City of Thornton – Standards and Specifications, City of Thornton, CO, Revised October 2012.

5. Outfall Systems Planning Update of Big Dry Creek Northern Tributaries Conceptual Preliminary Design Report (March 2007), Wright Engineers Inc., March 2007.


APPENDIX A – Reference Materials FEMA Flood Insurance Rate Map NRCS Soil Information Related Drainage Reports

Hydrologic Soil Group—Adams County Area, Parts of Adams and Denver Counties, Colorado(EASTCREEK NRCS WEB SOIL SURVEY)

Natural ResourcesConservation Service

Web Soil SurveyNational Cooperative Soil Survey

10/11/2016Page 1 of 4

4424

400

4424

500

4424

600

4424

700

4424

800

4424

900

4425

000

4425

100

4425

200

4424

400

4424

500

4424

600

4424

700

4424

800

4424

900

4425

000

4425

100

4425

200

503300 503400 503500 503600 503700 503800 503900 504000 504100 504200 504300 504400 504500 504600 504700

503300 503400 503500 503600 503700 503800 503900 504000 504100 504200 504300 504400 504500 504600 504700

39° 58' 38'' N10

4° 5

7' 4

1'' W

39° 58' 38'' N

104°

56'

40'

' W

39° 58' 8'' N

104°

57'

41'

' W

39° 58' 8'' N

104°

56'

40'

' W

N

Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS840 300 600 1200 1800

Feet0 50 100 200 300

MetersMap Scale: 1:6,600 if printed on A landscape (11" x 8.5") sheet.

Warning: Soil Map may not be valid at this scale.

CITY OF THORNTON – Standards and Specifications Revised: October 2012

400-3

1. The storm sewer grade shall be such that a minimum cover is maintained to withstand AASHTO HS-20 loading on the pipe. The minimum cover depends upon the pipe size, type and class, and soil bedding condition, but shall be not less than 18 inches for Reinforced Concrete Pipe (RCP) and 24 inches for High Density Polyethylene (HDPE) at any point along the pipe.

2. Refer to Section 200 and 300 for clearance requirements. 3. Uniform slopes shall be maintained between manholes.

C. Horizontal Alignment

The minimum horizontal separation between storm sewers and water mains shall be 10 feet measured from edge of pipe to edge of pipe.

D. Material

Storm sewers within the City shall be constructed using the following material and meet the applicable standard as presented below:

TABLE 400-2

STORM SEWER STANDARDS

Pipe Material Standard Application

Reinforced Concrete (ClassIII) ASTM C-76/C-506/C-507/C-789/C-850

or AASHTO M-170/M-206/M-207/M-259/M-273

Permitted for all public and private

storm sewer

High Density Polyethylene Polyvinyl Chloride Pipe

AASHTO M-294/M-252 or ASTM F-667ASTM F-679/F-794/F-1803/D-

3212/F-477 or AASHTO M-304

Permitted for all private storm sewer

1. High Density Polyethylene Polyvinyl Chloride Pipe (HDPE)

i. The maximum pipe size for High Density Polyethylene is 48 inch diameter.

ii. The minimum allowable pipe size for all public storm sewer, with the exception of detention pond outlets shall be 18 inches.

iii. The Responsible Party’s shall provide calculations for all concrete head and end walls required

due to the buoyancy of HDPE. E. Storm Sewer Hydraulics

All storm sewers shall be designed for the buildout condition of the street as depicted in the current Transportation Plan, and include the five (5) and 100 year HGL. The five (5) year HGL should be completely contained within the pipe and the 100 year HGL must be contained within the overall drainage system but cannot encroach onto any lots.

402.8 Inlets

1. All inlets in sump conditions must provide an emergency overflow that does not encroach upon

residential lots. All emergency overflows shall be designed for a major storm and the assumption that the storm sewer system is plugged. In addition, the 100 year ponding shall be shown on grading plans.

2. Care should be taken to not place inlets within areas which will be shadowed during the winter months by structures, landscaping, or fencing along the south side of east-west roadways. This may require additional inlets along north-south roadways to minimize flows to the south side of an east-west street.

A. Types of Inlets

Grate and slotted inlets and are not permitted.


400-1

SECTION 400 - STORM DRAINAGE DESIGN, GRADING, AND WATER QUALITY TECHNICAL CRITERIA 401 GENERAL PROVISIONS 401.1 Purpose

A. These standards are promulgated by the Public Works Director of the City in accordance with the authority

contained in the City Code. Improvements shall also be in conformance with all applicable provisions of the City Code. B. This section presents the minimum design and technical criteria for the analysis and design of storm drainage facilities located within the City. All subdivisions or any other proposed construction, which increase drainage from historic levels or otherwise alters storm runoff shall be subject to these Standards and Specifications. The primary resource for stormwater drainage policy and design is the Urban Drainage and Flood Control District’s (UDFCD) Urban Storm Drainage Criteria Manual (UDFCD Manual). The purpose of these Standards and Specifications is to further define the guidelines and/or to identify variations.

C. In addition to the above, these regulations are to establish minimum design criteria for water quality

control, flood control, and site grading, which are all closely related to stormwater management.

1. Design Criteria

Storm drainage system analysis and design shall meet or exceed these Standards and Specifications which were developed to support and supplement the policies and standards set forth by the UDFCD. Policies and technical criteria not specifically addressed in this document shall follow the provisions of the UDFCD Manual. The Responsible Party is also referred to the Colorado Department of Transportation's Standard Plans ("M-Standards") for additional design details not covered in these Standards and Specifications or the UDFCD Manual.

2. Review and Approval

a. The Development Engineering Manager shall review submittals as necessary for general compliance with these Standards and Specifications. An approval by the Development Engineering Manager does not relieve the Responsible Party from the responsibility of ensuring that the calculations, plans, specifications, construction, and record drawings are in compliance with these Standards and Specifications.

b. The UDFCD shall approve reports and construction plans for regional detention ponds or

Masterplan drainageway improvements as required by this Section or the UDFCD Manual. Where floodplain delineation is involved, UDFCD and FEMA approval is required. All submittals to either UDFCD or FEMA shall be made to the City, who will coordinate the submittal and approval.

402 STORM DRAINAGE DESIGN CRITERIA 402.1 Rainfall

1. Introduction

A. Colorado Urban Hydrograph Procedure (CUHP) or an equivalent method shall be used to generate an

inflow hydrographs from watersheds unless a variance is approved by the Development Engineering Manager.

B. Design Storm Distribution

The one (1) hour design point rainfall values obtained from the NOAA Atlas for Thornton are as follows:

TABLE 400-1

ONE (1) HOUR POINT RAINFALL (IN.)

2-YEAR 5-YEAR 100-YEAR .97 1.38 2.69

402.2 Runoff

A. Introduction This subsection presents the criteria and methodology for approximating the storm runoff design peaks

and volumes to be used in the City in the preparation of storm drainage studies, plans, and facility design.


400-2

The details of the rainfall/runoff models are presented in the UDFCD Manual. The specific input data requirements and modifications to the procedures are presented in this subsection.

B. CUHP

The CUHP method or equivalent UDFCD method shall be used to determine stormwater runoff calculations. The procedures for the CUHP, as explained in the Manual, Volume-1 "Runoff," shall be followed in the preparation of drainage reports or plans and storm drainage facility designs in the City.

402.3 Overlot Grading

For residential application (single family detached and duplex), the grading shall be designed so that no more than one lot shall drain through another lot.

402.4 Street Drainage

A. Introduction

The Responsible Party is directed to utilize the UDFCD Manual for allowable use of streets for storm runoff, with the exception that the allowable depth of water at the gutter flowline shall be 12 inches on local and collector roadways and streets shall be designed so that the runoff does not encroach onto residential lots.

402.5 Curb and Gutter

A. The minimum longitudinal slope of a gutter shall be 0.75%. B. The minimum cross slope of two (2)% for pavement drainage. C. Concrete cross pans may be used to convey runoff across intersections. However, cross pans will only be

permitted at locations where traffic is controlled by a stop sign. The minimum longitudinal slope for cross pans is 0.75%.

402.6 Roadside Ditches

A. Roadside ditches shall not be permitted in lieu of curb and gutter for public right-of-way except in instances

where the Responsible Party is only required to construct curb and gutter for one (1) side of the roadway, then roadside ditches are permitted and shall be designed to adequately carry the street runoff caused by the minor storm.

B. Freeboard of six (6) inches is required on all roadside ditches. C. Roadside ditches shall be designed with maximum side slopes of 4:1 and maximum velocities during the

minor storm of five (5) feet per second. D. Where the requirements of this section cannot be met, curb and gutter and/or storm sewer shall be

required.

E. Roadside ditches are not permitted in or adjacent to developed property. Are allowed only on a temporary basis and must be approved by the Development Engineering Manager. The primary function is to convey right-of-way drainage to an approved drainage system or approved drainageway.

402.7 Storm Sewers

A. Introduction 1. Storm sewers must be designed to convey the minor storm without surcharging the pipe. The CUHP

method is required to determine the peak flows that the storm sewers must be able to covey. Modeling shall be done using StormCAD or approved equal.

2. All storm sewer infrastructure in public right-of-ways shall be designed for the ultimate cross section

of the roadway. 3. The minimum allowable pipe size for all public storm sewer shall be 18 inches. 4. Private owned and maintained detention pond outlet pipes which do not discharge to public right-of-

way may be smaller than 18 inches. B. Vertical Alignment

DRAINAGE CRITERIA MANUAL (V. 1) RUNOFF

Figure RO-3— Watershed Imperviousness, Single-Family Residential Ranch Style Houses

2007-01 RO-15 Urban Drainage and Flood Control District

40%Imperviousness

2,400 sq. ft.

DRAINAGE CRITERIA MANUAL (V. 1) RUNOFF

Figure RO-5—Watershed Imperviousness, Single-Family Residential Two-Story Houses

Figure RO-6—Runoff Coefficient, C, vs. Watershed Percentage Imperviousness NRCS Hydrologic Soil Group A

2007-01 RO-17 Urban Drainage and Flood Control District

34%ImperviousnessTotal residentialimperviousnesscalculated assuming25% of site was aRanch Style Unit:

0.25(40%)+.75(34%)=35.5% Imperviousness

2,400 sq. ft.

MAP LEGEND MAP INFORMATION

Area of Interest (AOI)Area of Interest (AOI)

SoilsSoil Rating Polygons

A

A/D

B

B/D

C

C/D

D

Not rated or not available

Soil Rating LinesA

A/D

B

B/D

C

C/D

D


Soil Rating PointsA

A/D

B

B/D

C

C/D

D


Water FeaturesStreams and Canals

TransportationRails

Interstate Highways

US Routes

Major Roads

Local Roads

BackgroundAerial Photography

The soil surveys that comprise your AOI were mapped at 1:20,000.

Warning: Soil Map may not be valid at this scale.

Enlargement of maps beyond the scale of mapping can causemisunderstanding of the detail of mapping and accuracy of soil lineplacement. The maps do not show the small areas of contrastingsoils that could have been shown at a more detailed scale.

Please rely on the bar scale on each map sheet for mapmeasurements.

Source of Map: Natural Resources Conservation ServiceWeb Soil Survey URL: http://websoilsurvey.nrcs.usda.govCoordinate System: Web Mercator (EPSG:3857)

Maps from the Web Soil Survey are based on the Web Mercatorprojection, which preserves direction and shape but distortsdistance and area. A projection that preserves area, such as theAlbers equal-area conic projection, should be used if more accuratecalculations of distance or area are required.

This product is generated from the USDA-NRCS certified data as ofthe version date(s) listed below.

Soil Survey Area: Adams County Area, Parts of Adams andDenver Counties, ColoradoSurvey Area Data: Version 12, Sep 22, 2015

Soil map units are labeled (as space allows) for map scales 1:50,000or larger.

Date(s) aerial images were photographed: Mar 16, 2012—Sep18, 2014

The orthophoto or other base map on which the soil lines werecompiled and digitized probably differs from the backgroundimagery displayed on these maps. As a result, some minor shiftingof map unit boundaries may be evident.

Hydrologic Soil Group—Adams County Area, Parts of Adams and Denver Counties, Colorado(EASTCREEK NRCS WEB SOIL SURVEY)



10/11/2016Page 2 of 4

Hydrologic Soil Group

Hydrologic Soil Group— Summary by Map Unit — Adams County Area, Parts of Adams and Denver Counties, Colorado(CO001)

Map unit symbol Map unit name Rating Acres in AOI Percent of AOI

AdB Arvada loam, 0 to 3percent slopes

C 0.4 0.3%

AsC Ascalon sandy loam, 3 to5 percent slopes

B 8.7 7.3%

AsD Ascalon sandy loam, 5 to9 percent slopes

B 3.6 3.0%

NuB Nunn clay loam, 1 to 3percent slopes

C 2.3 2.0%

PlB Platner loam, 0 to 3percent slopes

C 60.3 50.6%

PlC Platner loam, 3 to 5percent slopes

C 9.9 8.3%

UlC Ulm loam, 3 to 5 percentslopes

C 26.1 21.9%

UlD Ulm loam, 5 to 9 percentslopes

C 7.8 6.6%

Totals for Area of Interest 119.2 100.0%

Hydrologic Soil Group—Adams County Area, Parts of Adams and Denver Counties, Colorado EASTCREEK NRCS WEB SOILSURVEY



10/11/2016Page 3 of 4

Description

Hydrologic soil groups are based on estimates of runoff potential. Soils areassigned to one of four groups according to the rate of water infiltration when thesoils are not protected by vegetation, are thoroughly wet, and receive precipitationfrom long-duration storms.

The soils in the United States are assigned to four groups (A, B, C, and D) andthree 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 thoroughlywet. These consist mainly of deep, well drained to excessively drained sands orgravelly sands. These soils have a high rate of water transmission.

Group B. Soils having a moderate infiltration rate when thoroughly wet. Theseconsist chiefly of moderately deep or deep, moderately well drained or well drainedsoils that have moderately fine texture to moderately coarse texture. These soilshave a moderate rate of water transmission.

Group C. Soils having a slow infiltration rate when thoroughly wet. These consistchiefly of soils having a layer that impedes the downward movement of water orsoils of moderately fine texture or fine texture. These soils have a slow rate of watertransmission.

Group D. Soils having a very slow infiltration rate (high runoff potential) whenthoroughly wet. These consist chiefly of clays that have a high shrink-swellpotential, soils that have a high water table, soils that have a claypan or clay layerat or near the surface, and soils that are shallow over nearly impervious material.These soils have a very slow rate of water transmission.

If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter isfor drained areas and the second is for undrained areas. Only the soils that in theirnatural condition are in group D are assigned to dual classes.

Rating Options

Aggregation Method: Dominant Condition

Component Percent Cutoff: None Specified

Tie-break Rule: Higher

Hydrologic Soil Group—Adams County Area, Parts of Adams and Denver Counties, Colorado EASTCREEK NRCS WEB SOILSURVEY



10/11/2016Page 4 of 4


APPENDIX B – Site Hydrology and Hydraulics % Impervious Calculations “C” Value Calculations SF2 & SF3 Rational Method Calculations Street Capacity Calculations Inlet Calculations Storm Sewer Design

PROJECT: EastcreekJOB NO.: 13049

CALC. BY: DFADATE: 10/17/2016

Impervious Percentages - from Urban Drainage Table 6-3

Residential 36%Paved 100%Parks 10%Walks 90%

Landscaping 2%Historic 2%

SOIL TYPE: C or D (use equation from Table 6-4)

PROPOSED COMPOSITE IMPERVIOUSNESS

Basin Area (ac) Residential Paved Parks Walks Landscaping Historic Imp. C2 C5 C10 C100

A-01 1.38 1.38 36% 0.32 0.36 0.46 0.67

A-02 1.68 1.68 36% 0.32 0.36 0.46 0.67

A-03 1.35 1.35 36% 0.32 0.36 0.46 0.67

A-04 1.45 1.45 36% 0.32 0.36 0.46 0.67

A-05 1.81 1.81 36% 0.32 0.36 0.46 0.67

A-06 0.93 0.93 36% 0.32 0.36 0.46 0.67

A-07 1.84 1.53 0.31 31% 0.28 0.32 0.43 0.65

A-7.1 0.33 0.05 0.28 24% 0.21 0.26 0.37 0.61

A-08 1.97 1.68 0.29 32% 0.28 0.33 0.43 0.65

A-09 0.72 0.72 36% 0.32 0.36 0.46 0.67

Weighted Impervious and C ValuesAreas (ac)

JANSEN STRAWN COMPOSITE C VALUES - PROP10/28/2016

13049-SF2 SF3.xlsx










A-10 0.29 0.29 36% 0.32 0.36 0.46 0.67

A-11 1.49 1.49 36% 0.32 0.36 0.46 0.67

A-12 0.55 0.55 36% 0.32 0.36 0.46 0.67

A-13 0.60 0.60 36% 0.32 0.36 0.46 0.67

A-14 2.11 2.11 36% 0.32 0.36 0.46 0.67

A-15 1.72 0.38 1.34 9% 0.08 0.13 0.27 0.55

OS-01 1.57 0.70 0.87 17% 0.15 0.20 0.33 0.58

OS-02 1.13 0.59 0.54 19% 0.17 0.22 0.34 0.60


13049-SF2 SF3.xlsx










Basin A 22.92 19.24 0.05 0.88 0.00 2.75 0.00 31% 0.27 0.32 0.43 0.65

B-01 0.66 0.66 36% 0.32 0.36 0.46 0.67

B-02 1.41 1.41 36% 0.32 0.36 0.46 0.67

B-03 3.08 3.08 36% 0.32 0.36 0.46 0.67

B-04 2.13 2.13 36% 0.32 0.36 0.46 0.67

B-4.1 0.41 0.41 36% 0.32 0.36 0.46 0.67

B-05 0.72 0.72 36% 0.32 0.36 0.46 0.67

B-06 2.34 2.34 36% 0.32 0.36 0.46 0.67

B-07 0.51 0.51 36% 0.32 0.36 0.46 0.67


13049-SF2 SF3.xlsx










B-08 0.70 0.70 36% 0.32 0.36 0.46 0.67

B-09 2.18 1.56 0.62 28% 0.25 0.30 0.41 0.64

B-10 1.42 1.10 0.32 30% 0.26 0.31 0.42 0.64

B-11 1.66 0.96 0.70 25% 0.22 0.27 0.38 0.62

B-12 1.53 1.53 36% 0.32 0.36 0.46 0.67

B-13 0.48 0.48 36% 0.32 0.36 0.46 0.67

B-14 2.32 2.32 36% 0.32 0.36 0.46 0.67

B-15 0.49 0.39 0.10 80% 0.71 0.75 0.79 0.87

B-16 4.20 4.20 36% 0.32 0.36 0.46 0.67

B-17 1.17 1.17 36% 0.32 0.36 0.46 0.67


13049-SF2 SF3.xlsx










B-18 1.00 0.34 0.66 41% 0.36 0.41 0.50 0.69

B-19 1.25 0.81 0.44 27% 0.24 0.28 0.40 0.63

B-20 2.34 1.05 1.29 21% 0.19 0.24 0.36 0.60

B-21 0.98 0.98 36% 0.32 0.36 0.46 0.67

B-22 1.52 1.52 36% 0.32 0.36 0.46 0.67

B-23 2.88 2.88 36% 0.32 0.36 0.46 0.67

B-24 1.74 1.74 36% 0.32 0.36 0.46 0.67

B-24.1 0.25 0.25 36% 0.32 0.36 0.46 0.67

B-25 2.65 2.65 36% 0.32 0.36 0.46 0.67

B-26 2.17 0.23 1.94 13% 0.11 0.16 0.29 0.57


13049-SF2 SF3.xlsx










B-27 2.48 0.80 1.68 18% 0.16 0.21 0.33 0.59

Basin B 46.67 38.19 0.73 7.65 0.00 0.10 0.00 32% 0.29 0.33 0.44 0.65

C-01 0.80 0.80 36% 0.32 0.36 0.46 0.67

C-02 0.85 0.85 36% 0.32 0.36 0.46 0.67

C-03 2.61 2.58 0.03 35% 0.31 0.36 0.46 0.67

C-04 2.72 2.72 36% 0.32 0.36 0.46 0.67

C-05 1.28 1.28 36% 0.32 0.36 0.46 0.67


13049-SF2 SF3.xlsx










C-06 2.27 2.27 36% 0.32 0.36 0.46 0.67

C-07 1.42 1.00 0.42 73% 0.65 0.69 0.74 0.84

C-08 0.91 0.24 0.36 0.31 52% 0.47 0.51 0.59 0.74

C-09 1.02 0.90 0.12 32% 0.28 0.33 0.43 0.65

C-10 0.83 0.83 10% 0.09 0.14 0.27 0.55

Basin C 14.71 11.64 1.36 1.59 0.00 0.12 0.00 38% 0.34 0.39 0.48 0.68

OS-03 1.50 1.50 10% 0.09 0.14 0.27 0.55


13049-SF2 SF3.xlsx










OS-04 0.49 0.49 10% 0.09 0.14 0.27 0.55

OS-05 0.12 0.12 10% 0.09 0.14 0.27 0.55

OS-06 5.22 5.22 10% 0.09 0.14 0.27 0.55

OS-07 0.20 0.20 10% 0.09 0.14 0.27 0.55

OS-08 0.42 0.42 10% 0.09 0.14 0.27 0.55

OS-09 2.33 2.33 10% 0.09 0.14 0.27 0.55

OS-10 0.55 0.55 10% 0.09 0.14 0.27 0.55

OS-11 3.56 3.56 10% 0.09 0.14 0.27 0.55

OS-12 2.15 0.89 1.26 21% 0.18 0.23 0.35 0.60

OS-13 0.18 0.15 0.03 85% 0.76 0.79 0.83 0.89


13049-SF2 SF3.xlsx










OS-14 1.53 0.88 0.65 63% 0.56 0.60 0.67 0.79


13049-SF2 SF3.xlsx

Calculated By: Project: EastcreekDate: Job No.: 13049

Checked By:

FINAL REMARKStc

DESIG: i C5 AREA LENGTH SLOPE ti LENGTH SLOPE VEL. tt COMP. TOT. LENGTH So tc (Equation 6-5)

Ac Ft % Min Ft % FPS Min tc Ft % Min Min(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16)

A-01 0.36 0.36 1.38 126 2.5 11.2 493 20 0.8 1.7 4.7 16.0 619 1.11 17.5 16.0

A-02 0.36 0.36 1.68 67 2.5 8.2 730 20 0.8 1.7 7.0 15.2 797 0.90 19.5 15.2

A-03 0.36 0.36 1.35 130 2.5 11.4 385 20 0.9 1.9 3.4 14.8 515 1.30 16.3 14.8

A-04 0.36 0.36 1.45 134 2.5 11.6 663 20 0.8 1.8 6.1 17.7 797 1.10 18.8 17.7

A-05 0.36 0.36 1.81 130 3.9 9.8 507 20 0.8 1.8 4.8 14.6 637 1.42 17.0 14.6

A-06 0.36 0.36 0.93 71 2.5 8.4 371 20 0.8 1.7 3.6 12.0 442 1.03 16.2 12.0

A-07 0.31 0.32 1.84 125 2.5 11.7 568 20 0.8 1.7 5.4 17.2 693 1.07 19.0 17.2

A-7.1 0.24 0.26 0.33 123 2.5 12.6 62 20 0.8 1.7 0.6 13.2 185 1.92 15.7 13.2

A-08 0.32 0.33 1.97 118 2.5 11.3 701 20 0.8 1.7 6.7 18.1 819 1.00 20.2 18.1

A-09 0.36 0.36 0.72 65 2.5 8.1 655 20 0.8 1.7 6.3 14.4 720 0.91 18.8 14.4

A-10 0.36 0.36 0.29 66 2.5 8.1 125 20 0.8 1.7 1.2 9.3 191 1.35 14.0 9.3

A-11 0.36 0.36 1.49 70 2.5 8.4 615 20 2.8 3.3 3.1 11.4 685 2.72 16.0 11.4

A-12 0.36 0.36 0.55 120 2.5 10.9 261 20 3.5 3.7 1.2 12.1 381 3.19 14.4 12.1

A-13 0.36 0.36 0.60 125 2.5 11.2 277 20 0.8 1.8 2.6 13.7 402 1.33 15.5 13.7

A-14 0.36 0.36 2.11 24 2.5 4.9 948 20 0.9 1.9 8.5 13.4 972 0.90 21.0 13.4

A-15 0.09 0.13 1.72 225 8.0 13.3 180 20 0.8 1.7 1.7 15.0 405 4.78 18.8 15.0

5.0

B-01 0.36 0.36 0.66 118 2.5 10.8 385 20 0.8 1.7 3.7 14.6 503 1.16 16.5 14.6

B-02 0.36 0.36 1.41 67 2.5 8.2 540 20 0.8 1.7 5.2 13.4 607 0.94 17.8 13.4

B-03 0.36 0.36 3.08 238 2.5 15.4 568 20 0.8 1.7 5.5 20.9 806 1.27 18.5 18.5

B-04 0.36 0.36 2.13 127 2.5 11.3 882 20 0.8 1.7 8.5 19.7 1,009 0.97 21.0 19.7

B-4.1 0.36 0.36 0.41 124 2.5 11.1 126 20 1.9 2.8 0.8 11.9 250 2.20 14.0 11.9

B-05 0.36 0.36 0.72 65 2.5 8.1 667 20 0.8 1.8 6.2 14.3 732 0.95 18.8 14.3

B-06 0.36 0.36 2.34 130 2.5 11.4 817 20 0.8 1.7 7.9 19.2 947 0.99 20.4 19.2

B-07 0.36 0.36 0.51 60 2.5 7.7 165 20 0.9 1.9 1.4 9.2 225 1.33 14.3 9.2

B-08 0.36 0.36 0.70 64 2.5 8.0 254 20 0.8 1.7 2.4 10.4 318 1.10 15.1 10.4

B-09 0.28 0.30 2.18 258 5.7 13.3 355 20 2.5 3.2 1.9 15.1 613 3.83 16.5 15.1

B-10 0.30 0.31 1.42 71 2.5 9.0 726 20 2.2 3.0 4.1 13.1 797 2.22 18.2 13.1

B-11 0.25 0.27 1.66 290 2.8 18.6 231 20 1.8 2.6 1.5 20.0 521 2.31 17.5 17.5

Cv

DFA10/17/2016

DATASUB-BASIN TRAVEL TIME

(tt)

STANDARD FORM SF-2TIME OF CONCENTRATION SUMMARY

tc CHECK(URBANIZED BASINS)

INITIAL/OVERLANDTIME (ti)

JANSEN STRAWNTOC

10/28/201613049-SF2 SF3.xlsx


Checked By:

FINAL REMARKStc



Cv

DFA10/17/2016


(tt)




B-12 0.36 0.36 1.53 65 2.5 8.1 813 20 2.3 3.0 4.5 12.5 878 2.31 17.4 12.5

B-13 0.36 0.36 0.48 98 2.5 9.9 243 20 1.3 2.3 1.8 11.7 341 1.65 14.8 11.7

B-15 0.80 0.75 0.49 13 3.5 1.5 688 20 2.8 3.3 3.4 5.0 701 2.81 8.2 5.0

B-16 0.36 0.36 4.20 205 2.5 14.3 726 20 2.5 3.2 3.8 18.1 931 2.50 17.5 17.5

B-17 0.36 0.36 1.17 300 3.0 16.3 417 7 3.0 1.2 5.7 22.0 717 3.00 16.0 16.0

B-18 0.41 0.41 1.00 204 3.3 12.2 22 20 0.8 1.7 0.2 12.4 226 3.05 12.9 12.4

B-19 0.27 0.28 1.25 230 2.5 16.7 126 20 1.3 2.3 0.9 17.7 356 2.08 16.3 16.3

B-20 0.21 0.24 2.34 184 2.0 17.0 204 20 1.3 2.3 1.5 18.5 388 1.63 17.7 17.7

B-21 0.36 0.36 0.98 122 2.0 11.9 465 20 2.8 3.3 2.3 14.2 587 2.59 15.6 14.2

B-22 0.36 0.36 1.52 135 2.5 11.6 361 20 2.8 3.3 1.8 13.4 496 2.68 15.1 13.4

B-23 0.36 0.36 2.88 142 2.5 11.9 655 20 1.1 2.1 5.2 17.1 797 1.35 18.2 17.1

B-24 0.36 0.36 1.74 188 2.5 13.7 304 20 1.0 2.0 2.5 16.2 492 1.57 15.9 15.9

B-24.1 0.36 0.36 0.25 27 3.0 4.9 242 20 1.3 2.3 1.8 6.7 269 1.44 14.5 6.7

B-25 0.36 0.36 2.65 120 2.5 10.9 910 20 1.0 2.0 7.6 18.5 1,030 1.17 20.4 18.5

B-26 0.13 0.16 2.17 185 10.0 10.9 130 20 0.8 1.7 1.3 12.1 315 6.18 17.5 12.1

B-27 0.18 0.21 2.48 250 10.0 12.0 180 20 0.8 1.7 1.7 13.7 430 6.13 17.0 13.7

5.0

C-01 0.36 0.36 0.80 63 2.5 7.9 394 20 0.8 1.8 3.7 11.6 457 1.03 16.3 11.6

C-02 0.36 0.36 0.85 124 2.5 11.1 306 20 1.8 2.7 1.9 13.0 430 1.99 15.2 13.0

C-03 0.35 0.36 2.61 180 2.5 13.4 300 20 0.8 1.7 2.9 16.3 480 1.41 16.0 16.0

C-04 0.36 0.36 2.72 156 5.5 9.6 650 20 1.8 2.7 4.1 13.6 806 2.50 16.8 13.6

C-05 0.36 0.36 1.28 63 2.5 7.9 195 20 1.2 2.2 1.5 9.4 258 1.52 14.4 9.4

C-06 0.36 0.36 2.27 121 2.5 11.0 636 20 1.3 2.3 4.6 15.6 757 1.49 17.7 15.6

C-07 0.73 0.69 1.42 40 3.0 3.3 841 20 1.1 2.1 6.7 10.0 881 1.18 11.6 10.0

C-08 0.52 0.51 0.91 105 3.0 7.7 215 20 0.8 1.8 2.0 9.7 320 1.52 11.9 9.7

C-09 0.32 0.33 1.02 152 2.0 13.9 195 20 0.8 1.8 1.8 15.7 347 1.33 15.8 15.7

C-10 0.10 0.14 0.83 300 11.0 13.7 180 20 0.8 1.7 1.7 15.5 480 7.16 18.6 15.5

5.0

OS-01 0.17 0.20 1.57 5.0

JANSEN STRAWNTOC

10/28/201613049-SF2 SF3.xlsx


Checked By:

FINAL REMARKStc



Cv

DFA10/17/2016


(tt)




OS-02 0.19 0.22 1.13 5.0

OS-03 0.10 0.14 1.50 5.0

OS-04 0.10 0.14 0.49 5.0

OS-05 0.10 0.14 0.12 5.0

OS-06 0.10 0.14 5.22 5.0

OS-07 0.10 0.14 0.20 5.0

OS-08 0.10 0.14 0.42 5.0

OS-09 0.10 0.14 2.33 5.0

OS-10 0.10 0.14 0.55 5.0

OS-11 0.10 0.14 3.56 5.0

OS-12 0.21 0.23 2.15 5.0

OS-13 0.85 0.79 0.18 5.0

OS-14 0.63 0.60 1.53 5.0

JANSEN STRAWNTOC

10/28/201613049-SF2 SF3.xlsx


Checked By: Design Storm: 5-YR1.38

DES

IGN

PO

INT

AREA

D

ESIG

N

AREA

(A

C)

RU

NO

FF

CO

EFF

t c

(MIN

)

C *

A

(AC

)

I

(IN

/HR

)

Q

(C

FS)

t c

(MIN

)

S (C

* A)

(CA) I

(IN/H

R)

Q

(C

FS)

SLO

PE

(%

)

STR

EET

FLO

W

DES

IGN

FLO

W (C

FS)

SLO

PE

(%

)

PIPE

DIA

M.

(IN.)

(2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) (17) (18) (19) (20) (21) (22)A-04 1 1.45 0.36 17.7 0.52 2.89 1.5 0.8% 1.5 92 1.7 0.9 Street flow to crosspan at DP4 and then to DP1

A-03 1 1.35 0.36 14.8 0.49 3.15 1.5 Street flow to sump inlet at DP1


1 18.5 0.5 2.82 1.4 Sump inlet at DP1

A-02 2 1.68 0.36 15.2 0.61 3.11 1.9 Sump inlet at DP2

A-05 5 1.81 0.36 14.6 0.65 3.17 2.1 Street flow to crosspan at DP5

A-07 7 1.84 0.32 17.2 0.60 2.94 1.7 Ongrade inlet at DP7

A-7.1 7.1 0.33 0.26 13.2 0.09 3.32 0.3 Street flow to ongrade inlet at DP7.1

7.1 17.2 1.3 2.94 3.9 Sump inlet at DP7.1

A-06 6 0.93 0.36 12.0 0.34 3.47 1.2 Sump inlet at DP6

A-09 8 0.72 0.36 14.4 0.26 3.20 0.8 0.8% 0.8 84 1.8 0.8 Street flow to DP9 and then to DP8

A-08 8 1.97 0.33 18.1 0.65 2.86 1.8 Street flow to inlet at DP8

8 18.1 0.9 2.86 2.6 Sump inlet at DP8

A-10 10 0.29 0.36 9.3 0.10 3.84 0.4 Sump inlet at DP10


A-13 11 0.60 0.36 13.7 0.22 3.26 0.7 2.5% 0.7 205 3.2 1.1 Street flow to crosspan at DP13, then to DP11


A-14 11 2.11 0.36 13.4 0.76 3.30 2.5 1.0% 2.5 58 2.0 0.5 Street flow to crosspan at DP14/DP12, then to DP11

11 14.8 1.7 3.15 5.4 Sump inlet at DP11

B-02 21 1.41 0.36 13.4 0.51 3.30 1.7 0.8% 1.7 21 1.7 0.2 Street flow to crosspan then to DP21

B-01 21 0.66 0.36 14.6 0.24 3.18 0.8 Street flow to DP21

14.6 0.7 3.18 2.4 Ongrade inlet at DP21

B-03 16 3.08 0.36 18.5 1.11 2.83 3.1 1.9% 3.1 65 2.8 0.4 Street flow to crosspan at DP15 then to DP16

STANDARD FORM SF-310/17/2016 STORM DRAINAGE SYSTEM DESIGN

(RATIONAL METHOD PROCEDURE)

PIPE

DFA

LEN

GTH

(F

T)

VELO

CIT

Y

(F

PS)

t t

(MIN

)

REMARKS

5-yr, 1-hour rainfall=

DIRECT RUNOFF TOTAL RUNOFF STREET

BASIN

JANSEN STRAWN5-YEAR

10/28/201613049-SF2 SF3.xlsx



DES

IGN

PO

INT

AREA

D

ESIG

N

AREA

(A

C)

RU

NO

FF

CO

EFF

t c

(MIN

)

C *

A

(AC

)

I

(IN

/HR

)

Q

(C

FS)

t c

(MIN

)

S (C

* A)

(CA) I

(IN/H

R)

Q

(C

FS)

SLO

PE

(%

)

STR

EET

FLO

W

DES

IGN

FLO

W (C

FS)

SLO

PE

(%

)

PIPE

DIA

M.

(IN.)

(2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) (17) (18) (19) (20) (21) (22)



PIPE

DFA

LEN

GTH

(F

T)

VELO

CIT

Y

(F

PS)

t t

(MIN

)

REMARKS



BASIN



B-07 17 0.51 0.36 9.2 0.18 3.86 0.7 0.9% 0.7 688 1.9 5.9 Street flows to crosspan at DP22 then DP17

B-06 17 2.34 0.36 19.2 0.84 2.77 2.3 Street flows to DP 17

B-4.1 17 0.41 0.36 11.9 0.15 3.48 0.5 Street flows to DP 17

19.2 1.2 2.77 3.3 Sump inlet at DP17



18 14.3 0.5 3.21 1.6 Sump inlet at DP18

B-17 17.1 1.17 0.36 16.0 0.42 3.03 1.3 2.6% 1.3 491 3.2 2.6 Street flow to DP17.1 then to DP23

B-18 23 1.00 0.41 12.4 0.41 3.41 1.4 1.1% 2.7 205 2.1 1.6 Street flow to DP23 then to DP24



24 18.6 1.7 2.82 4.9 Sump inlet at DP24

B-10 28 1.42 0.31 13.1 0.44 3.34 1.5 Ongrade inlet at DP28

B-09 36 2.18 0.30 15.1 0.65 3.12 2.0 2.2% 2.0 440 3.0 2.5 Street flows to DP36 then to DP29


B-12 29 1.53 0.36 12.5 0.55 3.40 1.9 Street flows to DP29

29 19.6 1.6 2.74 4.5 Ongrade inlet at DP29



B-22 32 1.52 0.36 13.4 0.55 3.30 1.8 Steet flows to DP32

32 15.0 1.1 3.14 3.4 Sump inlet at DP32

B-16 33 4.20 0.36 17.5 1.52 2.91 4.4 Sump inlet at DP33

JANSEN STRAWN5-YEAR

10/28/201613049-SF2 SF3.xlsx



DES

IGN

PO

INT

AREA

D

ESIG

N

AREA

(A

C)

RU

NO

FF

CO

EFF

t c

(MIN

)

C *

A

(AC

)

I

(IN

/HR

)

Q

(C

FS)

t c

(MIN

)

S (C

* A)

(CA) I

(IN/H

R)

Q

(C

FS)

SLO

PE

(%

)

STR

EET

FLO

W

DES

IGN

FLO

W (C

FS)

SLO

PE

(%

)

PIPE

DIA

M.

(IN.)

(2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) (17) (18) (19) (20) (21) (22)



PIPE

DFA

LEN

GTH

(F

T)

VELO

CIT

Y

(F

PS)

t t

(MIN

)

REMARKS



BASIN

B-15 34 0.49 0.75 5.0 0.37 4.68 1.7 Sump inlet at DP34


B-24.1 26 0.25 0.36 6.7 0.09 4.31 0.4 Steet flows to DP26




27 18.5 1.6 2.82 4.5 Sump inlet at DP27

C-07 36 1.42 0.69 10.0 0.98 3.73 3.7 Sump inlet at DP36

C-08 37 0.91 0.51 9.7 0.46 3.77 1.7 Sump inlet at DP37

C-01 38 0.80 0.36 11.6 0.29 3.51 1.0 1.2% 1.0 454 2.2 3.4 Street flows to DP38


C-03 39 2.61 0.36 16.0 0.94 3.04 2.8

16.3 1.5 3.01 4.6 Sump inlet at DP39

C-04 40 2.72 0.36 13.6 0.98 3.27 3.2 Sump inlet at DP40

C-05 41 1.28 0.36 9.4 0.46 3.82 1.8 1.8% 1.8 90 2.7 0.6 Street flows to DP41 then to 42

C-06 42 2.27 0.36 15.6 0.82 3.07 2.5 Street flows to DP42

15.6 1.3 3.07 3.9 Sump inlet at DP42

C-09 43 1.02 0.33 15.7 0.33 3.07 1.0 Sump inlet at DP43

JANSEN STRAWN5-YEAR

10/28/201613049-SF2 SF3.xlsx



DES

IGN

PO

INT

AREA

D

ESIG

N

AREA

(A

C)

RU

NO

FF

CO

EFF

t c

(MIN

)

C *

A

(AC

)

I

(IN

/HR

)

Q

(C

FS)

t c

(MIN

)

S (C

* A)

(CA) I

(IN/H

R)

Q

(C

FS)

SLO

PE

(%

)

STR

EET

FLO

W

DES

IGN

FLO

W (C

FS)

SLO

PE

(%

)

PIPE

DIA

M.

(IN.)

(2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) (17) (18) (19) (20) (21) (22)A-04 1 1.45 0.67 17.7 0.97 5.64 5.5 0.8% 5.5 92 1.7 0.9 Street flow to crosspan at DP4 and then to DP1



1 18.5 0.9 5.50 5.1 Sump inlet at DP1

A-02 2 1.68 0.67 15.2 1.12 6.07 6.8 Sump inlet at DP2

A-05 5 1.81 0.67 14.6 1.21 6.18 7.5 Street flow to crosspan at DP5

A-07 7 1.84 0.65 17.2 1.19 5.72 6.8 Ongrade inlet at DP7

A-7.1 7.1 0.33 0.61 13.2 0.20 6.47 1.3 Street flow to ongrade inlet at DP7.1

7.1 17.2 2.6 5.72 14.9 Sump inlet at DP7.1

A-06 6 0.93 0.67 12.0 0.62 6.76 4.2 Sump inlet at DP6

A-09 8 0.72 0.67 14.4 0.48 6.23 3.0 0.8% 3.0 84 1.8 0.8 Street flow to DP9 and then to DP8


8 18.1 1.8 5.58 9.8 Sump inlet at DP8

A-10 10 0.29 0.67 9.3 0.19 7.48 1.4 Sump inlet at DP10




A-14 11 2.11 0.67 13.4 1.41 6.43 9.1 1.0% 9.1 58 2.0 0.5 Street flow to crosspan at DP14/DP12, then to DP11

11 14.8 3.2 6.14 19.5 Sump inlet at DP11

B-02 21 1.41 0.67 13.4 0.94 6.44 6.1 0.8% 6.1 21 1.7 0.2 Street flow to crosspan then to DP21



B-03 16 3.08 0.67 18.5 2.06 5.51 11.3 1.9% 11.3 65 2.8 0.4 Street flow to crosspan at DP15 then to DP16



PIPE

DFA

LEN

GTH

(F

T)

VELO

CIT

Y

(F

PS)

t t

(MIN

)

REMARKS



BASIN

JANSEN STRAWN100-YEAR

10/28/201613049-SF2 SF3.xlsx



DES

IGN

PO

INT

AREA

D

ESIG

N

AREA

(A

C)

RU

NO

FF

CO

EFF

t c

(MIN

)

C *

A

(AC

)

I

(IN

/HR

)

Q

(C

FS)

t c

(MIN

)

S (C

* A)

(CA) I

(IN/H

R)

Q

(C

FS)

SLO

PE

(%

)

STR

EET

FLO

W

DES

IGN

FLO

W (C

FS)

SLO

PE

(%

)

PIPE

DIA

M.

(IN.)

(2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) (17) (18) (19) (20) (21) (22)



PIPE

DFA

LEN

GTH

(F

T)

VELO

CIT

Y

(F

PS)

t t

(MIN

)

REMARKS



BASIN




B-06 17 2.34 0.67 19.2 1.56 5.40 8.4 Street flows to DP 17

B-4.1 17 0.41 0.67 11.9 0.27 6.78 1.9 Street flows to DP 17

19.2 2.2 5.40 11.8 Sump inlet at DP17



18 14.3 0.9 6.25 5.9 Sump inlet at DP18

B-17 17.1 1.17 0.67 16.0 0.78 5.91 4.6 2.6% 4.6 491 3.2 2.6 Street flow to DP17.1 then to DP23

B-18 23 1.00 0.69 12.4 0.69 6.65 4.6 1.1% 9.2 205 2.1 1.6 Street flow to DP23 then to DP24



24 18.6 3.7 5.49 20.2 Sump inlet at DP24

B-10 28 1.42 0.64 13.1 0.91 6.50 5.9 Ongrade inlet at DP28







B-22 32 1.52 0.67 13.4 1.01 6.43 6.5 Steet flows to DP32

32 15.0 2.0 6.11 12.2 Sump inlet at DP32

B-16 33 4.20 0.67 17.5 2.80 5.67 15.9 Sump inlet at DP33


10/28/201613049-SF2 SF3.xlsx



DES

IGN

PO

INT

AREA

D

ESIG

N

AREA

(A

C)

RU

NO

FF

CO

EFF

t c

(MIN

)

C *

A

(AC

)

I

(IN

/HR

)

Q

(C

FS)

t c

(MIN

)

S (C

* A)

(CA) I

(IN/H

R)

Q

(C

FS)

SLO

PE

(%

)

STR

EET

FLO

W

DES

IGN

FLO

W (C

FS)

SLO

PE

(%

)

PIPE

DIA

M.

(IN.)

(2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) (17) (18) (19) (20) (21) (22)



PIPE

DFA

LEN

GTH

(F

T)

VELO

CIT

Y

(F

PS)

t t

(MIN

)

REMARKS



BASIN

B-15 34 0.49 0.87 5.0 0.43 9.12 3.9 Sump inlet at DP34


B-24.1 26 0.25 0.67 6.7 0.17 8.40 1.4 Steet flows to DP26




27 18.5 2.9 5.51 16.1 Sump inlet at DP27

C-07 36 1.42 0.84 10.0 1.19 7.28 8.7 Sump inlet at DP36

C-08 37 0.91 0.74 9.7 0.68 7.36 5.0 Sump inlet at DP37



C-03 39 2.61 0.67 16.0 1.74 5.92 10.3

16.3 2.8 5.86 16.6 Sump inlet at DP39

C-04 40 2.72 0.67 13.6 1.82 6.38 11.6 Sump inlet at DP40

C-05 41 1.28 0.67 9.4 0.85 7.45 6.4 1.8% 6.4 90 2.7 0.6 Street flows to DP41 then to 42

C-06 42 2.27 0.67 15.6 1.52 5.99 9.1 Street flows to DP42

15.6 2.4 5.99 14.2 Sump inlet at DP42

C-09 43 1.02 0.65 15.7 0.66 5.98 4.0 Sump inlet at DP43


10/28/201613049-SF2 SF3.xlsx

13049_Eastcreek UD-Inlet_v4.03.xlsm, A1 10/27/2016, 5:30 PM

Project:Inlet ID:

Gutter Geometry (Enter data in the blue cells)Maximum Allowable Width for Spread Behind Curb TBACK = 12.0 ftSide Slope Behind Curb (leave blank for no conveyance credit behind curb) SBACK = 0.040 ft/ftManning's Roughness Behind Curb (typically between 0.012 and 0.020) nBACK = 0.020

Height of Curb at Gutter Flow Line HCURB = 4.00 inchesDistance from Curb Face to Street Crown TCROWN = 17.0 ftGutter Width W = 2.00 ftStreet Transverse Slope SX = 0.020 ft/ftGutter Cross Slope (typically 2 inches over 24 inches or 0.083 ft/ft) SW = 0.083 ft/ftStreet Longitudinal Slope - Enter 0 for sump condition SO = 0.000 ft/ftManning's Roughness for Street Section (typically between 0.012 and 0.020) nSTREET = 0.015

Minor Storm Major StormMax. Allowable Spread for Minor & Major Storm TMAX = 10.6 17.0 ftMax. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX = 4.0 8.3 inches

Allow Flow Depth at Street Crown (leave blank for no) check = yes

MINOR STORM Allowable Capacity is based on Depth Criterion Minor Storm Major StormMAJOR STORM Allowable Capacity is based on Depth Criterion Qallow = SUMP SUMP cfs

ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm)(Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread)

EASTCREEKA1


Design Information (Input) MINOR MAJORType of Inlet Type =Local Depression (additional to continuous gutter depression 'a' from 'Q-Allow') alocal = 5.00 5.00 inchesNumber of Unit Inlets (Grate or Curb Opening) No = 2 2 Water Depth at Flowline (outside of local depression) Ponding Depth = 4.0 5.6 inchesGrate Information MINOR MAJORLength of a Unit Grate Lo (G) = N/A N/A feetWidth of a Unit Grate Wo = N/A N/A feetArea Opening Ratio for a Grate (typical values 0.15-0.90) Aratio = N/A N/AClogging Factor for a Single Grate (typical value 0.50 - 0.70) Cf (G) = N/A N/AGrate Weir Coefficient (typical value 2.15 - 3.60) Cw (G) = N/A N/AGrate Orifice Coefficient (typical value 0.60 - 0.80) Co (G) = N/A N/ACurb Opening Information MINOR MAJORLength of a Unit Curb Opening Lo (C) = 5.00 5.00 feetHeight of Vertical Curb Opening in Inches Hvert = 6.00 6.00 inchesHeight of Curb Orifice Throat in Inches Hthroat = 6.00 6.00 inchesAngle of Throat (see USDCM Figure ST-5) Theta = 63.40 63.40 degreesSide Width for Depression Pan (typically the gutter width of 2 feet) Wp = 2.00 2.00 feetClogging Factor for a Single Curb Opening (typical value 0.10) Cf (C) = 0.10 0.10Curb Opening Weir Coefficient (typical value 2.3-3.7) Cw (C) = 3.60 3.60Curb Opening Orifice Coefficient (typical value 0.60 - 0.70) Co (C) = 0.67 0.67

Low Head Performance Reduction (Calculated) MINOR MAJORDepth for Grate Midwidth dGrate = N/A N/A ftDepth for Curb Opening Weir Equation dCurb = 0.17 0.30 ftCombination Inlet Performance Reduction Factor for Long Inlets RFCombination = 0.38 0.53Curb Opening Performance Reduction Factor for Long Inlets RFCurb = 0.79 0.91Grated Inlet Performance Reduction Factor for Long Inlets RFGrate = N/A N/A

MINOR MAJOR

Total Inlet Interception Capacity (assumes clogged condition) Qa = 3.1 8.7 cfsInlet Capacity IS GOOD for Minor and Major Storms(>Q PEAK) Q PEAK REQUIRED = 1.4 5.1 cfs

INLET IN A SUMP OR SAG LOCATION

CDOT Type R Curb Opening

H-VertH-Curb

W

Lo (C)

Lo (G)

WoWP


Override Depths


Project:Inlet ID:







EASTCREEKA2