Final Drainage Report - City of Thorntonand Colorado, Final Drainage Report EES Page 7 303.572.7997...

Final Drainage Report Affordable Housing Project 104th Ave and Colorado Blvd City of Thornton, Colorado November 20th, 2015

Prepared For: Adams County Housing Authority 7190 Colorado Blvd, 6th Floor Commerce City, Colorado 80022

Prepared By:

EES Entitlement and Engineering Solutions, Inc. 518 17th Street, Suite 1575 Denver, CO 80202 Phone: (303) 572-7997 Contact: Jay Peters, PE Email: [email protected]

Certification Adams County Housing Authority hereby certifies that the drainage facilities for ‘Affordable Housing at 104th and Colorado’ will be constructed according to the design presented in this report. I understand that the City of Thornton does not and shall not assume liability for the drainage facilities designed and/or certified by my engineer. I understand that the City of Thornton reviews drainage plans but cannot, or behalf ‘Affordable Housing at 104th and Colorado’ guarantee that final drainage design review will absolve Adams County Housing Authority and/or their successors and/or assigns of future liability for improper design. I further understand that approval of the Plat and/or Development Permit does not imply approval of my engineer’s drainage deign. Attest: ___________________________________ Name of Responsible Party ____________________________ ___________________________________ Notary Public Authorized Signature I hereby certify that this report (plan) for the final drainage design of ‘Affordable Housing at 104th and Colorado’ was prepared by me (or under my direct supervision) in accordance with the provisions of the City of Thornton Standards and Specifications for the Design and Construction of Public and Private Improvements for the Responsible Parties thereof. I understand that the City of Thornton does not and shall not assume liability for drainage facilities designed by others Jay S. Peters P.E. Registered Professional Engineer State of Colorado No. 35068

104th and Colorado, Final Drainage Report

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TABLE OF CONTENTS

1.0 GENERAL LOCATION AND DESCRIPTION ...................................................... 2 2.0 DRAINAGE BASINS AND SUB-BASINS ............................................................ 3 3.0 DRAINAGE DESIGN CRITERIA .......................................................................... 4 4.0 DRAINAGE FACILITY DESIGN ........................................................................... 5 5.0 CONCLUSIONS ................................................................................................... 7 6.0 REFERENCES ..................................................................................................... 7 TABLES

1. Detention Basin Volume Summary

APPENDIX

Location map Hydrology Calculations Detention Pond EURV Calculations Pond Stage-Storage Table Hydraulic Calculations Inlet Capacity Calculations NRCS Soils Information Geotechnical Soils Tables Drainage Map


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1.0 GENERAL LOCATION AND DESCRIPTION 1.1 LOCATION 1.1.1 City, County, State Highway, and Local Streets The 104th and Colorado project is located in the City of Thornton at the intersection of 104th Avenue and Colorado Blvd (see Location Map). It is bounded by open space on the South, commercial development and Colorado Blvd. on the west, 104th Avenue on the north, and open space on the east. 1.1.2 Township, Range, Section The project lies within the NW ¼ of Section 18, Township 2 South, Range 67 West of the 6th Principal Meridian in the City and County of Denver, Colorado. 1.1.3 Surrounding Developments The site is bounded by the commercial development to the west and north, and open space to the east and south. 1.2 DESCRIPTION OF PROPERTY 1.2.1 General Project Description 104th and Colorado is an affordable housing project consisting mostly of residential townhomes and apartments buildings with some retail in the north building. There will be 3 multi-family residential buildings on the site. 1.2.2 Area The area of the site is 5.02 acres. 1.2.3 Ground Cover The project site is currently undeveloped. The site is primarily open space covered with short grasses. The site generally slopes to the east at around 1% to 5%. The NRCS soil survey lists the soils on the site as Platner and Ulm Loam, that are in Hydrologic Soil Group C. A geotechnical study for the Phase I improvements at Aria found lean clays on the site, indicating the soils are Group D. 1.2.4 Major Drainage-ways and Facilities


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No major drainage-ways or facilities exist on the project site. The site is located within the Grange Hall Creek watershed. 1.2.5 Existing Major Irrigation Facilities No major irrigation facilities exist within the site. 1.2.6 History of Flooding There are no reported flooding problems on the site. 1.2.7 Easements within and Adjacent to the Site There are no easements on the site. 2.0 DRAINAGE BASINS AND SUB-BASINS 2.1 MAJOR BASIN DESCRIPTION 2.1.1 Major Drainage-way Studies There is one previous major drainage-way study that included the project site, which is the Grange Hall Creek Major Drainage-way Planning Study completed in 1997. This Master Plan is currently being updated by UDFCD and the Project Sponsors. 2.1.2 Major Basin Characteristics The site is within the Grange Hall Creek watershed, specifically the Riverdale Tributary. The stream channel is about 400 feet to the south of the project site. The site is within sub-basins 8 and 54 of the planning study. The north portion of the site is within Sub-basin 8 and flows east to the creek. The south portion of the site is within sub-basin 54 and flows southeast to the creek. Runoff from the site is conveyed overland to the stream channel, there are no storm sewers or other types of formal conveyance systems between the site and the Creek. 2.1.3 Irrigation Facilities No irrigation facilities are located within the site. 2.2 SUB-BASIN DESCRIPTION 2.2.1 Historic Drainage Patterns


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The site generally conveys runoff overland to the east and southeast. Runoff flows overland to the creek through the open space. 2.2.2 On-Site and Off-Site Sub-basin Characteristics There is a portion of a small retail development to the west of the site that convey runoff overland onto the site. The north portion of the site flows east to the creek. The southern portion of the site flows southeast to the creek. 3.0 DRAINAGE DESIGN CRITERIA 3.1 REGULATIONS The 104th and Colorado Project design criteria were developed using regulations, standards, and criteria found within the City of Thornton’s Storm Drainage Design, Grading, and Water Quality Technical Criteria, CDOT’s Drainage Manual, and the Urban Drainage and Flood Control District’s Drainage Criteria Manual, Volumes I, II, and III. 3.2 DEVELOPMENT CRITERIA REFERENCE AND CONSTRAINTS 3.2.1 Previous Drainage Studies for the Site There are no known drainage studies specifically for the project site. 3.2.2 Relationship to and Implication of Adjacent Drainage Studies No adjacent drainage studies are available for this site. 3.2.3 Site Drainage Impact The site will not adversely impact surrounding drainage systems. 3.3 HYDROLOGIC CRITERIA Design Rainfall: 1-hour point rainfall depths of 1.38 and 2.69 for the 10- and 100-year storm

events, respectively. Depths were obtained from Table 400-1 of the City of Thornton’s Criteria.

Hydrologic Soil Group: NRCS hydrologic soil group C. Runoff Calculation Method: Rational Formula. Conveyance System Design Storm Recurrence Intervals: 5-year & 100-year Detention Release Rates: 0.30 cfs/acre for 10-year, 1.0 cfs/acre for 100-year Size detention ponds using the Excess Urban Runoff Volume Method (EURV).


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3.4 HYDRAULIC CRITERIA Size storm sewers for the 5-event. Size inlets for the 5-year event. Size major system for the 100-year event. Hydraulic Calculation Method: Standard Step Backwater. Do not adversely impact existing storm systems for surrounding developments. 3.5 WATER QUALITY CRITERIA Provide permanent BMPs in accordance with V3 of the UDFCD USDCM. 3.6 VARIANCES FROM CRITERIA

No waivers are requested for this portion of the project. 4.0 DRAINAGE FACILITY DESIGN 4.1 GENERAL CONCEPT The overall storm improvements at Aria will consist of: Inlets and storm sewers that convey runoff from the site to the NW Pond; Regional detention and water quality treatment pond to the south of the site. The project will implement new storm sewers and inlets within the on the site, and convey runoff to the regional pond to the south of the site. Storm sewers are sized for a minimum capacity of a 5-year storm event, with the 100-year storm event conveyed in the streets. Storm sewers in several locations are sized to convey the 100-year storm event to prevent runoff from entering property adjacent to the site, or where grades do not allow surface conveyance on the streets. 4.2 SPECIFIC DETAILS 4.2.1 Conveyance System The storm infrastructure improvements will consist of storm sewers, chases, and inlets. The new conveyance system for the site will consist of the following: Chases in parking lot medians. Type C and Type R inlets at low points on the site. 18- to 30-inch diameter storm sewer along the east side of the site. Several short 18-inch storm sewer laterals. Relocation of the inlets in 104th Avenue at the new drive access.


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Concrete pan above the retaining wall along the west site boundary. Chases will be installed within parking lot medians to allow runoff to be conveyed overland to the storm system on the east side of the site. There will be an 18- to 30- inch primary storm sewer with numerous inlets along the east boundary of the site. The storm sewer and inlets are sized to capture and convey the 100-year storm event to the regional detention pond. There is a new 18-inch storm sewer at the low point of the south access drive that captures runoff from the open space to the north, and runoff from the roadway. The storm sewer will connect to the new family dollar storm sewer. The storm sewer and inlets will capture and convey the 100-year storm event to the regional detention pond. Existing inlets within 104th Avenue will need to be removed and reconstructed to accommodate the deceleration lane to the project site. A concrete pan will be constructed immediately above the proposed retaining wall along the west boundary of the site. The pan will convey off-site runoff to the north around the planned development, and is sized for the 100-year event. 4.2.2 Water Quality Treatment Facilities and BMPs An extended detention basin (EDB) permanent BMP will be installed in the regional pond. The EDB is sized to capture and treat runoff from the entire site, in addition to the RTD light rail station and Colorado Marketplace retail center. Volumes and water surface elevations are provided in Section 4.2.3. 4.2.3 Detention Facilities The Regional pond will detain and treat runoff from the site, as well as the off-site watershed areas from the 104th Light Rail Station, and the retail center, for a total watershed area of 32.48 acres. Overall imperviousness for the watershed contributing to the detention pond is estimated to be 69%. The required volumes for the Northwest Detention Pond are summarized in Table 2 below.

Table 1 Detention Pond Summary

Pond Area, acres %

imperviousness EURV,

AF 100-year

Volume, AF Release Rate, cfs

Previous RTD 60% Design 27.48 64 1.75 3.40 27.48

Expanded for ADCHA Project 32.48 69 2.24 3.92 32.48


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4.2.4 Drainage Easements and Tracts An easement will be provided for the storm sewer that crosses through the public open space. No drainage easements are planned for the site, as the storm sewer will be private, and serving only one owner. 4.2.5 Maintenance The stormwater improvements on the project site are private improvements, and will be maintained by ADCHA. 4.2.6 Groundwater and Bedrock The storm sewers for the site are above the estimated groundwater and bedrock levels on the site. Pickering, Cole, and Hivner, LLC prepared a preliminary geotechnical investigation report for the Site in October 2014. The boring logs from the report are included in the appendix. 4.2.7 Wetland Mitigation and Preservation There are no wetlands on the site. 5.0 CONCLUSIONS 5.1 COMPLIANCE WITH STANDARDS This drainage report presents the drainage analysis for 104th and Colorado, and complies with the criteria and standards of the City of Thornton’s Storm Drainage Design, Grading, and Water Quality Technical Criteria. 5.2 DRAINAGE CONCEPT The drainage system provides a 100-year level of protection for the site. The conveyance system is designed to safely convey the 100-year storm. 5.3 WATER QUALITY Water quality treatment is provided for the site in accordance with the UDFCD Volume 3 USDCM. 6.0 REFERENCES


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1. Pickering, Cole, and Hivner, LLC. October 2014. Preliminary Geotechnical Engineering Report.

2. City of Thornton. October 2012. Standards and Specifications. 3. Colorado Dept. of Transportation. 2004. Drainage Design Manual.

4. Merrick and Company. August 2015. Thornton Family Dollar Construction Documents.

5. Regional Transportation District. May 2015. 104th Station 60% Preliminary Design

Documents. 6. Urban Drainage and Flood Control District. February 1997. Grange Hall Creek Major

Drainage-way Planning Study, Preliminary Design Report.


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APPENDIX

VICINITY MAP

SITE

104th and Colorado Proposed Hydrology.xls Summary

Design Point Contributing Basins

Area (acres)

5-Year (cfs)

100-Year (cfs)

1 SB50,SB70 0.82 2.0 4.42 SB10,SB20,SB30,SB40,SB50,SB60,SB70 2.37 6.1 13.2

3SB10,SB20,SB30,SB40,SB50,SB60,SB70, SB80,SB90 4.03 10.1 22.0

4SB10,SB20,SB30,SB40,SB50,SB60,SB70, SB80,SB90,SB125 4.20 10.3 22.6

5SB10,SB20,SB30,SB40,SB50,SB60,SB70, SB80,SB90,SB100,SB110,SB120,SB125 5.08 11.3 24.5

6 OS20,OS30,SB130 2.87 4.3 12.4

Table A-1Summary of Site Hydrology

104th and ColoradoThornton, Colorado

% Imp. C2 C5 C10035 0.25 0.33 0.5750 0.34 0.40 0.6080 0.60 0.63 0.742 0.04 0.15 0.5090 0.71 0.73 0.81

Area (acres) % Area (acres) % Area (acres) % Area (acres) % Area (acres) %SB10 0.19 0 0.0% 0.00 0.0% 0.00 0.0% 0.00 0.0% 0.19 100.0% 100.00% 90% 0.71 0.73 0.81SB20 0.33 0 0.0% 0.00 0.0% 0.00 0.0% 0.00 0.0% 0.33 100.0% 100.00% 90% 0.71 0.73 0.81SB30 0.32 0 0.0% 0.00 0.0% 0.00 0.0% 0.00 0.0% 0.32 100.0% 100.00% 90% 0.71 0.73 0.81SB40 0.33 0 0.0% 0.00 0.0% 0.00 0.0% 0.00 0.0% 0.33 100.0% 100.00% 90% 0.71 0.73 0.81SB45 0.38 0 0.0% 0.00 0.0% 0.00 0.0% 0.00 0.0% 0.38 100.0% 100.00% 90% 0.71 0.73 0.81SB50 0.58 0 0.0% 0.00 0.0% 0.58 100.0% 0.00 0.0% 0.00 0.0% 100.00% 80% 0.60 0.63 0.74SB60 0.38 0 0.0% 0.00 0.0% 0.00 0.0% 0.00 0.0% 0.38 100.0% 100.00% 90% 0.71 0.73 0.81SB70 0.24 0 0.0% 0.00 0.0% 0.00 0.0% 0.00 0.0% 0.24 100.0% 100.00% 90% 0.71 0.73 0.81SB80 0.26 0 0.0% 0.00 0.0% 0.00 0.0% 0.00 0.0% 0.26 100.0% 100.00% 90% 0.71 0.73 0.81SB90 1.40 0 0.0% 0.00 0.0% 1.40 100.0% 0.00 0.0% 0.00 0.0% 100.00% 80% 0.60 0.63 0.74SB100 0.21 0 0.0% 0.00 0.0% 0.00 0.0% 0.00 0.0% 0.21 100.0% 100.00% 90% 0.71 0.73 0.81SB110 0.33 0 0.0% 0.00 0.0% 0.00 0.0% 0.00 0.0% 0.33 100.0% 100.00% 90% 0.71 0.73 0.81SB120 0.34 0 0.0% 0.00 0.0% 0.00 0.0% 0.00 0.0% 0.34 100.0% 100.00% 90% 0.71 0.73 0.81SB125 0.17 0 0.0% 0.00 0.0% 0.00 0.0% 0.00 0.0% 0.17 100.0% 100.00% 90% 0.71 0.73 0.81SB130 0.41 0 0.0% 0.00 0.0% 0 0.0% 0.00 0.0% 0.41 100.0% 100.00% 90% 0.71 0.73 0.81OS10 1.80 0 0.0% 0.00 0.0% 0 0.0% 0.00 0.0% 1.80 100.0% 100.00% 90% 0.71 0.73 0.81OS20 0.98 0 0.0% 0.00 0.0% 0 0.0% 0.00 0.0% 0.98 100.0% 100.00% 90% 0.71 0.73 0.81OS30 1.48 0 0.0% 0.00 0.0% 0 0.0% 1.48 100.0% 0.00 0.0% 100.00% 2% 0.04 0.15 0.50

Total 10.13 0.00 0.0% 0.00 0.0% 1.98 19.6% 1.48 14.6% 6.67 65.8% 100.00% 75% 0.59 0.63 0.75

1. From Table RO-3 and RO-5 in the UDFCD USDCM2. C coefficients calculated by weighting global C values based on percentage of land use type.

Commercial/Parking Lot

Subbasin Total Area (acres)

C Coefficient2Composite Imperviousness 5-year

Land Use Area per Sub-BasinResidential Parks/Open Space

100-yearLow Density Medium Density Apartments 2-yearCommercial/Parking Lot % Check

Global Parameters1

ApartmentsParks/Open Space

Table A-2C Value Calculations

Aria Stormwater Master planDenver, Colorado

Medium Density Residential

Land UseLow Density Residential

104th and Colorado Proposed Hydrology.xls Q Peak 3 of 5

Tc Final Tc

Des

ign

Pt.

Basi

n ID

Area

C CA

C CA

C CA

Leng

th (3

00' m

ax)

Slop

e

ti Leng

th

Slop

e

Velo

city

tt tc=t

i+tt

Tota

l len

gth

Tc =

(l/1

80+1

0)

Fina

l Tc

2-ye

ar

5-ye

ar

100-

year

2-ye

ar

5-ye

ar

100-

year

acres ft % min. ft % fps min min ft min min in/hr cfs1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26

SB50 0.58 0.60 0.35 0.63 0.37 0.74 0.43 200 2.0% 9.7 0 2.0% 3.0 0.0 9.7 200 11.1 9.7 2.60 3.67 7.04 0.9 1.3 3.0SB70 0.24 0.71 0.17 0.73 0.18 0.81 0.19 40 2.0% 3.4 0 0.8% 3.0 0.0 3.4 40 10.2 3.4 3.52 4.96 9.52 0.6 0.9 1.9

1 0.82 0.63 0.52 0.66 0.54 0.76 0.62 9.7 2.60 3.67 7.04 1.4 2.0 4.4

SB10 0.19 0.71 0.13 0.73 0.14 0.81 0.15 130 2.0% 6.1 330 2.0% 3.0 1.8 8.0 460 12.6 8.0 2.80 3.94 7.56 0.4 0.5 1.2SB20 0.33 0.71 0.23 0.73 0.24 0.81 0.27 100 2.0% 5.4 120 2.0% 3.0 0.7 6.1 220 11.2 6.1 3.06 4.31 8.27 0.7 1.0 2.2SB30 0.32 0.71 0.23 0.73 0.23 0.81 0.26 60 2.0% 4.2 100 2.0% 3.0 0.6 4.7 160 10.9 4.7 3.27 4.61 8.84 0.7 1.1 2.3SB40 0.33 0.71 0.23 0.73 0.24 0.81 0.27 100 2.0% 5.4 220 3.0% 3.0 1.2 6.6 320 11.8 6.6 2.97 4.20 8.05 0.7 1.0 2.2SB50 0.58 0.60 0.35 0.63 0.37 0.74 0.43 200 2.0% 9.7 0 2.0% 3.0 0.0 9.7 200 11.1 9.7 2.60 3.67 7.04 0.9 1.3 3.0SB60 0.38 0.71 0.27 0.73 0.28 0.81 0.31 300 2.0% 9.3 0 0.8% 3.0 0.0 9.3 300 11.7 9.3 2.64 3.72 7.14 0.7 1.0 2.2SB70 0.24 0.71 0.17 0.73 0.18 0.81 0.19 40 2.0% 3.4 0 0.8% 3.0 0.0 3.4 40 10.2 3.4 3.52 4.96 9.52 0.6 0.9 1.9

2 2.37 0.68 1.62 0.71 1.67 0.79 1.88 9.7 2.60 3.67 7.04 4.2 6.1 13.2

SB10 0.19 0.71 0.13 0.73 0.14 0.81 0.15 130 2.0% 6.1 520 2.0% 3.0 2.9 9.0 650 13.6 9.0 2.67 3.77 7.23 0.4 0.5 1.1SB20 0.33 0.71 0.23 0.73 0.24 0.81 0.27 100 2.0% 5.4 120 2.0% 3.0 0.7 6.1 220 11.2 6.1 3.06 4.31 8.27 0.7 1.0 2.2SB30 0.32 0.71 0.23 0.73 0.23 0.81 0.26 60 2.0% 4.2 100 2.0% 3.0 0.6 4.7 160 10.9 4.7 3.27 4.61 8.84 0.7 1.1 2.3SB40 0.33 0.71 0.23 0.73 0.24 0.81 0.27 100 2.0% 5.4 220 3.0% 3.0 1.2 6.6 320 11.8 6.6 2.97 4.20 8.05 0.7 1.0 2.2SB50 0.58 0.60 0.35 0.63 0.37 0.74 0.43 200 2.0% 9.7 0 2.0% 3.0 0.0 9.7 200 11.1 9.7 2.60 3.67 7.04 0.9 1.3 3.0SB60 0.38 0.71 0.27 0.73 0.28 0.81 0.31 300 2.0% 9.3 0 0.8% 3.0 0.0 9.3 300 11.7 9.3 2.64 3.72 7.14 0.7 1.0 2.2SB70 0.24 0.71 0.17 0.73 0.18 0.81 0.19 40 2.0% 3.4 0 0.8% 3.0 0.0 3.4 40 10.2 3.4 3.52 4.96 9.52 0.6 0.9 1.9SB80 0.26 0.71 0.18 0.73 0.19 0.81 0.21 40 2.0% 3.4 240 0.8% 2.0 2.0 5.4 280 11.6 5.4 3.16 4.45 8.54 0.6 0.8 1.8SB90 1.40 0.60 0.84 0.63 0.88 0.74 1.04 200 2.0% 9.7 0 2.0% 2.0 0.0 9.7 200 11.1 9.7 2.60 3.67 7.04 2.2 3.2 7.3

3 4.03 0.66 2.64 0.68 2.74 0.78 3.13 9.7 2.60 3.67 7.04 6.9 10.1 22.0


SB125 0.17 0.71 0.12 0.73 0.12 0.81 0.14 120 2.0% 5.9 150 3.0% 3.0 0.8 6.7 270 11.5 6.7 2.96 4.17 8.00 0.4 0.5 1.14 4.20 0.66 2.76 0.68 2.87 0.78 3.26 10.1 2.56 3.61 6.92 7.1 10.3 22.6


SB100 0.21 0.71 0.15 0.73 0.15 0.81 0.17 60 2.0% 4.2 140 0.8% 2.0 1.2 5.3 200 11.1 5.3 3.17 4.47 8.57 0.5 0.7 1.5SB110 0.33 0.71 0.23 0.73 0.24 0.81 0.27 110 2.0% 5.6 160 3.0% 3.0 0.9 6.5 270 11.5 6.5 2.98 4.21 8.07 0.7 1.0 2.1

Table A-3Rational Method Hydrologic Calculations

Aria Stormwater Master PlanDenver, Colorado

Sub-Basin DataOverland Time (ti) Travel Time (tt) Tc Check

Time of Concentration, Tc2-year 5-year 100-year

C Values Intensity, I Peak Discharge, Q

104th and Colorado Proposed Hydrology.xls Q Peak 4 of 5

Tc Final Tc

Des

ign

Pt.

Basi

n ID

Area

C CA

C CA

C CA

Leng

th (3

00' m

ax)

Slop

e

ti Leng

th

Slop

e

Velo

city

tt tc=t

i+tt

Tota

l len

gth

Tc =

(l/1

80+1

0)

Fina

l Tc

2-ye

ar

5-ye

ar

100-

year

2-ye

ar

5-ye

ar

100-

year

acres ft % min. ft % fps min min ft min min in/hr cfs1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26

Table A-3Rational Method Hydrologic Calculations

Aria Stormwater Master PlanDenver, Colorado

Sub-Basin DataOverland Time (ti) Travel Time (tt) Tc Check

Time of Concentration, Tc2-year 5-year 100-year

C Values Intensity, I Peak Discharge, Q

SB120 0.34 0.71 0.24 0.73 0.25 0.81 0.28 100 2.0% 5.4 160 3.0% 3.0 0.9 6.3 260 11.4 6.3 3.02 4.26 8.18 0.7 1.1 2.3SB125 0.17 0.71 0.12 0.73 0.12 0.81 0.14 120 2.0% 5.9 150 3.0% 3.0 0.8 6.7 270 11.5 6.7 2.96 4.17 8.00 0.4 0.5 1.1

5 5.08 0.67 3.39 0.69 3.51 0.78 3.97 13.3 2.28 3.22 6.17 7.7 11.3 24.5

OS20 0.98 0.71 0.70 0.73 0.72 0.81 0.79 100 2.0% 5.4 120 2.0% 3.0 0.7 6.1 220 11.2 6.1 3.06 4.31 8.27 2.1 3.1 6.6OS30 1.48 0.04 0.06 0.15 0.22 0.50 0.74 100 2.0% 13.8 120 2.0% 3.0 0.7 14.5 220 11.2 11.2 2.45 3.46 6.64 0.1 0.8 4.9SB130 0.41 0.71 0.29 0.73 0.30 0.81 0.33 60 2.0% 4.2 100 2.0% 3.0 0.6 4.7 160 10.9 4.7 3.27 4.61 8.84 1.0 1.4 2.9

6 2.87 0.36 1.05 0.43 1.24 0.65 1.87 11.2 2.45 3.46 6.64 2.6 4.3 12.4

Notes:

2. I = 28.5P1/(10+Tc)0.786

3. Ti = 0.395(1.1-C5)(L)0.5/S0.33

4. Minimun Tc is 5.0 minutes for urban areas.

1. Flows calculated using the rational method, based on the methods provided in chapter 4 section 4 (rainfall), and Chapter 5 Section 2 (runoff) of the USDCM by UDFCD (2008).

104th and Colorado Proposed Hydrology.xls Rainfall

Recurrence Interval (yrs) 1-hr Rainfall Depth (in)

2 0.955 1.3410 1.5525 2.0050 2.25100 2.57

Note: From TOCR Criteria Manual

Table A-4Rainfall Data

Denver, Colorado

Steam UD-Detention_v2.35.xls 11/22/2015, 10:31 PM

Project:Basin ID:

32.48

69.0%

0

69.0%

Percentage of Area Area (acres)0.00.0

100.0% 32.5

Initial--f i Final--fo3 0.5 0.0018

(watershed inches) (acre-feet)

0.83 2.24 Design Oulet to Empty EURV in 72 Hours

100-year Detention Volume Including WQCV 5 1.45 3.92 32.48

Notes:

Hydrologic Soil TypeType AType B

Excess Urban Runoff Volume4

Infiltration (inches per hour)

Maximum Allowable Release Rate, cfs3

4) EURV approximates the difference between developed and pre-developed runoff volume.5) 100-yr detention volume includes EURV. No need to add more volume for WQCV or EURV

Detention Volumes 2,5

DETENTION VOLUME BY THE FULL SPECTRUM METHOD

104th and ColoradoRegional Detention Pond

1) Effective imperviousness is based on Figure ND-1 of the Urban Storm Drainage Criteria Manual (USDCM).

Area of Watershed (acres)

Subwatershed ImperviousnessLevel of Minimizing Directly Connected

Impervious Area (MDCIA)

* User input data shown in blue.

2) Results shown reflect runoff reduction from Level 1 or 2 MDCIA and are plotted at the watershed's total imperviousness value; the impact of MDCIA is reflected by the results being below the curves.3) Maximum allowable release rates for 100-year event are based on Table SO-1. Outlet for the Excess Urban Runoff Volume (EURV) to be designed to empty out the EURV in 72 hours. Outlet design is similar to one for the WQCV outlet of an extended detention basin (i.e., perforated plate with a micro-pool) and extends to top of EURV water surface elevation.

Recommended Horton's Equation Parameters for CUHP

Effective Imperviousness1

Type C or D

Decay Coefficient--a

0.00

0.50

1.00

1.50

2.00

2.50

0 20 40 60 80 100

Runo

ff Vo

ume

- Inc

hes

Percent Total Imperviousness

100-yr Vol Type A Soil

100-yr Vol Type B, C & D Soils

EURV Type A Soil

EURV Type B Soil

EURV Type C/D Soil

100-yr Storage Volume

EURV Storage Volume

Incremental Total Incremental Total5163.0 Pond Bottom 0 0 75 0 0 0.005164.0 1 1 75 75 75 0.005165.0 1 2 2,000 821 896 0.025166.0 1 3 7,037 4,263 5,159 0.125167.0 1 4 13,461 10,077 15,236 0.355168.0 1 5 20,229 16,731 31,966 0.735169.0 1 6 24,513 22,337 54,303 1.255170.0 EURV 1 7 28,883 26,668 80,971 1.865171.0 1 8 33,308 31,069 112,040 2.575172.0 100-year 1 9 37,845 35,552 147,593 3.39

1. Calculated using the Conical method.

Table 1Stage, Storage Data

60% RTD Pond

Elevation (ft., NAVD88) Description Depth (ft.) Area (sf) Volume (cubic-feet)1

Volume AF

104th and Colorado

Incremental Total Incremental Total5163.0 Pond Bottom 0 0 75 0 0 0.005164.0 1 1 75 75 75 0.005165.0 1 2 2,000 821 896 0.025166.0 1 3 7,037 4,263 5,159 0.125167.0 1 4 16,880 11,605 16,764 0.385168.0 1 5 26,010 21,281 38,045 0.875169.0 1 6 31,100 28,517 66,562 1.535170.0 EURV 1 7 35,592 33,321 99,883 2.295171.0 1 8 41,380 38,450 138,333 3.185172.0 100-year 1 9 46,180 43,758 182,091 4.18

1. Calculated using the Conical method.

Table 1Stage, Storage Data

Expanded Pond to Include 104th Site104th and Colorado

Elevation (ft., NAVD88) Description Depth (ft.) Area (sf) Volume (cubic-feet)1

Volume AF

Project Description

Friction Method Manning Formula

Solve For Full Flow Capacity

Input Data

Roughness Coefficient 0.013

Channel Slope 0.00400 ft/ft

Normal Depth 2.50 ft

Diameter 2.50 ft

Discharge 25.94 ft³/s

Rating Curve Plot

Rating Curve for Circular Pipe - 1

11/22/2015 8:36:11 PMBentley Systems, Inc. Haestad Methods Solution CenterBentley FlowMaster V8i (SELECTseries 1) [08.11.01.03]

27 Siemons Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 1of1Page

ResultsOpening

Area (sq.ft.) C

% Blockage H (ft)

Weir length (ft.)

% Blockage C H (ft)

100-Yr Ponding

Depth (ft.)

1 S-63 1 R 4.4 2.5 0.67 10% 0.13 5 10% 3.0 0.47 0.472 S-73 1 C 9.0 6 0.67 50% 0.31 12 50% 3.0 0.63 0.633 S-66 1 C 1.8 6 0.67 50% 0.01 12 50% 3.0 0.22 0.224 S-82 1 C 7.3 6 0.67 50% 0.20 12 50% 3.0 0.55 0.555 S-76 1 R 1.1 2.5 0.67 10% 0.01 5 10% 3.0 0.19 0.196 S-79 1 R 3.6 2.5 0.67 10% 0.09 5 10% 3.0 0.41 0.417 S-77 1 R 2.2 2.5 0.67 10% 0.03 5 10% 3.0 0.30 0.308 S-86 1 C 3.2 6 0.67 50% 0.04 12 50% 3.0 0.32 0.329 S-85 1 R 2.9 2.5 0.67 10% 0.06 5 10% 3.0 0.36 0.36

1. Orifice Equation: Q = (1-%blockage) CA (2gH)0.5

2. Weir Equation: Q = (1-%blockage) CLH1.5

No. of Inlets

Table 3Inlet Ponding Depth Calculations

100-year Design EventInlets in a Sag

Inlet ID Description Inlet Type 100-yr Q (cfs)

Orifice Calcs1 Weir Calcs2

Hydrologic Soil Group—Adams County Area, Parts of Adams and Denver Counties, Colorado(104th and Colorado)

Natural ResourcesConservation Service

Web Soil SurveyNational Cooperative Soil Survey

11/22/2015Page 1 of 4

4414

700

4414

740

4414

780

4414

820

4414

860

4414

900

4414

940

4414

980

4414

700

4414

740

4414

780

4414

820

4414

860

4414

900

4414

940

4414

980

505160 505200 505240 505280 505320 505360 505400

505160 505200 505240 505280 505320 505360 505400

39° 53' 6'' N10

4° 5

6' 2

2'' W

39° 53' 6'' N

104°

56'

12'

' W

39° 52' 55'' N

104°

56'

22'

' W

39° 52' 55'' N

104°

56'

12'

' W

N

Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS840 50 100 200 300

Feet0 20 40 80 120

MetersMap Scale: 1:1,590 if printed on A portrait (8.5" x 11") sheet.

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: Aug 30, 2014—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(104th and Colorado)



11/22/2015Page 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

PlB Platner loam, 0 to 3percent slopes

C 5.8 62.9%

ReD Renohill loam, 3 to 9percent slopes

D 0.2 1.7%

UlC Ulm loam, 3 to 5 percentslopes

C 3.3 35.3%

Totals for Area of Interest 9.3 100.0%

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.

Hydrologic Soil Group—Adams County Area, Parts of Adams and Denver Counties, Colorado 104th and Colorado



11/22/2015Page 3 of 4

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 104th and Colorado



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Proposed Apartment DevelopmentSE of East 104th Avenue and Colorado Boulevard - Thornton, COPCH Project No. 12.431.14

SUMMARY OF LABORATORY TEST RESULTS

Pickering, Cole and Hivner, LLC 1070 W. 124th Ave., Suite 300 • Westminster, Colorado 80234

LL PL PI

1 4 Sandy Lean Clay 7.3% 130 +5.2 500

1 9 Sandy Lean Clay 11.2% 120 51 31 20 11

1 14 Sandstone Bedrock 15.9% 108



2 4 Clayey Sand 8.3% 128 49 27 21 6


2 14 Claystone Bedrock 20.2% 108 +2.4 1,000

2 19 Claystone Bedrock 17.0% 114



3 2 Lean Clay with Sand 11.7% 113 75 45 18 27

3 4 Lean Clay with Sand 15.8% 105 +6.8 500 6,900

3 9 Lean Clay with Sand 17.8% 112 +5.4 500 5,800

3 14 Claystone/Sandstone Bedrock 15.0% 105

4 4 Silty Sand 7.2% 119 30

4 9 Silty Sand 7.7% 121 26

4 14 Claystone/Sandstone Bedrock 13.9% 122 +1.8 1,000

5 4 Sandy Lean Clay 14.4% 120 +6.0 500

5 9 Sandy Lean Clay 14.9% 115 51 29 21 8

5 14 Sandy Lean Clay 20.9% 105

5 19 Sandy Lean Clay 18.2% 116



6 4 Sandy Lean Clay 10.4% 118 66 37 19 18

6 9 Sandy Lean Clay 14.0% 1066 14 Sandy Lean Clay 19.8% 108 -1.2 1,000

Non-plastic

Non-plastic

Surcharge Pressure (psf)

Passing #200 Sieve (%)

Atterberg LimitsSwell (+) or Consolidation (-)

(%)

Water Soluble Sulfates (ppm)

Test Boring

Depth (ft) Soil Description

Dry Density

(pcf)

Moisture Content

(%)

N

1 INCH = FT.

0 50 100

50

BASIN RUNOFF SUMMARY

LEGEND

EASEMENT (BY SEPARATE DOCUMENT)

PROPERTY LINE

EXISTING FENCE

EXISTING CURB AND GUTTER

EXISTING WATER LINE

EXISTING UNDERGROUND COMM

EXISTING STORM SEWER

EXISTING SANITARY SEWER

EXISTING GAS LINE

EXISTING UNDERGROUND ELECTRIC

EXISTING STORM MANHOLE

EXISTING INLET

EXISTING SANITARY MANHOLE

EXISTING FIRE HYDRANT

BUILDING

6" CURB AND GUTTER

STORM SEWER

SANITARY SEWER

WATER LINE

STORM SEWER MANHOLE

INLET

SANITARY SEWER MANHOLE

FIRE HYDRANT

WATER METER

DRAINAGE FLOW PATTERN DIRECTION

BASIN AREA/C5/C100

DESIGNATOR

DATE:

DESIGNED BY:

PROJECT NO:

DRAWN BY:

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CALL UTILITY NOTIFICATION

CENTER OF COLORADO

CALL 3-BUSINESS DAYS (NOT INCLUDING INITIAL

DAY OF CONTACT) IN ADVANCE BEFORE YOU DIG,

GRADE, OR EXCAVATE FOR THE MARKING OF

UNDERGROUND MEMBER UTILITIES.

0-104th and Colorado Drainage Report 11-04-20151.0 GENERAL LOCATION AND DESCRIPTION2.0 DRAINAGE BASINS AND SUB-BASINS3.0 DRAINAGE DESIGN CRITERIA4.0 DRAINAGE FACILITY DESIGN5.0 CONCLUSIONS6.0 REFERENCES

1 vicinity map2 104th and Colorado Proposed HydrologySummaryC CoeffQ PeakRainfall

3 104th EURV UD-Detention_v2.35Full-Spectrum

4 104th Pond Volumes60% RTD PondExpanded Pond

5 Hydraulic calcs6 inletsSag Inlets

7 NRCS Soils Info8 Geotech Report Excerpts9 drainage map

Final Drainage Report - City of Thorntonand Colorado, Final Drainage Report EES Page 7 303.572.7997...

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Transcript of Final Drainage Report - City of Thorntonand Colorado, Final Drainage Report EES Page 7 303.572.7997...