West Sylvan Baseball Fields Stormwater Management Report · 2020. 2. 4. · West Sylvan Baseball Fields 4 . Detention . Using Peak Flow Matching approach to determining the required

West Sylvan Baseball Fields

Stormwater Management Report

Site Address:

8111 SW West Slope Drive

Beaverton, OR 97225

1S1W 12 BB Tax lot 00100

Owner:

Portland Public Schools

Prepared By:

Janelle Brannan, P.E.

205 SE Spokane Street, Suite 200

Portland, OR 97202

ph: 503-221-1131 fax: 503-221-1171 2019

October 17, 2019

cruiz

Text Box

Received Planning Division

cruiz

Date

West Sylvan Baseball Fields 1

Project Description

The project is located at 8111 SW West Slope Drive. The proposed are of work is 5.3 acres and will

improve 176,800sf sports fields and 54,463sf of program area supporting the sporting the sports fields,

including hitting facility, restrooms, concessions, dugouts, pressbox, bleachers and walking path.

Existing Site Conditions

The existing site is developed and maintained as a natural grass sports field with clay infield for baseball

and softball. A cider walking path is located at the perimeter of the sports fields.

The site generally slopes from east to west. The existing sports fields are gently sloped at 1.5%, and

beyond the field the slope steepens to approximately 15%.

Per the Web Soil Survey provided by NRCS, the site soil is Cornelius and Kinton silt loams, hydrologic soil

group C. Infiltration testing has been conducted for the project, and preliminary test results show a

0in/hr infiltration rate.

Stormwater Management Requirements

City of Beaverton has adopted the current version of the Clean Water Service Design and construction

Standards.

Water Quantity Control Requirements

The development shall incorporate techniques for mitigating its impacts on the public stormwater

system (Section 4.02.1, CWS R&O 19-5)

On-Site facilities shall be constructed be constructed when there is an identified downstream deficiency,

identified regional detention site within the boundary of the development, or when required by District-

adopted watershed management plan. (Section 4.02.2, CWS R&O 19-5)

Hydromodification Approach Requirements

New developments which create and/or modify 1,000sf or greater of impervious area, are required to

implement or fund techniques to reduce impacts to the downstream receiving water body. (Section

4.03.1, CWS R&O 19-5)

Water Quality Treatment Requirements

New developments which create and/or modify 1,000sf or greater of impervious area, are required to

implement permanent water quality approached to reduce contaminants enter the storm and surface

water system. (Section 4.04.1, CWS R&O 19-5)

Hydromodification Assessment

Using the Hydomodification Map the reach-specific risk level and development class are determined to

be High Risk Level in a Developed area.

The project size is large, greater than 80,000sf.


This project falls within Category 3. Category 3 has the option for peak-flow matching detention and

LIDA or Flow Duration Curve Matching Detention.

This project will use peak-flow matching and LIDA to meet the hydromodification requirements.

The following are the design storms to be used in peak-flow hydrologic analysis:

Storm Event Precipitation Depth (inches)

2year, 24 hour 2.50

5year, 24 hour 3.10

10year, 24 hour 3.45

25year, 24 hour 3.90

The peak-flow matching requirement is such that the post-development runoff rates do not exceed the

pre-development runoff rates as shown in the table below. Pre-development is defined as the project

site’s surface condition prior to the proposed development (Section 1.03.56, CWS R&O 19-5).

Post-Development Peak Runoff Rate Pre-Development Peak Runoff Rate Target

2year, 24 hour 50% of the 2year, 24 hour

5year, 24 hour 5year, 24 hour

10year, 24 hour 10year, 24 hour


Stormwater Management Calculations

Areas

Total 231,263sf, 5.31 acres

Synthetic Turf 179,550sf, 4.12 acres

Natural Grass / Landscape 5,875sf, 0.13 acres

Impervious 23,136sf, 0.53 acres

Gravel 22,699sf, 0.52 acres

Water Quality

The design storm to be used in water quality evaluation is 0.36inches over 3hours.

Water Quality Flow:

Project Area: 231,263sf (5.31acre) Impervious Area

�� =0.36�ℎ��(��)

12��3ℎ��60

�ℎ�

�60��

WQF = 0.64cfs

Vegetated Swale Calculations:

Swale Bottom Width, 9.0ft

Side Slopes, 4H:1V

Swale Longitudinal Slope, 0.005

Using Civil Tools to Calculate Velocity, 0.19fps

Required Swale length:

0.19fps x 9min x 60sec/min = 103LF (design

length is 115LF)


Detention

Using Peak Flow Matching approach to determining the required detention, the SBUH method was used

to determine the peak flows.

Area CN

Pre-Developed 5.31 acres 79

Developed

Synthetic Turf 98 179,550sf, 4.12 acres

Natural Grass / Landscape 90 5,875sf, 0.13 acres

Impervious 98 23,136sf, 0.53 acres

Gravel 91 22,699sf, 0.52 acres

Peak Flows:

Storm Event Pre-Developed Required Developed Released Elevation Storage

2yr 0.535 0.27 2.938 0.263 102.82 26,588

5yr 0.935 0.935 3.714 0.604 102.95 27,531

10yr 1.192 1.192 4.166 0.848 103 27,846

The following pages include the report from Hydraflow Hydrographs.

WEST SYLVANBASEBALL FIELDS

EXISTING CONDITIONS

SD

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00

00

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00

STMSTM

STMSTM

STMSTM

STM STM STM STM STM STM STM STM STM

STM STM STM STM STM

STMSTM

STMSTM

STMSTM

STM


STORMWATERMANAGEMENT OPTION 1

Stormwater Management Option 1Summary:

Design Approach- LIDA & Peak FlowMatching Detention

Areas: Total Area of Improvements, 5.31 acres Synthetic Turf, 4.12 acres Landscape, 0.13 acres Impervious, 0.53 acres Gravel, 0.52 acres

Stormwater Management LIDA Swale, 2,360sf UG Detention, 28,900 cf

Synthetic Turf

Natural Grass / Landscape

Impervious(bldg, dugout, concrete, asphalt)

Gravel

LIDA Swale

UG Detention

0

SCALE: 1" = 60'

30 60 120

HHPR, BOR-19A, 09/16/2019


STORMWATERMANAGEMENT

Details

30 ML impermeableliner

Drain rock

Non-woven geotextile

Growing medium

3H: 1V max. side slopes(4:1 without side shelf)

Subgrade

Jute matting

Choker Course 9”3”

UG Detention

Vegetated Swale

Vegetated Swaleand

UG Detention

Hydraflow Table of Contents BOR19A Option1 Hydraflow.gpw

Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 Monday, 09 / 16 / 2019

Hydrograph Return Period Recap............................................................................. 1

2 - YearHydrograph Reports................................................................................................................... 2

Hydrograph No. 1, SBUH Runoff, Pre-Developed................................................................... 2TR-55 Tc Worksheet............................................................................................................ 3

Hydrograph No. 3, SBUH Runoff, Turf..................................................................................... 4Hydrograph No. 4, SBUH Runoff, Natural Grass..................................................................... 5Hydrograph No. 5, SBUH Runoff, Impervious.......................................................................... 6Hydrograph No. 6, SBUH Runoff, Gravel................................................................................. 7Hydrograph No. 7, Combine, Developed................................................................................. 8Hydrograph No. 9, Reservoir, Detained Flows......................................................................... 9

Pond Report - Underground Detention.............................................................................. 10

5 - YearHydrograph Reports................................................................................................................. 11

Hydrograph No. 1, SBUH Runoff, Pre-Developed................................................................. 11Hydrograph No. 3, SBUH Runoff, Turf................................................................................... 12Hydrograph No. 4, SBUH Runoff, Natural Grass................................................................... 13Hydrograph No. 5, SBUH Runoff, Impervious........................................................................ 14Hydrograph No. 6, SBUH Runoff, Gravel............................................................................... 15Hydrograph No. 7, Combine, Developed............................................................................... 16Hydrograph No. 9, Reservoir, Detained Flows....................................................................... 17

10 - YearHydrograph Reports................................................................................................................. 18

Hydrograph No. 1, SBUH Runoff, Pre-Developed................................................................. 18Hydrograph No. 3, SBUH Runoff, Turf................................................................................... 19Hydrograph No. 4, SBUH Runoff, Natural Grass................................................................... 20Hydrograph No. 5, SBUH Runoff, Impervious........................................................................ 21Hydrograph No. 6, SBUH Runoff, Gravel............................................................................... 22Hydrograph No. 7, Combine, Developed............................................................................... 23Hydrograph No. 9, Reservoir, Detained Flows....................................................................... 24

Hydrograph Return Period Recap

1

Hyd. Hydrograph Inflow Peak Outflow (cfs) Hydrograph

No. type hyd(s) Description

(origin) 1-yr 2-yr 3-yr 5-yr 10-yr 25-yr 50-yr 100-yr

1 SBUH Runoff ------ ------- 0.535 ------- 0.935 1.192 1.544 ------- ------- Pre-Developed

3 SBUH Runoff ------ ------- 2.374 ------- 2.976 3.325 3.774 ------- ------- Turf

4 SBUH Runoff ------ ------- 0.049 ------- 0.068 0.080 0.094 ------- ------- Natural Grass

5 SBUH Runoff ------ ------- 0.305 ------- 0.383 0.428 0.485 ------- ------- Impervious

6 SBUH Runoff ------ ------- 0.211 ------- 0.288 0.333 0.392 ------- ------- Gravel

7 Combine 3, 4, 5,6

------- 2.938 ------- 3.714 4.166 4.745 ------- ------- Developed

9 Reservoir 7 ------- 0.263 ------- 0.604 0.848 1.369 ------- ------- Detained Flows

Proj. file: BOR19A Option1 Hydraflow.gpw Monday, 09 / 16 / 2019

Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020

Hydrograph Report


Hyd. No. 1

Pre-Developed

Hydrograph type = SBUH Runoff Peak discharge = 0.535 cfsStorm frequency = 2 yrs Time to peak = 490 minTime interval = 2 min Hyd. volume = 16,142 cuftDrainage area = 5.310 ac Curve number = 79Basin Slope = 0.0 % Hydraulic length = 0 ftTc method = TR55 Time of conc. (Tc) = 30.80 minTotal precip. = 2.50 in Distribution = Type IAStorm duration = 24 hrs Shape factor = n/a

2

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

0.10 0.10

0.20 0.20

0.30 0.30

0.40 0.40

0.50 0.50

0.60 0.60

0.70 0.70

0.80 0.80

0.90 0.90

1.00 1.00

Q (cfs)

Time (min)

Pre-Developed

Hyd. No. 1 -- 2 Year

Hyd No. 1

TR55 Tc Worksheet3

Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020

Hyd. No. 1

Pre-Developed

Description A B C Totals

Sheet FlowManning's n-value = 0.150 0.011 0.011Flow length (ft) = 300.0 0.0 0.0Two-year 24-hr precip. (in) = 2.50 0.00 0.00Land slope (%) = 1.50 0.00 0.00

Travel Time (min) = 29.95 + 0.00 + 0.00 = 29.95

Shallow Concentrated FlowFlow length (ft) = 100.00 0.00 0.00Watercourse slope (%) = 1.50 0.00 0.00Surface description = Unpaved Paved PavedAverage velocity (ft/s) =1.98 0.00 0.00

Travel Time (min) = 0.84 + 0.00 + 0.00 = 0.84

Channel FlowX sectional flow area (sqft) = 0.00 0.00 0.00Wetted perimeter (ft) = 0.00 0.00 0.00Channel slope (%) = 0.00 0.00 0.00Manning's n-value = 0.015 0.015 0.015Velocity (ft/s) =0.00

0.000.00

Flow length (ft) ({0})0.0 0.0 0.0

Travel Time (min) = 0.00 + 0.00 + 0.00 = 0.00

Total Travel Time, Tc .............................................................................. 30.80 min

Hydrograph Report


Hyd. No. 3

Turf

Hydrograph type = SBUH Runoff Peak discharge = 2.374 cfsStorm frequency = 2 yrs Time to peak = 474 minTime interval = 2 min Hyd. volume = 33,960 cuftDrainage area = 4.120 ac Curve number = 98Basin Slope = 0.0 % Hydraulic length = 0 ftTc method = User Time of conc. (Tc) = 5.00 minTotal precip. = 2.50 in Distribution = Type IAStorm duration = 24 hrs Shape factor = n/a

4

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

1.00 1.00

2.00 2.00

3.00 3.00

Q (cfs)

Time (min)

Turf


Hyd No. 3

Hydrograph Report


Hyd. No. 4

Natural Grass

Hydrograph type = SBUH Runoff Peak discharge = 0.049 cfsStorm frequency = 2 yrs Time to peak = 478 minTime interval = 2 min Hyd. volume = 722 cuftDrainage area = 0.130 ac Curve number = 90Basin Slope = 0.0 % Hydraulic length = 0 ftTc method = User Time of conc. (Tc) = 5.00 minTotal precip. = 2.50 in Distribution = Type IAStorm duration = 24 hrs Shape factor = n/a

5

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

0.01 0.01

0.02 0.02

0.03 0.03

0.04 0.04

0.05 0.05

0.06 0.06

0.07 0.07

0.08 0.08

0.09 0.09

0.10 0.10

Q (cfs)

Time (min)

Natural Grass


Hyd No. 4

Hydrograph Report


Hyd. No. 5

Impervious


6

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

0.05 0.05

0.10 0.10

0.15 0.15

0.20 0.20

0.25 0.25

0.30 0.30

0.35 0.35

0.40 0.40

0.45 0.45

0.50 0.50

Q (cfs)

Time (min)

Impervious


Hyd No. 5

Hydrograph Report


Hyd. No. 6

Gravel


7

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

0.05 0.05

0.10 0.10

0.15 0.15

0.20 0.20

0.25 0.25

0.30 0.30

0.35 0.35

0.40 0.40

0.45 0.45

0.50 0.50

Q (cfs)

Time (min)

Gravel


Hyd No. 6

Hydrograph Report


Hyd. No. 7

Developed

Hydrograph type = Combine Peak discharge = 2.938 cfsStorm frequency = 2 yrs Time to peak = 474 minTime interval = 2 min Hyd. volume = 42,091 cuftInflow hyds. = 3, 4, 5, 6 Contrib. drain. area = 5.300 ac

8

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

1.00 1.00

2.00 2.00

3.00 3.00

Q (cfs)

Time (min)

Developed


Hyd No. 7 Hyd No. 3 Hyd No. 4 Hyd No. 5

Hyd No. 6

Hydrograph Report


Hyd. No. 9

Detained Flows

Hydrograph type = Reservoir Peak discharge = 0.263 cfsStorm frequency = 2 yrs Time to peak = 1398 minTime interval = 2 min Hyd. volume = 41,556 cuftInflow hyd. No. = 7 - Developed Max. Elevation = 102.82 ftReservoir name = Underground Detention Max. Storage = 26,588 cuft

Storage Indication method used.

9

0 600 1200 1800 2400 3000 3600 4200 4800 5400 6000

Q (cfs)

0.00 0.00

1.00 1.00

2.00 2.00

3.00 3.00

Q (cfs)

Time (min)

Detained Flows


Hyd No. 9 Hyd No. 7 Total storage used = 26,588 cuft

Pond Report 10


Pond No. 1 - Underground Detention

Pond Data

UG Chambers -Invert elev. = 100.00 ft, Rise x Span = 3.75 x 6.40 ft, Barrel Len = 150.00 ft, No. Barrels = 11, Slope = 0.00%, Headers = No

Stage / Storage Table

Stage (ft) Elevation (ft) Contour area (sqft) Incr. Storage (cuft) Total storage (cuft)

0.00 100.00 n/a 0 00.38 100.38 n/a 3,954 3,9540.75 100.75 n/a 3,914 7,8681.13 101.13 n/a 3,833 11,7021.50 101.50 n/a 3,708 15,4101.88 101.88 n/a 3,535 18,9452.25 102.25 n/a 3,305 22,2502.63 102.63 n/a 3,006 25,2563.00 103.00 n/a 2,614 27,8703.38 103.38 n/a 2,075 29,9453.75 103.75 n/a 1,163 31,108

Culvert / Orifice Structures Weir Structures

[A] [B] [C] [PrfRsr] [A] [B] [C] [D]

Rise (in) = 12.00 2.50 0.00 0.00

Span (in) = 12.00 2.50 0.00 0.00

No. Barrels = 1 1 0 0

Invert El. (ft) = 100.00 100.00 0.00 0.00

Length (ft) = 50.00 0.00 0.00 0.00

Slope (%) = 5.00 0.00 0.00 n/a

N-Value = .013 .013 .013 n/a

Orifice Coeff. = 0.60 0.60 0.60 0.60

Multi-Stage = n/a Yes No No

Crest Len (ft) = 3.14 0.00 0.00 0.00

Crest El. (ft) = 102.85 0.00 0.00 0.00

Weir Coeff. = 3.33 3.33 3.33 3.33

Weir Type = 1 --- --- ---

Multi-Stage = Yes No No No

Exfil.(in/hr) = 0.000 (by Wet area)

TW Elev. (ft) = 0.00

Note: Culvert/Orifice outflows are analyzed under inlet (ic) and outlet (oc) control. Weir risers checked for orifice conditions (ic) and submergence (s).

0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00

Stage (ft)

0.00 100.00

1.00 101.00

2.00 102.00

3.00 103.00

4.00 104.00

Elev (ft)

Discharge (cfs)

Stage / Discharge

Total Q

Hydrograph Report


Hyd. No. 1

Pre-Developed


11

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

0.10 0.10

0.20 0.20

0.30 0.30

0.40 0.40

0.50 0.50

0.60 0.60

0.70 0.70

0.80 0.80

0.90 0.90

1.00 1.00

Q (cfs)

Time (min)

Pre-Developed


Hyd No. 1

Hydrograph Report


Hyd. No. 3

Turf


12

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

1.00 1.00

2.00 2.00

3.00 3.00

Q (cfs)

Time (min)

Turf


Hyd No. 3

Hydrograph Report


Hyd. No. 4

Natural Grass

Hydrograph type = SBUH Runoff Peak discharge = 0.068 cfsStorm frequency = 5 yrs Time to peak = 476 minTime interval = 2 min Hyd. volume = 980 cuftDrainage area = 0.130 ac Curve number = 90Basin Slope = 0.0 % Hydraulic length = 0 ftTc method = User Time of conc. (Tc) = 5.00 minTotal precip. = 3.10 in Distribution = Type IAStorm duration = 24 hrs Shape factor = n/a

13

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

0.01 0.01

0.02 0.02

0.03 0.03

0.04 0.04

0.05 0.05

0.06 0.06

0.07 0.07

0.08 0.08

0.09 0.09

0.10 0.10

Q (cfs)

Time (min)

Natural Grass


Hyd No. 4

Hydrograph Report


Hyd. No. 5

Impervious


14

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

0.05 0.05

0.10 0.10

0.15 0.15

0.20 0.20

0.25 0.25

0.30 0.30

0.35 0.35

0.40 0.40

0.45 0.45

0.50 0.50

Q (cfs)

Time (min)

Impervious


Hyd No. 5

Hydrograph Report


Hyd. No. 6

Gravel


15

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

0.05 0.05

0.10 0.10

0.15 0.15

0.20 0.20

0.25 0.25

0.30 0.30

0.35 0.35

0.40 0.40

0.45 0.45

0.50 0.50

Q (cfs)

Time (min)

Gravel


Hyd No. 6

Hydrograph Report


Hyd. No. 7

Developed


16

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

1.00 1.00

2.00 2.00

3.00 3.00

4.00 4.00

Q (cfs)

Time (min)

Developed



Hyd No. 6

Hydrograph Report


Hyd. No. 9

Detained Flows



17

0 600 1200 1800 2400 3000 3600 4200 4800 5400 6000

Q (cfs)

0.00 0.00

1.00 1.00

2.00 2.00

3.00 3.00

4.00 4.00

Q (cfs)

Time (min)

Detained Flows



Hydrograph Report


Hyd. No. 1

Pre-Developed


18

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

1.00 1.00

2.00 2.00

Q (cfs)

Time (min)

Pre-Developed


Hyd No. 1

Hydrograph Report


Hyd. No. 3

Turf


19

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

1.00 1.00

2.00 2.00

3.00 3.00

4.00 4.00

Q (cfs)

Time (min)

Turf


Hyd No. 3

Hydrograph Report


Hyd. No. 4

Natural Grass


20

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

0.01 0.01

0.02 0.02

0.03 0.03

0.04 0.04

0.05 0.05

0.06 0.06

0.07 0.07

0.08 0.08

0.09 0.09

0.10 0.10

Q (cfs)

Time (min)

Natural Grass


Hyd No. 4

Hydrograph Report


Hyd. No. 5

Impervious


21

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

0.05 0.05

0.10 0.10

0.15 0.15

0.20 0.20

0.25 0.25

0.30 0.30

0.35 0.35

0.40 0.40

0.45 0.45

0.50 0.50

Q (cfs)

Time (min)

Impervious


Hyd No. 5

Hydrograph Report


Hyd. No. 6

Gravel


22

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

0.05 0.05

0.10 0.10

0.15 0.15

0.20 0.20

0.25 0.25

0.30 0.30

0.35 0.35

0.40 0.40

0.45 0.45

0.50 0.50

Q (cfs)

Time (min)

Gravel


Hyd No. 6

Hydrograph Report


Hyd. No. 7

Developed


23

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

1.00 1.00

2.00 2.00

3.00 3.00

4.00 4.00

5.00 5.00

Q (cfs)

Time (min)

Developed



Hyd No. 6

Hydrograph Report


Hyd. No. 9

Detained Flows



24

0 480 960 1440 1920 2400 2880 3360 3840 4320 4800 5280

Q (cfs)

0.00 0.00

1.00 1.00

2.00 2.00

3.00 3.00

4.00 4.00

5.00 5.00

Q (cfs)

Time (min)

Detained Flows



West Sylvan Baseball Fields Stormwater Management Report · 2020. 2. 4. · West Sylvan Baseball Fields 4 . Detention . Using Peak Flow Matching approach to determining the required

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