HomeMy WebLinkAboutGlass Doctor - Parking Lot Improvements - Stormwater Management Calculations!� XMt
7 h ENGINEER
Stormwater Management Calculations
for
GLASS DOCTOR - PARKING LOT IMPROVEMENTS
52 S. Meridian Rd
Meridian, Idaho
Prepared for
Cary Hooper
GLASS DOCTOR
44 S. Main St
Meridian, Idaho
(208)888-1096
Prepared by
Lance Warnick, P.E.
Aspen Engineers, Chartered
10077
nfT011'111'2v
Date Prepared
October 11, 2012
Aspen File 13046
P,\2013\13046\Documents\Storm Ca1cs\RevA\1. Storm Calculation Introduction.doc
Aspen Engineers, Chartered
485 W. Main St, Suite B
PO Box 205
Kuna, Idaho 83634
(208) 466-8181
w .AspenEngineers.com
Stormwater Management Calculations for
Glass Doctor — Parking Lot Improvements
52 S. Meridian Rd
Meridian, Idaho
Table of Contents
Lim
Section and Description Page
1. Project Description............................................................................................................................. 3
2. Sources of Information....................................................................................................................... 3
3. Applicable Standards..........................................................................................................................4
4. Drawing Showing Site Drainage Areas............................................................................................... 5
5. Stormwater Runoff Calculations for Drainage Area#1...................................................................... 6
Appendices
A. Runoff Coefficient and Rainfall Intensity......
B. Infiltration Rate Information .........................
C. Dimensions and Details for proposed Swale
..........................:...............................................2 pages
............................................................................1 page
.......................................................................... 2 pages
P:\2013\13046\Documents\Storm CaI&RevA\1. Storm Calculation Introducton.doc Page 2
Stormwater Management Calculations for
Glass Doctor—Parking Lot Improvements
52 S. Meridian Rd
Meridian, Idaho
1. Project Description
#w'5a ;
These calculations and attachments provide the background for the design for a new stormwater
management system associated with a parking lot expansion just south of the Glass Doctor on a
vacant lot at 52 S. Meridian Rd in Meridian, Idaho.
These calculations, together with the details included in Appendix C are meant to provide
information on the proposed size and location of the swale that will be used to manage
stormwater runoff from the proposed parking lot.
Grading design for the parking lot is outside the scope of this design, therefore it is anticipated
that the Contractor will grade the asphalt paving to direct the stormwater runoff to a curb cut that
drains to a proposed swale located in the southwest corner of the property throughout the site.
The swale was sized to handle the anticipated runoff from the 100 -year, 1 -hour storm event using
a combination of internal storage in the Swale and the calculated percolation volume during the 1 -
hour design storm event.
The bottom of the swale will be constructed with an ASTM C-33 filter sand infiltration window.
This will help provide some treatment before the stormwater infiltrates into the subsurface as well
as promote infiltration into the subsurface. Since no site specific soils report was provided, it is
assumed that the window will need to be excavated to free draining material in order to drain
properly and provide the required storage volume.
The elevation of seasonal high groundwater was estimated to be at 7-10 feet below existing grade
based on experience in the surrounding area.
2. Sources of Information
The following sources of data were used in preparing these calculations:
A. Urban Runoff Control Handbook for Ada and Canyon Counties, Idaho Ada/Canyon Waste
Treatment Management Committee (January 1977).
B. Architectural Site Layout provided by Architecture Northwest (October 2013).
PA2013\13046\Documents\Storm Ca1cs\RevX1. Storm Calculabon Introduction.doc Page 3
Stormwater Management Calculations for
Glass Doctor — Parking Lot Improvements
52 S. Meridian Rd
Meridian, Idaho
3. Applicable Standards
The following standards were used in preparing these calculations:
A. Idaho Standard Public Works Construction Committee. Idaho Standards for Public Works
Construction, Current Edition.
B. City of Meridian, Ada County, Idaho. Supplementation Specification and Drawings to the
Idaho Standards for Public Works Construction. 2008.
C. Linsley, Ray, et al, 1992. Water Resources and Environmental Engineering, Fourth Edition,
McGraw-Hill, Publishers, Inc.
P12013\13046\Documents\Storm Calcs\RevA\1. Storm Calculation Introduction.doc Page 4
PAGE 5
4. SITE DRAINAGE AREAS
0 10 20 40
N SCALE (FT)
Project: Glass Doctor Parf ing Lot improvements_
Subject: Stormwater Runoff Calculations
By: L. Warrick ...-
5. RUNOFF CALCULATIONS FOR DRAINAGE AREA I
Number: _13046
Date: !(),'10111133
ENGE_ IN
S�GPRERS
Page:
Assume: The time of concentration (tc) for this area is defined as the time needed to reach
the iniats from the point that is farthest away, it is assumed the time is 10 minutes.
mvm�s�
1) Find Percent Coverage for Drainage Area
Given:
Impervious Area 5,040 sf See Page 5
Landscape Area1,710 sf See Page 5
Total Area 6.750sf-7 See Page 5
0.155 acres
M W4 iia
Surface
Area
Impervious Area,.
Landscape Area
O.05
Total Area
0.76
2) Find Weighted Runoff Coefficient (C)
Assume:
it is assumed that the drainage area is covered by. roofs, pavement and landscaping.
Each surface area will be calculated and used to generate a weighted runoff coefficient (C').
The calculation is based on the estimated area of the respective type of surface.
Given:
Imperious Coefficient 0:95 See Section 104.1
Landscape Coefficient -010
Surface Area (A) C
A*C
ImperviousArea 75% 0,95 -0,71
Landscape Area 25% 020 -
O.05
Total Area 000A -
0.76
Therefore-,
Weighted Runoff Coefficient (C') is
Design Storm --100--yr,10-min
using the Rational Method (0 = CIA) for the 100 yr, 10 -min storm which is the estimated
time of concentration.
Given.
C Runoff Coefficient 0,76 See Appendix A-1
I Intensity 3.1 lnft See Appendix A,2
PA2013113G460ocumentslStorrn CaJcs\RevA\3. Storm Caics - 13046
Project: Glass Doctor Parking Lot ImPrOvernents
Subject:
By: L- Warrick
Number,
13046 . ......
EN
Date:
�1011X130113�,�ZCNNF�ERS
Given:0J5
Page:
-1
see Appendix A.1
Design Storm I �00-
Using the Rational Method (a = CIA) for the 100 -yr, I -hT storm which is the estimated
time of concentration-
d Design Water Depth
Given:0J5
Be Bottom Area
105 sf 3-11 Side Slopes
see Appendix A.1
C
Runoff Coefficient
I inthr
See Appendix A-2
I
A
Intensity
Drainage Area
0:15 acres
L__912 cls
See Page 5
O
Discharge = C'I*A
_J
t
Storm Duration
1 fir
Solution:
Vr Runoff Volume = Wt
E. FIND AVAILABLE STORAGE VOLUME IN SWALE
Given:
Weighted Volume of variably shaped pond
d Design Water Depth
1,5 of Swale #1
Be Bottom Area
105 sf 3-11 Side Slopes
We Water Surface Area
418 sf
Solution:
Volume
F----3676 of
Va Available Storage
F, FIND VOLUME FROM INFILTRATION
Given:
As Area of bottom of infiltration vVindow, 105 sf Bottom area of swale
r infiltration Rate 8 in1hr Typical of filter sand
t Duration I hr
Solution:
V, Volume from infiltration =As*tr/12)*t 70 cf
Given:
Va Available Storage Volume 366 of
VI Volume from Infiltration 70 of
Solution:
Vt Total Volume = Va + Vi 436 of _J
H. COMPARE TOTAL VOLUME TO RUNOFF VOLUME
Check:
Vt Available Capacity Volume
436 of
— I
p:\2013i13046\DocumentslStorm Caics%RevAt3, Storm Calos - 13046
Li I'd
Project: Glass Doctor Parkinq Lot improvements Number: 13046
Subject.. Stormwater Runoff Calculations DatV —Loll (3113 ON*
By: L. Warrick Page:
--------
1, CHECK TIME REQUIRED TO EMPTY SWALE
Given! 424 cf
Vr Ronoff Volume = Q't 105 sf Bottom area of Swale
Ap Percolation Area 8 m1hr Assumed minirnUn' infiltraltion
r Percolation Rate
Solution: hr
t Time to percolate= Vrl(Ap*r/12)
Percolation Time < 24 hr? OK
P12013k13046\DoCuments`tStOrm Calcs\RevA�3- Storm Caics -13046
Stormwater Management Calculations for
Glass Doctor — Parking Lot Improvements
52 S. Meridian Rd
Meridian, Idaho
APPENDIX A
RUNOFF COEFFICIENTS AND RAINFALL INTENSITY
P:\2013\13046\Documents\Storm CaIcS\RevA\1. Storm calculation Introduction.doc
r
EXHIBIT "A"
Recommended "C" Coefficients
for "Rational Method Equation"
Peak Rate of Discharge
Description of Run -Off Area
Runaff Coefficients "C'
Business
Downtown areas
0,95
Urban neighborhood areas
0.70
Residential
Single-family
0.50
Multi -family
0.75
Residential (rural)
0.40
Apartment dwelling areas
0.70
Industrial and Commercial
Light areas
0.80
Heavy areas
0,90
Parks, cemeteries
0.10
Playgrounds
0,20
Railroad yard areas
0-20
Unimproved areas
0.10
Streets
Asphalt
0.95
Concrete
0.95
Brick
0.85
Drives and walks
0.85
Roofs
0.95
Fields: Sandy soil
Flat 2%
0.05
Average 2-7%
010
Steep 7%
015
Fields: Clay soil
Flat 2%
013
Average 2-7%
0A8
Steep 7%
0.25
Adapted from ASCE (1972
1
A.1
— USE 0.80
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Stormwater Management Calculations for
Glass Doctor—Parking Lot Improvements
52 S. Meridian Rd
Meridian, Idaho
APPENDIX B
INFILTRATION RATE INFORMATION
P:\2013\13046\Documents\Storm Calcs\RevA\1. Storm Calculation Introduction.doc
TABLE 3 - INFILTRATION RATES
SCS Group and Type
Infiltration Rate
(inches Per Hour)
A. Sand
g
A. Loamy Sand
2
B. Sandy Loam
1
B. Loam
0.5
C. Silt Loam
0.25
C. Sandy Clay Loam
0.15
D. Clay Loam & Silty Clay Loam
<0.09
D. Clays
<0.05
`Minimum rate, soils with lesser rates should not be considered as
candidates for Infiltration facilities.
8013.4 Sediment and Grease Traps
Properly sized standard sediment and grease traps shall be installed upstream
of infiltration facilities.
8013.5 Ground Water Elevations
Groundwater elevation shall be established in accordance with Section 8010.5.
If groundwater is encountered during construction of the facility at an elevation
higher than that shown on the plans, the facility shall be re -designed to account
for the higher elevation.
Water quality testing may be required by the District, Idaho Department of
Water Resources or Central District Health Department.
8014 PERCOLATION FACILITIES
8014.1 Design
In general percolation facilities are designed to contain the design inflow
without overtopping. The water is stored within the effective pore volume and
percolates into the ground.
Percolation facilities may be designed to contain the runoff from the design
storm for a primary system if the facility has a positive outflow to a secondary
system. If there is not a positive outflow to a secondary system, the percolation
facility must be designed to accommodate the runoff from the design storm for
Adopted: Res. 468 (7/13/94) 8000-17
Revised: 7119195; 2114196; Res. 657 (8128102)
Stormwater Management Calculations for
Glass Doctor—Parking Lot Improvements
52 S. Meridian Rd
Meridian, Idaho
APPENDIX C
N
DIMENSIONS AND DETAILS FOR THE PROPOSED SWALE
P:\2013\13046\Documents\Storm Calcs\RevA\1. Storm Calculation Introduction.doc
-------------
APPE.GVED1 FbR CoNsTRUCTIC
Q O�IDiAid RI;BL;C V'r';:+t'IKQ5lw
k
0 5 10 20
SCALE (FT)
CA
SCALE: N.T.S.
CONTRACTOR SHALL GRADE PARKING LOT TO
STORMWATER RUNOFF TO SWALE AND
/DIRECT
PROVIDE CUTS IN CURB AS NEEDED TO ALLOW '
s RUNOFF TO ENTER SWALE
p
a
M
N,
N-
i
I.
Fill11, v
rFA
PROVIDE AT LEAST 0.5' OF FREEBOARD--
\ SO TOP OF SWALE IS AT LEAST 2.0' ABOVE
BOTTOM OF SWALE
r 11
SCALE: N.T.S.
I 'DESIGN WATER SURFACE (418 SF)
AT 1.5' ABOVE BOTTOM OF SWALE
BOTTOM AREA OF SWALE (105 SF)
CONSTRUCT ASTM C-33 SAND INFILTRATION WINDOW
DOWN TO FREE—DRAINING MATERIAL
O
p
a
M
N,
N-
i
I 'DESIGN WATER SURFACE (418 SF)
AT 1.5' ABOVE BOTTOM OF SWALE
BOTTOM AREA OF SWALE (105 SF)
CONSTRUCT ASTM C-33 SAND INFILTRATION WINDOW
DOWN TO FREE—DRAINING MATERIAL
APPR nR� tia®r uCoNsTp
B�ic �r%0 -kKS
GRASS
3 BOTTOM OF SWALE:
�1�Ii (SEE PLAN)
z
(SEE PLAN)
TYPICAL
SCALE: N.T.S.
DESIGN WATER LEVEL
1.5' ABOVE BOTTOM
2" DRAIN ROCK OR EXPOSED SAND WINDOW
AS DIRECTED BY OWNER
TOP OF SWALE
2.0' MIN ABOVE
SWALE BOTTOM
ASTM C-33 FILTER SAND INFILTRATION WINDOW
(ASSUMED TO BE AT LEAST 8' DEEP OR DEEPER
IF NEEDED TO REACH FREE DRAINING SOIL)
BOTTOM OF FILTER SAND SHALL EXTEND
THROUGH CALICHE OR OTHER IMPERMEABLE
LAYER 1' MIN. INTO FREE DRAINING MATERIAL
NOTES:
1. THE CONTRACTOR SHALL HAVE PLANS STAMPED "APPROVED
FOR CONSTRUCTION" BY CITY OF MERIDIAN PUBLIC WORKS
DEPARTMENT ON SITE AT ALL TIMES.
2. ANY CHANGE FROM THE PLANS SHALL BE APPROVED BY THE
DESIGNER AND THE CITY OF MERIDIAN PUBLIC WORKS
DEPARTMENT.
3. THE CONTRACTOR SHALL CONTACT THE CITY OF MERIDIAN
PUBLIC WORKS DEPARTMENT FOR INSPECTION OF ALL STORM
WATER FACILITIES PRIOR TO THE PLACEMENT OF FILTER FABRIC,
MINIMUM 24-HOUR NOTICE IS REQUIRED. APPROVAL IS
CONTINGENT UPON INSPECTION.
4, THE CONTRACTOR SHALL CONTACT THE DESIGN ENGINEER AT
(208) 466-8181 FOR PERIODIC OBSERVATION OF STORM DRAIN
CONSTRUCTION. A MINIMUM OF 48-HOUR NOTICE IS REQUESTED.
5. THE CONTRACTOR SHALL EXCAVATE A MINIMUM OF ONE TEST
HOLE TO DETERMINE IF IMPERMEABLE LAYERS OR GROUNDWATER
EXIST WITHIN 4 FEET OF PROPOSED BOTTOM OF DRAINAGE
FACILITY. CONTACT THE ENGINEER FOR REVISED BEDS IF
EITHER CONDITION IS FOUND. CONTACT MERIDIAN PUBLIC
WORKS FOR INSPECTION OF TEST HOLE PRIOR TO BACKFILL.
6, THE CONTRACTOR SHALL EXCAVATE THE TEST HOLE IN THE
PRESENCE OF THE DESIGN ENGINEER.
7. TEST HOLES SHALL BE OBSERVED BY THE ENGINEER PRIOR TO
BACKFILL. BACKFILL TEST HOLES WITH ASTM C-33 SAND_
8. ADDITIONAL EXCAVATION MAY BE NEEDED BEYOND THE
ANTICIPATED BOTTOM OF THE FILTER SAND TO REACH SOILS
SUITABLE FOR INFILTRATION.
C.2