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DESIGN ASSOCIATES
CHIPOTLE - 1737 S MERIDIAN
DRAINAGE REPORT
DUSTIN HAYES, PE
JUNE 2, 2023
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EXECUTIVE SUMMARY
The purpose of this report is to confirm that the storm water management system design for the
proposed buildings and adjacent parking and sidewalks are adequate for the specified design storms per
City of Meridian design standards.
DESCRIPTION
The subject property is located at 1737 S Meridian Rd, Meridian, ID. The limits of construction are
approximately 1-acre, as shown on the attached drainage exhibit. See Appendix A for a copy of the
plan.
Currently,the site consists of mostly dirt and undeveloped terrain with minimal slope, as well as existing
parking and a planter along the east side, and drainage is achieved by percolation through surface soils
and runoff to a planter swale along the east side of the existing improvements.
Proposed improvements consist of one new building and one pad ready site, parking, and adjoining
concrete sidewalks. Stormwater draining from the buildings (one in future), parking lot and concrete
sidewalks will sheet flow to proposed catch basins, which are conveyed into proposed seepage beds.All
stormwater within the limits of construction will be contained on site to the extent possible with the
addition of the proposed improvements.
Infiltration rate is estimated at 0.50 in/hr conservatively per the Geotech report.
SEEPAGE BED DESIGN
Based on the attached seepage bed calculations, it is adequately sized to ensure no ponding occurs on
the surface and that storm water will infiltrate within the seepage bed.The geotechnical engineering
report prepared by Atlas, dated March 13, 2023, identified that no groundwater was encountered
during test pit excavations at depths of 14.5 BGS.
For seepage bed 1 (SB-1), a design infiltration rate of 0.5 inches per hour was used for the design per
recommendations from Atlas SB-1 will have 7-feet of washed rock along with a 1.5-foot section of sand
above the groundwater layer. A minimum separation of 3 feet will be maintained between the bottom
of rock and anticipated groundwater level.The required volume to retain for SB-1 is 3,229 CF.This
required volume was calculated by accounting for 1-inch of storm water over the tributary area draining
to SB-1. A 25%oversize was also applied to account for sedimentation. SB-1 will provide 3,229 CF of
storage. A 1,000 gallon grease trap is proposed prior to the seepage bed for pre-treatment.
APPENDIX A
DRAINAGE EXHIBIT
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CCE DESIGN ASSOCIATES INC.
CCEMERIDIAN: 3597 E Monarch Sky Ln, Suite 240, Meridian, ID 83646 p-21566
IDAHO-CALIFORNIA-FLORIDA
P:208.418.2359 J, 7/6/23 0
DESIGN ASSOCIATES www.ccedesignassociates.com OGTF OF C:)
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DUSTIN J. HAYES, P.E.
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20.0'WATER AND
SEWER EASEMENT TBM
\7INSTALL 12 LF OF 6" PVC
_ _ _ _ _E_AS_E- STORM DRAIN @ 2.85% _
- GAS GAS G � GAS AS GAS GAS
6"x4"x4"WYE 9 INSTALL 44 LF OF 4" PVC ° cn
O GREASE TRAP 4 DI f IE=2621.15 STORM DRAIN @ 2.85% 1 ° 1 ri 0
_T_17
RIM(N)=2625.65 TG=2623.68 45°BEND 1 '
RIM(S)=2625.66 IE IN/OUT=2619.55 >
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IE IN=2619.48 \� I E 2622.
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IE OUT=2619.38 D SD SD
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INSTALL 15 LF OF 12" PVC ° 1° 0 10 20 40 60
STORM DRAIN @ 1.50% -� c�0 3 1 10 10
INSTALL 43 LF OF 6" PVC ° ° �, 1 Scale 1" = 20 ft
INSTALL 3 LF OF 12" PVC S� ° STORM DRAIN @ 2.85%
STORM DRAIN[@ 1.50/° SD ° °S 3 CB ° 20.0'WATER °
TG=2624.67 1
- g Q INSTALL 9 LF OF 12" PVC IE OUT=2620.67 AND SEWER °28 0,a
° STORM DRAIN @ 0.50% EASEMENT PE E,STRI N
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s PROPOSED BUILDING I E S(EME T I o
FF 262540= .
INSTALL51LFOF12" PVC 9 ° �� 1 s DRAINAGE CONSTRUCTION KEYNOTES / LEGEND
STORM DRAIN @ 0.50%
INSTALL 44 LF OF 12" PVC I (A
STORM DRAIN @ 1.50% I o � INSTALL 49 LF OF 12"PVC 1 � 1 INSTALL UNDERGROUND SEEPAGE BED SB-1 PER DETAIL ON SHEET C0.1
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INSTALL 56 LF OF 12 PVC ° I - O )
° STORM DRAIN @ 0.50/° TOP OF ROCK SECTION=2621.50
INSTALL 3 LF OF 12" PVC o STORM DRAIN @ 0.50% I
STORM DRAIN @ 1.50°�° 1 18"PERF IE=2619.38
INSTALL 30 LF OF 12" PVC INSTALL 9 LF OF 12" PVC
° 1 0
° 2614.50
STORM DRAIN @ 0.50% STORM DRAIN @ 0.50% ° c� L 2611.50
3 cBl o ° BOTTOM OF ROCK SECTION_
12"x4"WYE 7 ESTIMATED SEASONAL HIGH GROUNDWATER=
TG=2624.47 L.... :;.'.::: cn ° IE=2620.320
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IE oUT=262o.a7' I1... o PAP a ° ss 1 ss O2 INSTALL 1000 GALLON GREASE TRAP,BOISE VAULT,OR APPROVED EQUAL, PER ACHD STORMWATER
a. :.,.Q::. 7 12"x4"WYE 7 12"x4"WYE _r
°
�IE=2620.12 PAP,'
=2620.22 10 s DESIGN GUIDELINES STANDARD DRAWING BMP-01. L u'
9 '1�s O INSTALL TYPE II CATCH BASIN PER ISPWC STANDARD DRAWING SD-602. O o
SD 1 SD 7 SD SD SD $D _ D ° _ - - I J .,
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z I o ° 6 ° ° 11( 4 INSTALL AMCOR 30"DROP INLET W/TRAFFIC RATED AND GRATED LID(OR APPROVED EQUIVALENT). ,
5 U) 12"x12"x12"TEE Oe8 ° g S ° S S ° S S CB 3 O INVERT AS SHOWN ON PLAN. o
= 1 ° TG=2624.67 0 °D
I IE 2619.85 ° � - d 1, � � �N
6 IE OUT-2620.45 o cn
_, °W 12"x4"WYE 0 5 INSTALL OBSERVATION WELL PER ACHD STORMWATER DESIGN GUIDELINES BMP 20.
INSTALL 55 LF OF 12" PVC ° 7 IE=2620.36 ° INSTALL 3 LF OF 12"PVC M Q O O
STORM DRAIN @ 0.50% o INSTALL 21 LF OF 12" PVC STORM DRAIN @ 0.50% o 0 6 INSTALL 4"NDS AREA DRAIN W/ATRIUM GRATE,OR APPROVED EQUAL.CONNECT TO MAIN LINE AT Uj
`"
° STORM DRAIN @ 0.50% 12"x12"x12"TEE I U z 0 2.0° MIN.SLOPE.
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I PROPOSED BUILDING IE-2620.43 O 3S as o
FF = 2625.45 I E SEMENT W 07 INSTALL PVC WYE CONNECTION.
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10 1 O8 INSTALL PVC TEE.
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° Og INSTALL STORM DRAIN 45°BEND.
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10 CONSTRUCT 4"PVC ROOF DRAIN 24"MIN BELOW FINISHED FLOOR.COORDINATE WITH PLUMBING
I m 12"x12"x6"WYE SD 3:: SD SD SD SD SD ' I O PLANS FOR CONTINUATION OF SERVICES WITHIN BUILDING.EXTEND TO MAIN STORM LINE AS 1
°
Z� IE=2620.13 6"x4"x4"WYE 7 Q g SHOWN @ 1.0%MIN.
m C IE=2620.61 45°BEND 9 fa '
INSTALL 48 LF OF 6" PVC IE=2621.11
DI STORM DRAIN @ 1.0% INSTALL 50 LF OF 4" PVC ENTER
3 0 RIM=2623.50 INSTALL 18 LF OF 12" PVC STORM DRAIN @ 1.0% / ONLYI
IE=2620.22
J I I STORM DRAIN @ 0.50%_ �
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UTILITY NOTES
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- AND 1. BACKFILLING AND COMPACTION FOR ALL TRENCHES PER APPLICABLE AGENCY STANDARDS AND SHALL BE INSPECTED AND 00
�r-vvcr< CH�cMENT S89°59'13"W-2 .98' APPROVED BY THE GEOTECHNICAL ENGINEER. p
2. CONTRACTOR TO VERIFY ALL EXISTING INVERT ELEVATIONS FOR STORM DRAIN AND SANITARY SEWER CONSTRUCTION PRIOR TO Q
w w I ANY SITE WORK.ALL WORK FOR STORM DRAIN AND SANITARY SEWER INSTALLATION SHALL BEGIN AT THE DOWNSTREAM
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- - - - - - - - - - - - - - - - - - - - CONNECTION POINT.THIS WILL ALLOW FOR ANY NECESSARY ADJUSTMENTS TO BE MADE PRIOR TO THE INSTALLATION OF THE Q
ENTIRE LINE. IF THE CONTRACTOR FAILS TO BEGIN AT THE DOWNSTREAM CONNECTION POINT AND WORK UPSTREAM,THEY p
G) SHALL PROCEED AT THEIR OWN RISK AND BE RESPONSIBLE FOR ANY ADJUSTMENTS NECESSARY.
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L J 3. ALL WORK ON-SITE AND IN THE PUBLIC RIGHT OF WAY SHALL CONFORM TO CITY STANDARDS AND REQUIREMENTS. NOTE THE
REQUIREMENT OF ADDITIONAL PERMITS TO BE OBTAINED FROM THE CITY PRIOR TO ANY WORK BEING DONE IN THE
RIGHT-OF-WAY.
4. GENERAL CONTRACTOR SHALL COORDINATE ALL UNDERGROUND UTILITIES.PROVIDE 6-INCHES MINIMUM BETWEEN PIPES Uj
CROSSING ELECTRICAL LINES HORIZONTALLY AND 12-INCHES MINIMUM BETWEEN PARALLEL PIPES CROSSING ELECTRICAL LINES. J
5. FOR UTILITY MATERIALS AND TYPES,SEE CITY STANDARDS AND/OR THE PROJECT SPECIFICATIONS.
6. WATER LINES SHALL BE 12"MINIMUM ABOVE SANITARY SEWER LINE AT ALL CROSSINGS. O
7. MINIMUM COVER FOR WATER LINES IS 3-FEET.
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• ® DRAWN BY: DJH
Q CHECKED BY: STAFF
JOB # 22073
Know what's below. SUBMITTAL: 7/6/23
Call before you dig.
NOTICE TO CONTRACTORS
CONTRACTOR TO NOTIFY USA (UNDERGROUND SERVICE ALERT)AT
811 A MINIMUM OF 48 HOURS BEFORE BEGINNING UNDERGROUND DRAINAGE EXHIBIT
WORK FOR VERIFICATION OF THE LOCATION OF UNDERGROUND
UTILITIES
1
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CALCULATIONS
ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method
NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These
calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted.
arge Rate�ational M�!Slated for
Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab)
User input in yellow cells.
1 Project Name
2 Is area drainage basin map provided? YES
(map must be included with stormwater calculations)
3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 100
4 Enter number of storage facilities(25 max)
Click to Show More Subbasins ❑
Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin
1 Subbasin 2 3 4 5 6 7 8 9 10
5 Area of Drainage Subbasin(SF or Acres) SF 33,690 6,390
Acres 0.92
6 Determine the Weighted Runoff Coefficient(C) 0.90 0.35
C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avg1 0.81
7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate
to Min. Estimated Runoff Coefficients for Various Surface
min
- Type of Surface Runoff Coefficients"(
8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 2.58 in hr Business
Downtown areas 0.70-0.95
9 Calculate the Post-Development peak discharge(QPeak) Qpe.k 1.93 cfs Urban neighborhoods 0.50-0.70
Residential
Single Family 0.35-0.50
10 Calculate total runoff vol(V)(for sizing primary storage) V 2,583 ft3 Multi-family 0.60-0.75
V=CI(Tc=60)Ax3600 Residential(rural) 0.25-0.40
11 Calculate Volume of Runoff Reduction Vrr Apartment Dwelling Areas 0.70
Industrial and Commercial
Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in Light areas 0.80
Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr 1,614 W Heavy areas 0.90
12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs Parks,cemeteries 0.20-0.25
Playgrounds 0.20-0.35
Railroad yard areas 0.20-0.40
13 Volume Summary Unimproved areas 0.10-0.30
Surface Storage:Basin Streets
Asphalt 0.95
Basin Forebay V 258 ft' concrete 0.95
Primary Treatment/StorageBasin V 2,325 ft' Brick 0.95
Subsurface Storage Roofs 0.95
Gravel 0.75
Volume Without Sediment Factor(See BMP 20 Tab) V 2,583 ft3 Fields:Sandy soil Soil Type
Slope A B C D
Flat:0-2% 0.04 0.07 0.11 0.
Average:2-6% 0.09 0.12 0.15 0.
Steep:>6% 0.13 0.18 0.23 O.
Adapted from ASCE
E:\CCE\PROJECTS\Chipotle Meridian Rd\Drainage\Section8000_ACHD_SD_CALC\ACHD_SD_CALCS_112018 6/2/2023,2:32 PM
Version 10.5,November 2018
ACHD Calculation Sheet for Sizing Seepage Bed With Optional Chambers
NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's
calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that
meet or exceed these calculations in order to be accepted.
Note this spreadsheet pulls information from the"Peak QV"tab
Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab)
User input in yellow cells.
1 Project Name 0
2 Enter number of Seepage Beds(25 max) 1
3 Design Storm 100
4 Weighted Runoff Coefficient C 0.81 Link to: LQV _
QV TR55
5 Area A(Acres) 0.92 acres
6 Approved discharge rate(if applicable) 0.00 cfs
7 Is Seepage Bed in Common Lot? No V 3,229 ft3 25%Sediment
8 Set Total Design Width of All Drain Rock W 30.0 ft
9 Set Total Design Depth of All Drain Rock D 7.0 ft
Rock Only,Do Not Include Filter Sand Depth or Cover
10 Void Ratio of Drain Rock Voids 0.4
0.4 for 1.5"-2"drain rock and 3/4"Chips
11 Design Infiltration Rate(8 in/hr max) Perc 0.50 in/hr
12 Size of WC.Perf Pipe(Pert 180°) Dia pipe 18 in
13 Size of Overflow Perf Pipe(Perfs 360°),REQD if Q100>3.3 cfs in
14 Calculate Total Storage per Foot Spf 85.4 Oft
15 Calculate Design Length L 49 50 ft
Override Value Required for Chambers
16 Variable Infiltration Window L SWL 50 ft
17 Variable Infiltration Window W SWW 30.0 ft
18 Time to Drain 467 hours
90%volume in 48-hours minimum
19 Length of WQ&Overflow Perf Pipes 50 ft
20 Perf Pipe Checks.Qperf>=Qpeak;
where Qperf=CdxAxy(2xgxH)
Optional Storage Chambers
Note:This assumes chambers are organized in a rectangular layout.
1-StormTech,
1 Type of Chambers SC740
2 Volume to Store V 0 ft3
3 Installed Chamber Width Cw 4.25 ft
Installed Chamber Depth Cd 2.50 ft
Installed Chamber Height Ch 7.12 ft
4 Chamber Void Factor
5 Chamber Storage Volume,Without Rock,Per Manuf 45.90 ft3/Unit
6 Chamber Storage Volume,With Rock,Per Manuf 74.90 ft3/Unit
7 Total Number of Units Required 0 ea
8 Area of Infiltration Aperc ft2
9 Volume Infiltration Vperc 0 ft3/hr
10 Time to Drain hours
90%volume in 48-hours minimum
E:\CCE\PROJECTS\Chipotle Meridian Rd\Drainage\Section8000_ACHD_SD_CALC\ACHD_SD_CALCS_112018 6/2/2023,2:34 PM
Version 10.0,May 2018