CC - Storm Drainage Calcs TM
4VOMcNEIL ENGINEERING
Economic and Sustainable ❑esigns,Professionals You Know and Trust
8610 South Sandy Parkway, Suite 200 Sandy, Utah 84070 801.255.7700 mcneilengineering.com
DRAINAGE NARATIVE
Gold Stream Subdivision
3220 E Victory Road
Meridian, ID
Project Number. 21070
Prepared for:
Gold Stream LLC
Jim Petersen
197 W 4860 S
Salt Lake City, UT 84107
Prepared by:
McNeil Engineering
8610 S. Sandy Parkway, Suite 200
Sandy, Utah 84070
May 17, 2021
1983-2021
Over 38 Years of Providing Quality Engineering &Surveying
www.mcneilengineering.com
2
Summary
The proposed Starbucks site is designed for no stormwater discharge to the public right of way due to the
grades sloping away from Eagle and Victory Road. All storm water onsite will be retained and the
calculations in Appendix A show retention requirements for the project site for the 100-year, 24-hour storm
events.
The storm water calculations included are for the Starbucks site only. A temporary berm to impound and
retain storm water has been shown on sheet C2.01 of the construction drawings for water that will be
collected part of the future development of lots 2 and 3. All stormwater facilities and calculations for the
future lots will be provided at the time of site amendment application(s).
1983-2021
Over 38 Years of Providing Quality Engineering &Surveying
www.mcneilengineering.com
3
Appendix A — Stormwater Calculations
1983-2021
Over 38 Years of Providing Quality Engineering & Surveying
www.mcneilengineering.com
STORM RUNOFF Title: Starbucks Meridian
CALCULATION Scope: Site Drainage Design
SHEET Tributary Area 1 Retention Facilities
Mcneil Engineering Project No. Engineer: TJD Check: RJP
8610 S.Sandy Pkwy,Sandy, UT 1 21070 lAuthority: Meridian, ID IRev. No.: 0
Design Philosophy:
The storm water runoff from the project site will sheet flow to the drive isles where
stormwater fill flow in gutters to a curb cut where storm water will flow through a curb
cut to a site retention basin sized for the 100-year storm.
Area Identification Runoff Coefficient
(A) (C) (C-A)
Paved 5,106 sf (0.12 ac) 0.85 = 4,340 sf
Roof Area 1,150 sf (0.03 ac) 0.90 = 1,035 sf
Landscaped 1,664 sf (0.04 ac) 0.15 = 250 sf
Total 7,920 sf (0.18 ac) 0.71 (ave) 5,625 sf
Allowable Discharge Rate = 0.00 cfs/ac
100-Year, 24-Hour Storm: Allowable Peak Discharge = 0.00 cfs
Time Rate Rainfall Q in Add'I Q in Total Q in Q out Storage
(min) (in/hr) (Inches) (cfs) (cfs) (cfs) (cfs) (cf)
5 6.36 0.53 0.83 0.00 0.83 0.00 248
10 4.86 0.81 0.63 0.00 0.63 0.00 380
15 4.00 1.00 0.52 0.00 0.52 0.00 469
30 2.70 1.35 0.35 0.00 0.35 0.00 633
60 1.67 1.67 0.22 0.00 0.22 0.00 783
120 0.91 1.82 0.12 0.00 0.12 0.00 853
180 0.62 1.85 0.08 0.00 0.08 0.00 867
360 0.33 1.98 0.04 0.00 0.04 0.00 928
720 0.19 1 2.29 1 0.02 0.00 0.02 0.00 1,073
1440 0.10 1 2.46 1 0.01 0.00 0.01 0.00 1,153
Surface Storage Provided:
Pond Area(sf) Depth (ft) Volume (cu.ft.)
Basin 1 2328 1 1164 cf
Total Surface Storage 1164 cf
Total Retention Provided : 1,164 cf
Total Retention Required : 1,153 cf
STORM RUNOFF Title: Starbucks Meridian
CALCULATION Scope: Site Drainage Design
SHEET Tributary Area 2 Retention Facilities
Mcneil Engineering Project No. Engineer: TJD Check: RJP
8610 S.Sandy Pkwy,Sandy, UT 1 21070 lAuthority: Meridian, ID IRev. No.: 0
Design Philosophy:
The storm water runoff from the project site will sheet flow to the drive isles where
stormwater fill flow in gutters to a curb cut where storm water will flow through a curb
cut to a site retention basin sized for the 100-year storm.
Area Identification Runoff Coefficient
(A) (C) (C-A)
Paved 1,395 sf (0.03 ac) 0.85 = 1,186 sf
Roof Area 1,150 sf (0.03 ac) 0.90 = 1,035 sf
Landscaped 3,765 sf (0.09 ac) 0.15 = 565 sf
Total 6,310 sf (0.14 ac) 0.44 (ave) 2,786 sf
Allowable Discharge Rate = 0.00 cfs/ac
100-Year, 24-Hour Storm: Allowable Peak Discharge = 0.00 cfs
Time Rate Rainfall Q in Add'I Q in Total Q in Q out Storage
(min) (in/hr) (Inches) (cfs) (cfs) (cfs) (cfs) (cf)
5 6.36 0.53 0.41 0.00 0.41 0.00 123
10 4.86 0.81 0.31 0.00 0.31 0.00 188
15 4.00 1.00 0.26 0.00 0.26 0.00 232
30 2.70 1.35 0.17 0.00 0.17 0.00 313
60 1.67 1.67 0.11 0.00 0.11 0.00 388
120 0.91 1.82 0.06 0.00 0.06 0.00 422
180 0.62 1.85 0.04 0.00 0.04 0.00 429
360 0.33 1.98 0.02 0.00 0.02 0.00 460
720 0.19 1 2.29 1 0.01 1 0.00 0.01 0.00 532
1440 0.10 1 2.46 1 0.01 0.00 0.01 0.00 571
Surface Storage Provided:
Pond Area(sf) Depth (ft) Volume (cu.ft.)
Basin 1 2294 0.5 574 cf
Total Surface Storage 574 cf
Total Retention Provided : 574 cf
Total Retention Required : 571 cf
STORM RUNOFF Title: Starbucks Meridian
CALCULATION Scope: Site Drainage Design
SHEET Tributary Area 3 Retention Facilities
Mcneil Engineering Project No. Engineer: TJD Check: RJP
8610 S.Sandy Pkwy,Sandy, UT 1 21070 lAuthority: Meridian, ID IRev. No.: 0
Design Philosophy:
The storm water runoff from the project site will sheet flow to the drive isles where
stormwater fill flow in gutters to a curb cut where storm water will flow through a curb
cut to a site retention basin sized for the 100-year storm.
Area Identification Runoff Coefficient
(A) (C) (C-A)
Paved 5,086 sf (0.12 ac) 0.85 = 4,323 sf
Roof Area 0 sf (0.00 ac) 0.90 = 0 sf
Landscaped 5,647 sf (0.13 ac) 0.15 = 847 sf
Total 10,733 sf (0.25 ac) 0.48(ave) 5,170 sf
Allowable Discharge Rate = 0.00 cfs/ac
100-Year, 24-Hour Storm: Allowable Peak Discharge = 0.00 cfs
Time Rate Rainfall Q in Add'I Q in Total Q in Q out Storage
(min) (in/hr) (Inches) (cfs) (cfs) (cfs) (cfs) (cf)
5 6.36 0.53 0.76 0.00 0.76 0.00 228
10 4.86 0.81 0.58 0.00 0.58 0.00 349
15 4.00 1.00 0.48 0.00 0.48 0.00 431
30 2.70 1.35 0.32 0.00 0.32 0.00 582
60 1.67 1.67 0.20 0.00 0.20 0.00 720
120 0.91 1.82 0.11 0.00 0.11 0.00 784
180 0.62 1.85 0.07 0.00 0.07 0.00 797
360 0.33 1.98 0.04 0.00 0.04 0.00 853
720 0.19 1 2.29 1 0.02 0.00 0.02 0.00 987
1440 0.10 1 2.46 1 0.01 0.00 0.01 0.00 1,060
Surface Storage Provided:
Pond Area(sf) Depth (ft) Volume (cu.ft.)
Basin 1 2270 0.5 1135 cf
Total Surface Storage 1135 cf
Total Retention Provided : 1,135 cf
Total Retention Required : 1,060 cf