HomeMy WebLinkAboutCORRESPONDENCE •Sep 12 03 10:05a Rabon Metcalf Engineering 9796900329 p.2
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Rational Method Calculations
GENERAL INFORMATION
Description: Lot 1 & 2 Pre - Development conditions
Drainage Area (APRE) = 0.42 acres
TIME OF CONCENTRATION (T,.)
GIVEN RESULT
Maximum Travel Distance (D : 200 ft Tc(PRE) = 6.7 min.
Velocity of Runoff (V = 0.50 ft /sec
Coefficient of Runoff (C = 0.55
* *NOTE: Minimum T allowed = 10 min.
2 YEAR FREQUENCY, RATE OF DISCHARGE (Q)
Coefficient (e) = 0.806 Rainfall Intensity (1 2 ) = 6.327 '" /
Coefficient (b) = 65 Q 'LAO cfs
Coefficient (d) = 8
5 YEAR FREQUENCY, RATE OF DISCHARGE (Q)
Coefficient (e) = 0.785 Rainfall Intensity (1 = 7.693 '" /hr
Coefficient (b) = 76 Q 141 Cfs
Coefficient (d) = 8.5
10 YEAR FREQUENCY, RATE OF DISCHARGE (Q)
Coefficient (e) = 0.763 Rainfall Intensity (I = 8.635 " /hr
Coefficient (b) = 80 410 1111 2.03 da
Coefficient (d) = 8.5
25 YEAR FREQUENCY, RATE OF DISCHARGE (Q)
Coefficient (e) = 0.754 Rainfall Intensity (1 25 ) = 9.861 '" /hr
Coefficient (b) = 89 f 2.32 Cis
Coefficient (d) = 8.5
50 YEAR FREQUENCY, RATE OF DISCHARGE (Q)
Coefficient (e) = 0.745 Rainfall Intensity (I = 11.148 '"/hr
Coefficient (b) = 98 Q2 !' 2.62 cis
Coefficient (d) = 8.5
100 YEAR FREQUENCY, RATE OF DISCHARGE (Q)
Coefficient (e) = 0.73 Rainfall Intensity (I = 11.639 '" /hr
Coefficient (b) = 96 Q 214 de
Coefficient (d) = 8
118 -0133 Rational Method (Simple) - Revised A -1
• e
Rational Method Calculations
GENERAL INFORMATION
Description: Lot 1 & 2 Pre - Development conditions
Drainage Area (A = 0.06 acres (increased impervious area)
Drainage Area (A = 0.36 acres (as -is)
TIME OF CONCENTRATION (T,.)
GIVEN RESULT
Maximum Travel Distance (D,) = 50 ft T = 1.7 min.
Velocity of Runoff (V,) = 0.50 ft /sec
Coefficient of Runoff (C = 0.95
Maximum Travel Distance (D2) = 150 ft Tc2 = 2.5 min.
Velocity of Runoff ("2) = 1.00 ft / sec
Coefficient of Runoff (C = 0.55
* *NOTE: Minimum T allowed = 10 min. Tc(Posr) = 4.2 min.
2 YEAR FREQUENCY, RATE OF DISCHARGE (Q) Rainfall Intensity (1 = 6.327 '" /h
Coefficient (e) = 0.806 QAREA 1 = 0.370 cfs
Coefficient (b) = 65 QAREA 2 = 1.274 cfs
Coefficient (d) = 8 02 = 1 4 01s
5 YEAR FREQUENCY, RATE OF DISCHARGE (Q) Rainfall Intensity (1 = 7.693 in /hr
Coefficient (e) = 0.785 QAREA 1 = 0.450 cfs
Coefficient (b) = 76 QAREA 2 = 1.549 cfs
Coefficient (d) = 8.5 05: 2.00 eh)
10 YEAR FREQUENCY, RATE OF DISCHARGE (Q) Rainfall Intensity (I = 8.635 i° /hr
Coefficient (e) = 0.763 QAREA 1 = 0.505 cfs
Coefficient (b) = 80 QAREA 2 = 1.738 cfs
Coefficient (d) = 8.5 Qu =' 2.24 cfs
25 YEAR FREQUENCY, RATE OF DISCHARGE (Q) Rainfall Intensity (1 = 9.861 '" /hr
Coefficient (e) = 0.754 QAREA 1 = 0.576 cfs
Coefficient (b) = 89 QAREA 2 = 1.985 cfs
Coefficient (d) = 8.5 Qv; _
50 YEAR FREQUENCY, RATE OF DISCHARGE (Q) Rainfall Intensity (I = 11.148 1° /hr
Coefficient (e) = 0.745 QAREA 1 = 0.651 cfs
Coefficient (b) = 98 QAREA 2 = 2.244 cfs
Coefficient (d) = 8.5 Cleo * 2.90 cis
100 YEAR FREQUENCY, RATE OF DISCHARGE (Q) Rainfall Intensity (1 = 11.639 ' /hr
Coefficient (e) = 0.73 QAREA 1 = 0.680 cfs
Coefficient (b) = 96 QAREA 2 = 2.343 cfs
Coefficient (d) = 8 Q100 3.02 cfs
118 -0133 Rational Method (Simple )-Revised A-2
Brett McCully - 500 College Main Page 1
From: Brett McCully
To: Rabon A Metcalf
Date: 9/17/2003 8:18:59 AM
Subject: 500 College Main
Rabon,
I received your fax regarding my foundation related review comment. The sketch does clarify that
significant grading is not intended adjacent to the existing building. I will place this information in the file
and consider this comment resolved.
Brett
Sep 12 03 10:05a Rabon Metcalf Engineering 9796900329 p.l
RABON METCALF CALF GNGINF.ERING
O I \ POSE OFFICE BOX 97.53 19791 690 -037.9 How
!4/91690 -0329 -PAX X
COLLEGE STATION. 'TEXAS 77812 !9191 -4L/4 - CELI
EMAIL: RMENGINJTR�i1.7UNO.COM
FACSIMILE TRANSMITTAL SHEET
1'O:
FROM
Brett McCully, P.E. Rabon Metcalf, P.E.
COMPANY: L)ATI-.
City of College Station September 12, 2003
FAX NUMBER: TOTAL NO. OF PAGES INCLUDING COVER:
764-3496 3
PHONE NUMBER: CC:
Parviz
RE: CC FAX NUMBER:
500 South College Main 764-9601
0 URGENT El FOR REVIEW El PLEASE. COMMENT H PLEASE REPLY 0 FOR YOUR RECORDS
NOTES /COMMENTS:
Brett,
I am not sure if I understand your concern with the existing foundation and proposed parking
lot The foundation is not a slab on grade, but a pier and beam type. Also, the top of
sidewalk will only be an 1" or so below the existing natural ground. I have attached a few
sketches for your review.
Rabon
The information contained in this fax is confidential and is exclusively for the use of the previously addressed party.
Please call the above number to correct any difficulties with the transmission of this fax.
*Sep 12 03 10:12a Rabon Metcalf Engineering 9796900329 p.1
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