CITY OF ANAHEIM
PUBLIC WORKS ENGINEERING DEPARTMENT
SUBDIVISION SECTION

Grading Design Manual

APPENDIX H - Sample of Sump Pump Design

I. CALCULATION OF TOTAL DYNAMIC HEAD (T.D.H.)

A.Static Head:
(Maximum force main elevation - minimum wetwell elevation)

Elevation of force main discharge: 100.24
Elevation floor of wetwell:               89.07
                         off level:                0.50

                                                   87.57
Static head:                                 10.67

B. FRICTION HEAD:

H = L x f
f = (V/1.318 x C x R 0.63) 1.852
V: Velocity fps
C: Hazen Williams coefficient
R: Hydraulic radius = D/4

1. Force main:

4" P.V.C., L = 70.36 ft, C = 150
Q = 283.33. G/P.M.
R = 0.0833
f = 0.0288
h= 709.36 x 0.0288 = 2.03 ft

2. Spool force main:

4" D.I.P., L = 3 ft., c= 120
f = 0.0435*
h = 3 x 0.0435 = 0.13 ft.

3. Fittings (Valves and Elbows):

Description
Quantity
Equivalent length
of straight pipe
P.V.C. to D.I.P. fitting 4" x 6" 2 ea 1.00 ft.
Vertical swing check valve 4" 1 ea 31.00 ft.
90 elbow 4" 2 ea 22.00 ft.
P.V.C. 4" 1.50 ft.
Tee 4" x 4" 4" 1 ea 17.00 ft.
Reducer 3" x 4" 1 ea 0.35 ft
Total 72.85 ft.
h = 72.85 x 0.0435 * = 3.17 ft.
T.D.H. = 10.67 + 2.03 + 0.13 + 3.17 = 16 ft.

II. CALCULATION OF FLOAT SETTING IN WELL TO SATISFY PUMPS:

Well storage: 7.48 gal. x 4' x 4' = 119.68 gal.
Q = 283.33 G.P.M
Float setting in well: 283.33/119.68 = 1.99 ft. say 2 ft.

2 feet is float setting between lead pump on and off position in well to satisfy pump cycle. (The recessed area of the well was not considered in figuring the float setting due to displacement of pumps and fitting).