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Spreadsheet Instructions

Input the Vertical Datum to which the elevations to be provided correspond.

This spreadsheet is to be used as a tool for design engineers to design pump station and force main systems to connect to the Brunswick County Collection System. The use of this spreadsheet does not relieve the design engineer of the responsibility of verifying the results of the spreadsheet and taking into account conditions which may not be accounted for with the spreadsheet. Should such conditions which are not accounted for in this spreadsheet be present, the designer should contact the Brunswick County Engineering Department prior to submittal. Data should only be entered into shaded cells. User entered data will be linked to calculations in subsequent sheets as required. Warnings and approval messages appear behind Bold & Italicized text.

Begin with the "Tributary Flow Calculations" tab. Insert the number of applicable units corresponding to the description in the Establishment column. Add additional flow generating establishments as required which are not included in the list. The flow generated by these units is subject to Brunswick County approval.

Move to the "Design Pumping Flow Rate" tab. The Minimum Pumping Rate Required is calculated. The designer should enter the desired Design Pumping Rate in the shaded cell. The Design Pumping Rate should not be less than the Minimum Pumping Rate Required. Additional pumping capacity may be beneficial to allow for non-clog pumps, larger force main diameters, etc.

Move to the "Cycle Time & Wet Well Geometry" tab. Input the target cycles per hour in the Target Cycles per Hour box. Pick a Wet Well Diameter and Wet Well Cycle in the "Determine Wet well Diameter" box. The Volume in Cycle value should closely match the Required Volume value. If not, adjust desired Cycles Per Hour, Wet Well Diameter, and Wet Well Cycle values. Note: Wet well diameter to be standard precast wet well inside diameter. Submit manufacturer's cut sheet of proposed wet well.

Input the existing Ground Elevation and the Sanitary Sewer Invert In elevation. Do not enter the Bottom Invert Elevation until the specific pump has been determined in instruction item #11. The vertical distance between Pump Off and Bottom Invert Elev shall provide for complete pump submergance, and not be less than 4'.

Move to the "Force Main & Piping Design" tab. Input the proposed force main diameter. Resultant velocity should be between 2-5 fps. Check for warnings below the velocity line. Enter the length of force main from the downstream connection point to the transition at the valve vault piping.

Enter the Connection Point in the shaded box. Example Values are as follows: Existing 12" FM at Mt. Misery Rd & Cedar Hill Rd, Existing MH at Hwy 17 & Holden Beach Rd., etc.

Select Valve Vault and Wet Well Piping Size. This piping may be slightly smaller than the Off-Site Force Main. Enter the appropriate quantity of fittings and the total length of pipe the flow travels through from one pump until transiting to the larger off-site force main diameter, or leaving the valve vault (if Pump Station Piping and Off-Site Force Main are same diameter). Add additonal fittings and associated L/D values as required.

Spreadsheet Instructions

If Wet Well ballast is required as indicated on the last box on the sheet submit proposed concrete anchor design for approval.

Enter data provided by Brunswick County in the GPM, Pressure Head at Connection Condition "All Pumps On", and Pressure Head at Connection Condition "Only Proposed Pump On" columns. The Engineer shall determine the appropriate value to input into the “Static Head” column from either 1) the “Connection Point Elevation” minus the wetwell “Pump Off” elevation or 2) the Force Main High Point elevation minus the wetwell “Pump Off” elevation. Option #2 is appropriate when the High Point Elevation exceeds the Hydraulic Grade Line elevation at the location of the proposed force main High Point. As a quick check to see if option #2 needs further investigation, sum the “Pressure Head at Connection” and the “Connection Point Elevation” to calculate the Connection Point Hydraulic Grade Line for both the “All On” and “Only Proposed Pump Station On” scenarios. If the Connection Point Hydraulic Grade Line exceeds the High Point Elevation for both conditions then option #1 is the appropriate choice for determining the static head. If static head is determined by option 2 for any condition, the designer shall indicate the flow rate above which static head as defined by option 1 is the approperate value.

Select a pump that can provide the “Minimum Required Pumping Rate” at the head in the column "’All On TDH”. Check to ensure the proposed pump will also provided the Design Flow Rate at the head in column "’All Off TDH”. Use the graph provided on the "System Curve" tab to aid in determining operating points. All pumps should be non-overloading at the impeller diameter chosen. Note: If the proposed force main discharges to a non-pressurized point such as a gravity manhole or to a WWTP outfall, or option 2 above governs static head, the values for both “Pressure Head at Connection” columns will be 0.” Note: Velocity Head is not included in spreadsheet calculation due to neglidgeable value for normal force main operating velocities.

Enter specific pump information in the shaded areas. Attached manufacturer's cut sheet. Move to "Cycle Time & Wet Well Geometry" tab and enter Wet Well Invert Elevation based on the depth required to provide complete submergence for the specific pump chosen.

Move to the "Operational Check" tab. The operational points entered should be points on the pump curve that intercept the system curves.

Check for Warnings in Red at the bottom of the page. If both read OK, then the pump and force main design can be submitted to Brunswick County for review. If warnings are present adjust previously entered values as required to obtain a cycle time between 2-8 cycles per hour. Values which can affect cycle time include: wet well diameter, wet well cycle, pump selection, etc.

Move to the "Buoyancy Calculations" tab. Input the outside diameter of the wet well, diameter of the extended base, extended base slab thickness, and top slab thickness in appropriate shaded boxes. Provided manufacturer's cut sheet to verify dimensions.

Enter the Saturated unit weight of soil. Use 50 pcf for the submerged unit weigh of soil unless geotechnical investigations justify greater values. Attach supporting geotechnical information if applicable.

Once the design of the pump station and force main is complete, move to the "Cover & Summary" tab. Input the project specific data as required. Note these cells are not shaded.

Brunswick CountyWastewater Pump Station

& Force Main

Design Calculations

Project Name:

Location:

Designed By:

Checked By:

Date:

Project no.:

Brunswick CountyWastewater Pump Station

&Force Main

Project Summary

Project Name:

Average Daily Flow (gpm):

Pump Operational Point No. 1 (gpm@tdh):

Pump Operational Point, No. 2 (gpm@tdh):

Pump Manufacturer:

Model Number:

Impeller Diameter:

Horse Power:

Voltage:

Force Main Diameter (in):

Force Main Length (ft):

Tributary Wastewater Flow Calculations

Establishment Unit Type

Residential (To NEWWTF) 360 Residence

Residential (all other Treatment Facilities) 210 Residence

Barber Shops 50 Chair

Beauty Shops 125 Booth or Bowl

Business - General & Office 25 Employee per shift

Business - Factories Excluding Industrial Waste 25 Employee per shift

Business or Factories w/showers or food preparation 35 Employee per shift

Business - Warehouse 100 Loading bay

Business - Warehouse Self Storage (not including Caretaker Residence) 1 Unit

Churches without kitchens, day care, or camps 3 Seat

Churches with kitchens 5 Seat

Churches providing day care or camp 25 Person (child+employee)

Fire or Rescue without on-site staff 25 Person

Fire or Rescue with on-site staff 50 Person per shift

Food & Drink - Banquet Dining Hall 30 Seat

Food & Drink - Bars, Cocktail Lounges 20 Seat

Food & Drink - Caterers 50 100 sf floor space

Food & Drink - Restaurants, Full Service 40 Seat

Food & Drink - Restaurants, Single Service Articles 20 Seat

Food & Drink - Restaurants, Drive-in 50 car space

Food & Drink - Restaurants, Carry out only 50 100 sf floor space

Food & Drink - Institutions, Dining Halls 5 meal

Food & Drink - Deli 40 100 sf floor space

Food & Drink - Bakery 10 100 sf floor space

Food & Drink - Meat Dept., Butcher, Fish Market 75 100 sf floor space

Food & Drink - Specialty Food Stand or Kiosk 50 100 sf floor space

Hotels/Motels/B&B without in-room cooking facilities 120 Room

Hotels/Motels/B&B with in-room cooking facilities 175 Room

Hotels/Motels- Resort Hotels 200 Room

Hotels/Motels- Cottages, Cabins 200 Unit

Laundries (Self-Service) 500 Machine

Medical or Dental offices 250 Practitioner per shift

Medical - Veterinary offices without boarding 250 Practitioner per shift

Medical - Veterinary, Kennels, with boarding 20 Pen, Cage, Kennel, Stall

Medical - Medical Hospitals 300 Bed

Medical - Mental Hospitals 150 Bed

Medical - Convalescent, Nursing, Rest Homes without Laundry 60 Bed

Medical - Convalescent, Nursing, Rest Homes w/ Laundry 120 Bed

Medical - Residential Care Facilities 60 Person

Parks & Rec. - Campgrounds w/comfort station but without water & sewer hookup 75 Campsite

Parks & Rec. - Campgrounds with water & sewer hookup 100 Campsite

Parks & Rec. - Campground Dump Station facility 50 Space

Parks & Rec. - Construction, Hunting, or Work camps with flush toilets 60 Person

Parks & Rec. - Construction, Hunting, or Work camps with chemical or portable toilets 40 Person

Parks & Rec. - Parks with Restrooms 250 Plumbing Fixture

Parks & Rec. - Summer camps without food prep or laundry facilitates 30 Person

Parks & Rec. - Summer camps with food prep and laundry facilitates 60 Person

Parks & Rec. - Swimming Pools, Bath Houses, Spas 10 Person

Public Access Restrooms 325 Plumbing Fixture

Unit Value (Gal/Day/Unit)

Tributary Wastewater Flow Calculations

Establishment Unit TypeUnit Value

(Gal/Day/Unit)

Schools - Preschools & Daycares 25 Person (child+employee)

Schools with Cafeteria, Gym, & Showers 15 Student

Schools with Cafeteria 12 Student

Schools without Cafeteria, Gym, & Showers 10 Student

Schools, Boarding 60 Person (student+employee)

Service Stations, Gas Stations 250 Plumbing Fixture

Car Wash Facilities (if recycling water, see Rule .0235 of 2T regulations) 1200 Bay

Sports Centers - Bowling 50 Lane

Sports Centers - Fitness, Exercise, Karate, Dance 50 100 sf floor space

Sports Centers - Tennis, Racquet ball 50 court

Sports Centers - Gymnasium 50 100 sf floor space

Sports Centers - Golf Course with only minimal food service 250 Plumbing Fixture

Sports Centers - Country Clubs 60 Member or Patron

Sports Centers - Mini Golf, Putt-Putt 250 Plumbing Fixture

Sports Centers - Go-Kart, Motorcross 250 Plumbing Fixture

Sports Centers - Batting Cages, Driving Ranges 250 Plumbing Fixture

Sports Centers - Marinas without Bathhouse 10 Slip

Sports Centers - Marinas with Bathhouse 30 Slip

Sports Centers - Video Game Arcades, Pool Halls 250 Plumbing Fixture

Stadiums, Auditoriums, Theatres, Community Centers 5 Seat

Stores, Shopping Centers, Malls & Flea Markets:

Auto, Boat, RV dealerships/showrooms with restrooms 125 Plumbing Fixture

Convenience Stores, with Food Preparation 60 100 sf floor space

Convenience Stores, without Food Preparation 250 Plumbing Fixture

Flea Markets 30 Stall

Shopping Centers and Malls with Food Service 130 1000 sf

Stores and Shopping Centers without Food Service 100 1000 sf

Transportation Terminals - Air, Bus, Train, Ferry, Port & Dock 5 Passenger

Other -

Other -

Other -

Other -

From 15A NCAC 02T .0114 Average Daily Flow (gallons per day)

Tributary Wastewater Flow Calculations

# of Units Discharge, GPD

500 180,000

0 0

0 0

5 625

100 2,500

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

100 3,000

0 0

0 0

0 0

0 0

0 0

10 500

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

368 3,680

0 0

Tributary Wastewater Flow Calculations

# of Units Discharge, GPD

0 0

0 0

1000 12,000

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0

0

0

0

Average Daily Flow (gallons per day) 202,305

Design Pumping Flow Rate

Peaking Factor Calculation

Service Area Population = 100,000

Peak Factor = 18 + √P

4 + √P

Calculated Peak Factor = 2.0

Design Peak Factor = 2.5

Determine Minimum Pump Rate

Average Daily Flow = 202,305 GPD

Peak Flow = 505763 GPD

Minimum Pumping Rate Required = 351 GPM

Design Pumping Rate = 575 GPM

Cycle Time & Wet Well Geometry

Target Cycles Per Hour

ADF = 140 gpm

Pumping Rate = 575 gpm

Time = 15.0 min.

Cycles Per Hour = 4.0

Check Cycles Per Hour: OK

Check Cycles Per Hour: OK

Determine Wet well Diameter

Required Volume = 1592 Gallons

Pick Wet Well Diameter = 8.0 Ft

Pick Wet Well Cycle = 4.0 Vert. Ft

Volume in Cycle = 1504 Gallons

Vertical Datum Used: NAVD 88

Determine Wet Well Invert & Float Elevations

Wet well Dia. = 8.0 Ft

Top Elev= 50.50

Gnd Elev= 50.00

SS Invert In= 42.00

Alarm = 37.00

Lag On = 36.00

Lead On = 35.00

Pumps Off = 31.00

Bottom Invert Elev* = 27.00

*As required for complete submergence

OK

Force Main & Piping Design

Off-Site Force Main Data

Design Pump Rate (gpm) = 575

Select Force Main Size (in) = 8

Velocity (fps) = 3.67

Meets Minimum Velocity Requirement? OK

Meets Maximum Velocity Requirement? OK

Required Pump? Use Non-Clog Pump

Line Length (ft) = 10,320

Account for Minor Losses = 5%

Equiv Length (ft) = 10,325

Connection Point: 24" Force Main @ North Brunswick WWTP

Pump Station Piping Data

Design Pump Rate (gpm) = 575

Pick Wet Well & Valve Vault Piping Size (in) = 6

Velocity (fps) = 6.52

Meets Minimum Velocity Requirement? OK > 2 FPS

Meets Maximum Velocity Requirement? OK < 8 FPS

Item Number of Fittings L/D Ratio Equivalent Length

45 bend 0 16 0.0090 bend 2 30 30.0022.5 bend 1 9 4.50Branch Tee Flow 1 60 30.00Check valve 1 135 67.50Plug Valve 1 17 8.50

0.000.00

0.00Equivalent Fitting Length (ft) = 141

Wet Well & Valve Vault Piping Length (ft) = 20Total Equivalent Pump Station Pipe Length (ft) = 161

Equivalent Off-Site Diameter Length (ft) = 651

Total Equivalent Force Main Length (ft) = 10976

Pump Selection

Force Main Diameter (in) =

Equivalent Force Main Length (ft) =

Hazen-Williams C Factor =

Minimum Required Pump Rate (GPM) =

Design Pumping Rate (GPM) =

GPM Static Head "All On" TDH

100 14 0 20 37 23

300 16.6 0.4 20 58 42

600 20.8 1.4 20 119 100

900 25.5 2.9 0 191 169

1200 30.5 5 0 313 287

Pump Manufacturer: Flygt

Model Number: NP 3171 SH 63-275-00-1070

Impeller Diameter: 195 mm

Horsepower: 35

Voltage: 460v 3phase

Pressure Head at Connection "All

On"

Pressure Head at Connection "Only

Proposed Pump Station On"

"Only Proposed

Pump Station On" TDH

Pump Selection

8

10976

130

351

575

Velocity (fps) Pump Head

0.6 245

1.9 197

3.8 135

5.7 74

7.7

Pg. 8

0 200 400 600 800 1000 1200 14000

50

100

150

200

250

300

350

Pump and Force Main System Curve

Pump Head

All On System TDH

All Off System TDH

Flow (GPM)

TD

H (

FT

)

Station Operation Check

Proposed Operational Point No.1

600 GPM @ 135 TDH

Check Wet well Cycle Times

Wet well Wet well Wet well Wet well

Diameter Area Cycle Volume

(feet) (gal / VF) (ft) (gal)

8.0 376 4.0 1503

Fill = Wet well Volume = 10.7 minutes

ADF

Run = Wet well Volume = 3.3 minutes

Pump Rate - ADF

Total = 14.0 minutes

Cycle Time = 4.3 Cycles / Hour

Meets Minimum Cycle Time? OK

Meets Maximum Cycle Time? OK

Station Operation Check

Proposed Operational Point No. 2

640 GPM @ 125 TDH

Check Wet well Cycle Times

Wet well Wet well Wet well Wet well

Diameter Area Cycle Volume

(feet) (gal / VF) (ft) (gal)

8.0 376 4.0 1503

Fill = Wet well Volume = 10.7 minutes

ADF

Run = Wet well Volume = 3.0 minutes

Pump Rate - ADF

Total = 13.7 minutes

Cycle Time = 4.4 Cycles / Hour

Meets Minimum Cycle Time? OK

Meets Maximum Cycle Time? OK

Buoyancy Calculations

Wet well Outside Dimensions 9.00 Feet

Wet well Inside Dimensions 8.00 Feet

Wet well Top Slab Elevation 50.50 Feet

Wet well Invert Elevation 27.00 Feet

Extended Base Slab Diameter 11.00 Feet

Extended Base Slab Thickness 1.00 Feet

Top Slab Thickness 0.50 Feet

Calculate Total Volume of Wet well Structure

Volume of Wet well Riser Sections= 1494 cf

Volume of Wet well Extended Base= 95 cf

Total Volume of Wet well Structure= 1589 cf

Calculate Total Volume of Water Displaced

H20 Displaced = (Volume of Wet well Structure) * (62.4 lbs/cf)

H20 Displaced= 99168 lbs

Calculate Submerged Weight of Wet well Components

Section Total Ht Weight

Top Slab Thickness (ft.) 0.50 2786

Riser - Total Vertical Ft. 23.50 27486

Base Slab Thickness (ft.) 1.00 8325

Totals= 25 38597

Total Weight of Concrete in Wet well= 38597 lbs.

Calculate Weight of Soil Above Extended Base/Footing

Total Area of Extended Base 95 sf

Total Area of Wet well Riser 64 sf

Area of Extended Base less Wet well 31 sf

Height of Soil Above Extended Base 23 ft

Volume of Soil Above Extended Base 723 cf

Weight of Soil Above Extended Base (estimated) 50 lbs/cf

Total Weight of Soil Above Extended Base 36128 lbs/cf

Flotation Protection Required?

Weight of Concrete and Weight of Soil Above Extended Base: 74726

Weight of Water Displaced By Wet Well: 99168

Flotation Protection Required? YES

lbs

lbs