Math question, need help with garden.?

I'm moving into a new house. I want a circular flower garden in the middle of the yard. In the centre I want a pond where I'll keep fish, water plants, etc. I'll give you the dimensions:





It will be 10 feet away from the deck.


The total diameter of the garden/and pond is 10 feet.


The middle pond of the circular garden is 6 feet in diameter.


The outer 2 feet is the garden part.





I know I need to:


1. Excavate the pond to a depth of 3 feet (flat bottom).


2. Line the pond basin with a pond liner.


3. Add 2 inches of topsoil to the flower bed.





Supplies and services (I can only get these in the whole units):


1. Excavation: $1.49 per cubic foot + 6% GST (Canadian federal tax)


2. Soil: $1.99 per 1 ft(cubed) bag + 6% GST %26amp; 7% PST (Canadian Provincial Tax)


3. Pond Liner: $75.00 + 6% GST %26amp; 7% PST.





Any help with this is much appreciated!

Math question, need help with garden.?
I'm assuming your question is: How much is this going to cost?





Excavation:


I'm assuming the hole dug for the pond will be dug straight down, ie the pond volume will be like a circular tank and not a half-sphere.


Volume to be excavated = pi (6ft/2)^2 (3ft) = 84.8 ft^3


E = ($1.49/ft^3)( 85 ft^3)(1.06) = $134.25





Soil:


If you "unravel" the donut, the volume of soil is a rectangular solid with height 2 inches, width = circumference of pond, length = circumference of garden. Volume = hwL. Circumference = pi * diameter.


V = (2/12 ft) pi (6 ft) pi (10 ft) = 98.7 ft^3


S = ($1.99/ft^3)(99 ft^3) (1.13) = $222.62





Pond Liner:


P = $75 (1.13) = $84.75





Answer: E + S + P = $441.62