How to Calculate Geotextile Quantities July 03 2014

First, the easy way...

Table of cover with 1.2m overlap for 4.5m wide Geotextile:-

This works out the number of strips that you need.
Multiply the number of strips by the length of each strip to calculate the amount required!
Simple!

If you want to work it out the hard way... here's the algebra!

W = 3.3 n + P

Let:

W = Width of Arena to be covered

L = Length of Arena to be covered

n = Number of strips of Geotextile required

P = Overlap specified

w = Width of Geotextile Roll

l = Length of Geotextile Roll

3.3 is derived from 4.5m (w) – 1.2m (P)

Example (for a 40m Length x 20m Width arena):

          20 = 3.3n + 1.2

and    3.3n = 20 – 1.2

          n = (20 – 1.2) / 3.3 = 5.7 strips (use 6 no)

So:

l = (L + 0.5)6       (because we need length + 0.5m to dress up kicker)

l = (40 + 0.5)6     = 243m

or let 20m = L and 40m = W (laying the other way round)

n = (40-1.2)3.3    = 11.75 strips (use 12 no)

l = (20+0.5)12      = 246m

The rolls are 100m long so 3 rolls are required to complete the job.