|Monitored Zone||Channel Number||Depth to Center of Port
(from ground surface)
|1||1||20 ft (6.1 m)|
|2||2||30 ft (9.1 m)|
|3||3||50 ft (15.2 m)|
In our example (Table 2) there are ports at 20 ft, 30 ft and 50 ft (6.1 m, 9.1 m and 15.2 m) depths. Each monitoring zone is 2 ft (0.6 m) length. Sand Cartridges are a nominal 1 ft (0.3 m) length, therefore, a total of six Sand Cartridges will be required to complete this installation. The annulus volume of filter sand required is about 0.015 cu.ft/ft (0.0014 cu.m/m) per Sand Cartridge, therefore, a 50 lb (23 kg) bag of sand will provide an ample 25 ft (7.6 m) of sand pack.
Each 50 lb (22.7 kg) bag of sand will fill about 25 ft (7.6 m) of sand cartridges.
In this example, we will use a 3 ft (0.9 m) bentonite seal on either side of our monitoring zone, with an exception at Port 3, the deepest. We chose not to place a bentonite seal below Port 3. Thus, three monitoring zones equates to five 3 ft (0.9 m) sealed areas. As the Bentonite Spring Cartridges are nominally 1 ft (0.9 m) in length, five seal locations, each 3 ft (0.9 m) long, mean fifteen Cartridges will be needed. Each Cartridge will require about 1 lb (0.5 kg) of 3/8" dia. bentonite pellets, therefore about 15 lbs (7.5 kg) is required.
Each Bentonite Spring Cartridge will require about 1 lb (0.5 kg) of 3/8" dia. bentonite pellets.