The Horizontal Grid is located fifteen miles west north west of Dog Area. The grid area consists of 2700 square feet and contains twenty-eight sampling rows spaced at 100 ft. intervals. Sampling stations are located every 100 feet on each row. (Eight of these rows have been modified to provide for sampling at 50 foot intervals.)

Each row has an independently controlled piped vacuum system, with the vacuum provided by an 85 cfm vacuum pump. Three 75 kw generators provide the power necessary for the operation of the grid.

Downwind sampling is accomplished on this grid through the use of four lines extending to the north and four to the South. Sampling stations are positioned as follows: 68 stations located at 100 foot intervals on the 3/4 mile line; 54 stations located at 150 foot intervals on the 1 mile line; 38 stations located at 300 foot intervals on the 1 1/2 mile line; and 35 stations located at 400 foot intervals on the 2 1/2 mile line. The lines are wired for 220 volt, three phase power and require the use of individual motor-vacuum pump assemblies at each station. Power is supplied by portable 30 KW generators.

The Horizontal Grid is used primarily for the testing of biological munitions and dissemination devices when total dose sampling is desired.

The following   diagram #1 and diagram #2 illustrate the basic sampling array and outer array for this grid.