Recommended number of soil borings, pits or permeameter tests for bioretention design. Designers select one of these methods.
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Surface area of stormwater control measure (BMP)(ft2) Borings Pits Permeameter tests
< 1000 1 1 5
1000 to 5000 2 2 10
5000 to 10000 3 3 15
>10000 41 41 202

1an additional soil boring or pit should be completed for each additional 2,500 ft2 above 12,500 ft2
2an additional five permeameter tests should be completed for each additional 5,000 ft2 above 15,000 ft2