Sequence of Field Testing Typical Order from Left to Right

Comments

Type of test

Data needed

Test Pits

Backhoe pit; also inspect road cuts, drainage Depth of profile, texture, structure, restricting layers

Test Borings

Drilled or augered, also logs of local wells for soils data and water levels Depth to groundwater, depth to barrier

Infiltration

Tests3

Basin method, if possible

Infiltration rate

Soil Chemistryb

Review NRCS soil surveys

Nutrients, salts, pH, exchangeable sodium percentage

Then

Need for hydraulic

Groundwater flow

Hydraulic

Soil amendments,

estimate

conductivity tests

direction

capacity

crop limitations

More tests

Hydraulic

Horizontal

for

conductivity, if

conductivity, if

necessary

necessary

Also

Loading rates

Groundwater

Quality of

estimate

mounding, need for

percolate

drainage

Number of

Three to five

Three-per-site

Two-per-site

Depends on type

tests

minimum per

minimum, more for

minimum,

of site, soil

site, more for

soil aquifer

more for large

uniformity,

larger sites or

treatment than slow

sites or poor

wastewater

poor soil

rate, more for poor

soil

characteristic

uniformity

soil uniformity

uniformity

a Required only for land application of wastewater; some definition of subsurface permeability is necessary for pond and biosolids systems. b Typically required only for land application of biosolids or wastewater.

Source: Adapted from USEPA, Process Design Manual: Land Treatment of Municipal Wastewater, EPA 6125/1-81-018, CERI, Cincinnati, OH, 1981.

surface for wastewater. These samples should be reserved for future testing. The walls of the backhoe pits should be examined carefully to define the characteristics listed in Table 2.14. Useful sources for more details are Crites et al. (2000) and USEPA (2002, 2005).

The test pit should be left open long enough to determine if groundwater seepage occurs, and then the highest level attained should be recorded. Equally important is any indication of seasonally high groundwater, most typically demonstrated by mottling of the soils. Soil borings should penetrate to below the groundwater table if the groundwater is within 30 to 50 ft (10 to 15 m) of the surface. At least one boring should be located in every major soil type on the

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