Factors

Rating

Condition Value3

Dominant vegetation

Pine 2

Hardwood or mixed 3 Vegetation age (yr) Pine:

20-30 3

<20 4 Hardwood

30-50 2

<30 3 Mixed pine/hardwood

25-40 2

7-35 6 Distance to surface waters (m)

15-30 1

30-60 2

>60 3 Adjacent land use

High-density residential 1

Low-density residential 2

Industrial 2

Undeveloped 3

a Total rating: 3-4, not suitable; 5-6, poor; 9-14, good; >15, excellent.

Source: Adapted from Taylor, G.L., in Proceedings of the Conference of Applied Research and Practice on Municipal and Industrial Waste, Madison, WI, September 1980.

TABLE 2.10

Rating Factors for Biosolids or Wastewater in Forests (Subsurface Factors)

Rating Rating

Condition Value3 Condition Value3

TABLE 2.10

Rating Factors for Biosolids or Wastewater in Forests (Subsurface Factors)

Rating Rating

Condition Value3 Condition Value3

Depth to seasonal groundwater (m)

NRCS shrink-swell potential for the soil

<1

0

High

1

1-3

4

Low

2

>10

6

Moderate

3

Depth to bedrock (m)

Soil cation exchange capacity (mEq/100 g)

<1.5

0

<10

1

1.5-3.0

4

10-15

2

>3

6

>15

3

Type of bedrock

Hydraulic conductivity of soil (cm/hr)

Shale

2

>15

2

Sandstone

4

<5

4

Granite-gneiss

6

5-10

6

Rock outcrops (% of total surface)

Surface infiltration rate (cm/hr)

>33

0

<5

2

10-33

2

5-10

4

1-10

4

>15

6

None

6

NRCS erosion classification

Severely eroded

1

Eroded

2

Not eroded

3

a Total rating: 5-10, not suitable; 15-25, poor; 25-30, good; 30-45, excellent.

a Total rating: 5-10, not suitable; 15-25, poor; 25-30, good; 30-45, excellent.

Source: Adapted from Taylor, G.L., in Proceedings of the Conference of Applied Research and Practice on Municipal and Industrial Waste, Madison, WI, September 1980.

Forested sites for either wastewater or biosolids are presented as a separate category in Table 2.9 and Table 2.10. In the earlier cases, the type of vegetation to be used is a design decision to optimize treatment, and the appropriate vegetation is usually established during system construction. It is far more common for forested sites to depend on preexisting vegetation on the site, so the type and status of that growth become important selection factors (McKim et al., 1982). The total rating combines values from Table 2.9 and Table 2.10. The final ranking, as with other methods, must include the transport distance; the values in Table 2.7 can be used for wastewater systems.

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