South Carolina Forestry Commission
Best Management Practices

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Stream Crossings

Culvert Installation
Woody Fill

An effort has been made to italicize technical words or phrases and clearly define them in the glossary.

Stream crossings are sometimes necessary for access to forestlands. All crossings need to be planned to minimize environmental impacts. Specific practices are recommended in this section to assure minimum impacts on water flow and aquatic organisms. Bridges, culverts, and fords are all acceptable stream crossings when matched to the site and installed properly.

Bridge construction across navigable waterways is under the jurisdiction of the South Carolina Department of Health and Environmental Control DHEC.* (Opens in new window) Permanent bridges (those that would remain in place for a period greater than six months) must meet higher standards than temporary bridges. Anyone planning to construct a bridge across a navigable waterway must contact DHEC for permit application forms and technical design information.

*DHEC: 2600 Bull St., Columbia, S.C. 29201 (803-734-5360)


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Culvert Installation

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Woody Fill

Woody material may be used as fill to protect stream banks and bottoms in crossing small intermittent and ephemeral streams with well-defined channels if:


Table 1: Recommended Diameters for Permanent/Temporary Culverted Crossings

10 24" 12" 30" 24"
50 36" 18" 48" 48"
100 48" 24" 54" 60"
200 60" 36" 72" 72"
10 12" 12" 18" 12"
50 18" 12" 30" 24"
100 24" 18" 36" 30"
200 30" 24" 42" 36"
(Culvert diameters are based on U.S. Geological Survey (USGS) data as reported in USGS Report 91-4157, Columbia, S.C., 1992.)

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Temporary culverts are sized for storm flows with a two-year -recurrence interval. Permanent culverts are sized for storm flows with 25-year-recurrence intervals. Multiple smaller culverts designed to carry equivalent water flow can be substituted for the above culvert sizes.

For example:

Two 48" culverts can be substituted for a 60" culvert.
Two 54" culverts can be substituted for a 72" culvert.

An alternative is a combination of a smaller culvert and rock surfaced road dips where the culvert is sized for annual storm flows, and the rock surfaced road dip is designed to handle the flow from larger storm events. Landowners are encouraged to contact a local U.S. Natural Resources Conservation Service representative or other qualified professional to design culverted crossings specifically for each site.

Table 2: Recommendations for Seeding, Mulching, and Fertilizing
Roads, Fills, and Other Disturbed Areas

MOUNTAINSKentucky 31 Fescue (early spring) 30 lbs./acreKentucky 31 Fescue30 lbs./acre
(or) Orchard Grass (late spring) 12 lbs./acreAnnual Rye10 lbs./acre
Browntop Millet10 lbs./acre* Unscarified Sericea Lespedeza25 lbs./acre
*Scarified Sericea Lespedeza20 lbs./acre
PIEDMONTKentucky 31 Fescue (early spring) 30 lbs./acreKentucky 31 Fescue30 lbs./acre
Browntop Millet 10 lbs./acreAnnual Ryegrass5 lbs./acre
Bahia10 lbs./acreAnnual Rye10 lbs./acre
*Scarified Sericea Lespedeza20 lbs./acre * Unscarified Sericea Lespedeza25 lbs./acre
COASTAL PLAINBermuda grass (hulled) 4 lbs./acreBahia30 lbs./acre
Bahia 25 lbs./acre* Unscarified Sericea Lespedeza60 lbs./acre
*Scarified Sericea Lespedeza25 lbs./acreAnnual Rye20 lbs./acre
Browntop Millet 10 lbs./acre
* Sericea may be left off on low erosion hazard areas.
NOTE: Fertilize with 800 to 1,000 per acre of 6-12-12. Mulch slopes with 4,000 lbs. small grain straw or 5,000 lbs. hay per acre.

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Streamside Management Zones / Forest Road Construction / Timber Harvesting / Site Preparation / Reforestation / Prescribed Burning / Pesticides / Fertilization / Minor Drainage / Endangered Species Act / Additional Management Options: Wildlife Management / Glossary

Forest Management/ Reference Resources / Environmental Forestry/ Braided Stream Systems