Alabama s Best Management Practices

Transcription

1 Alabama s Best Management Practices Protection of Water Quality During Timber Harvesting Water Quality Responsibility Landowners and/or involved professional forestry practitioners such as: Forest resource managers, Timber purchasers, Loggers, Vendors or contractors, Forest engineers, and Others 1

2 Silvicultural Non Point Source Pollutants Sediment Organic materials Temperature Trash Pesticides Nutrients (Fertilizers) Harvesting and Site Prep Effects Increases water yield Sediment export 4.1 t/ac/yr first year after harvest Nutrient loss, Phosphate eutrophication Nitrate health hazard Both below harmful standards d Fertilization may lead to high nutrient loads 2

3 BMP s are Effective (Nitrogen) BMP s are Effective (Sediment) 3

4 Sediment and Nutrient Yield 20 acres, 2 years BMPs Timber harvest planning Streamside management zones Wetlands Stream crossings Road planning and construction Harvest area 4

5 Timber Harvest Planning Tactical planning When to harvest particular tracts When to build roads and landings Operational planning Road, trail, and landing location Stream crossings Slopes Soils Road and crossing construction Drainage Surfacing Selection and size Water Quality Protection by SMZs Temperature Organic matter Nutrients Sediment 5

6 Riparian Area Important to system health/function Provides shade Provides organic matter input Delays water release Traps sediment Ties up nutrients SMZ Perennial Streams Tree cover at least 50% canopy, 35 feet from the bank, for wildlife 50 feet Shading Leaf and twig input for food and habitat Tree falls for habitat Bank trees for channel stability Avoid disturbance >= 35 ft from stream bank Comply with stream crossing BMPs 6

7 SMZ Perennial Streams Tree cover Avoid disturbance >= 35 ft from stream bank Leaf and plant cover minimize erosion within the SMZ Leaf and plant cover slow upland runoff and drop out sediment Undisturbed soil maximizes infiltration of runoff and rainfall Plant growth removes nutrients from runoff Comply with stream crossing BMPs SMZ Intermittent Streams Avoid disturbance >= 35 ft from stream bank Maintain leaf litter and ground cover Comply with stream crossing BMPs 7

8 SMZ Ephemeral channel No specific requirements Avoid disturbance near streams and to stream banks SMZ - Wildlife Habitat Wider SMZ (50 ft) for use as corridors or habitat Mast (hard mast) producing species retained Recognition of timber type boundaries outside of SMZ Riparian areas 8

9 Wetlands USACE Federal Manual for Delineating Jurisdictional Wetlands May include: Coves and lower slopes, Branch bottoms, Creek bottoms, River bottoms, Muck swamps, Peat swamps and cypress/gum ponds, and wet fiats Alteration of land use in wetland requires 404 4permit Silviculture operations exempt from 404 if BMPs are followed Intention is to maintain land use Good idea to have mgmt plan to support exempt status Fifteen federal Mandatory BMPs (Page 19) Federal Wetland BMPS 1. Roads and trails should be the minimum feasible number, width, and total length 2. Roads and trails should be located sufficiently far from streams or other water bodies (except for crossings) ; 3. Road fill shall be bridged, culverted or otherwise designed to prevent the restriction of expected flood flows; 4. Road fill shall be properly stabilized and maintained during and following construction to prevent erosion 9

10 Federal BMPS 5. Minimize machine traffic outside the fill area; 6. Minimize disturbance of vegetation in designing, constructing and maintaining roads; 7. Design, construction and maintenance of the road crossing shall not disrupt movement of aquatic species 8. Borrow material shall be taken from upland sources whenever feasible Federal BMPS 9. The discharge shall not take, or jeopardize the continued existence of a threatened or endangered species as defined under the Endangered Species Act, or adversely modify or destroy the critical habitat of such species; 10. Discharges into breeding and nesting areas for water fowl, spawning and wetlands shall be avoided if less harmful alternatives exist; 10

11 Federal BMPS 11. No fill in the proximity of a public water supply intake; 12. No fill in areas of concentrated shellfish production; 13. No fill in a component of the National Wild and Scenic River System; 14. Fill must be free from toxic pollutants in toxic amounts; and 15. All temporary fills shall be removed in their entirety and the area restored to its original elevation. Wetland BMPs Perennial SMZs Perimeter of major drainage Along any open water (oxbow, sloughs) Restore any minor alterations in drainage to preharvest conditions Road construction should not affect hydrology Cross drainage Fill 11

12 Stream Crossing Impact Link upland sources of sediment to streams Sediment from crossing construction and use Sediment from poor construction and failure Barriers to fish passage Stream Crossing BMPs Minimize number of crossings Expensive and major source of sediment Layout and type Crossing location Approach design Choice of crossing Maintenance and removal 12

13 Crossing location Minimize length of road in floodplain Minimize slope into crossing Avoid locations with wide channels, multiple channels, or wide floodplains Cross perpendicular to stream flow Road Approach Design Straight road (50 ft) into the crossing A curve into the crossing Increases the disturbance in the flood plain Increases the crossing width (longer culverts, wider bridges) Angled/curved roads may lead to bank erosion following flooding Increases disturbance in the SMZ 13

14 Road Approach Design Road surface drainage Slope road surface Construct broadbased dips Surface road with rock and grass especially highly erodible steep slope Direct runoff into SMZ Not into ditch that dumps into stream Minimize slope into crossing Choice of Crossing Fords Natural and constructed Culverts Bridges Temporary and permanent 14

15 Fords Low bank height Hard bottom Constructed Hardbottom made with geotextile, rock, and geoweb Challenges Sediment from construction and use Least suitable for all season roads Avoid damming or adding fill to stream Ford Design 15

16 Culverts Proper installation techniques Culvert size Based on acreage and landform for 20? year event Accommodate high flow in approach Low spot in approach should be just above culvert top and away from the main channel Culverts Long term issues Removal Maintenance Sediment from construction and use less than ford Culvert failure is a major source of sediment 16

17 Streams: Culvert Sizing Recommended Culvert Diameter (Table II, Page 7) Drain area (ac) L. Coastal Plain U. Coastal Plain Piedmont Mountains x 48 Culvert Installation Length of culvert (ft) Width of road + Width of fill slope * Short culverts Buried by fill slopes 17

18 Culvert Length Road Surface 15 ft 18 fill 1:1 Fill slope 36 pipe =4.5 ft +1ft +1ft 4.5 ft 15 ft 4.5 ft =26 ft Multiple culverts 36 inch pipe with 18 inch fill 2*24 inch pipes pp with 12 inch fill 18

19 Culvert Failure Culvert too small Culvert too short Culvert installed poorly Incorrect slope of culvert Culvert poorly tamped in Outlet or inlet above channel Too little fill overtop Inlet unprotected Poor location Culvert Failure High water design/relief Culvert damage Crushed ends Debris dams Sedimentation of inlet and culvert 19

20 Bridges For truck roads Highly engineered Well designed approaches and sills For skid trails Standard bridge sections of metal or wood Relatively short span Least sediment since little l or no in-stream activity Most expensive for permanent crossings, low cost per use for temporary crossings Skidder Bridge with Slash Mat 20

21 Crossings with Fill Logs, slash, rock or soil crossings are undesirable Difficult to restore channel Federal BMPS If it restricts flow it violates 3 If it is on a perennial stream it violates 7 If it is not removed following activity it violates 15 Road Construction and Planning Minimize road grade Avoid SMZs other than crossings Avoid highly erodible soils Avoid dredge and fill in wetlands or in locations that may reach the waters of the state Avoid old roads, ditches and gullies that are highly eroded 21

22 Road Construction Design to likely traffic levels Log right-of-way before clearing and grubbing Don t bury stumps or logs Minimize cut and fill slopes Install road drainage and water diversion 22

23 Road Drainage Slope of road surface 2-4% to prevent water traveling down the road surface Crowned Outslope Inslope Turnout (wing) ditches moves water from road edge or ditch to undisturbed soil Distance between turnouts dependent on road slope Intervals Between Structures Distance between Distance between Broad-based % Slope water bars dips, turnouts TABLE 3, PAGE 12 23

24 Road Drainage Culverts move water from channels or ditches under road Avoid excess volume in the ditch ditch erosion Avoid water running over road Distance between culverts based on road slope Broad-based dips on inslope or outslope roads divert runoff into turn out or wing ditch Road Drainage: Broad-based Dips Effective way to divert water from permanent road that does not interfere with truck of skidder traffic Outslope of 3% Depth of 9-15 inches Fill with crushed rock 24

25 Broad Based Dips Road Maintenance Protect culvert or wing ditch outfall from erosion with rock or organic debris, especially on steep terrain Control traffic Ruts on road counteract slope (crown, inslope, outslope) channel water down the road, and wear down BBD s Establish vegetation on less travelled roads Rock surface main roads and steep slopes Mulch fill and cut slopes where vegetation won t be quickly established 25

26 Harvest Area Locate landings and trails outside of SMZs and drainage pattern Landings Uphill, gently sloping Skid trails avoid steep slopes have breaks in slope when steep slopes are necessary Felling Do not leave trees, tops, or slash in streams Maintain recommended tree cover in SMZs Retirement Harvest Area Retirement Trails and temporary roads Establish water bars at recommended distances Restore natural drainage Remove ruts especially on steep terrain, low areas Remove debris and fill from streams and channels Revegetation ti seed, fertilize, lime highly hl erodible areas Landings 26

27 Types of Water Bars Shallow Constructed prior to and during logging, temporary structure Deep Use of road or trail is finished, permanent structure Water Bar and BBD Failure Berm erodes Berm is fill material and gets waterlogged Too much runoff Not high enough Traffic over the berm (when wet) Depression fills with sediment Angle too shallow No outlet Slope Outlet erodes Angle too steep Road or roadside too steep Outlet in to ditch or stream 27

28 Intervals Between Structures Depends on Road Gradient Distance between Distance between Broad-based % Slope water bars dips, turnouts TABLE 3, PAGE 12 Harvest Area Retirement Trails and temporary roads Landings Address debris piles (knock down, redistribute, burn) Smooth, restore drainage Revegetate Trash disposal 28

29 Revegetation Follow recommendations in Erosion Control & Wildlife Planting for Forestry Operations Get local advice for best, low cost high success cover planting Georgia BMP Implementation

30 Georgia BMP Compliance % of problem crossings were skidder fords and debris type crossings Alabama Inspections 2007, 35 complaints, 5 (1 forestry related) turned over to ADEM (enforcement) Northern (05-06) Aerial survey of 635 harvest sites, 3 sites out of compliance Ground survey of 112 harvest sites (subset of 635), 3 sites out of compliance Southern (06-07) Aerial survey of 700 harvest sites, 2 sites out of compliance Ground survey of 147 harvest sites (subset of 700), 2 sites out of compliance 30