Hickory Hills Lake Management Committee

1. Hickory Hills Lake Management Committee Erosion Control sub committee Tom Bertram Jane Blake

2. Objectives • Research options • Area’s of need, TBD • Permitting, TBD • Discussion

3. Traditional Erosion Control Techniques

4. Rip Rap • Use of rock riprap is the most common type of erosion control project.  It involves the placement of filter cloth on the shoreline, over which rock of varying in diameter is placed.  This combination of fabric and large rock provides excellent protection against the eroding wave action.  Sometimes the shoreline must be recontoured prior to placement of any protection to insure that the slope is satisfactory to retain the material. • Advantages Provides some structure for smaller fish/crayfish species. May prevent further erosion of site, if correctly installed. May provide immediate erosion control – reduced wave action. • Disadvantages Riprap protects only the land immediately behind the barrier, and not the adjacent areas. In fact, erosion may increase by wave reflection from the structure. Riprap does not reduce water temperature, or filter soil from the land above the lake. Riprap must be done correctly to have desired effect, the initial cost is high, and it does require maintenance as rock settle and fall into the lake. Riprap does not maintain natural look of the lake. Lakes with a riprap shore are less likely to have ducks or geese – waterfowl like to be able to walk out of water. • Costs Riprap stone material costs approximately $30 to $50 per cubic yard, with an additional $10 to $15 per cubic yard in labor costs for a contractor to spread the material with a small excavator. For a modest riprap installation that provides a 2-foot thick layer of stone over a 7-foot wide shoreline zone, the resultant costs are approximately $20 to $35 per linear foot of shoreline. Source http://www.bbmwd.org/erosion_control.htm

5. Vegetative Control • Vegetative erosion control is the use of native plants and trees to stabilize the soil near the shore. Cattails and reeds can be used in the water to lessen the effects of wave action. These plants are very hardy and can withstand changes in lake water levels. On shore, landowners can use shrubs, willows, to shade the lot and reduce erosion. • Advantages • Trees shade the lake. This can lower water temperatures. Increased spawning ground for fish. Cuts down on mowing, and therefore less maintenance. Soil and fertilizers are filtered through buffer strip, so less ends up in the lake. Ducks favor this type of habitat – less food source for geese. • Disadvantages • Increases chance encounter with water snakes, ticks. Does not provide “neat” shoreline view with park-like grass • Source http://www.lmvp.org/Waterline/spring2003/erosion.htm

6. Combination Control Technique • Combination of shoreline erosion control uses both of the previous methods. Riprap is first installed on the site, with soil added to the areas away from the water's edge. Tree plantings are then scattered within the rock riprap. • Advantages Immediate erosion control, with future benefits of vegetation • Disadvantages Most expensive, since you have to do both riprap and plantings. Choose plants, such as willows, that are able to withstand fluctuations in water level. Combination does require some maintenance to keep trees and rock in place. Usually only one tree species is planted on the site. • Source http://www.lmvp.org/Waterline/spring2003/erosion.htm

7. Sea Wall • The most lasting form of erosion protection is a seawall.  Various materials can be used, but it is critical that any wall be constructed properly to prevent erosion under or around the structure. • Advantages Many choices of material and construction techniques. • Disadvantages Costly and difficult to permit for new applications. • Source http://www.bbmwd.org/erosion_control.htm

8. Traditional Erosion Control • Hay Bail Silt Fence • Advantages Proven Technology • Disadvantages Often ineffective costly to install and remove

9. Non – Traditional Erosion Control • Silt Sack are a tubular mesh product, filled with a custom woodchip compost blend.  They form a portable, easily installed, highly effective alternative to traditional erosion control methods in virtually every application.  By utilizing the technology of our pneumatic blower trucks, we are able to apply product in hard to reach areas, while causing very little disturbance to sensitive environments. • Advantages Silt Sacks provide superior physical, chemical and biological filtration, by trapping sediment and silt at the point of contact.  Because they are heavier than traditional methods, they require little staking and no trenching for a successful install.  Unlike hay bales, Silt Sacks maintain a constant ground contact, leaving no areas for unfiltered material to flow thru.  A unique feature of Silt Sacks is that they do not necessarily need to be removed at project’s end. • Disadvantages Costly and requires heavy equipment • Cost $2.75 to 3.25 per linear foot

10. Other Erosion Control • Clay Soil Shelf • Underwater Stone Berm • Submerged Sheet Pilings • Exposed Sheet Pilings • Inter-planted Boulders • Coir Roll • Source  http://cbgscience.org/shoreline/shoreline_erosion_control/shoreline_erosion_control.htm

11. Next Steps • Define Areas of Need • Research Permitting Process

12. Discussion