AGENDA #8
MEMORANDUM
TO: Mayor and Town Council
FROM: W. Calvin Horton, Town Manager
SUBJECT: Report on Soil Erosion and Sedimentation Issues
DATE: November 22, 1999
This report discusses issues raised by the Town Council after the January 6, 1999 workshop on soil erosion and sedimentation. The Town Council is currently considering proposed amendments to the Chapel Hill Soil Erosion and Sedimentation Control Ordinance (the “Ordinance”) relating to enforcement and penalties for violations (follow-up report is scheduled for January 24th). The following information regards other concerns and questions noted by the Council, which are not directly related to Ordinance enforcement and penalties.
If, after review of this report, the Council wishes to further pursue the development of a Town ordinance to control land-disturbing activities on a watershed specific basis, we think that a Council work session on this matter would be useful.
In June 1998 the Lake Ellen Homeowners Association presented a petition to the Council which brought attention to the detrimental effects of soil erosion and sedimentation in Lake Ellen. Subsequently, the Council convened a panel of experts in fields relating to soil erosion and sedimentation. These experts made presentations to the Council at a work session held in January of 1999. Following the work session, the Council expressed interest in improving efforts by the Town to mitigate soil erosion and sedimentation problems that result from land disturbing activities.
In March of 1999, the Council received a report and adopted a resolution directing the Manager to revise and improve the Ordinance. The resolution directed the Manager to report back to the Council first on issues regarding enforcement and penalties for violations of soil erosion and sedimentation control regulations; and by the end of 1999 on other issues relating to soil erosion and sedimentation control. These other issues are the subject of this report. Attachment #1 is a copy of the March 22, 1999 agenda item #4j for reference.
The following issues are discussed in this report:
1. More rigorous and innovative structural controls to manage soil erosion and sedimentation.
2. Phased or staged construction within a given watershed to mitigate soil erosion and sedimentation.
3. Pertinent features of other local government soil erosion and sedimentation control ordinances (including the City of Olympia, Washington).
4. Improved soil erosion and sedimentation standards and lines of communication to all parties, including contractors.
5. The rights of the Town to require developers to restore damaged streams and ponds; and/or to sue developers for soil erosion and sedimentation damages and apply awards to mitigation of such damages.
6. Delineation of responsibility for soil erosion and sedimentation controls, and when such responsibility ends (Developer vs. Builder vs. Homeowner).
7. Applicable federal/State requirements of the NPDES – Phase II regulations.
8. Soil erosion and sedimentation management efforts in the Neuse River Basin and their applicability to the Chapel Hill Ordinance.
Having reviewed local and State soil erosion and sedimentation regulations in North Carolina and elsewhere, and having carefully evaluated available technology, we provide the following information on soil erosion and sedimentation issues of interest to the Town Council and others:
1.) More rigorous and innovative structural controls to manage soil erosion and sedimentation. Current techniques and equipment for managing soil erosion and controlling sedimentation include the following:
Stabilization - Placement of temporary and/or permanent ground cover such as grass, mulch, matting, rock, etc. to hold soil in place and minimize erosion.
Construction Exit - A gravel drive-over area (often with wash facilities) to remove mud from construction vehicles before it is tracked onto streets.
Stream Crossing - A temporary travel way across a watercourse to minimize disturbance of the channel and resultant erosion caused by construction traffic.
Slope Drains - Pipes and/or ditches which intercept and convey water over cut and fill slopes or other steep topography to prevent erosion.
Diversions - Berms and/or ditches which divert water away from critical areas and into sediment control devices.
Channelization - Improved drainageways designed to convey water without damage to the channel or erosion of the surrounding soil.
Outlet Protection - Energy-dissipation devices, such as stone aprons, stilling basins, or impact structures, at the lower end of pipes or channels, to reduce discharge velocity and mitigate erosion.
Straw Bales - Bales of straw anchored across the flow of water to filter out sediment.
Filter Strip - areas of vegetation through which water sheet flows to filter out sediment.
Brush Barrier - Piles of brush placed across the flow of water to reduce velocity and allow sediment particles to settle out.
Silt Barrier - Wood stakes with filter cloth stretched between and placed across the flow of water to filter out sediment.
Silt Fence - Steel posts connected by wire reinforced filter cloth and located across the flow of water to reduce velocity and filter out sediment.
Stone Filters - Piles of various size rocks placed across the flow of water to reduce velocity and filter out sediment.
Sediment Trap - Constructed or natural depression in the ground with silt fencing, stone filters, or a combination of both placed in a baffle arrangement to create indirect flow routing and to reduce velocity, thereby both filtering and settling out sediment.
Sediment Basin - Constructed or natural impoundment where sediment laden water is held temporarily to allow sediment to settle out.
These techniques are commonly used throughout the State and region. Chapel Hill and most of Orange County include soils that erode into extremely small particles, which are difficult to filter or settle out of water once they are suspended. This often results in turbid water even after passing through sediment control devices described above.
The most common device for capturing suspended soil particles is a sediment basin. These basins are designed to hold runoff until the sediment settles out before the water passes downstream. This process works well on the larger, more granular sediments, but the colloidal size clay particles may remain suspended in the basin discharge water and pass on downstream as a muddy or turbid looking discharge.
We have not identified any new technologies for controlling soil erosion. We think the most effective way to reduce erosion (and resulting sedimentation) is to limit the amount of disturbed area to the extent possible and to require rigorous and prompt application of existing erosion control measures when land is disturbed. These ideas are discussed further in following sections of this report.
With regard to sedimentation control, we have investigated alternative control measures and we have been working with Dr. Richard McLaughlin, Associate Professor of Soil Science, North Carolina State University, Cooperative Extension Service, to test and evaluate several innovative devices and techniques for controlling sedimentation, as follows:
SKIMMER - The skimmer is a device that floats on the water surface of a sediment basin. As sediment settles to the bottom of the basin the water near the surface is the cleanest. The skimmer takes the cleanest water in from the top of the basin and discharges it downstream. Attachments #2 and #3 are diagrams involving the skimmer. We are encouraged with the performance of skimmers. Although they do not prevent all sediment from leaving basins, they do reduce the amount of sediment in the discharged water.
LEVEL SPREADER - The level spreader is a device which causes the sediment laden water to sheet flow through an area of vegetation at relatively shallow depths. The vegetation filters and settles out much of the residual sedimentation. Attachment #4 shows a diagram of a level spreader. The level spreader has proven to be effective provided it can be sited to provide discharges to large flat areas. Sites located on hilly or rolling terrain may not be appropriate for level spreader technology.
FLOCCULANTS - sediment basins are often ineffective at reducing water turbidity caused by suspended particles of clay and silt. Flocculants are agents which attract individual sediment particles creating clusters which more readily will settle out of the water. Gypsum is commonly used as a flocculent to reduce the turbidity of water. Gypsum is considered to be relatively benign and does not seem to adversely affect the health of the receiving waters.
The use of flocculants has worked well under laboratory conditions, where all elements of the test were controlled. However, under actual field conditions the amount of flocculent needed and the proper time of application vary from site to site and storm to storm. The use of flocculants seems promising, but more work is needed to develop practical application procedures. We will continue to work with Dr. McLaughlin and others on this. Attachments #5 and #6 are technical papers that discuss the flocculation process.
FILTERS - products are now being developed which filter sediments out of water. One such device, called the “Dirt Bag”, is being used on our Willow Drive Bridge Replacement Project. This technology involves slowly pumping water into a large filter bag which captures all but the very finest clay particles. The filtration process can be effective, but it has not yet been developed to handle large development projects with significant runoff water discharges.
The State of North Carolina has not established specific, measurable requirements for sediment removal rates. The only performance criteria for sediment basins are that they be designed to handle a 10 year/24 hour storm event. These basins and associated sediment trapping devices must be constructed, at a minimum, to handle the amount of water expected from this storm, and to hold this water, allowing the sediment particles to settle out as much as possible before being released downstream.
We considered the idea of establishing and enforcing specific performance requirements for sediment removal. However, we think that this would be impractical for the following reasons:
Monitoring - It would be necessary to continuously monitor all water entering and exiting each site to determine if removal rates were being met at all times.
Origin of Sediment - It would be very difficult to identify the actual origin of all sediment that may constitute a violation. If a violation occurred, we would need to somehow prove where the violating sediment originated, onsite or offsite or both.
Staffing - Additional Town and/or County staff would be necessary to continuously monitor each construction site for compliance.
Available Technology - We are not aware of any practical new technology or techniques that could significantly improve our ability to remove the clay sediments in runoff water from land disturbing activity. The most effective way to reduce sedimentation is to reduce erosion. Until sediment removal technology improves, we think our efforts should focus on limiting land disturbance and reducing erosion which creates sedimentation problems.
2.) Phased or staged construction within a given watershed to mitigate soil erosion and sedimentation. As part of its 1999 legislative agenda, the Town Council requested special enabling legislation to “regulate the timing and number of private development projects which may be permitted and under construction concurrently within a designated watershed in order to achieve the purpose of this Article” (the Erosion and Sedimentation Control Act). The enabling legislation, as modified by the General Assembly, authorizes the Town to enact an ordinance to “require enhanced and increased sedimentation protection by reason of the concurrent construction of two or more projects in the same watershed.”
The wording of the adopted legislation is general, and does not provide authorization for the Town to regulate the timing and number of development projects which can occur concurrently within a given watershed. As we stated in previous information about this particular issue, it is the Town Attorney’s opinion that the Town cannot legally restrict the pace and number of development projects within a watershed without specific enabling legislation from the State.
Current legislation allows the Town to enact a local ordinance, which would require enhanced and increased sedimentation protection for concurrent development within the same watershed. We believe that Chapel Hill does require enhanced and increased sedimentation protection from new development projects. These enhancements include increased detention capacity (25 year storm), and use of new technology such as skimmers, level spreaders, flocculants, and filters.
If the Council wishes to formalize Town requirements by adopting an ordinance, we think that a Council work session would be helpful to discuss how we might best craft such an ordinance that would be practical and enforceable and could reasonably achieve the Council’s objectives.
Some of our questions regarding such an ordinance include:
How would a “watershed” be defined?
Would a watershed have a minimum size?
Would slope and/or location and/or soil type and/or vegetation type factor into defining a watershed?
Would restrictions apply to all development, or would preferred types of development receive special consideration?
Could concurrent development occur within a watershed provided certain soil erosion and sedimentation measures were implemented?
Would development permits in given watersheds be strictly “first come, first served”?
A watershed specific development ordinance such as this could have implications similar to those of the Resource Conservations District Ordinance, and it would need to be as carefully crafted. In addition to the legal implications, we believe that enforcement of such an ordinance would likely require additional staff and equipment.
3.) Pertinent features of other local governments soil erosion and sedimentation control ordinances (including the City of Olympia, Washington). All North Carolina local soil erosion and sedimentation control programs are authorized by the State through the Sedimentation Pollution Control Act of 1973 (the “Act”). Therefore, all North Carolina local programs are consistent with the requirements of the Act. We are not aware of any North Carolina local program that does more to control and manage soil erosion and sedimentation than is currently being done here in Orange County and Chapel Hill. Other local programs throughout the State routinely consult with our staff to discuss procedures and our work with skimmer devices, level spreaders, flocculation, and the Resource Conservation District.
We contacted Mr. Emmett Dobey, Policy & Program Development Manager with the City of Olympia, Washington about their soil erosion and sedimentation control regulations. Generally, in Olympia, all stormwater discharge is required to be retained onsite and no sediment is allowed to leave a construction area. Olympia is able to successfully implement these unusual regulations primarily because of the type of soils found in their region of the country.
Soils in the Olympia area are granular and very porous. The soil particles that do become suspended in water are much larger than the fine clay particles we experience in our region of the country. The granular sediments settle out quickly, and the rocky/sandy soil allows water in detention basins to percolate into the earth. In Chapel Hill, our clay sediments settle out very slowly, our soils are typically not permeable, and surface water will not seep into the ground quickly or in large volumes. We do not think that the regulations and procedures used in Olympia would be applicable here in Orange County.
4.) Improve soil erosion and sedimentation standards and lines of communication to all parties, including contractors. Chapel Hill and Orange County work with the Cooperative Extension Service, the private engineering sector, area universities contractors and others to develop and test innovative techniques for controlling soil erosion and sedimentation. As new techniques are proven to be effective, we incorporate them into our standards and utilize them routinely.
Currently, Orange County staff administers the Chapel Hill Soil Erosion and Sedimentation Control Ordinance. Orange County staff provides inspection services and directions to contractors and/or developers on erosion and sedimentation control issues. Town engineering and building inspectors provide assistance by notifying the County when they observe soil erosion and/or sedimentation problems on construction projects.
It is important for all communication to the contractor to come from one source (in this case Orange County staff). This reduces conflicting directions or duplicating efforts to resolve issues. However, we also think that it is important to have a formal process for communicating Town concerns directly to the County for information and action. Therefore, we have developed a work order system whereby Town staff can fill out a service request (copy attached), and forward it by both e-mail and regular mail to the County asking for assistance on specific soil erosion and sedimentation issues. Once County staff has resolved an issue, they notify the Town (using the same form) as to what corrective actions were taken and the current status of the problem.
We agree that good communication is critical, and we will continue to maintain open and effective lines of communication with citizens, developers, engineers, contractors, the University, utility companies, governmental officials, and others as appropriate.
5.) The rights of the Town to require developers to restore damaged streams and ponds; and/or to sue developers for soil erosion and sedimentation damages and apply awards to mitigation of such damages. The Town’s Soil Erosion and Sedimentation Control Ordinance (the Ordinance) is enacted under authority provided by the North Carolina Sedimentation Pollution Control Act of 1973 (the Act). Three types of remedies are authorized by the Act: injunctive relief, penalties (both civil and criminal), and damages. The remedies are discussed below:
Injunctive Relief - The Act authorizes the Town to require remedial work where there is reasonable cause to believe that a person is violating or threatening to violate the Ordinance. Civil lawsuits may be enacted in the name of the local government to require such corrective action, and the court is authorized to enter “any order or judgment that is necessary to abate the violation, to ensure that restoration is performed, or to prevent the threatened violation.”
Penalties - Both civil and criminal penalties are authorized under the Act and the Ordinance. Criminal Penalties require a higher standard of proof and demonstration that a person “knowingly or willfully” violated a provision of the Act or Ordinance. Fines collected as criminal penalties would be processed and distributed in the same manner as other monetary penalties collected through the court system for other violations and would not be available to the Town for remedial work.
Civil Penalties do not require proof of a knowing or willful violation. According to N.C.G.S. Sec. 113A-64(a)(5), civil penalties collected by local government for violation of the Ordinance “shall be credited to the general fund of the local government as non-tax revenue.” Thus, these funds could be available to the Town for damage mitigation. There is a recent court decision, however, which suggests that if there were any type of appeal prior to imposition of the civil penalty, such civil penalties could not be retained by the Town, despite the statutory provision.
Damages - Damages (in this sense) involve monetary compensation to persons injured by others. Under the Act, “any person injured” by a violation of a local ordinance can collect damages for injury caused by the violation. If the amount of actual damages determined by the court or jury is $5,000 or less, costs, (including attorney and witness fees) shall also be awarded. An injured party recovering damages may elect to use the money awarded to take corrective action to remedy the injury. If the Town were determined to be an injured party, it could collect damages and apply them to mitigation of the injury.
Remedies under other Environmental Laws - At its January 6, 1999 work session on soil erosion and sedimentation issues, the Council heard from a number of persons with expertise in the area of environmental regulations. One of the speakers, Mr. Rick Dove of the Neuse River Foundation, made reference to provisions of Federal law under which private citizens can be empowered to seek remedial action by contractors and developers if the State does not take action. To the extent that potential violation of soil erosion and sedimentation regulations may also constitute violations of federal law, including the Federal Clean Water Act, under some specific set of facts these procedural remedies may also be available.
Based on our understanding of the law, the Town does not have the authority to order developers to restore streams and ponds on the property of others which are damaged as a result of their developments. The Town could, however, sue developers for damages to Town property resulting from soil erosion and sedimentation caused by their developments. A monetary award received by the Town could be applied to mitigation and restoration of damaged streams and ponds.
6.) Delineation of responsibilities for soil erosion and sedimentation controls, and when such responsibilities ends (Developer vs. Builder vs. Homeowner). Town staff and developers have periodically raised questions about when a developer’s responsibilities end for soil erosion and sedimentation controls on a construction project. Typically, a land developer will subdivide a parcel of land into building lots, and construct the streets and other public infrastructure necessary to support whatever is being built. The associated land disturbance is usually greater than ½ acre and requires an erosion control plan. The developer is responsible for installation and maintenance of the erosion control devices in accordance with the plan.
Once the infrastructure construction is complete, a developer typically sells the project to builders or investors and no longer has a direct connection to the development. Subsequent construction may or may not require an erosion control plan. For example, a contractor building a house on a single lot would probably not disturb more than ½ acre and, therefore, would not be required to provide an erosion control plan or install soil erosion and sedimentation control devices.
The result, in some cases, is that many individual contractors may be working on small pieces (i.e. lots) of a development, the total of which is creating a significant amount of land disturbance. However, the original land developer is no longer involved with the project and the individual contractors may not be required to provide soil erosion and sedimentation protection. In this situation, no one is accountable for the installation and maintenance of erosion and sedimentation control facilities.
As part of our earlier report to the Council on enforcement and penalty issues, we proposed an amendment to the Ordinance (Section 5-97.1 Bonds) which would require a performance bond or other financial guarantee to cover “the restoration of failed or failing soil erosion and sedimentation control measures and/or of areas affected by the failure.” This financial guarantee would clearly define responsibilities for the operation and maintenance of the control measures and the term of the guarantee.
The developer would have the option of passing the cost of the guarantee on to the lot buyers; or, if they so agreed, the lot buyers could assume the responsibility of the control devices by posting a new guarantee, satisfactory in form and format to the Town Manager, to replace the developers’ guarantee. We think that this procedure would assure continuity of soil erosion and sedimentation controls for the duration of land disturbing activity by placing the financial responsibility on developers and/or builders.
7.) Applicable Federal/State requirements of the National Pollutant Discharge Elimination System (NPDES) -Phase II regulations. On October 29, 1999 the EPA signed the final NPDES-Phase II regulations. The six control measures required by local programs are:
* Public Education and Outreach
* Public Participation/Involvement
* Illicit Discharge Detection and Elimination
* Pollution Prevention/Good Housekeeping
* Construction Site Runoff Control
* Post-Construction Runoff Control
NPDES-Phase II permits will be required within three years from the date the regulations are published in the Federal Register (expected in November 1999).
The specific requirements for stormwater controls on Phase II construction activity would be defined by the NPDES permitting authority on a state by state basis. In North Carolina it is anticipated that the Department of Environment, Health, and Natural Resources will be the permitting authority. We expect the following requirements to be implemented by the State:
Construction sites less than 5 acres but greater than ½ acre will be required to have a NPDES permit. These permits will include three main requirements:
1.) Submission of a Notice of Intent (NOI) that includes general operator and site information, and a certification that the activity will not impact endangered or threatened species.)
2.) The development and implementation of a Stormwater Pollution Prevention Plan with appropriate BMP’s to minimize the discharge of pollutants from the site.
3.) Submission of a Notice Of Termination (NOT) when final stabilization of the site has been achieved as defined in the permit.
Municipalities will be required to include the following elements in their erosion control programs:
1.) An Ordinance requiring the implementation of proper erosion and sediment controls.
2.) Procedures for pre-construction review of construction site plans.
3.) Procedures for regular inspection during construction.
4.) Defined penalties for non-compliance.
5.) Procedure for the receipt and consideration of information submitted by the public.
6.) Identification of appropriate best management practices (BMPs) and measurable goals.
We believe that our existing regulations and programs already provide for many of the NPDES-Phase II requirements. The Town has an active water quality testing program, and is currently mapping the community drainage infrastructure to help identify and locate illicit discharges. We require the use of BMPs and bioretention facilities whenever possible. We will be working with the State to review specific elements of our program to assure full compliance, and will advise the Council of any program changes and/or additions which may be necessary for the NPDES-Phase II permit application.
8.) Soil erosion and sedimentation management efforts in the Neuse River Basin and their applicability to the Chapel Hill ordinance. The most applicable element of the Neuse River Basin regulations is the requirement for fifty foot wide vegetative buffers along streams to mitigate soil erosion and to filter out sediment. [We note that almost all of Chapel Hill is the Cape Fear Ruin Basin.]
Our Resource Conservation District Ordinance (RCD) ordinance restricts land disturbing activities near perennial streams and requires a minimum buffer width of 75 feet. We think that our local regulations in this regard meet or exceed similar regulations in the Neuse River Basin.
The Neuse River is monitored regularly to identify sources of soil erosion and sedimentation which impact it. We also monitor our local streams on a regular basis, and identify projects or locations where significant soil erosion and sedimentation is adversely affecting our waterways and ponds. We then try to correct the situation to the extent possible.
Chapel Hill and Orange County provide State-wide leadership in our efforts to manage and control soil erosion and sedimentation.
We understand that the Council wants us to do more, and we will continue to identify, evaluate, and incorporate where appropriate new and innovative technology that would be feasible for use in our area of the country.
We previously proposed several changes in our regulations which we think would allow more rigorous control over land disturbing activities and resultant soil erosion and sedimentation.
We will maintain open and effective lines of communication regarding the Town’s regulations and expectations for the control of soil erosion and sedimentation.
We seek additional Council guidance on preparing an ordinance to institute development controls on a watershed-specific basis as provided in State enabling legislation granted last session.
1. Agenda item #4j, March 22, 1999 (begin new page 1)
2. Skimmer Diagram (p. 35)
3. Skimmer Diagram (p. 36)
4. Level Spreader Diagram (p. 37)
5. Flocculation Technical Article (p. 38)
6. Flocculation Technical Article (p. 43)
TO: Mayor and Town Council
FROM: W. Calvin Horton, Town Manager
SUBJECT: Materials Related to Soil Erosion and Sedimentation Issues
DATE: January 10, 2000
Council Member Bateman requested that the attached materials be provided to the Council.