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helpful for the plan designer
(including channel design, technical checklist information, vegetative stabilization and NOI tips)


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E&S Plan Designer Tips (in no particular order)
A compilation of "Tech Tips" published over the years in our Quarterly Newsletter "Northampton Notes"

PLEASE only submit one (1) copy of the E&S plan to us for initial E&S review. Only include E&S related calculations/drawings etc. for the E&S review. The District has no use for maps and calculations of footcandles, truck turnaround diagrams or HVAC schematics, etc.. We will request additional copies of E&S plans if needed for NPDES permit recommendation or issuance.

· Use the Rational Method, TR-55 or Standard Worksheet #18 to determine required discharge capacity of channels.

· Include "maximum during construction" drainage area maps for basins, traps and channels with your submittal.

· Maximum total drainage area for inlet protection is 1.0 acre (only 0.5 acre for silt sacks); 5.0 acres for sediment traps.

· Silt fence should be depicted as installed on existing level grade

· Rock filters should only be used to control sediment laden runoff within constructed channels. One filter placed at the end of the channel is appropriate.

· All sediment traps and basins should discharge to stable, erosion resistant watercourses or approved alternatives.

· The Construction Sequence should be site specific.

· There are usage limitations on many of the soils naturally occurring in Northampton County. Each plan should list those limitations and propose a resolution to overcome those limitations. The locations of all soil types should be provided in plan view on the drawings.

· The sediment basin discharge capacity data should be summarized on Standard Worksheet #17. Discharge capacities should be analyzed for orifice, weir and pipe flow to determine the most restrictive section of the discharge structures.

· Super silt fence materials can be used in lieu of plywood when specifying sediment basin baffles. The substitution can occur if the specified height of the baffle is correctly calculated and the baffle is constructed to the appropriate height.

· Special attention should be given to proposed entrances to sites that slope toward public roads or streams. The District has inspected many sites where stormwater has bypassed a sediment basin and discharged directly to a public road or stream via the construction entrance.

· Lawn establishment is generally considered earth disturbance and should be included in any limits of disturbance. Appropriate BMPs are required downslope of all earth disturbance.

· Northampton County Conservation District staff is available to meet with plan preparers to discuss proposed erosion and sediment control BMPs prior to plan submission.

· Complete, legible plans can make the review process easier and may save time:
· The E&S plan drawings should contain a complete mapping symbols legend including unique symbols for all existing/proposed utilities, temporary/permanent erosion and sediment control BMPs, existing/proposed contours and grades, limit of disturbance, NPDES boundary, etc. All symbols should be provided on the E&S plan drawing and agree between the legend and the plan.
· Existing and proposed improvements such as roads, buildings, utilities, etc. should be illustrated on the E&S plan drawings (i.e. sanitary sewer, storm sewer, water line, gas line, underground electric, etc.). Providing locations of these features assists the E&S technician in his/her site visit and plan review.
· For clarity, the District recommends removing zoning setback lines, lighting fixtures, parking spaces, landscaping features (such as trees, shrubs, flower beds, etc.) and any other symbols unrelated to the Erosion and Sediment Control Plan.

· Maximum during construction and offsite drainage areas to all proposed sediment basins, sediment traps, and channels should be clearly delineated and provided either on the Erosion and Sediment control plan drawing(s) or on separate plan drawing(s) titled Maximum During Construction Drainage Area Map.

· Proposed vegetated channels discharging into a sediment basin or trap should receive erosion control lining that extends at least 10 feet across the bottom of the sediment basin or trap to prevent accelerated erosion and sedimentation. If lining is not extended across the bottom of the basin, other outlet protection (such as rip rap aprons) should be provided.

· If a proposed outfall does not discharge at the bottom of a proposed sediment basin or trap, a downslope channel should be constructed and stabilized with erosion control lining to convey the flow to the bottom of the basin or trap. Supporting channel calculations and details should also be provided in the narrative and on the E&S plan drawings.

· Appropriate discharge areas from proposed outfalls and swales should be provided to avoid re-concentrating flow and accelerated erosion and sedimentation downstream. Discharges from outfalls and swales should be to existing or constructed stabilized swales, waters of the Commonwealth, or approved alternatives. The receiving waterway or approved alternative should be illustrated on the E&S plan drawing.

· To avoid re-concentrating flow downstream of a proposed level spreader, the maximum distance from the structural level spreader to an existing or constructed defined drainage way is 100 feet with a 5% maximum slope where a well-established vegetative cover exists within the receiving area.

· Riprap aprons should be installed on level grade in order to adequately function and prevent scour at pipe and channel outfalls. Riprap aprons should be illustrated at level grade on the E&S plan drawing.

· When converting a sediment basin into a stormwater detention basin, the sediment basin should be dewatered, cleaned out, re-graded (if required) and re-stabilized. The sediment basin's temporary outlet structure, principal spillway or skimmer should remain functioning until permanent stabilization is achieved within the detention basin. The conversion should be addressed in the construction sequence.

· Whether temporary or permanent, vegetated channels require separate calculations demonstrating sufficient capacity and adequate protection both in the un-vegetated and vegetated conditions. Supporting channel calculations should be provided in the E&S narrative (re: Standard Worksheet #21).

· Alternative BMPS should meet the New Products and Procedures Criteria on page 136 of the Pennsylvania D.E.P. Erosion and Sediment Control Program Manual (April 2000). When proposing an alternative BMP, all necessary supporting information should be included on the E&S plan drawing and in the narrative.

· The E&S control plan mapping must display a PA One Call System Incorporated symbol including the site identification number. (This is a numbered symbol not a note)

· Appropriate discharge areas from proposed outfalls and swales should be provided to avoid re-concentrating flow and accelerated erosion and sedimentation downstream. Discharges from outfalls and swales should be to existing or constructed stabilized swales, waters of the Commonwealth, or approved alternatives. The receiving waterway or approved alternative should be illustrated on the E&S plan drawing.

· To avoid re-concentrating flow downstream of a proposed level spreader, the maximum distance from the structural level spreader to an existing or constructed defined drainage way is 100 feet with a 5% maximum slope where a well-established vegetative cover exists within the receiving area.