State-Technical-Bulletins

“He who fails to plan, plans to fail….” is an oft-quoted proverb. Its original author is unknown, but it is frequently attributed to such famous individuals as Benjamin Franklin, Abraham Lincoln and Winston Churchill. Regardless of who coined the phrase, failure to plan (properly) is never more evident than in a poorly thought out erosion and sediment control plan. Once a slope has eroded, or an infiltration basin has failed, it is too late to ‘plan’. It is only time to react and correct. And usually, it costs more to do something twice, than to do it right the first time.

Though not an exhaustive list, the following represent many of the primary design considerations and constraints in preparing an effective erosion control plan. Effective erosion control should be integrated into planning for stormwater management, and not done as an after-thought. A properly developed plan should address the following aspects of site construction when designing for erosion control:

General Considerations-

1.Design report included and submitted to the district

2.Table of Contents for the design report denoting location of erosion control designs

3.Plan drawn at proper scale (usually not less than 1:50)

4.Erosion Control Plan sheets labeled, signed and sealed by a NJ Licensed Engineer or Architect

5.Pre and post construction contours clearly labeled and depicted

6.Limits of disturbance clearly delineated and corresponding to area of disturbance on the application form

7.Temporary controls such as sediment barriers, inlet filters graphically depicted on plan sheets

8.Details for erosion control applications clearly shown on a ‘detail sheet’; dimensions correspond to deign report

9.District notes, vegetative stabilization specifications and other notes shown on the detail page

10.Soil delineations shown on the erosion control plan sheets

11.Other natural features, such as streams, wetlands and buffers delineated on plan sheets

12.Permanent structures graphically depicted on plan sheets (piping, basins, rip rap outlets, swales, basins etc)

13.Offsite improvements (sewer, water, storm drainage, electrical utilities) shown and included in area calculations

14.Proposed staging and stockpile areas depicted (on and off site).

Construction Disturbance Considerations-

1.Phasing of disturbed areas (minimizing open soil areas)

2.Sequence of construction specific to the site (avoid generic sequencing)

3.Stormwater management on a construction site

a.Temporary sediment basins with design support and appropriate details

b.Diversions & swales

c.Grading

d.Filtering via pumped discharge

e.Dewatering excavations and points of discharge

4.Temporary stabilization with vegetation, mulch, man-made materials etc.

5.Location of temporary controls such as inlet filters, sediment barriers, construction entrances

6.Soil movement – cuts, fills, removal, stockpiles and importation shown on plans

7.Minimization of soil compaction – restrict vehicle travel, avoid working wet soils, restore if needed

Hydrologic Design Considerations-

1.Correct application of hydrologic analysis both onsite and within the local drainage area

a.Correct unit hydrograph (i.e., Delmarva for coastal plain areas)

b.Pre and post drainage area maps with Tc flow paths and POI’s identified

c.Realistic sheet flow length in time of concentration (in all cases, not to exceed 100’)

d.Correct pre and post development runoff coefficients

e.Influence of geology (esp. limestone prone areas)

f.Submission of electronic modeling files to the district

g.Submission of Hydrologic Summary forms for each basin

2.Assessment of pre and post development flows for the 2, 10 and 25 (rip rap) year storm events

3.Determination of soil types and their associated limitations (i.e., depth to ground water, slope stability) using theWeb Soil Survey (http://websoilsurvey.nrcs.usda.gov/app/HomePage.htm)

4.Final points of discharge from the site and stability at those locations

5.Discharging to agricultural fields (generally not permitted due to stability concerns)

6.Infiltration and failure analysis for stability

7.Impact of discharge beyond the limits of the project (off site stability)

8.Stability of slopes – both from overland flow as well as impacts due to infiltration saturation

9.Proper use of permanent vegetative cover – species selection, irrigation, soil quality, maintenance

10.Use of turf reinforcement matting on steep slopes or channel lining

11.Rock rip rap sizing, gradation and availability; alternate use of gabions or reinforced concrete

12.Grass water way designs using vegetative retardance (D & E) factors, soil conditions, velocity, proper vegetationand reinforcement mating

Requirements of Other Agencies-

1.NJ Department of Environmental Protection-

a. Stormwater Rules

b.Wetlands

c.Highlands

d.Stream Encroachment

2.Residential Site Improvement Standards

3.NJ Department of Transportation

4.NJ Pinelands Commission

5.County and municipal construction codes