1. EFFECTIVE EROSION AND SEDIMENTATION CONTROLS FOR IN-CHANNEL PROJECTS
Written By:
RICHARD L. SNYDER, CPESC
RESOURCE CONSERVATIONIST
DAUPHIN COUNTY CONSERVATION DISTRICT

2. “Financial and Other Support for this Project is Provided by the Pennsylvania Association of Conservation Districts, Inc. Through a Grant from the Pennsylvania Department of Environmental Protection Under Section 319 of the Clean Water Act, Administered by the U.S. Environmental Protection Agency.”

3. CONSIDERATIONS APPROPRIATE CHAPTER 105 PERMIT(S) PROJECT SCHEDULING
Obtained from DEP (or Delegated CCD)
Designs shall Adhere to Permit Conditions
PROJECT SCHEDULING
Low Flow Seasons
BASE FLOW DIVERSION
Minor Stream Channels (Normal Flow Width < 10’)
Major Stream Channels (Normal Flow Width > 10’)
PROJECT STABILIZATION
EQUIPMENT STAGING
Top of Bank
Temporary Crossing / Causeway
MATERIAL STAGING / STOCKPILING
Outside Channel Floodway
PUMPED WATER
Filtered Prior to Discharge into Surface Waters

4. PROJECT SCHEDULING
LOW FLOW SEASONS??

5. PROJECT SCHEDULING
LOW FLOW SEASONS!!

6. BASE FLOW DIVERSION BYPASS CHANNEL WITH NON-EROSIVE LINING
Figure 3.9
RIGID OR FLEXIBLE PIPE FLUME THROUGH A WORK AREA
Figure 3.10
TEMPORARY COFFERDAM AND PUMP BYPASS AROUND IN-CHANNEL WORK AREAS
Figure 3.11
IN-STREAM COFFERDAM DIVERSION
Figure 3.12

7. BYPASS CHANNEL WITH NON-EROSIVE LINING
FIGURE 3.9, PAGE 44
TEMPORARY BYPASS CHANNEL SHALL BE LINED WITH A GEOTEXTILE PROTECTIVE LINING (MINIMUM)
< 3 DAYS, NORMAL BASE FLOWS
> 3 DAYS, BANK-FULL FLOW
CONSTRUCTED DOWNSTREAM UPWARD

8. BYPASS CHANNEL WITH NON-EROSIVE LINING
THE GOOD…

9. BYPASS CHANNEL WITH NON-EROSIVE LINING
THE BAD…

10. …THE UGLY

11. RIGID OR FLEXIBLE PIPE FLUME THROUGH A WORK AREA
FIGURE 3.10, PAGE 45
SIZING: NORMAL FLOW DEPTH IN PIPE (d) < OR = ½ DIAMETER OF PIPE (D)

12. RIGID OR FLEXIBLE PIPE FLUME THROUGH A WORK AREA

13. TEMPORARY COFFERDAM AND PUMP BYPASS AROUND IN-CHANNEL WORK AREAS
FIGURE 3.11, PAGE 46
< 2 WEEK DURATION
PUMP INTAKE
Coffedam Constructed to Impound Water
NO Excavation for a Sump Area Within the Stream Channel

14. TEMPORARY COFFERDAM AND PUMP BYPASS AROUND IN-CHANNEL WORK AREAS

15. TEMPORARY COFFERDAM AND PUMP BYPASS AROUND IN-CHANNEL WORK AREAS

16. IN-STREAM COFFERDAM DIVERSION
FIGURE 3.12, PAGE 47
VARIOUS TYPES
Sandbag Diversion Dam / Cofferdam
Jersey Barrier Cofferdam
CONFORM TO MANUFACTURER’S SPECIFICATIONS

17. IN-STREAM COFFERDAM DIVERSION

18. PROJECT STABILIZATION
ALL DISTURBED AREA(S) WITHIN CHANNEL SHALL BE STABILIZED PRIOR TO BASE FLOW BEING RETURNED TO CHANNEL

19. EQUIPMENT STAGING
WHEREVER POSSIBLE, EXCAVATIONS SHALL BE DONE FROM TOP OF BANK…
EXCEPTION: If Mature Trees Need to be Removed to Access Channel

20. EQUIPMENT STAGING …NOT FROM WITHIN CHANNEL
NOT POSSIBLE, TEMPORARY CROSSING / CAUSEWAY MAY BE USED

21. TYPICAL CAUSEWAY FIGURE 3.8, PAGE 43 PROJECT COMPLETION Removed
All Channel Entrances Restored to Pre-Construction Configurations
Stabilized

22. TYPICAL CAUSEWAY

23. MATERIAL STAGING / STOCKPILING
ALL EXCAVATED CHANNEL MATERIALS STOCKPILED OUTDE CHANNEL FLOODWAY
APPROPRIATE SEDIMENT BARRIER SHALL BE INSTALLED / CONSTRUCTED BETWEEN STOCKPILE AND STREAM CHANNEL

24. PUMPED WATER SHALL BE FILTERED PRIOR TO DISHARGE INTO SURFACE WATERS
Pumped Water Filter Bag
Sump Pit
Other Sediment Trapping Best Management Practice (BMP)

25. Q&A / PROGRAM EVALUATION