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

“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.”

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

PROJECT SCHEDULING LOW FLOW SEASONS??

PROJECT SCHEDULING LOW FLOW SEASONS!!

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

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

BYPASS CHANNEL WITH NON-EROSIVE LINING THE GOOD…

BYPASS CHANNEL WITH NON-EROSIVE LINING THE BAD…

…THE UGLY

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)

RIGID OR FLEXIBLE PIPE FLUME THROUGH A WORK AREA

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

TEMPORARY COFFERDAM AND PUMP BYPASS AROUND IN-CHANNEL WORK AREAS

TEMPORARY COFFERDAM AND PUMP BYPASS AROUND IN-CHANNEL WORK AREAS

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

IN-STREAM COFFERDAM DIVERSION

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

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

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

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

TYPICAL CAUSEWAY

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

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

Q&A / PROGRAM EVALUATION