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STREAMBANK STABILIZATION GUIDELINES FOR PRACTICE SELECTION
YES ROCK RIFFLE GRADE CONTROL
NO
------------------- YES STOP ---TREAT SEEPS AND/OR SPRINGS
NO
YES STONE TOE PROTECTION
NO
YES BENDWAY WEIRS OR STREAM BARBS
NO
YES BENDWAY WEIRS & STONE TOE PROTECTION OR STREAM BARBS
NO
--- CALL FOR ASSISTANCE
AVERAGE SURVEYED GRADIENT > VALLEY SLOPE FROM TOPOG ORBED IN RIFFLE LOCATION IS SILT OR CLAY ORWIDTH/DEPTH RATIO < 10 & ENTRENCHMENT RATIO <1.4
SEEPS OR SPRINGS PRESENT AT PROJECT SITE
BANKFULL WIDTH @ SITE < 130% WIDTH AT RIFFLE
UNVEGETATED POINT BAR < 30% WIDTH AT RIFFLE
RADIUS/WIDTH RATIO > 1.8
RADIUS/WIDTH RATIO > 4.0
UNVEGETATED POINT BAR < 50% BANKFUL DEPTH
UNVEGETATED POINT BAR MATERIAL < 1 INCH DIA.
RADIUS/WIDTH RATIO < 4
UNVEGETATED POINT BAR < 50% BANKFULL DEPTH
UNVEGETATED POINT BAR MATERIAL < 1 INCH DIA.
STREAM BARBS ORTRADITIONAL BANK TREATMENT
IS STP THE RIGHT SOLUTION?
• IS THE CHANNEL BED STABLE?
• IS THE BANKFULL WIDTH IN BEND LESS THAT 130% OF BANKFULL WIDTH AT RIFFLE
• IS UNVEGETATED POINT BAR LESS THAN 30% OF BANKFULL WIDTH AT RIFFLE
IS STP THE RIGHT SOLUTION?
• IS THE CEM STAGE IV OR V?
• IS THE RADIUS OF CURVATURE/BANKFULL WIDTH RATIO GREATER THAN 1.8?
CONSIDER GRADE CONTROL!!
A REALLY GOOD INSURANCE IS TO ADD A SMALL ROCK
RIFFLE GRADE CONTROL TO YOUR STP PROJECT!!
IF RADIUS IS TOO SMALL
FOR RADIUS/Wbkf IS LESS THAN 1.8--CONSIDER USING
“TRADITIONAL BANK PROTECTION”!!
Scour Depth
• Assume Scour Depth will equal Max. Bankfull Flow Depth
• Assumes bed material allows full Sine Wave Flow to develop over time
West Branch Hurrican Creek
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0 500 1000 1500 2000 2500
Distance (ft)
Ele
v. (
ft)
Series1Gradeline --slope =0.0024ft/ft
0
Bankfull Hydraulic Gradeline3.5 ft. above channel gradeline
Lowest Anticipated Scour3.5 ft. below channel gradeline
STP DESIGN
• START AND STOP AT STABLE POINT
• DESIGN HEIGHT SHOULD BE A MINIMUM OF 1.5 FT. ABOVE DOWNSTREAM RIFFLE ELEVATION
• DESIGN HEIGHT SHOULD INCREASE AS “BANKFULL DEPTHS” INCREASE AND/OR Rc/Wbkf DECREASES
STP DESIGN
• GOAL IS TO PROTECT TOE IN AREA BELOW POINT WHERE VEGETATION CAN BE ESTABLISHED---
• THEREFORE USE VEGETATION IN A “STABLE” AREA AS A GUIDE FOR REQUIRED HEIGHT OF STP
STP DESIGN
• CREST ELEVATION SHOULD BE UNIFORM THROUGH OUT ENTIRE BEND
• ALIGNMENT SHOULD BE AS SMOOTH AS POSSIBLE
• “KEYS” SHOULD ALWAYS BE LOCATED AT U.S AND D.S ENDS
STP DESIGN
• ADDITIONAL “KEYS” SHOULD BE PLACED AT REGULAR INTERVALS THROUGH THE ENTIRE REACH AT A MAXIMUM OF 100 FT. SPACING
• MAY BE SPACED CLOSER IN SMALL RADIUS BENDS (50-75 FT)
STP DESIGN
• PLACE STP IN “WINDROW” WITH SMALL DEPRESSIONAL AREA BEHIND PEAK TO CAPTURE SILT AND CREATE A “BENCH” FOR VEGETATIVE GROWTH.
QUANTITIES
• WILL VARY ALONG REACH DEPENDING ON WATER DEPTH
• USUALLY BEST TO FIGURE AVERAGE DEPTH THROUGH REACH TO CALCULATE QUANTITIES
• 1 TON/FT DESIGN WILL NOT BE 1 TON/FT FOR ENTIRE LENGTH TREATED
QUANTITIES
• RIFFLE ELEVATION - MAX. BANKFULL DEPTH = MAXIMUM SCOUR DEPTH ELEVATION
• EXAMPLE
• RIFFLE = 100.0
• MAX. Dbkf= 4.0 FT.
• MAX. SCOUR DEPTH = 96.0
QUANTITIES
• POOL DEPTH IS 3 FT. BELOW RIFFLE ELEVATION
• ANTICIPATE ADDITIONAL 1 FT. OF SCOUR--ADD ROCK TO LAUNCH INTO DEEPENED POOL WITHOUT LOSING ELEVATION @ CREST BY WIDENING CREST WIDTH.
QUANTITIES
• CALCULATE AVE. HT. OF STP AS HT. ABOVE WATER + AVERAGE WATER DEPTH + ANTICIPATED SCOUR DEPTH
• END AREA IS APPROX. =
• 3H X H /2 = SQ. FT (1.5:1 SIDESLOPES)
• MULTILPLY BY 105 LBS/ CU. FT. AND CONVERT TO TONS/FT OF STP
QUANTITIES
• EXAMPLE
• 1.5 FT. ABOVE WATER + 1.0 FT AVE. WATER DEPTH + 1 FT. ANTICIPATED SCOUR = 3.5 FT. OF STP
• 3(3.5) X 3.5)/ 2 = 18.4 CU. FT.
• 18.4 CU. FT. X 105 LBS/CU. FT. = 1932 LBS. = 0.966 TONS/ FT
SIZING MATERIAL
• 1. CHECK VELOCITY FROM I&E FORM
• 2. MULTIPLY MEAN VELOCITY BY 2
• 3. CHECK TABLE OF VELOCITIES TO MOVE DIFFERENT DIAMETER STONES
• 4. SELECT STONE SIZE WHERE MAXIMUM STONE WILL NOT BE MOVED
STONE CLASSES
NEW- A OLD -RR D-100 D-50
A-4 RR-4 1.3 FT. 7.4 IN.
A-5 RR-5 1.7 FT. 9.8 IN.
A-6 RR-6 2.0 FT. 12.1 IN.
A-7 RR-7 2.5 FT. 14.6 IN.
SUMMARY
• CHECK BED STABILITY & Rc
• CHECK WIDTH OF CHANNEL AND POINT BAR
• CHECK ELEV. OF VEGETATION IN STABLE AREA (@RIFFLE?) ABOVE RIFFLE ELEV.
• CHECK POOL DEPTH
SUMMARY (cont.)
• ADD---HT. OF VEG. ABOVE WATER
• AVE. WATER DEPTH IN REACH
• ANTICIPATED SCOUR DEPTH
• TOTAL = HEIGHT OF STP
• END AREA = 3H X H/2
• VOLUME = END AREA X 105 LBS/CU. FT. (DIVIDE BY 2000 TO GET TON/FT)