DESIGNING STONE TOE PROTECTION

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

Lanes Balance

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)

SUMMARY (cont.)

• MAKE CREST UNIFORM

• KEEP IT PEAKED

• KEEP IT SMOOTH

• BE SURE TO “KEY” IT IN

• SIZE STONE TO RESIST 2 X MEAN VELOCITY