Rationale for Alternative Crossing Design Approach

Marty E. Rye, P.E. Hydrologist

Superior National Forest Lake Superior Watershed Ditch and Culvert Design Workshop

Duluth, MN March 6, 2013

Liability Has Always Been A Part of Design Code of Hammurabi (Babylonian – 1772BC)

229 If a builder build a house for some one, and does not construct it properly, and the house which he built fall in and kill its owner, then that builder shall be put to death.

230. If it kill the son of the owner the son of that builder shall be put to death.

231. If it kill a slave of the owner, then he shall pay slave for slave to the owner of the house.

232. If it ruin goods, he shall make compensation for all that has been ruined, and inasmuch as he did not construct properly this house which he built and it fell, he shall re-erect the house from his own means.

233. If a builder build a house for some one, even though he has not yet completed it; if then the walls seem toppling, the builder must make the walls solid from his own means.

Why is There an “Standard of Practice”?

• Implicit contract with society or ‘social contract’ to provide a level of service…implicit in this is risk management

• Accountability for the performance of the design

• Codified and litigated • Technically the best approach • Tradition

Professional Engineers Work for the Public

Hold paramount the: • safety, • health, and • welfare of the public

Professional Engineering Code of Ethics

Brief History of Culvert and Stream Crossing Design

Sources of information:

Chow, Ven Te. Hydrologic Determination of Waterway Areas for the Design of Drainage Structures in Small Drainage Basins. University of Illinois Experiment Station. Urbana, IL. 1962

McEnroe, Bruce. Historical Design of Bridges and Culverts: A Historical Review. Great Rivers History – ASCE. 2009

Potter, William D, Peak Rates of Runoff from Small Watersheds. Federal Highway Administration. 1961

Willard,E.V. Drainage Areas of Minnesota Streams and Method of Estimating Probable Flood Flows. 1922

Early Discussion (mid 19th century)

1851: Irish engineer Thomas McIvany describes Rational Formula (not widely adopted) 1853: American design textbook, “Greatest quantity of water which they can ever be required to pass and should be at least 18 inches square or large enough to admit a boy to enter to clean them out”

Meyer 1879: Meyer Formula A = C √D where A = area of opening (sq ft) D= drainage area (acres) C = coefficient (1-4) based upon general description of drainage area

(flat, hill, rocky) – developed from observation of judicious gagings in the area….and applied to smaller pipes

• Major E.T.C. Meyer, Chief engineer of the Richmond,

Fredricksburg, and Potomac Railway after the Civil War • Presented at a club in Cleveland in 1879 • Used by railroad engineers in the east and Virginia • Used in Wisconsin and Connecticut as late as 1960’s

1880: Burkl – Ziegler Q = Cr √SA where Q = discharge (cfs) r = rainfall intensity (in/hr) S = watershed slope (ft / 1,000 ft) A = drainage area (ac) C = coefficient generally 0.62,

ranged from 0.31 to 0.75 = (nature of surface)

• Swiss engineer and adopted in US by Rudolph Hering in 1881 in Report to the National Board of Health regarding Sewerage Works in Europe

• No guidance on how to calculate intensity (r) or slope • Used by 8 of 43 states (19%) in 1960’s

Burkl - Ziegler

A.M. Wellington

• 1886: Wellington, “It is natural for fallible man to wish to reduce everything to a rule, even if it be only a rule of thumb. The responsibility of the individual is much diminished if he has something of that kind to lean on, and in so doubtful a matter as the proper sizing of culverts, this is especially natural……..guess at the proper size and double it. We apprehend this formula will give far more satisfactory and trustworthy results”

University of Illinois Professor A.N. Talbot

1887: Talbot Formula A = C (D¾) where A = area of opening (sq ft) D= drainage area (acres) C = coefficient 1/6 to 2/3 based

upon shape of drainage area, snow or rain dominance, land use

• “any formula will be approximate….judgment must be the main dependence, the formula being a guide to it…”

• Physically based as well - Look at the stream, high water marks, and similar streams in the area

• Widespread popularity for railroad and highway engineer

• 1960’s 25 of 43 states used the Talbot formula

Rational Formula…not yet

1889: Kuichling introduced Rational Formula to America (though not in familiar form)

• Again, slow acceptance because there is

no guidance on how to calculate C or i

Dun’s Table • 1890 – 1906: James Dun’s Table (Sante

Fe Railroad) initially in 1890 - revised several times until 1906

• Applied from a few acres to 6,400 sq miles • Illinois to Texas / N. Mexico with several

subregions • Widely adopted by highway engineers • 5 of 43 states still used in the 1960’s

So, in Missouri and Kansas a drainage area of 8 sq miles requires an area of 601 sq ft of bridge area

Civil Engineering Text 1902: A.T. Byrne (A Treatise on Highway Construction) Design factors affecting sizing of drainage structures include: - rate of rainfall - soil condition - inclination of the surface - condition and inclination of the stream bed - Watershed shape and location of tributaries - form of the mouth and culvert bed - is it acceptable to back up water Suggested Design Procedure (field-based)

• look at existing crossings • measure cross-section at high flow • look for high water marks

Describes limitations and error and don’t get concerned about the “mathematical exactness…the real question is whether at 2-ft or and 8-ft pipe is needed”

Minnesota 1922 “Drainage Areas of Minnesota Streams and Method of Estimating Probable Flood Flows”

• Controlling floods, • Developing water powers, • Furnishing water supply for municipal

consumption, • Designing adequate culverts and bridges, • Providing sufficient capacity for drains, and • All kindred problems

Minnesota (E.V. Willard) Department of Drainage and Waters

Q = A 0.6

where, Q = cfs and A = square miles

Correction Coefficient Ranges from 0.35 to 15!

Progression to Present 1917: Miami (OH) Conservancy District published first

reliable rainfall frequency map for eastern USA 1935: Yarnell’s USDA Rainfall Frequency Data published 1940’s: Research by Bureau of Public Roads – frequency

based sizing 1949: John’s Hopkins University Story Drainage Research

Project endorsed Rational Method 1953: Izzard – Bureau of Public Roads – widely used 1954: SCS Curve Number Method 1960’s: USGS and others begin to develop regional

flood-frequency by regression rather than graphical methods

Standard of Practice in 1962 (Chow) Reviewed 102 empirical and semi-empirical formulas

• 12 Waterway area formulas a(sq ft) = C f(A) • 30 Simple flood formulas

Q = f(Drainage Area) select desired velocity and compute flow area from continuity a(sq ft) = Q/V

• 24 Rainfall intensity formulas Q = CIA • 5 Frequency formulas Q = a + bf(T) • 31 Elaborate discharge formulas

Standard of Practice 1962 (Chow) Talbot Rational Other Dun BPR USGS Historical

AlabamaArizonaArkansasCaliforniaColoradoConnecticutDelawareFloridaGeogriaIdahoIllinoisIndianaIowaKansasKentuckyLouisianaMaineMarylandMassachusettsMichiganMinnesotaMississippiMissouriMontanaNebraskaNevadaNew HampshireNew JerseyNew MexicoNew YorkNorth CarolinaNorth DakotaOhioOklahomaOregonPennsylvaniaRhode IslandSouth CarolinaSouth DakotaTenesseeTexasUtahVermontVirginiaWashingtonWest VirginiaWisconsinWyoming

Formula Table or ChartBurkli-Ziegler

State's Own

State's Own

MN:

•BPR •Rational

WI: •Other •Rational

Independent5 10 15 20 25 30 35 40 50 100 Historical Investigation

AlabamaArizonaArkansasCaliforniaColoradoConnecticutDelawareFlorida +GeogriaIdahoIllinoisIndianaIowaKansasKentuckyLouisianaMaineMarylandMassachusettsMichiganMinnesotaMississippiMissouriMontanaNebraskaNevadaNew HampshireNew JerseyNew MexicoNew YorkNorth CarolinaNorth DakotaOhioOklahomaOregonPennsylvaniaRhode IslandSouth CarolinaSouth DakotaTenesseeTexasUtahVermontVirginiaWashingtonWest VirginiaWisconsinWyoming

Return FrequencyStandard of Practice 1962 (Chow)

“Secondary Highways”

MN = 25 yr

WI = 50 yr

Most Common = 25 yr

Existing Standard of Practice

• “Frequency-based” discharge

• Clear water hydraulics

USGS Regression Equations • Note assumptions – independent of land use • Note methods – dependant upon where applied • Lake / storage distribution not considered • Note error / confidence limits!!

Frequency Curve for Manitou River at Timber CrossingBased Upon Regression Equations

USGS Report 97-4249

0200400600800100012001400

110100

Exceedence Probability (%)

Disc

harg

e (c

fs)

90% Confidence Limits 500 cfs to

1,400 cfs

Equal Probability of Being “Right”

Equal Probability of Being “Right”

NRCS Curve-Number Method • Rainfall Distribution matters!!!

– A Q10-yr Type II can be larger than a Q100-yr Type I – Note assumptions if using a single-event model

• Time / season matters (especially important for ecohydraualics) – plowed field in April ≠ corn field in August

• Antecedent Moisture Content????

NRCS Curve Number “The sample variability in CN can

be due to infiltration, evapotranspiration, soil moisture, lag time, rainfall intensity, temperature, etc. Antecedent moisture condition (AMC) was used to represent this variability. The AMC I is the lower enveloping CN, AMCII is the median CN, and AMCIII is the upper developing CN (Mockus 1964)”

Source: Rallison, Robert and Miller, N. “Past, present, and future SCS runoff procedure”. Rainfall-Runoff Relationship - Edited by V.P. Singh, Water Resources Publications, 1982.

How has the Existing Standard of Practice Performed?

• Has it provided the protection “promised” in our social contract?

• Are there unanticipated effects of using this standard of practice?

Road infrastructure that passes water from

a stream Stream infrastructure that passes vehicles

What is a Culvert Crossing??

Streams Are Complex Systems

Water/ Ice

Bugs

Vegetation

Sediment Mussels Beaver

Fish

Wood

Trees / Roots

Healthy Natural Systems Are Continually Under Construction

Process of Demolition and Reconstruction is Inherent - Vegetation - Streambanks

Change can be either gradual or due to a sudden disturbance

We Have to Remember That Fluvial Processes Are Within the Context of

Natural Disturbance Dynamics

Traditional Clear Water Hydraulic Culvert Design Assumptions w/

Riverine Structures Typically Include • No change over time in:

– Hydraulics – Hydrology – Sediment Supply

• No disturbances / debris • Functional design event

What is Failure??? • Does it mean never washing out or being

over-topped • What about other services such as aquatic

organism passage? • Ability to safely convey vehicles during

“design events” even if overtopped

Consequences of Crossing “Failures” are Profound

• Human Life • Economic • Ecological • Political / Opportunity

Mpls Tribune 6-05

Why Do Crossings Fail?

• Water

Why Do Crossings Fail?

• Sediment

Why Do Crossings Fail? • Ice

Why Do Crossings Fail?

• Debris

Why Do Crossings Fail?

• Beaver

Why Do Crossings Fail? • Frost Heave (smaller pipes)

Traditional Clear Water Hydraulic Culvert Design Does Not Do a Good Job

Considering What Else is in the Stream…..

Revised Design Method is a Hybrid • Considers Performance at Low Flow as

Well as During the “Design Event”

• Physical Analysis – Understand the specifics of the setting the

crossing is being placed

• Frequency Analysis – Manage the risk / transportation system

Fish Passage in One Slide

Pass through what is swimming at you If can get up to the culvert If can get down to the culvert Then it should get through the culvert

• The culvert should not be the limiting factor,

so mimic the existing condition (depth / velocity, boundary conditions, no physical barriers, etc.)

Pass through what is coming at you Accomplished through correct culvert:

• Elevation • Slope • Width • Effective width (alignment and free area) • Area • Substrate / roughness

Sediment Transport in One Slide

Pass through what is coming at you Clear Span Width…Width…..Width Alignment Height

Woody Debris Passage in One Slide

• I don’t know • Maintenance issue - steam the smaller ones • Put in some flood plain culverts – they’re

relatively cheap and should help (though need to document)

Ice Accumulation in One Slide

• I don’t know • Maintenance issue • Trap them • Large enough crossing may be sufficient • Floodplain culverts offer some more protection • I am personally not a fan of Clemson levelers • Why do some beaver build above the crossing?

Beaver Accommodation in One Slide

I don’t know Maintenance issue Perhaps more of a subpavement issue?

Frost Heave in One Slide

Important to Document, Fully Understand, and Communicate the Specific Project

Performance Criteria

• Quantification of Risk

• Allows Evaluation

• Accountability

• Manages Liability

• Reconcile Competing Objectives

First Step in Crossing Design is Often Ignored

IS THE CROSSING NEEDED??

• Really – can other crossings be used, etc.? • Does it need to be permanent – can it be

pulled when done (such as a timber sale)? • Can the transportation system be designed to

minimize crossings?

Some Quick Thoughts About Floodplain Culverts

• Increase conveyance capacity • Benefit for beaver management??? (stay tuned) • Emergency capacity if main is plugged / frozen • Can maintain some better flowlines

– Don’t concentrate flow (velocity) in channel – Retain energy flow in floodplains – Potentially reduce ineffective flow area

• Evaluate – especially valuable where large floodplain conveyance

Schematic of Flowlines Prior to Crossing

1

1

1

2

Single Crossing w/o Floodplain Culverts

Incorporating Floodplain Culverts

Examples of Installed Floodplain Culverts

Inventory found 10-15% of the culverts were undersized and fish passage barriers Additional 20+ crossings not shown

The SNF Has Been Replacing Culverts

Tait River

1935 - Bridge (19’span)

The SNF Has Been Replacing Culverts

Bridge (19’span)

Culvert (12’ span)

Tait River, 1955

Tait River, 2001

Bridge (24’span)

Bridge (19’span)

Culvert (12’ span)

Summary • Streams are complex and dynamic and we

need to recognize the role of: – Sediment -- Wood – Ice -- Beaver – Disturbance dynamics

• The public is demanding a continuation of environmental services….. – fancy way of saying that we need to minimize impacts

on the environment – including accommodating fish passage and allow wood in stream

Summary • Standard of practice evolves over time –

and the present standard is relatively young.

• Clear water hydraulic design alone does not adequately protect the public safety and has unacceptable environmental impacts

• Simply looking at the existing channel (physically-based) does not adequately evaluate extreme conditions – need to quantify risk management

Summary As the body of research work and experience increases, it will be increasingly difficult to justify clear water flood hydraulic design alone as the standard of practice. This will likely impact liability exposure of designers and owners alike with failures / damages during flood events and long term ecological impacts.

Summary Using a hybrid design that includes “channel simulation” and flood hydraulic analysis provides protection to the public that is consistent with the social contract of assumed risk and increased ecological performance We need to ensure we adequately communicate the risks and assumptions made through the development of specific project performance criteria

Questions and Discussion