Lake Monona Causeway - Madison, Wisconsin, USA

Missouri University of Science and Technology Scholars' Mine International Conference on Case Histories in (1984) - First International Conference on Case Geotechnical Engineering Histories in Geotechnical Engineering 08 May 1984, 10:15 am - 5:00 pm Lake Monona Causeway - Madison, Wisconsin, USA W. W. Warzyn Warzyn Engineering Inc., Madison, Wisconsin C. A. Stoll Warzyn Engineering Inc., Madison, Wisconsin Follow this and additional works at: https://scholarsmine.mst.edu/icchge Part of the Geotechnical Engineering Commons Recommended Citation Warzyn, W. W. and Stoll, C. A., "Lake Monona Causeway - Madison, Wisconsin, USA" (1984). International Conference on Case Histories in Geotechnical Engineering. 20. https://scholarsmine.mst.edu/icchge/1icchge/1icchge-theme3/20 This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License. This Article - Conference proceedings is brought to you for free and open access by Scholars' Mine. It has been accepted for inclusion in International Conference on Case Histories in Geotechnical Engineering by an authorized administrator of Scholars' Mine. This work is protected by U. S. Copyright Law. Unauthorized use including reproduction for redistribution requires the permission of the copyright holder. For more information, please contact [email protected]. Lake Monona Causeway - Madison, Wisconsin, USA W. W. Warzyn Senior Consultant, Warzyn Engineering Inc., Madison, Wisconsin C. A. Stoll Principal Geotechnical Engineer, Warzyn Engineering Inc., Madison, Wisconsin SYNOPSIS In 1965 and 1966, a 3,500 1 long, hydraulically-placed, highway embankment was constructed over the very soft lakebed deposits of Lake Monona. The compressible deposits, which ranged in thickness from 40' to 80 1 , included marl, organic silt and silty clay. An incipient shear failure occurred near the end of the 1965 construction season, necessitating embankment design and construc tion modifications. Pertinent slope stability and settlement data are summarized, as are time dependent changes in in-situ subsoil parameters. Measured settlements, which currently range from 3' to more than 12 1 , agree well with basic consolidation theory and engineering predictions formula ted at project inception. General observations with respect to design, construction and overall performance of the causeway embankment are also provided. INTRODUCTION less than 50 feet thick and typically consist of stratified clay, silt, sand and marl. The Monona Causeway, Figure 1, is located in Madison, Wisconsin, U.S.A., at the southwestern terminus of Lake Monona. It is part of a roadway system which carries traffic from a PROJECT DESCRIPTION southerly beltline highway to downtown Madison. The highway project includes a land approach Initial project interest dates back to 1927 from the south and a causeway across Lake when the Wisconsin State Legislature estab Monona. The route begins about 3,000' south lished a "dock line" for right-of-way. In west of Lake Monona. The causeway portion of 1961, a preliminary study funded by the City the route is about 3,500 1 1 ong and is bounded of Madison concluded that a budget of approx on the west by the existing railroad causeways imately $1,000,000 would be required to con and on the east by the dock line. struct the lake portion of the project. The causeway embankment is designed to permit John A. Strand and Associates, Inc., Consult ultimate construction of a six-lane divided ing Engineers, Madison, was retained by the highway. In addition, three (3) bridge openings City of Madison in 1963 to perform the engi- are provided to permit adequate circulation of neering work for the highway project. Warzyn water between the 1 ake and bay, as well as for Engineering Inc., Madison, served as the boat access thereto. geotechnical consultant. GEOTECHNICAL INVESTIGATION GEOLOGICAL SETTING The purpose of the initial subsurface investi The City of Madison is located within the gation, which was performed in 1963, was two upper Yahara River basin, Figure 2. The Yahara fold: 1) to provide pertinent geotechnical River has few tributaries and a somewhat aim engineering parameters for embankment design, less drainage pattern. Lakes Me.ndota, Monona, construction and maintenance; and 2) to locate Waubesa, Kegonsa and Wingra dominate the valley. a potential, nearby source of sand fill. The Lake levels range between Elevations 842 and investigation included 28 soil borings; see 849, u.s.G.S.; basin depths range from about Figure 3. Sixteen (16) borings, spaced at 1 1 1 20' to 85 • Generally, the lowlands adjacent 300 to 500 intervals, were performed within to the lakes and the Yahara River are marshy, the project right-of-way. Four (4) borings, whereas the uplands are well-drained. spaced at 500 1 to 700' intervals, were performed through the existing railroad embankments. The The Quartenary age surficial deposits, which balance of the borings were performed in an generally are of glacial origin, vary greatly area approximately 1 ,000' to 2,000 1 east of in thickness and composition within short the southern terminus of the proposed causeway distances. These deposits include unconsoli route to delineate a suitable sand borrow dated loess, marsh deposits, glacial lake area. Boring depths ranged from 30 1 to 135 1 • deposits, outwash, and alluvium and morainal deposits. The glacial lake deposits are usually The soil borings were performed in accordance 713 First International Conference on Case Histories in Geotechnical Engineering Missouri University of Science and Technology http://ICCHGE1984-2013.mst.edu Figure 1. Monona Causeway, 1975 Aerial Photograph. with ASTM procedures for "Standard Penetration SUBSURFACE CONDITIONS Test and Split Barrel Sampling of Soils" (ASTM Designation: D-1586). This method consists of Subsurface conditions along the length of the driving a 2-inch outside diameter split barrel proposed causeway route are quite variable. In sampler using a 140 pound weight falling freely general, the subsoil profile consists of two or through a distance of 30 inches. The number three distinct substrata of very soft, compres of blows required to drive the sampler 12" into sible lakebed sediments overlying granular the existing subsoils, at various depth inter deposits of medium to very dense relative den vals, is recorded on the log of boring and is sity. The contact between the uppermost lakebed known as the standard penetration test (SPT). sediments and underlying granular deposits ranges from about 45 1 to 95 1 below lake level, Relatively undisturbed samples of the compres generally increasing as one moves north across sible lakebed deposits were obtained by hydraul the bay. ically forcing 2" and 3" outside diameter, thin-walled tubes into the soils. Water depths along the causeway route, at the time of the borings, typically ranged from The accompanying laboratory testing program con 5 I to 15 I o sisted primarily of simple classification and strength tests. Several conventional, one-dimen The lakebed sediments, in descending order, sional consolidation tests were also performed. include gray, spongy, calcareous silt, dark gray organic silt and tan silty clay. Figure 4 graphically depicts the variation in subsurface conditions as one moves north along the causeway route. The calcareous si 1t deposit, or marl, is not present at Boring No. 3 ( Sta. 86+21), where the compressible lakebed sediments extend to a depth of about 45 1 below lake level. The marl is first encountered at Boring No. 5 (Sta. 94+65), though it does not exceed about 5 1 in thickness. At Boring No. 11 (Sta. 108+10), the marl reaches its maximum thickness of 35 1 to 40 1 and the compressible lakebed sediments extend to depths in excess of 90 1 bel ow 1 ake level. It is further noted that the uppermost, calcar eous silt deposit is often referred to as marl. The origin of this marl is small mollusk shells, such as snails, and lime carbonate deposited through the action of 1 ow forms of vegetation chiefly growing in water of shallow lakes and ponds. 0 Using the results of laboratory classification and strength tests, physical properties of the N three (3) lakebed sediments are summarized in Figure 2. UQper Yahara River Basin. Table I. 714 First International Conference on Case Histories in Geotechnical Engineering Missouri University of Science and Technology http://ICCHGE1984-2013.mst.edu ~~~-·· LAKE MONONA (NORMA~ WL E~EV. 845.60, U.S.G.S.l CHICAGO, Ml.W, ST. PAUL SORINGS PERFORMED MAY- SEPT. 1963 & PACIFIC RR. ~SOli. Figure 3. Boring Location Plan. Figure 5, which is a Plasticity Chart, further Completion of the overall highway project was illustrates the variation in physical properties scheduled for July, 1967. of the three (3) lakebed sediments. In 1964, ultimate settlement was estimated at 10' to 12', which corresponded to long-term settlement of the adjacent ra.ilroad fills as EMBANKMENT CONSTRUCTION interpolated from existing boring information. Time of consolidation was estimated to exceed John A. Strand and Associates, Inc., in their 10 years; consequently, two (2) relevelings of January, 1964 report to the City of Madison, the causeway surface, including replacement of recommended that the future, six-lane divided the highway base course and bituminous surfac highway embankment be constructed of sand ing, were figured into the original cost esti fill, dredged from the lake bottom and piped mate. and placed hydraulically at the causeway site. Estimated cost for the lake crossing, including Preconstruction slope stability studies were pavement construction and maintenance, was now performed on a parametric basis, assuming set at $1 250,000. Bid quantities included that undrained shear strengths ranged from 278,000 yd1 of dredged fill and all embankment 100 to 300 lbs/sq foot. On this basis, the work was to be completed by the end of 1965. stability analyses suggested that slope failure would likely occur, along the northern half of the causeway route, as the fill surface emerged above lake level--unless the very soft lakebed B-3 B-5 B-11 sediments gained additional strength via time STA 86•21, STA 94+65.

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