1 Introduction 



The Prototype 



Bums Waterway Harbor is a man-made harbor located on the southern tip 

 of Lake Michigan, about 9 miles 1 east of Gary Harbor and 14 miles west of 

 Michigan City Harbor. Burns Harbor was primarily constructed to facilitate 

 shipping materials to and from steel industries in northern Indiana. The Burns 

 Harbor structures include a 4,600-ft-long rubble-mound breakwater with an 

 east-west alignment positioned at the north side of the harbor, a 1 ,200-ft-long 

 rubble-mound breakwater with a north-south alignment located at the west side 

 of the harbor, and a steel sheet-pile cell structure (Figure 1). 



The rubble-mound structures use a multi-layered random placement design 

 with a toe elevation of about -43 ft low water datum (lwd) and a crest 

 elevation of + 13 ft lwd. Armor stones, cut from Indiana Bedford limestone, 

 weigh from 10-16 and 16-20 tons on the trunk and head, respectively. 



Since completion of construction in 1969, two problem areas have arisen. 

 Maintenance of the design crest elevation and structure cross section has 

 required the addition of large amounts of stone (an average of 7,640 tons per 

 year for the first 19 years of operation). Also, unacceptably large wave 

 conditions within the harbor (recorded data show transmission coefficients as 

 high as 25 percent) have led to cases of extensive damage to harbor facilities 

 and moored vessels. 



Purposes of Model Investigation 



The purposes of the investigation described herein were as follows: 



a. Evaluation of stability/transmission using a 1985 condition survey and 

 February 1987 storm conditions. 



b. Evaluation of stability/transmission improvements with a submerged 

 breakwater placed 75 to 200 ft lakeward of the existing breakwater. 



1 A table of factors for converting non-SI units of measurement to SI units is presented on 

 page v. 



Chapter 1 Introduction 



