Minneapolis Sczvcr System 425 



branch of this Bassett's Creek sewer has been built (in 1906) from 

 1st Av. N. and Irving south under the Creek and across its valley on 

 the line of Irving Av. to Laurel Av. in Bryn Mawr. Much difficulty 

 was experienced in crossing this bog. The oval shaped concrete 

 sewer was made on a grillage of timbers resting on piles from 30 

 to 60 ft. long; while the lateral pressure of the slippery blue clay below 

 the peat caused a tremendous pressure on the sheathing and bracing. 



With the planned extension from the present end at Laurel Av. up 

 the Avenue the Bryn Mawr district will get sewerage connections. An- 

 other sub-branch is planned from 1st Av, N. and Irving to the Cedar 

 Lake road and up Logan Av. N., to complete the drainage of this 

 northwest section of the city up to about 20th Av. N. 



The natural drainage character of this Bassett's Creek Valley and 

 its difficult engineering character as a peat and clay bog without the 

 city's usual underlying foundation of limestone are interestingly 

 explained by our state geologist as due to the former course of the 

 Mississippi river thru this valley. By turning southward from its 

 present bed at its junction with Bassett's creek the Mississippi river 

 once evidently flowed through the present Bassett's creek valley in the 

 city and thru the chain of lakes from Cedar to Harriet, and thence, 

 it is supposed, into the Minnesota river. During the thousands of 

 years of this course of the river the lime stone stratum was worn 

 away and a deep channel was excavated, which was later filled with a 

 deposit of silt and vegetable matter. The advance of the last glacial 

 age blocked this channel and turned the river into its present course 

 from Bassett's creek to Fort Snelling. Only this little creek, then, 

 Qow remains in this engineeringly troublesome valley and meanders 

 in a reverse direction from the once mighty river which dug out the 

 valley. 



The importance of this Bassett's Creek valley is also seen in its 

 size. Within the city limits it drains 2800 acres, or 4.37 sq. miles; 

 while its additional drainage adjacent to the city makes a total of 

 about 25 sq. miles. The volume of water in the creek varies from noth- 

 ing in a dry season to 1,000 cub. ft. per second in a flood season, with 

 an average of some 10 to 12 cub. ft. 



The plan of diverting the creek into Cedar Lake and so out thru 

 the chain of city lakes into Minnehaha Creek would only take off 

 about half of this natural flow. (For a discussion of this proposed 

 divertion of Bassett's Creek see my report "On the Proposed Diver- 

 sion of Bassett's Creek," presented to the City Council, June 8, 1906). 

 Could this storm water drainage, which will always thus be con- 

 siderable, be confined into an open or closed channel, as in the 

 straightened portion between Western and 6th Avs. the large region of 

 present bog would undoubtedly be drained dry as Hoag's Lake, be- 

 tween 4th and 6th Avs. ..., was dried up by the North Minneapolis 

 tunnel. Also where a natural means of surface drainage is at hand 

 it is good policy to utilize this means and thus tax the sewer systems 

 only with the house sewerage; as has been done in our Kenwood dis- 

 trict where the storm water drains into Lake of the Isles, so that 

 only a 18" pipe from the end of 27th St. around the boulevard is suf- 

 ficient for the house sewerage. 



