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Home My WebLink About6.h. Approve Change Order 1 - Well 16I:\City Clerk\Agenda Items\Approved Items\6.h. Approve Change Order 1 - Well 16.docx EXECUTIVE SUMMARY City Council Meeting: July 21, 2015 AGENDA ITEM: Approve Change Order 1 - Well 16, City Project 416 AGENDA SECTION: Consent PREPARED BY: Patrick Wrase, PE, Director of Public Works / City Engineer AGENDA NO. 6.h. ATTACHMENTS: Well 16 Status Update; Change Order 1 APPROVED BY: ddj RECOMMENDED ACTION: Motion to Approve Change Order 1 for of Well 16, City Project 416 ISSUE: A change order is required for the construction of Well 16 due to an obstruction encountered during the drilling process. BACKGROUND: The attached Change Order describes the issues encountered while drilling Well 16. An obstruction was encountered at a depth of approximately 141 feet below ground surface. This obstruction has caused the need to adjust the plans and re-design Well 16 as a triple-cased design with a 30-inch outer casing down to 141 feet, a 24-inch casing down to 203 feet, and an 18-inch inner liner casing down to full depth (approximately 495 feet). The design change has been reviewed and approved by the Minnesota Department of Health. The cost of this change order is $8,375. SUMMARY: Staff recommends Council approval of Change Order 1 for Well 16, City Project 416. engineering planning environmental construction 477 Temperance Street St. Paul, MN 55101 Tel: 651-286-8450 Fax: 651-286-8488 Equal Opportunity Employer wsbeng.com C:\Users\abrotzler\AppData\Local\Microsoft\Windows\Temporary Internet Files\Content.Outlook\7HWTCHIC\062215 LTR - DJohnson - Project Update for Well No 16.docx June 23, 2015 Mr. Dwight Johnson City Administrator City of Rosemount 2875 145th Street West Rosemount, MN 55068 Re: Well No. 16 Status Update WSB Project No. 1582-18 Dear Mr. Johnson: We are providing this letter to update you on the status of the Well No. 16 construction project. Construction started on May 18th, 2015 with site grading. On June 1st, the Contractor began installing the outer 30-inch diameter well casing. As of June 18th, the 30-inch outer casing had been installed to about 141-feet below the ground surface (bgs). The total expected depth of the required outer casing is approximately 203-feet bgs. An outer casing is required to be extended in to the top of the Prairie Du Chien bedrock formation. At about 118-feet the driller encountered glacial till in the hard pan and reached refusal at about 141- feet. Refusal occurs when the casing can no longer be drilled to a further depth. It is suspected that boulders pushing against a 30-inch casing are creating too much friction and will not allow the 30- inch casing to proceed any further. If additional attempts are made at this point to advance the casing further, damage can occur to the casing as well as the well may be misaligned, both of which can be costly and can poorly affect the quality of the well construction. On Friday, June 19th, a conference call between the Contractor (E.H. Renner and Sons, Inc.), Field Service Provider (Leggette, Brashears and Graham, Inc.), and WSB & Associates, Inc. occurred to determine the best way to proceed. It was decided that the best solution was to revise the initial double cased well design into a triple cased well design. Effectively, the 30-inch casing would remain where refusal was reached (approximately 141 feet bgs), a 24-inch casing would then be drilled to the original designed depth for the outer casing (approximately 203 feet bgs), and an 18- inch inner liner casing would be installed in lieu of the originally designed 24-inch inner casing. Both the original double cased well design, as well as the proposed triple cased design, are included as attachments to this letter for your reference. In comparison to the nearby existing municipal production wells, Well No. 14 and Well No. 15, Well No. 15 is a double cased well and Well No. 14 is a triple cased well. The need for a triple case well at Well No. 14 also occurred during construction when the outer casing reached refusal. Refusal is reached based both on depth of drilling and geology encountered. Well No. 16 was designed as a double cased well to provide the City with the most cost -effective option possible; however, due to Mr. Dwight Johnson June 23, 2015 Page 2 C:\Users\abrotzler\AppData\Local\Microsoft\Windows\Temporary Internet Files\Content.Outlook\7HWTCHIC\062215 LTR - DJohnson - Project Update for Well No 16.docx the geology encountered, Well No. 16 will need to be completed as a triple cased well. The design included the use of an outer 30-inch casing so that if refusal was encountered, the use of a 24-inch middle casing and an 18-inch inner casing could be used without compromising the pumping capacity of the well. In addition, the open hole diameter of 24-inch will remain for the proposed design. Due to the smaller diameter of the inner casing in the change order, maintaining the 24-inch diameter of the open hole will reduce the velocity at the casing entrance and prevent sanding. The revised design was submitted to the Minnesota Department of Health for approval on Friday, June 19th. The Contractor has already supplied a cost estimate for the revised design. Installing a triple cased well will result in a change order of approximately $8,400 (a 2.2% increase in the total project cost). WSB will be working to process a contract change order in this amount between the City and the Contractor. The change order will be submitted to the City in July for approval at a regular City Council meeting. We appreciate the opportunity to assist you with this project. If you have any questions regarding the status of this project or the proposed change order, please feel free to contact me at (651) 286-8457. Sincerely, WSB & Associates, Inc. Jamie Wallerstedt, PE Project Manager Attachments cc: Chris Watson, City of Rosemount Andy Brotzler, WSB & Associates, Inc. jw engineering planning environmental construction 477 Temperance Street St. Paul, MN 55101 Tel: 651-286-8450 Fax: 651-286-8488 July 16, 2015 Mr. Dwight Johnson City Administrator City of Rosemount 2875 145th Street West Rosemount, MN 55068 Re: Change Order No. 1 Well No. 16 Construction City of Rosemount Project No. WSB Projects No. 1582-18 Dear Mr. Johnson: Please find enclosed Change Order No. 1 for the above-referenced project in the amount of $8,375.00. The change order has been reviewed and agreed upon by the contractor, and we hereby recommend that the City of Rosemount approve Change Order No. 1 for E.H. Renner and Sons, Inc. Please return two executed copies to our office, one for our files and one for the contractor. If you have any questions, please contact me at 651-286-8457. Sincerely, WSB & Associates, Inc. Jamie Wallerstedt, PE Project Manager Enclosures cc: Roger Renner, E.H. Renner & Sons, Inc. Andy Brotzler, City of Rosemount Phil Olson, City of Rosemount Leslee Storlie, WSB & Associates, Inc. Equal Opportunity Employer wsbeng.com K:\01582-180\Admin\Construction Admin\CO No. 1\1582-18 LTR CO 1 CTY-D Johnson-071615.docx Page 2 of 2 K:\01582-180\Admin\Construction Admin\CO No. 1\ 1582-18 CO 1 070715.xlsCO 1 Detail MUNICIPAL PRODUCTION WELL NO. 16 CITY PROJECT NO. 416 CITY OF ROSEMOUNT, MN WSB PROJECT NO. 1582-18 Item No.Mat. No.Description Qty Unit Price Extended Amount A DRILL & DRIVE 24" CASING 54 L.F.$235.00 12,690.00 B DRIVE SHOE 24" DIAMETER 1 L.S.$995.00 995.00 D DRILL 24" OPENHOLE - PDC 203 LF $195.00 39,585.00 E F & I PEA GRAVEL OPEN HOLE 11 CYDS $186.00 2,046.00 F INSTALL 18" CASING 410 LF $84.00 34,440.00 G BELL SHOE 18" DIAMETER 1 LS $375.00 375.00 H REMOVE PEA GRAVEL OPEN HOLE 11 CYDS $186.00 2,046.00 $92,177.00 Item No.Mat. No.Description Qty Unit Price Extended Amount 2A DRILL & DRIVE 30" CASING 64 LF $265.00 16,960.00 3A DRILL 30" NOM OPEN HOLE 193 LF $195.00 37,635.00 4A INSTALL 24" CASING 259 L.F.$98.00 25,382.00 C BELL SHOE 24" DIAMETER 1 LS $425.00 425.00 21A SILT FENCE 100 LF $10.00 1,000.00 22A SOUND BARRIER 480 SQ FT $5.00 2,400.00 $83,802.00TOTAL DELETED ITEMS CHANGE ORDER NO. 1 CHANGE ORDER NO. 1 DETAIL ADDED ITEMS TOTAL ADDED ITEMS CHANGE ORDER NO. 1 JULY 15, 2015 DELETED ITEMS