Memorandum
City of Lawrence
Public Works
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TO: |
David Cronin, P.E., City Engineer |
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FROM: |
Matt Bond, P.E., Stormwater Engineer |
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CC: |
Charles Soules, P.E., Director of Public Works |
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DATE: |
September 8, 2015 |
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RE: |
Maple Street Pump Station, 6th & Maple Street, Project No. PW1133, Bid No. B1542 - Project History, Description & Action Request |
Project History & Description
In 2005 a comprehensive drainage study, known as the North Lawrence Drainage Study (NLDS), was completed for North Lawrence. This study examined existing flooding issues and provided options to improve or resolve them. "System 6" was one of the sub watersheds listed within the NLDS (see Figure A). The Maple Street Pump Station was identified as being too small to adequately drain "System 6" resulting in localized flooding of ditches, streets, and yards of area residents.
In November 2008 the community voted in support of a 0.3% sales tax increase to fund infrastructure improvements. The Maple Street Pump Station was identified as one of the projects to utilize these newly generated funds at an estimated construction cost of $4.5 million.
The engineering design team of Bartlett & West Engineers, Inc. and CDM Smith was chosen to perform the engineering design services. During and after the development of the engineering drawings several public meetings were conducted. These meetings consisted of a general public information meeting at the Train Depot, two presentations to the North Lawrence Neighborhood Association as well as meeting with individual property owners. The engineering drawings for the project have been reviewed and approved by the U.S. Army Corps of Engineers.
The existing pump station is located near the northwest corner of 6th & Maple Streets. The existing pump station is a converted sanitary sewer lift station with an 9” diameter outfall pipe and has a capacity of only 6 cubic feet per second (cfs). The “System 6” water shed contains roughly 192 acres and experiences localized flooding during significant rainfall events. The majority of the watershed is north of the Union Pacific Railroad Tracks and its vertical elevation is approximately ten feet below the tracks profile grade. The property to construct both the pump station and the wet well were acquired in 2010 (see Figure B).
Once stormwater has been collected at the pump station location it will then be pumped underneath the railroad tracks and into a junction box on the northwest corner of the intersection of 6th & Locust Streets. From there it will drain by gravity to the Kansas River. Coinciding with the construction of the new pump station a new outfall, gate well structure and the corresponding piping will be constructed through the levee. All of the private utilities have been relocated so that there are no conflicts with the proposed storm sewer alignment.
On March 3rd, 2015 bids were received for the Maple Street Pump Station Project No. PW1133, City Bid No. B1503 from the two (2) bidders listed in the table below. The base bid included the pump station at 6th & Maple Street and the downstream system under the railroad and through the levee to the Kansas River. In addition to the base bid, contractors also provided an alternate bid for the additional storm sewer work upstream from the pump station. The alternate bid included extending the storm sewer from the pump station north along the west side of 6th Street and then east along the south side of Lincoln Street to Lyons Park.
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March 3, 2015 Bid Letting Results |
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CONTRACTOR |
Engineer’s Estimate |
Nowak Construction, Inc. |
BRB Contractors |
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BASE BID TOTAL (levee to pump station) |
$4,128,379.00 |
$6,525,544.00 |
$5,947,275.00 |
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ALTERNATE BID (pump station to park) |
$1,047,267.00 |
$1,503,376.00 |
$1,589,338.00 |
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GRAND TOTAL |
$5,175,646.00 |
$8,028,920.00 |
$7,536,613.00 |
Due to the lowest bid significantly exceeding the engineer’s estimate, City Staff recommended that the bids be rejected. The City Commission formally rejected the bids at its March 10th, 2015 City Commission Meeting.
Subsequently City Staff and Bartlett & West Engineers, Inc., discussed potential ways with the bidding contractors to reduce costs. The following design changes were implemented into the revised plans after getting direction from the City Commission to do so at its May 5th, 2015 meeting:
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Ř Modified the hydrologic criteria to reduce the overall design flow from 195 cfs to 100 cfs. This resulted in reducing the necessary pumping capacity of the pump station and the corresponding storm sewer pipe sizes while still maintaining the return design frequency at a 10-year return period for peak design flows. Staff and Bartlett & West Engineers, agreed that with the sandy soil types as well as the open and relatively flat road side ditches in North Lawrence justified the use of a lower range of the American Society of Civil Engineers (ASCE) runoff coefficients for the basis of the design flow. |
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Ř Utilized submersible pumps which are more readily available than the previously specified unique vertical turbine pumps. This also resulted in higher upstream flow line elevations for the storm sewer system which in turn lowered installation costs. |
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Ř Allowed the reuse of excavated soil as backfill for storm sewer installation. |
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Ř Added polypropylene pipe as an alternate to concrete pipe for the storm sewer. Allowing alternate pipe materials provided additional competition between pipe suppliers. |
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Ř Specified the reconstruction the entire width of 6th Street as an asphalt road instead of replacing half of the road in concrete. |
Although the above changes were implemented into the redesign of the project, and the rebid of the project did result in a lower total cost, it unfortunately was once again higher than the engineer's estimate that Bartlett & West Engineers, Inc. developed. The results of the September 1st, 2015 rebid are shown in the table below.
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September 1, 2015 Bid Letting Results |
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CONTRACTOR |
Engineer’s Estimate |
Nowak Construction,Inc. |
BRB Contractors |
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BASE BID TOTAL |
$3,752,114.00 |
$4,179,157.00 |
$4,716,880.00 |
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BASE BID (RCP OPTION) |
$736,005.00 |
$942,559.00 |
$859,980.00 |
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BASE BID (POLYPROPYLENE OPTION) |
$646,705.00 |
$1,107,710.00 |
$912,720.00 |
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BASE BID + RCP OPTION TOTAL |
$4,488,119.00 |
$5,121,716.00 |
$5,576,860.00 |
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BASE BID + POLY OPTION TOTAL |
$4,398,819.00 |
$5,286,867.00 |
$5,629,600.00 |
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ALTERNATE BID |
$501,445.00 |
$460,071.50 |
$513,281.00 |
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ALTERNATE BID (RCP OPTION) |
$368,725.00 |
$355,844.00 |
$281,975.00 |
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ALTERNATE BID (POLY OPTION) |
$292,520.00 |
$394,754.00 |
$284,455.00 |
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ALTERNATE BID + RCP OPTION TOTAL |
$870,170.00 |
$815,915.50 |
$795,256.00 |
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ALTERNATE BID + POLY OPTION TOTAL |
$793,965.00 |
$854,825.50 |
$797,736.00 |
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GRAND TOTAL BASE + ALTERNATE (W/RCP OPTIONS) |
$5,358,289.00 |
$5,937,631.50 |
$6,372,116.00 |
The total bid for Nowak Construction, Inc. was the lowest of the two bidders totaling $5,937,631.50 for both the base and alternate bids utilizing the reinforced concrete pipe (RCP) option. It is important to note that Lyons Park will continue to experience localized flooding unless the alternate bid is included with the awarded construction project.
Project Funding
This project is being funded with the previously mentioned Infrastructure Sales Tax Revenue in the amount of $4.5 million. The remaining balance of the project would be funded with the issuance of a General Obligation (G.O.) Bond for an additional $1,750,000 in bonding capacity. The debt service additional $220,000 per year would be paid directly from the Stormwater Utility Fund. The current forecast for the utility fund has capacity for the repayment due to stormwater projects previously debt funded to be paid off in 2018. Although this total is in excess of $300,000 over the awarded contract price it allows for a contingency against unforeseen circumstances, for example dewatering due to an usually wet year. It should be noted that this additional bonding capacity will only be used if needed. The NLDS estimated the construction cost for this project at $4.279 million.
Action Request
Approve the award of the base bid and alternate bid using RCP pipe for the Maple Street Pump Station, Project No. PW1133, Bid No. B1542 in the amount of $5,937,631.50 to Nowak Construction, Inc. provided they meet the requirements of the signed contract.
Adopt Resolution No. 7141, ordering the improvement and authorizing the issuance of General Obligation bonds for the construction of the Maple Street Pump Station in an amount $1,750,000.00.