HomeMy WebLinkAboutItem 07 - Wastewater Treatment PlantMEMO TO: HONORABLE MAYOR AND MEMBERS OF THE CITY COUNCIL
FROM: BRUNO RUMBELOW, CITY MANAGER /
MEETING DATE: AUGUST 6, 2013
SUBJECT: CHANGE ORDER #5 — WASTEWATER TREATMENT PLAN
HEADWORK FACILITY & ENGINEERING SERVICES
RECOMMENDATION:
City Council consider approving Change Order # 5 to the construction contract for the
Wastewater Treatment Plant Headworks Facility with Legacy Contracting, L.P. dba
(Control Specialist Services L.P.) in an amount of $248,782.61, an amendment to the
Engineering Services contract with Freese & Nichols, Inc. in the amount of $65,736.00,
and a project contingency in the amount of $15,000.00, authorize staff to execute
Change Order #5 and Engineering Services contract amendment, and take any
necessary action.
FUNDING SOURCE:
Funds are available and programmed in the unappropriated Utility Fund Balance.
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On June 19, 2012, the Headworks Facility construction contract was awarded to Legacy
Contracting in the amount of $2,757,600.00 and Change Order # 1 was approved as a
deduction of (-$262,507.00), for a total contract of $2,495,093.00. As the attachment
shows, with the $248,782.61 in additions we are seeking approval for in change order #5
this evening, the net change over the original contract price is $23,101.52.
On February 5, 2013, City Council approved Change Orders #2, #3 and #4 in the total
amount of $36,825.91 that included electrical modifications, disposal of contaminated
sludge and removal of an underground concrete sludge digestion tank.
During construction of this project, additional items were discovered that need
replacement, relocation or installation. Change Order #5 addresses these items as
detailed below:
Emergency Repair Work for Collapsed 24" Ductile Iron pipe; The existing 24" pipe
downstream of the existing headworks had segments where the top of the pipe had
collapsed or was on the verge of collapsing due to hydrogen sulfide gas corrosion.
These had to be addressed immediately to avoid contamination of the area.
($22,774.17)
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24" Pipe Replacement: Investigation of this line revealed substantial deterioration along
its length. This deterioration interfered with the planned phasing of the construction.
The wastewater treatment plant is required to stay functional during construction by
starting and stopping different sections (Trains) of the plant while other pipe routes are
installed. This operational need required out of construction sequence installation of the
PVC pipe to replace this 24" ductile iron pipe. ($57,262.12)
Train 1 Air Piping The existing cast iron pipe from the air blowers to the Train 1 aeration
basin is severely deteriorated over its entire length and can no longer perform as
needed. This existing piping was installed approximately 30 years ago. The proposed
12" ductile iron piping will be elevated above the ground to help reduce future corrosion
and extend its life. ($47,976.36)
8" PVC backwash piping from new filters under design at Trains 2 & 3; The TCEQ
requires the Wastewater Treatment Plant to regulate suspended solids being released
from the plant. Public Works is finishing design of a new filtering system for Trains 2 & 3
to replace the existing non-functioning filters. These filters require backwashing on a
regular basis. This change order adds a long run of 8" PVC line to return the backwash
water to the headworks. Installing the 8" pipe now will be substantially less expensive
and disruptive than including its construction in the filter construction project.
($22,790.10)
6" Backwash line rerouting for Train 1: The filter for Train 1 backwashes into the
aeration basin for Train 1. Due to the modifications being made to the Train 1 aeration
basin, the Train 1 backwash line needs to be relocated and extended to a different point
in the basin for full contact time and treatment. ($9,395.88)
Reroute/Repair 20" & 24" Pipes To & From Train 1 clarifier: The two new 24" PVC pipes
from the headworks to Trains 2 & 3 are planned to be routed between the existing
aeration basin and clarifiers for Train 1. These two structures pose significant physical
constraints to the planned pipes, however, there are no viable alternatives to route these
two lines. An existing 24" pipe from the clarifier conflicts with the two new pipes and
must be adjusted. There are also two existing 20" ductile iron pipes (installed in 1969)
connecting the aeration basin with the two clarifiers that are located deep in this same
space. Exposing parts of these two lines has revealed that they are both deteriorated
and leaking. ($89,887.23)
Deletion of Influent Weir Wall: (Deduct: - $1,303.25)
The total time to be added to this contract for change order work is 141 calendar days.
The start date for this contract was August 20, 2012. The contract had 365 calendar
days for construction. Adding the 141 days extends the construction completion date to
January 8, 2014.
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The Freese and Nichols staff and City staff, have reviewed the Change Order items and
found the cost and time extension to be reasonable. Freese and Nichols staff have
been actively involved in this project, identifying problems and solutions, modifying and
preparing construction plans and participating in regularly scheduled progress meetings.
The initial level of effort programmed from Freese and Nichols did not anticipate the
level of effort that their staff has had to provide and will continue to provide to
completion. Freese & Nichols Staff have prepared designs for the air supply line
relocation and the 24" pipeline replacement out of sequence at a cost of $7,414.00 and
$6,812.00 respectively. They have also provided us an estimate for continued General
Representation Services through the end of the project. ($51,510.00)
Staff recommends approval.
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