To: Honorable Mayor and Members of Town Council
From: Mark Marlowe, P.E., Utilities Director
Title
Resolution: Approving a Construction Contract Award to Velocity Constructors Inc. for Construction of the Plum Creek Alluvial Well Field Project for the Plum Creek Water Purification Facility
Body
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Executive Summary
The purpose of this memorandum is to request Town Council approval of a contract award to Velocity Constructors Inc. for construction of the Plum Creek Alluvial Well Field project, which includes three new alluvial wells in the Central Well Field to provide renewable water supply for the Plum Creek Water Purification Facility (PCWPF) (see Attachment A). The Central Well Field consists of seven alluvial wells located in The Meadows development near Meadows Parkway Bridge over East Plum Creek. Three wells in the Central Well Field were completed in 2013 and a fourth one was added in 2014. This authorization request is for completing the three remaining planned alluvial wells in the Central Well Field.
Given the high growth in the past several years, with high water demands in September and October 2015, schedule uncertainty regarding the completion of the Plum Creek Diversion, and experience over the last three years with maintenance requirements for alluvial wells, three additional wells are needed in order to keep up with the projected water demand in 2016 provide additional long term renewable supply capacity and maintenance redundancy. These wells were originally part of the PCWPF project, but were not constructed due to previous budget limitations, and they were not needed at that time to meet water demands. Rather than invest in new nonrenewable groundwater infrastructure, Utilities recommends adding these alluvial wells in early 2016 to supplement our water supply as originally envisioned.
These wells were not included in the 2016 budget as the need for these wells became more apparent after the high growth in 2015 and record demand for water in October (229 million gallons in Oct 2015 compared to 154 million gallons in Oct 2014). The growth, plus the record demands in the fall of 2015 and work on the update to our Water Resources Strategic Master Plan, have required us to re-examine our water demand projections. Without adding new water supply, the Town could face a water shortage in summer 2016. These additional wells will help reinforce water supply reliability plus they will continue to provide high quality renewable, sustainable water for years to come and fit into the Town’s goal for sustainable water supply. The design for these wells was completed with the original project, and we simply only had to bid this work for construction. No additional design work was required.
The Town pre-selected five qualified bidders due to the limited construction window imposed by The Meadows Habitat Conservation Plan (MHCP). The Town received two bids for the project. Staff recommends approving a contract award to the qualified bidder with the lowest bid, Velocity Constructors Inc., in the amount of $1,722,543 for construction services. In addition, Utilities requests a 7% Town-managed contingency in the amount of $120,578 for a total authorization of $1,843,121. Funding would be derived from the revenues collected through system development fees, keeping consistent with the philosophy that growth pays for growth. Construction is planned to begin in late December 2015, pending Town Council approval, and be complete by April 30, 2016 for the work authorized in this request. This fits into the habitat conservation plan window for working within Preble’s Meadow Jumping Mouse habitat, and will allow water to be available for the summer demand season.
Discussion
A need for a sustainable long-term water supply was identified in the Town’s Water Resources Strategic Master Plan (WRSMP). One of the major goals of that plan is to establish renewable, sustainable water supplies that account for 75% of the annual demand for water in Castle Rock. Renewable water sources may include Plum Creek alluvial wells and surface water using existing Town water rights and imported surface water. Utilities initiated a project that consists of capturing and treating existing Plum Creek water rights along East Plum Creek. To meet the projected water demands, it is critical that this well field development project be delivered and operational for the peak demand season starting in 2016.
In 2013, the Town completed one of the Legacy Water Projects, the Plum Creek Water Purification Facility Project. As part of the PCWPF project, the Town designed and constructed the Plum Creek Alluvial Well Project. This project was a combination of wells in the South Well Field and Central Well Field. There were seven well sites identified in the Central Well Field (see Attachment B), clustered in two areas. The northern cluster of four wells near Atrium Drive was constructed in 2013 and 2014. The three wells located near the Meadows Parkway Bridge were designed, but never constructed; Utilities proposes to construct them now due to a projected water supply shortfall in summer 2016 as a result of increased growth. The graph below shows the growth that was forecasted in 2012, what has happened over the last 3 years, and what we project for the next 5 years. As of October 31, 2015, Utilities is billing nearly 19,000 accounts, which is slightly higher than the forecasted value (see Attachment C).
The need for this project was identified during work on the Water Resources Strategic Master Plan update. With the natural decline in production of the deep aquifer wells and higher growth within the Town, the Town has identified a need to increase its water supply this summer, well in advance of the Plum Creek Diversion and WISE projects that are planned to come online in 2017. Additionally, in a recent meeting with the Army Corps of Engineers, the permitting for the Plum Creek Diversion structure may take longer than first anticipated. This alluvial well project will provide some additional insurance that the water supply will be available if the completion of the Plum Creek Diversion is delayed.
Additionally, after operating the existing alluvial wells for three years, the Town has learned through experience that there is higher maintenance required to maintain optimal production. These new alluvial wells will allow the Operations Division more flexibility in rotating wells out of service for cleaning and preventive maintenance. Also, the alluvial water quality is cleaner than the water quality anticipated from the future diversion structure due to the natural filtering that occurs in the sands around the alluvial wells. These additional wells will provide more blending of water before the treatment process, reducing the treatment costs at the PCWPF. This project has been identified as work that can be completed in a relatively short period of time to increase the Town’s renewable water supply without constructing new, deep groundwater wells. However, drilling some new deep wells to replace existing deep wells will be required in the future as this existing infrastructure ages and the water production rates in the wells continue to decrease.
Long term, these three additional wells in combination with the existing alluvial wells and planned Plum Creek Division give the Town more overall capacity to capture water when it is available on East Plum Creek, for example during free river conditions. Construction within The Meadows Habitat Conservation Plan (MHCP) is restricted to October 15th to April 30th. Due to the critical nature of this project and the limited construction window, the Town selected five qualified contractors to invite to bid on the project. Two contractors submitted competitive bids for the project, and the results are shown in the following table.
|
Contractor |
Bid Amount |
|
Velocity Constructors |
$1,722,543 |
|
T Lowell |
$2,000,000 |
|
Engineering Estimate |
$1,575,733 |
The work will include the horizontal directional drilling of lateral arms on the wells. The arms will be screened to provide increased production capacity from the wells as compared to the standard vertical wells along the stream bank. Staff estimates the three wells will produce close to the decreed amounts, 250 gallons per minute (gpm) per well, using this method. The Town knows that developing the local water supplies is the most cost effective for its customers. To put the costs in perspective, the Town estimates designing and constructing renewable water projects along the South Platte will cost approximately $22,000 - $25,000 per acre-foot. If the Town had to develop a project for this same amount of water along the South Platte, it would cost between $24.6 and $28 million not including the costs of the water rights. This project is a very cost effective way to capture the Town’s existing native water rights, continue to deliver high quality drinking water, improve operational flexibility, and minimize the impacts of the permitting issues and possibly resulting in delays associated with the diversion structure.
Budget Impact
The Utilities Department did not budget for this project in 2015 or in 2016. If Council approves the project, Utilities will prepare the appropriate budget transfers from 211-4375-443.77-30 in the amount of $1 million and 211-4375-443.77-75 in the amount of $843,000, to this project. The costs associated with this project will be charged to the project line item budgets as shown below. Ultimately, the funds for this project will be derived from system development fee revenues.
Project Amount Contingency Total Amount
211-4375-443.76-63 $1,722,543 $120,578 $1,843,121
Central Well Field
Staff Recommendation
Staff recommends approval of a contract award to Velocity Constructors Inc. for construction of the Plum Creek Alluvial Well Field in the amount of $1,722,543; plus a 7% Town-managed contingency in the amount of $120,578, for a total authorization request of $1,843,121.
Proposed Motion
I move to approve a Resolution Approving a Contract Award to Velocity Constructors Inc. for Construction of the Plum Creek Alluvial Well Field Project for the Plum Creek Water Purification Facility
Attachments
Attachment A: Resolution
Exhibit 1: Contract
Attachment B: Location Map