To: Honorable Mayor and Members of Town Council
From: Mark Marlowe, P.E., Utilities Director
Title
Resolution Approving a Contract Award to Directed Technologies Drilling, Inc. for Construction of the Plum Creek South 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 Directed Technologies Drilling (DTD) for construction of the horizontal wells of the Plum Creek South Alluvial Well Field project, (which includes one horizontal lateral alluvial well and two new horizontal lateral alluvial arms in the South Well Field) to provide additional renewable water supply for the Plum Creek Water Purification Facility (PCWPF) (see Attachment A). These improvements are estimated to double renewable water production based on 2015’s production data. The South Well Field consists of five alluvial wells located in East Plum Creek alluvium east of MedVed auto facility (see Attachment B). Two wells in the South Well Field were replaced and three were rehabilitated in 2013. This authorization request is for completing the two remaining planned horizontal alluvial lateral arms and replacing one of the wells that staff suspect has failed in the South Well Field.
Given the rapid population 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, the additional improvements to the 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. Staff anticipates rehabilitating one-third of the alluvial wells per year. These improvements to the 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 non-renewable groundwater infrastructure, Utilities recommends adding these improvements to the alluvial wells in early 2016 to supplement our water supply and increase our renewable water percentage as envisioned in the Water Resources Strategic Master Plan.
In 2015, the team identified the need for a multidisciplined project in the East Plum Creek corridor at the South Well Field near the future Perry Street crossing, east of I-25. The components included design and permitting for improvements in floodplain management, stream stabilization, source water infrastructure, facilities and environmental planning. The team identified that the improvements to the well field needed to be streamlined and that portion of the project was pushed ahead of the other design components and is ready for construction.
The team selected Directed Technologies Drilling as the best contractor to perform the horizontal well drilling for the project. They have successful experience drilling horizontal water supply wells. DTD is also a sub-consultant to Velocity Constructors Inc. on the Central Well Field Project, who was awarded the contract as a qualified bidder.
The Town completed a Sole Source Justification (see Attachment C) before requesting a proposal for the construction of the new horizontal wells due to the limited construction window before demand season. In comparison, the cost per linear foot of the Central Well Field Expansion is $482 per linear foot compared to the South Well Field Improvement Project which is estimated to be $413 per linear foot. Thus, Staff believes that the Town is receiving good value for the construction services with a company that has a strong resume for horizontal well installation. Staff recommends approving a contract award to the Directed Technology Drilling in the amount of $850,719.98 for construction services. In addition, Utilities requests a 10% Town-managed contingency in the amount of $85,072.00 for a total authorization of $935,791.98. Funding would be derived from the available funding in Alternative Source of Supply Project. Construction is planned to begin in late March 2016, pending Town Council approval, and be complete by June 30, 2016 for the work authorized in this request. This will allow water to be available for the summer demand season.
History of Past Town Council, Boards & Commissions, or Other Discussions
On February 24, 2016, Utilities Commission voted unanimously to recommend to Town Council approval of the contract award to Directed Technologies Drilling for the Plum Creek South Alluvial Well Field project.
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 the improvements to the well field 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 (PCWPF). 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 five well sites identified in the South Well Field (see Attachment B), clustered in two areas. Two wells in the South Well Field were replaced and three were rehabilitated in 2013. The horizontal alluvial lateral arms for Wells 11R and 13R 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. In addition, the data for Well 12R shows that the well needs to be replaced. The current growth is greater than the growth that was forecasted in 2012. As of October 31, 2015, Utilities is billing nearly 19,000 accounts, which is slightly higher than the forecasted value.
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, following 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 assurance that the renewable water supply will be available if the completion of the Plum Creek Diversion is delayed. The project was original combined with the East Plum Creek Stream and South Well Field Project for design and permitting. However, it was deemed necessary to separate the projects after meeting with Army Corps of Engineers and the delays that could occur with the necessary permitting that was needed for the originally scoped project. The design of the alluvial horizontal lateral arms and well were redesigned so that a permit from the Army Corps of Engineering was not needed.
Additionally, after operating the existing alluvial wells for three years, the Town has learned through experience that there are higher levels of maintenance required to obtain optimal production. These new improvements to alluvial wells 11R and 13R and the replacement of well 12R 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 improvements to the 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 deep wells continue to decrease.
Long-term, these additional improvements to the wells and replacement in combination with the existing alluvial wells and planned Plum Creek Diversion give the Town more overall capacity to capture water when it is available on East Plum Creek, for example, during free river conditions.
Due to the critical nature of this project and the limited construction window, the Town decided to sole-source the project to a qualified contractor, DTD. DTD is also a subcontractor to the qualified contractor for the Central Well Field Project which is currently in progress. DTD has submitted a proposal for $850,719.98.
The work will include the horizontal directional drilling of one horizontal well and two lateral arms. 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. In 2015, eleven percent of the water supply production was renewable. The addition of the two well fields would have increased the renewable production to between thirty to forty percent. The Town knows that developing the local water supplies is the most cost effective way to provide water 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 $25 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 delays associated with the diversion structure.
Budget Impact
The Utilities Department did not budget for this project in 2016. If Council approves the project, Utilities will transfer appropriated funds from the Alternative Source of Supply project Account Number 211-4375-443.77-30 which has $4.46 million dollars remaining to date. The project will be charged to the project line item budgets as shown below.
Project Amount Contingency Total Amount
211-4375-443.76-64 $850,719.98 $83,860.50 $934,580.48
PC -South Well Field
Staff Recommendation
Staff recommends approval of a contract award to Directed Technology Drilling for construction improvements of the Plum Creek South Alluvial Well Field in the amount of $850,719.98; plus a 10% Town-managed contingency in the amount of $83,860.50, for a total authorization request
of $934,580.48.
Proposed Motion
I move to approve a Resolution Approving a Contract Award to Direct Technology Drilling for Construction of the Plum Creek South Alluvial Well Field Project for the Plum Creek Water Purification Facility.
Attachments
Attachment A: Resolution
Exhibit 1: Contract
Attachment B: Location Map
Attachment C: Sole Source