To: Honorable Mayor and Members of Town Council
Through: David L. Corliss, Town Manager
From: Mark Marlowe, P.E., Director of Castle Rock Water
David Van Dellen, Stormwater Manager
Title
Resolution Approving a Construction Contract with 53 Corporation, LLC for the Metzler Ranch Pond Retrofit Project
Body
________________________________________________________________________________
Executive Summary
The purpose of this memo is to request Town Council authorization of Resolution (see Attachment A) Approving an Agreement for a Construction Contract between the Town of Castle Rock and 53 Corporation LLC for the Metzler Ranch Pond Retrofit Project (see Exhibit 1). The value of this contract agreement (Base Bid plus Bid Alternate 3) is $772,736 plus a 10% Town managed contingency in the amount of $77,274 for a total authorization of $850,010. This project will restore 3.8 acre-feet of water quality capture volume and flood control volume to the detention pond and is needed in order for the Town to maintain compliance with their MS4 permit and reduce risk of flooding on Front Street. This is the second phase of a two phase project to address deficiencies in the regional pond designed to treat over 450 acres of residential and commercial property, including Metzler Ranch and the Target merchandise complex. The first phase of the project was completed in 2005 and addressed vertical elevation errors in the two main storm sewer trunk lines entering the pond. At that time, it was identified that the pond did not meet design volumes nor did it meet current design standards for treating water quality and regional flood control. The second phase of this project was also identified in the “Tributary C and D Watersheds Master Plan” (Plan), prepared by RESPEC Consulting, dated July 2014.
This project is located at the downstream end of Reach 2 of Tributary D; located at the southeast corner of the intersection of Front Street and Sam Walton Lane, adjacent to the Metzler Ranch Park. (see Attachment B). Improvements include grading, excavation, material haul-off, concrete trickle channels, two new inlet pipe forebays, upgrade two existing forebays, water quality micro-pool at the outlet, stabilized maintenance access routes, selective tree removal and vegetation restoration. This project was identified as a legacy Stormwater infrastructure project as part of the Council authorized bank loan. Below is a summary of the total cost of the project.
|
Phase I Total (2005) |
Phase II Engineering |
Phase II Construction |
Total Cost |
|
$353,000 |
$86,520 |
$850,010 |
$1,289,530 |
Notification and Outreach Efforts
The project is located within Town owned open space and designated drainage easements adjacent to the Metzler Ranch Park. Staff will provide notifications via email and/or direct mailings to adjacent property owners, news releases and social media postings, as needed. Project details and updates will be provided on CRgov.com/water.
History of Past Town Council, Boards & Commissions, or Other Discussions
Castle Rock Water Commission was presented this contract agreement at the scheduled December 9, 2020 meeting. Castle Rock Water Commission voted [unanimously] in favor of recommending Town Council approval of this agreement.
Discussion
The Metzler Ranch Detention Pond (Pond) was built as part of Metzler Ranch Filing 1 in 2001. In 2005, the Town completed improvements including the lowering of storm sewer pipe end sections and adding two forebays for sediment management. Analysis of the regional detention pond concluded that approximately 3.5 acre-feet of additional water quality capture is needed to restore the design capacity of the facility. It is believed that a survey bust in the original construction and sediment accumulation during upstream development activity in the watershed contributed to the loss of pond volume.
The Pond currently receives stormwater flows through four separate existing storm sewer pipes varying in size from 30-inch diameter to 78-inch diameter in addition to surface flows from the adjacent terrain. Flow from the four inlet pipes travels across the vegetated pond floor to the outlet structure located on the west side of the Pond. Over the years, channels have eroded into the pond floor creating areas of water ponding and growth of volunteer trees and vegetation all of which impedes maintenance and the design function of the Pond.
The proposed improvements will increase the pond volume by 3.8 acre-feet, add improvements to control sediment entering the pond and provide Town maintenance crews access to critical locations within the pond to perform routine maintenance. Specific proposed improvements include:
• Increase the pond volume by removing 7,400 CY of material from the pond bottom.
• Upgrade two forebays constructed in 2005 to include concrete floors replacing the existing rip-rap floors and provide maintenance access into the forebay.
• Install two new forebays with concrete floors and maintenance access into the forebay.
• Install low-flow concrete trickle channels from each forebay to the outlet structure to enhance erosion control and maintenance.
• Install a micro-pool, for enhanced water quality at the outlet structure.
• Install stabilized maintenance access route from the top berm of the Pond onto the Pond floor and to all pipe inlet locations. These stable routes provide safe access during wet soil conditions.
Following approval of the design documents, the project was advertised for public bid from qualified contractors on October 26, 2020 on the Town’s Rocky Mountain Bid Net site. Bids were received from five contractors on Monday November 16, 2020.
The Bid Document included the Base Bid and three Bid Alternatives. The total bids for each bidder are summarized below:
• The bid from 53 Corporation, LLC, located in Sedalia, CO was $980,123.00.
• The bid from Western States Reclamation, Inc., located in Frederick, CO was $1,683,799.00.
• The bid from Frontier Environmental Services, LLC, located in Arvada, CO was $1,496,751.00.
• The bid from HPM, Inc., located in Englewood, CO was $1,037,602.80.
• The bid from Goodland Construction, Inc., located in Golden, CO was $1,268,759.00.
• The Engineer’s estimate for the project was $998,796.00.
Each contractor was determined to be equally qualified to perform the detention pond retrofit work.
Following the bid opening for the Metzler Ranch Pond Retrofit Project it was found that 53 Corporation, LLC was the low bidder for the project. Upon further review of the bids, project budget and project scope, Stormwater staff decided to proceed with award and construction of the Base Bid and Bid Alternate No.3 for the project. Bid Alternate No. 1 included an alternative aggregate material for the maintenance access routes to that included in the Base Bid. The cost of this alternate in the 53 Corporation bid is $28,963.00. Bid Alternate No. 2 included modifying the pond spillway configuration. The cost of this alternate in the 53 Corporation bid is $178,424.00. Due to budget limitations, alternatives 1 and 2 were not included. The existing spillway configuration has a minimal risk related to an overflow event and the cost of the improvements do not correlate with the potential benefits. Alternate No. 3 replaces the existing rip-rap floors within the two largest pipe inflow forebays with new concrete floors and improves maintenance crew access into each forebay for sediment removal. The cost of this alternate in the 53 Corporation bid is $96,870.00. The bid from 53 Corporation, LLC, for the Base Bid plus Bid Alternate No. 3 totaled $772,736.00. When comparing the 53 Corporation bid for Base Bid plus Bid Alternate No. 3 to all other bids, 53 Corporation remains the lowest bidder for this scope of work.
Budget Impact
Funds for this construction will be charged to the stormwater account below. Project funds will be appropriated in a budget transfer from the Stormwater capital account for East Plum Creek which experienced delays due to environmental permitting. Sufficient funds are available in the current budget within stormwater capital to cover this project.
|
Fund Description |
Account Number |
Amount |
Contingency |
Total |
|
Metzler Ranch Pond Retrofit Project |
212-4475-444.77-18 |
$772,736 |
$77,274 |
$850,010 |
Staff Recommendation
Staff recommends authorization of a resolution awarding the Agreement for a Construction Contract between the Town of Castle Rock and 53 Corporation LLC for the Metzler Ranch Pond Retrofit Project in the amount of $772,736 plus a Town managed 10% contingency in the amount of $77,274 for a total authorization of $850,010.
Proposed Motion
“I move to approve the Resolution as introduced by title.”
Attachments
Attachment A: Resolution
Exhibit 1: Construction Contract
Attachment B: Project Site Map