Consideration of and action on authorization of a Construction Contract with NBG Constructors, Inc., in the amount of $576,835.00, for the construction of the Flood Control Improvements - Dam III Oyster Creek at Lexington Project, CIP CDR2103.

Dam III, constructed in the late 1960's, is owned by the City of Sugar Land (COSL) and operated by the Gulf Coast Water Authority (GCWA). The dam is located along Oyster Creek, approximately 2.4 miles downstream of US Highway 59/Oyster Creek, and about 500 feet north of the intersection of Settlers Way Blvd and Lexington Blvd. Dam III is used both for flood control purposes and to impound water along Oyster Creek as part of a series of dams constructed for water supply for the former Imperial Sugar Refinery of Sugar Land, Texas.

GCWA's canal system is composed of manmade canals and natural channels beginning at the GCWA’s Shannon Pump Station on the Brazos River south of Fulshear, Texas. This Brazos River water is pumped to Jones Creek and flows downstream through the GCWA canal system. This canal system conveys water through Jones Creek to Old Second Lift Dam (the beginning of Oyster Creek near Pecan Grove), sequentially Dam I, Dam II, and Dam III, all along Oyster Creek. Water also enters the canal system from rainfall events directly over the canal system as well as local runoff along the canal system. Water released from Dam III is made during flood events via a concrete service spillway consisting of 6 metal slide gates with electric actuators. 

The Texas Commission on Environmental Quality (TCEQ) is the regulatory agency responsible for the administration of the dam safety rules in Texas. TCEQ adopted new dam safety rules in January 2009. After TCEQ’s new dam safety rules came into effect, the COSL contracted with Freese & Nichols, Inc. (FNI) in 2010 to perform an initial assessment of all three (3) Dams located across Oyster Creek within the City. Based on this initial assessment by FNI, Dam III was found to be hydraulically inadequate of passing 75% of the probable maximum flood (PMF) required by TCEQ. The PMF is defined as the flood that may be expected from the most severe combination of critical meteorological and hydrologic conditions. 

After this assessment, COSL contracted with FNI to perform a Preliminary Engineering Report (PER) on Dam III in 2015 and to provide alternatives for modifications of the dam in order to comply with TCEQ regulations. The PER concluded that Dam III could be improved to safely pass the critical event with the construction of flood control improvements.

The design was completed in 2018, and construction funding for this project was approved as one of the 2019 General Obligation (GO) bond projects for FY21 funding. The scope of work for this project includes the following items: mobilization, tree plant protection, care of water, site clearing, construct a reinforced concrete trapezoidal channel spillway to the east of the existing this reinforced concrete gated service spillway, install all-weather access road, install a staff gauge, install a security camera system, install riprap slope protection with backfill, earthwork excavation/backfill, and reinforced concrete slope pavement.

On August 19 and 26, and October 2 of 2020, the City published an Invitation to Bid (ITB) for construction of this project. The bids were opened on September 17, 2020. The COSL received seven bids for this project.  A bid summary table is provided below:

Complete Concrete was the apparent low bidder. However, after FNI performed an evaluation of the bids, FNI indicated that the bid from Concrete Complete to be unbalanced and abnormally low on some lump sum bid items. In addition, FNI checked references and could not verify that Complete Concrete completed three projects (required in the bid documents) in the past five years which were similar in size and scope. Therefore, FNI concluded that Complete Concrete's bid did not meet submittal requirements and are not a responsible bidder. FNI made the recommendation to award NBG Constructors, Inc. as the lowest responsible bidder.

Funding for this project is from CIP CDR2103, with an available budget of $800,000.00. After awarding the construction contract of $576,835.00 to NBG Constructors, Inc., the remaining funds will be used for construction administration, materials testing, and contingency.

In accordance with Policy CO-0110, Notification of Construction Impacts and Service Interruptions, this project is classified as a Localized Project. The project will have no service interruptions (i.e., water/sewer interruption, transportation interruptions).

The Notice to Proceed for the project is anticipated to be issued in November 2020, and construction should be completed within 150 calendar days. The substantial completion of the construction is anticipated in March 2021.

The Engineering and Public Works Departments recommend that the City Council authorize the approval of the construction contract in the amount of $576,835.00 with NBG Constructors, Inc., for the construction of the Flood Control Improvements – Dam III Oyster Creek at Lexington, CIP CDR2103.