IFB 10-21 SWM FACILITIES IMPROVEMENTS – MT. VERNON RETROFIT AND CITY OF ROCKVILLE WATER TREATMENT PLANT STREAM STABILIZATION AND INFRASTRUCTURE PROTECTION (The Project) is a stormwater retrofit, culvert replacement, stream stabilization and infrastructure protection project at two (2) separate locations: Mt Vernon SWM Facility and The City of Rockville Water Treatment Plant. The Project includes furnishing of all materials, labor, equipment, tools and services, and all other associated work as shown on the Construction Drawings and included in these documents.
SWM Facilities Improvement: Mt Vernon Retrofit and Culvert Replacement
The Mt Vernon retrofit and culvert replacement project is located at the southwest corner of Richard Montgomery High School on the 400 block of Mt. Vernon Place in Rockville, Maryland. The stormwater management facility was originally constructed in 1980. In 2003, the facility was converted into a shallow wetland system to provide water quality treatment to a 69.80 acre drainage area (48.99 acres impervious). The Mt. Vernon SWM Facility is located within the Cabin John Creek Watershed (MD Basin Code 02140207).
The project will remove sediment that has accumulated within the pool areas and provide water quality treatment to the maximum extent practicable in accordance with current stormwater management regulations. Woody vegetation will be removed from the embankment and a new culvert at Mt. Vernon Place will be installed to comply with MD-378 Pond Code and April 2015 Maryland Department of Environment Embankment Retrofit Design Guidelines. A forebay with an access road is proposed to facilitate future maintenance and access. This project realizes the community’s expressed preference for an attractive, yet maintainable enhancement to the neighborhood while providing 65% of the current water quality standard.
The project also includes an area outside of the LOD of approximately 1.2 acres of non-native/invasive (NNI) species control. The area of concern is located adjacent to the Mt. Vernon stormwater management facility, between Mount Vernon Place, Fleet Street, Richard Montgomery School, and Blandford residential development; as shown on the NNI Removal Plan.
Water Treatment Plant Infrastructure Protection and Stream Stabilization
The City of Rockville Water Treatment Plant is located at 10998 Sandy Landing Road, Potomac, Maryland. The restoration project is located within the stream approximately 750-feet west of the plant entrance, and within a portion of a Montgomery County unimproved right-of-way (Sandy Landing Road). Water, communication, and electric utility lines within Sandy Landing Road are currently threatened by an active stream diversion. The stream diversion has bypassed an existing 72-inch by 44-inch arched concrete metal pipe (CMP) culvert and exposed a concrete-encased duct bank for the utility lines. The stream diversion has completely washed out a section Sandy Landing Road preventing downstream maintenance access to utilities located in the floodplain. Further downstream from the bypassed culvert - gabion baskets, which are installed along the bank of the main channel to protect the utility duct bank as well as the primary intake line, are also failing.
The project restores flow through the existing culvert while reestablishing Sandy Landing Road. Clay plugs are proposed at the upstream and downstream limits to prevent the active stream diversion from reforming. The upstream clay plug will be protected with stacked boulder slope protection to ensure long-term stability of the project. Accumulated sediment within the existing culvert will be removed, and the bypassed channel downstream of the culvert will be regraded to ensure positive drainage.
A riffle-pool system is proposed to traverse the steep transition and reestablish the oxbow stream meander. Sill rock grade control structures are proposed at the upstream and downstream ends of the channel improvements to improve the longevity of the restoration. The failed gabion baskets will be removed and replaced with an imbricated rock wall. Riprap toe protection is proposed along the imbricated rock wall to prevent undercutting.
SUMMARY OF WORK
The City of Rockville intends to enter into a Contract with a qualified firm to provide construction and construction-related services for the Mt. Vernon Retrofit and the WTP Infrastructure Protection projects. SWM FACILITIES IMPROVEMENTS – MT. VERNON RETROFIT AND CITY OF ROCKVILLE WATER TREATMENT PLANT STREAM STABILIZATION AND INFRASTRUCTURE PROTECTION shall be paid for as follows:
Mt. Vernon SWM Facility in accordance with Pay Item No. 1 through Pay Item No. 28 and Pay Item No. 1001 through Pay Item No. 1024
City of Rockville Water Treatment Plant in accordance with Pay Item No. 29 through Pay Item No. 54 and Pay Item No. 2001 through Pay Item No. 2007
For the purposes of this Contract, the “City” shall refer to City of Rockville staff or a designated representative and the “Engineer” shall refer to the design engineer.
The engineering drawings and specifications are intended to cover a complete project. It should be distinctly understood that failure to mention any work which would normally be required to complete the project shall not relieve the Contractor of their responsibility to perform such work.
A virtual, telepresence pre-bid meeting will be held on TUESDAY MAY 04, 2021 AT 10:00 AM. Individuals interested in viewing the project locations are encouraged to do so independently prior to the pre-bid meeting. Bidders shall assume complete responsibility and liability for any and all visits. Bidders must register below in order to attend the meeting. This meeting is not mandatory; however, bidders are strongly encouraged to attend.
Register for the Virtual Pre-bid Meeting Here: Registration Link
DEADLINE FOR QUESTIONS
Questions pertaining to this bid may be directed to Jonathan Pierson, Principle Buyer via email only at no later than THURSDAY, MAY 13, 2021 AT 10:00 AM. Oral answers to questions relative to interpretation of specification or the bid process will not be binding on the City. When submitting questions include the following information in the email subject line:
IFB #10-21 Bid Question.
The estimated cost/classification of this project is within the range of $1,000,000 to as $2,500,001 (Class D). This range is in accordance with project classifications established by the State of Maryland DGS.