RFP for Lincoln St Stormwater Infrastructure Design Original RFP Documents Issued: June 25, 2019 RFP ADDENDUM #1 Page 1 of 1 Springfield Lincoln St Stormwater Infrastructure Design RFP ADDENDUM #1 July 11, 2019 NOTICE TO ALL POTENTIAL RESPONDENTS The Request for Proposals (RFP) is modified as set forth in this Addendum. The original RFP Documents remain in full force and effect, except as modified by this Addendum, which is hereby made part of the RFP. Respondent shall take this Addendum into consideration when preparing and submitting its Proposal. PROPOSAL SUBMITTAL DEADLINE The Proposal submittal deadline remains the same and is not changed by this Addendum. 1.0 – QUESTIONS AND ANSWERS The following questions and answers are provided as a matter of information to clarify issues raised about the RFP. Item Questions and Answers 1.1 Question: Was a preliminary design report prepared with the 30% plan, and if so, can it be shared? Answer: A formal preliminary design report was not prepared, however some additional information that may be helpful is attached to this addendum. 1.2 Question: Were any test pits or soil borings completed to verify subsurface conditions along the proposed storm drainage route or in the area of the proposed infiltration trench? Answer: Yes, the results of the test pit are attached to this addendum. Also attached is a site map depicting the location of the test pit. 1.3 Question: Will the AutoCad file and/or survey developed for the 30% design be available for use in the 100% design? Answer: Yes. END OF ADDENDUM
Transcript
RFP for Lincoln St Stormwater Infrastructure Design Original RFP Documents Issued: June 25, 2019
RFP ADDENDUM #1 Page 1 of 1
Springfield Lincoln St Stormwater Infrastructure Design RFP ADDENDUM #1
July 11, 2019
NOTICE TO ALL POTENTIAL RESPONDENTS
The Request for Proposals (RFP) is modified as set forth in this Addendum. The original RFP Documents remain in full force and effect, except as modified by this Addendum, which is hereby made part of the RFP. Respondent shall take this Addendum into consideration when preparing and submitting its Proposal.
PROPOSAL SUBMITTAL DEADLINE
The Proposal submittal deadline remains the same and is not changed by this Addendum.
1.0 – QUESTIONS AND ANSWERS
The following questions and answers are provided as a matter of information to clarify issues raised about the RFP.
Item Questions and Answers
1.1 Question: Was a preliminary design report prepared with the 30% plan, and if so, can it be shared? Answer: A formal preliminary design report was not prepared, however some additional information that may be helpful is attached to this addendum.
1.2 Question: Were any test pits or soil borings completed to verify subsurface conditions along the proposed storm drainage route or in the area of the proposed infiltration trench? Answer: Yes, the results of the test pit are attached to this addendum. Also attached is a site map depicting the location of the test pit.
1.3 Question: Will the AutoCad file and/or survey developed for the 30% design be available for use in the 100% design? Answer: Yes.
END OF ADDENDUM
ATTACHMENTS
Memo
To: Chris Yurek, Rick Logan, Jeff Strong, Naomi Johnson
From: Matthew Bissell
Date: February 1, 2019
Re: Project Narrative Summary
In 2018 the Southern Windsor County Regional Planning Commission (SWCRPC) in partnership with the Town of Springfield and the Health Care and Rehabilitation Services (HCRS) retained Dufresne Group to develop a solution to address the erosion issue to the east of Lincoln Street, adjacent to the HCRS parking lot. Figure 1 shows the project area. The bank is continuing to erode towards the parking lot, threatening the integrity of the areas west of the bank. This narrative summary identifies site/design considerations, permitting needs, and water quality improvement objectives and goals.
Stormwater flowing over the bank travels about 300 ft horizontally with a 100 ft drop in elevation before entering a stream at the base of the bank. Although the average grade is about 33%, there are significantly steeper sections including eroded and bare areas with vertical faces. The objective of the project is to redirect stormwater from the top of bank in an effort to stop further erosion.
A kick-off meeting was held December 4, 2018 to discuss the project need, design considerations and specific site constraints. Key discussion items are listed below.
• The Town of Springfield would like any infrastructure to be easily accessible by municipal staff for maintenance and repair.
• HCRS requested that existing building access and parking lot layout not be altered.
• The Vermont Department of Environmental Conservation representatives indicated a preference for above grade treatment and low-cost construction alternatives. They also noted any remediation work in the existing eroded area must be a second phase as the current grant will not fund the bank stabilization.
Stormwater from the residential areas adjacent to Lincoln Street is collected by a storm drainage network with catch basins along town streets. The storm drains are routed across HCRS property and discharge from an outfall north of the erosion area, with overland flow to the stream.
To mitigate continued erosion of the bank, the approach is to collect stormwater from the east end of Lincoln Street, direct it to a location within the HCRS property and install a treatment system for improved water quality prior to discharge. After the treatment
practice, the collected stormwater can be combined with the stormwater from the upstream residential areas at a storm drain manhole in the northeast corner of the HCRS property.
Under the Vermont Stormwater Manual, Tier 1 treatment options include dry swales, dry wells, infiltration systems and other practices for pollutant removal and runoff reduction. Tier 1 practices are expected to achieve the highest levels of treatment, when properly designed, constructed and maintained, with 80% total phosphorus and 98% total suspended solids removal.
Unless there are site or design constraints, such as poor soils or other conditions that prevent infiltration, or a high seasonal groundwater table, a Tier 1 water quality practice should be implemented.
The NRCS soil at the site is Windsor loamy sand with a permeability rating of 1-100 inches per hour. This soil is suitable for an infiltration practice. A test pit excavation at the HCRS property was performed to determine soil characteristics and estimate seasonal high groundwater. The excavation went to a depth of 6.7’ with no sign of seasonal high groundwater. Soil classifications and depths are listed below. The test pit location is shown in Figure 1.
Depth Soil Color Code Soil Color Description Soil Type
0-8” 10YR 3/3 Dark Brown Sandy Loam
8-48” 10YR 5/6 Yellowish Brown Fine Sandy Loam
48-80” 10YR 5/6 Yellowish Brown Fine Sand
Due to the classification of these soils, it is safe to assume a moderate to high infiltration rate, making a Tier 1 infiltration method of stormwater management feasible for the project.
There are no identified permit requirements for the project as the project does not involve expansion of impervious surface or disturbance greater than 1 acre.
The next step into design development will be to develop a conceptual design for the stormwater collection and treatment systems. Any recommended alternative treatment systems will be presented, and 30% complete design plans will be developed for review by the project team.
THE DRAWINGS FOR THIS PROJECT SHALL NOT BE REUSED OR ALTERED IN ANY WAY WITHOUT THE WRITTEN APPROVAL AND AUTHORITY OF DUFRESNE GROUP ANY REVISIONS SHALL BE MADE BY THE ENGINEER.
