8.2. SR 11-03-2014 - Laserfiche WebLink

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Rivers Edge Commons Park Alley Improvements 10/28/14 O Page 3 TASK 2 - DEVELOP PRELIMINARY WATER QUALITY IMPROVEMENTS Task 2.1—Develop Water Quality and Volume Control Options Once the theoretical pollutant loading is developed and the efficacy of a water quality and volume control system is determined, Bolton&Menk will be begin developing preliminary design options. The options will incorporate pervious pavement and an underdrain system that focuses on filtration and/or infiltration of stormwater to maximize pollutant removal and runoff volume reduction. The system will also incorporate high flow control structures and emergency overflows that tie into the existing drainage system and follow overland routes that minimize erosion and protect public safety. "On-grade"options will be considered in the higher sloped, north end of the alleyway. It is anticipated that traditional subgrade and drainage for pervious pavement will be difficult to employ and alternative methods will be necessary. Also, the flat area at the south end of the alley will utilized to the fullest extent to treat runoff from the highly impervious watershed. Task 2.2—Analyze Anticipated Pollutant Removal and Volume Reduction Each preliminary design option will include an analysis of the theoretical pollutant removal based on the loading calculations in Task 1. MtDS will be used to model the proposed option for TP and TSS removal. The hydraulic model will be utilize to determine anticipated volume reductions, analyze the impacts to the existing storm sewer system, and develop overland flow routes for larger rainfall events. Task 2.3—Summarize Preliminary Design Options The preliminary design options will be presented to the City, and additional options analyzed or refined based on City recommendations. Once the preliminary options are agreed upon,Bolton&Menk will summarize the options and the water quality and rate control outcomes in a report. We will also make recommendations for final design. TASK 3 - DESIGN PLANS AND SPECIFICATIONS Task 3.1—Develop Design Plans and Project Specifications Once the City and Bolton&Menk have agreed on a final design option, design plans and project specifications will be developed. We anticipate using Autodesk Civil 31)to develop plan sheets that meet City plan standards,including effective erosion and sediment control and City construction details. We will present preliminary design plans to the City at the 60% and 95% development stages for review. All comments and design modifications will be incorporated into the final plan set. TASK 4 - CONTRACT BIDDING AND AWARD Task 4.1—Prepare Contract Bidding and Award Bolton&Menk will prepare,if necessary, opinion of cost, advertisement for bids, answer bidder's questions,issue addenda, and assist with bid opening and prepare letter of award. If advertisement is not necessary, quotes will be solicited from multiple contractors.