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Town of Winchester, Massachusetts Weston & Sampson Project No. 2150665

October 30, 2015 Ms. Margaret White Project Manager Town of Winchester 71 Mount Vernon Street Winchester, MA 01890 Re: 416 Cambridge Street 40B Development Peer Review Ms. White: In accordance with our Agreement for Engineering Services, dated October 14, 2015, Weston & Sampson is pleased to present our peer review of the FX Winchester, LLC development at 416 Cambridge Street in Winchester. The purpose of our review was to evaluate the development’s impacts on the Town of Winchester’s Sewer, Water, and Drain Infrastructure. In addition, Weston & Sampson reviewed the site/civil design to verify that the site layout complies with standard engineering practice. Our review is based on the information submitted to the Town by FX Winchester, LLC, as part of the Comprehensive Permit Application. Weston & Sampson reviewed the following documents provided by the Town of Winchester:

• Stormwater Drainage Report, Dated: July 20, 2015, by: BOHLER Engineering • Site Development Plans: Winchester North at 416 Cambridge Street Dated: July 6, 2015, by:

BOHLER Engineering • Fire Truck, Driveway, Loading, and Snow Storage Exhibits emailed to David M. Elmer, PE,

Weston & Sampson on Monday, October 26, 2015 at 2:16 PM. Project Description FX Winchester, LLC’s proposed 40B Development at 416 Cambridge Street (Winchester North) includes 96 housing units on a 2.99 acre parcel. The proposed housing units include: 3 studio apartments, 43 – 1 bedroom apartments, 39 – 2 bedroom apartments, 10 – 3 bedroom apartments, and 1 – single family house (3 bedrooms). The main entrance to the development will be located on Wainwright Road, adjacent to the entrance to The Ledges condominiums. Sewer System Evaluation The sewer system for Winchester North will connect to the Town’s wastewater collection system on Wainwright Road at sewer manhole SB-195. Wastewater discharged from the development flows by gravity on Wainwright Road to Cambridge Street and then to Everett Avenue and Edgewater Place before it enters the MWRA collection system.

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The proposed development will produce a Title V flow of 17,270 gpd (157 bedrooms x 110 gpd/bedroom) and a peak flow of 69,080 gpd (17,270 gpd x 4 peaking factor). Weston & Sampson evaluated the existing sewer infrastructure between Wainwright Road and the MWRA connection at Edgewater Place. As part of the evaluation, Weston & Sampson performed a hydraulic capacity analysis (Appendix A) of the sewers downstream of the proposed development and reviewed 2015 sewer manhole and sewer pipe inspection data of the area (Figure 1). Hydraulic Capacity Analysis Weston & Sampson performed a hydraulic capacity analysis of the sewers downstream of the proposed development. The purpose of the analysis was to determine if the existing sewers have adequate capacity to accommodate the proposed sewer flows from the Winchester North Development. The hydraulic capacity analysis table (Appendix A) was constructed using sewer pipe invert elevations, diameters, lengths, and materials from sewer record drawings provided by the Winchester Engineering Department. The existing dry weather sewer flow between the proposed Winchester North development and Wildwood Street was estimated using a building/bedroom count (provided by the Town) and Title V flow rates. The estimated dry weather flow rate was calculated to be 100,374 gpd. Adding the Winchester North peak flows (69,080 gpd) increases the flow to 169,454 gpd. To be conservative, Weston & Sampson assumed that the total flow (169,454 gpd) enters the system at station 72+35 (Wainwright Road at Cambridge Street). The hydraulic capacity analysis indicates that the minimum theoretical carrying capacity is 553,749 gpd. The line segment with the limiting capacity is SB-192 to SB-147 (STA 69+85 to STA 65+05). Therefore, the existing sewer capacity on Cambridge Street, upstream of Wildwood Street, is adequate to accommodate the proposed dry weather sewer flows. The dry weather sewer flow on Cambridge Street between Wildwood Street and Everett Avenue was estimated using existing flow data from Meter #6, collected as part of the Hamilton Farms Flow Analysis in March and April, 2008. The Meter #6 flow rate includes flow from approximately 108,800 lf of sewer. The Meter #6 data indicates that the average dry weather flow is 937,000 gpd. To be conservative, Weston & Sampson assumed that the total average daily flow, including the proposed Winchester North peak flow (1,006,080 gpd), enters the Cambridge Street sewer at Wildwood Street, manhole SB-74 (STA 36+52). The hydraulic capacity analysis indicates that the minimum theoretical carrying capacity is 1,323,019 gpd. The line segment with the limiting capacity is SB-67 to SB-66 (STA 20+60 to STA 16+76). Therefore, the existing sewer capacity on Cambridge Street, between Wildwood Street and Edgewater Place, is adequate to accommodate the proposed dry weather sewer flows. Although the hydraulic capacity analysis indicates that the theoretical carrying capacity of the downstream sewers will not be exceeded during dry weather conditions, sanitary sewer overflows have been observed on Cambridge Street during significant wet weather events. During significant wet weather events the additional flow from the proposed Winchester North development will increase sewer system overflow volumes at Edgewater Place. Sewer System Investigation & Recommended Rehabilitations Weston & Sampson reviewed the 2015 sewer manhole and sewer pipe inspection data on Cambridge Street, Everett Avenue, and Edgewater Place in the downstream flow path of the proposed development. Television inspection was not performed on Wainwright Road. Sewers on Cambridge

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Street, Everett Avenue, and Edgewater Place include 3,287 lf of asbestos cement (AC) pipe, 7,639 lf of vitrified clay (VC) pipe, and 226 lf of reinforced concrete (RC) pipe that range from 8-inches to 24-inches in diameter. Our review identified 4,323 gpd of removable peak infiltration. Structural defects, including cracked pipe, broken pipe, holes, and surface spalling, were also identified in 18 sewer segments (3,678 lf). Weston & Sampson recommends performing the following sewer rehabilitations:

• Perform cementitious lining of manholes: 2 manholes, 13 vf • Perform chemical root treatment of sewers: 3,715 lf • Perform clean, inspect, test and seal: 4,855 lf • Grout sewer service connections: 9 services • Install cured-in-place short liners: 121 lf • Install manhole to manhole cured-in-place pipe: 740 lf • Perform television inspection of Wainwright Road sewer (SB-195 to SB-193): 313 lf

The estimated cost of these sewer rehabilitations is $174,282. The proposed sanitary sewer rehabilitations are indicated on the project map included as Figure 2. Utility Plan Review Weston & Sampson reviewed the Utility Plan (Sheet 6 of 14), produced by Bohler Engineering. The proposed 8-inch PVC service connection has a 5.0% slope. However, based on the invert elevations indicated on the plans and proposed pipe length of 88 lf, the slope is actually 5.93% [(111.42 - 106.2) / 88 lf). The Utility Plan should be revised to indicate the correct incoming invert elevation at the sewer manhole on Wainwright Road (107.42). Weston & Sampson identified a potential conflict between the 8-inch PVC sewer service and 15-inch HDPE drain, 46 lf downstream of manhole SMH-1. The proposed sewer invert at this location is 109.12 and the proposed drain invert is 107.9. The elevation at the top of the 15-inch HDPE drain is 109.15. The layout of the sewer and drain infrastructure should be evaluated to determine if the sewer line could be laid under the drain. At a minimum, the slope of the sewer and/or drain should be revised to provide a minimum 12-inch separation. All sewer pipes shall be SDR35 PVC pipe and all manholes shall be precast. The sewer system shall comply with all ASCE Manual on Engineering Practice – NO. 60, DEP, and Town of Winchester Requirements. Drain System Evaluation Summary The impact land development has on a drainage basin is a critical concern for tributary communities. Concerns center on stormwater quality and quantity which are directly impacted by the percentage of pervious and impervious land cover within a watershed. Pervious land cover, such as grass, soil, and woods, decrease the amount of stormwater runoff, while impervious land cover, such as pavement and buildings, increase the amount of stormwater runoff from a storm event.

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The Winchester North Development Project, drainage calculations have not met the following requirements.

1. Document Adequate Drainage at Low Points and Impervious Areas – Show inlet capacity calculations comparing inlet capacity to proposed inflow.

2. Preserve the existing hydrologic regime through the use of Low Impact Development (LID).

3. Precipitation data was not NRCC Publication RR 93-5 as required. Drainage calculations shall be updated to reflect the required precipitation data, including pre and post construction flow rates and volumes.

4. The 25-year design storm intensity for collection system design in the Hydraflow Storm

Sewer results table should be confirmed and used consistently in the calculations. The results table uses varying intensities and is not consistent.

5. Analysis of the closed drainage system for the 100-year event velocity check and routing of

overflows was not completed.

6. The proposed project includes a new connection from Infiltration Basin 2 to Town owned drainage system on Wainwright Road. Analysis of the Wainwright Road drainage system and downstream drainage is required for the 25, and 100 year storm events to confirm available capacity exists for the new flow.

7. Post construction volume calculations show an increase in runoff volume compared to

existing conditions.

8. Provide a profile drawing of utility crossings to avoid potential conflicts. There are several utility crossings along the route of the proposed drainage structures.

9. Provide confirmation of maintenance inspection port installation. Inspection ports are not

optional as show on the construction details sheet 14.

10. Is there adequate protection/collection for any runoff from the west slope?

11. The outlet from Infiltration Basin 1 creates a new outlet at the Town line with Woburn. Based on the contours it appears that the new discharge location may direct runoff in a different direction. Additional information is required in this area. New overland flow to Woburn is not permitted.

These deficiencies have limited our ability to review and comment on compliance with the Massachusetts Stormwater Standards.

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Massachusetts Stormwater Management Standards Review Massachusetts Stormwater Standards 1 thru 10 are applicable to the project. We have determined that the proposed stormwater system is not in compliance with the standards to the extent described below. Standard 1 - No New Untreated Discharges – No new s tormwater conveyances (e.g., outfalls) may discharge untreated stormwater directly to or c ause erosion in wetlands or waters of the Commonwealth. Upon review of the Stormwater Drainage Report and Site Plan we have determined that the information presented is incomplete. Confirmation that all impervious area is triburtary to the Stormceptor systems is required and explanation on why the outfall from Infiltration Basin 1 is not considered a new outfall. Standard 2 - Peak Rate Attenuation – Stormwater man agement systems must be designed so that post-development peak discharge rates do not e xceed pre-development peak discharge rates. Upon review of the Stormwater Drainage Report and Site Plan we have determined that the information as presented may be inaccurate. Additional runoff design points appear to be required which will affect the results. Standard 3 - Recharge to Groundwater – Loss of annu al recharge to ground water shall be eliminated or minimized through the use of infiltra tion measures. Upon review of the Stormwater Management Report, Site Plan and hydrologic modeling computations we have determined that the attenuation calculations (Standard 2) and recharge calculations (Standard 3) require further update and modification. Upon receipt of updated calculations a determination of compliance with Standard 2 and Standard 3 can be verified. Standard 2 and 3 Comments

1. It appears that the selection of two (2) stormwater design points is insufficient and will affect the pre and post construction peak flow rate comparison. The total area of 1.88 Acres for E-1 is not tributary to DP1. Overland flow to the property line that does not reach DP1 requires additional design points. Please provide an existing contour plan similar to sheet 5 Grading Plan with existing contours and additional design points only. Recalculate existing and proposed runoff rates with new design points.

2. The inclusion of P-1 in the flow calculations at DP1 may show a false reduction of flow rate

from the existing to proposed condition.

3. Design Point DP2 should be represented as two points in the proposed analysis. Existing runoff travels overland to Cambridge Street and to downstream drainage on Cambridge Street. Proposed runoff travels overland to Cambridge Street and piped from Infiltration Basin 1 to a drain on Wainwright Road.

4. Provide backup data for ADS StormTech system to document volumes per depth of storage.

(Storage vs Elevation Curve)

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5. Provide detailed HYDROCAD Data for runoff volumes per design point to compare with the summary sheets provided.

6. The dimensions provided for the field storage appear inaccurate as they do not account for

a reduction for manifold and pipe connections. Is storage volume for the ADS StormTech system end caps included in the volume provided?

7. Confirm Prismatoid dimensions on HYDROCAD Storage input

8. Document ADS StormTech effective area used in HYDROCAD.

9. Provide a table sumarizing pre and post primary outlet flow to each design point that

correlates with the HYDROCAD output. Standard 4 - Water Quality – Stormwater management systems must be designed to remove 80% of the average annual post-construction load of Total Suspended Solids (TSS). Upon review of the Stormwater Management Report, Site Plan, hydrologic modeling computations, BMP sizing data, and TSS calculation worksheet the data is incomplete. TSS calculation sheets need to be developed for each outlet train with all BMP’s included. Deep Sump Catch Basin are not included and only one TSS worksheet was submitted. Confirm location of stormceptors and their ability to collect all impervious areas. Standard 5 –Land Uses With Higher Potential Polluta nt (LUHPPL) Upon review of the Stormwater Management Report, Site Plan, and hydrologic modeling computations it appears that the project is not a LUHPPL with a high intensity parking lot and does not generate higher concern. Standard 6 –Area of Critical Environmental Concern (ACEC) Upon review of the Stormwater Management Report and Site Plan, the project does not appear to be in a ACEC. Standard 7 –Project Classification – New Developmen t or Redevelopment Upon review of the Stormwater Management Report and Site Plan, the project appears to be in compliance as a new development project pending review of updated calculations. Standard 8 – Construction Period Pollution Preventi on – Erosion and Sedimentation Controls Upon review of the Stormwater Management Report, the project appears to be incomplete. Please provide an itemized list of Construction Pollution Prevention measures. Potentially missing items include:

• Stabilized Construction Exits – for offsite sediment protection • Pavement Sweeping – for sediment removal

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• Temporary Sedimentation Basins and Diversion Basins - as necessary for fine-grained sediment protection

• Dewatering Protocol – for sediment removal Standard 9 – Operation and Maintenance Plan Upon review of the Stormwater Management Report the project appears to be incomplete. Please provide an itemized list of Operation and Maintenance Plan items. Potentially missing items include: Long-Term Operation and Maintenance Plan components:

• Maintenance of Pavement Systems • Maintenance of Vegetative areas • Management of Snow and Ice

Standard 10 – Prohibition of Illicit Discharges Upon review of the Stormwater Management Report and Site Plan, the project appears to be in compliance. Conclusion The proposed Winchester North Project is not in compliance with evaluation criteria, including Massachusetts Stormwater Standards and Town of Winchester Standards. Weston & Sampson recommends a meeting with the Applicant’s Engineer to review and discuss our comments. Water System Evaluation Weston & Sampson completed an evaluation of the water system for the proposed 96 unit Winchester North apartment building located at 416 Cambridge Street in Winchester. The proposed building’s water service will be obtained from the 10-inch water main in Wainwright Road. By changing the location of the normally closed division gate valve on Wainwright Road to the intersection with Cambridge Street, this 10-inch main will be included in the town’s West High Service system. The purpose of this evaluation was to determine if the proposed apartment building would receive adequate water service (pressure and flows), and if it would have an adverse impact on town of Winchester’s water distribution system. A computer based hydraulic model was used to evaluate the capabilities of the water distribution system in the area of the proposed apartment building. Regulations & Evaluation Criteria Massachusetts Department of Environmental Protection (DEP) regulations were used as the basis for our determination. DEP Guidelines and Policies for Public Water Systems and Massachusetts General Law (310 CMR 22.04) require that any public water system must provide 35 pounds per square inch (psi) pressure to all homes and businesses, under all normal conditions of flow. Normal conditions include peak hour demands, usually the most severe demand condition that occurs during the hottest summer days. DEP Guidelines and Policies for Public Water Systems and Massachusetts General law (310 CMR 22.19) require that any public water system shall provide 20-psi pressure under fire flow situations. System adequacy is evaluated under a fire flow situation occurring during a maximum day domestic

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demand condition. Service Area & Model Development Bently® WaterCAD® V8i (SELECTseries 4), hydraulic modeling software, was used to model the impact of the proposed apartment building on the water distribution system. A plan showing the site layout for the proposed apartment building was provided by BOHLER Engineering. Information from this plan was used to model the apartment building relative to the existing water main on Wainwright Road. The available fire flow to the proposed apartment building was modeled at the location of the parking garage. We modeled the new water main as 10-inch and 8-inch cement lined ductile iron pipe to service all points of the apartment building. The length of the proposed water main was scaled from the plans and included into the model accordingly. The proposed apartment building includes 157 bedrooms. The domestic water demands for the proposed apartment building were estimated utilizing Title 5 wastewater design guidelines of 110 gpd per bedroom, multiplied by 157 total bedrooms. These estimates generally represent the maximum day water use. This demand value was then considered the maximum day demand for the proposed apartment building. Peak hour demand was obtained by multiplying the maximum day demand by 4. These demands are typical of those we’ve seen in suburban communities similar to Winchester. Table 1 shows the estimated water demands for the proposed apartment building.

TABLE 1 Estimated Water Demands

Demand Condition Water Demand (gpd)

Water Demand (gpm)

Maximum Day 17,270 12.0

Peak Hour 69,080 48.0

It should be noted that the demands shown in Table 1 are to be used for planning purposes. The demand does not represent the true peak demand based on fixture count that will be used for sizing water services and meters. Modeling Evaluation The model was run to determine if the following demand conditions could be met: • Maintain a minimum working pressure of 35 psi under the peak hour demand condition in the water

distribution system. • Provide the ISO needed fire flow to the apartment building during maximum day demand at a

pressure greater than 20 psi. Modeling Results Peak Hour Demand Pressures The hydraulic model indicates that the town’s water distribution system (including the apartment building) maintains pressures well above 35 psi during peak hour demand periods. For peak hour

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demands the pressure at the apartment level’s ground level is anticipated to be approximately 112 psi. This pressure exceeds the 80 psi threshold and will require a pressure reducing valve or valves to meet plumbing codes. Required Fire Flow We modeled the proposed apartment building with 8-inch water main served from Wainwright Road. The available fire flow in the apartment building at the garage level was approximately 2,600 gpm at 20 psi. Although it is impossible to calculate the required fire flow of the apartment building at this stage in the design, we highly recommend calculating the required fire flow and verifying that it does not exceed the available capacity of the system. Apartment complexes similar to the one proposed typically require a flow in the range of 2,500 gpm at 20 psi for firefighting. Water Mains, Hydrants, and Valves The current location of the normally closed division gate valve places the new apartment building on the town’s Middle Low service system. The division gate must be changed from its current location approximately 100 feet west of the proposed entrance to a location on Wainwright Road near its intersection with Cambridge Street. This change would allow the apartment building to be served from the town’s West High service area. The West High service area receives water from the MWRA through a pressure reducing valve. No change will be required to the pressure reducing valve. The developer’s site plans show the apartment building being served by an 8-inch water main off the town’s 10-inch main in Wainwright Road. We recommend installing a 10-inch water main to serve the apartment building. The 10-inch water main should branch off into a three way manifold with a properly sized domestic water line, properly sized fire sprinkler service line, and a minimum of 8-inch line to serve the hydrants on the property. Each of the three lines should have a gate valve near the street/property line so that the three lines can be isolated separately. This is beneficial so that if one line were compromised, the gate valve could be closed and the remaining lines would still maintain service and pressure. Also, the maximum length of 6-inch hydrant lateral should be kept below 40 feet. We suggest that the developer modify the locations of at least three of the four proposed fire hydrants. The fire hydrant adjacent to the entrance south of the building can remain in its proposed location. The proposed hydrant to the west of the entrance is located up a steep embankment and does not appear to be accessible by fire truck. The two proposed hydrants to the north of the building would require a fire truck to drive through the lower level garage, which is a safety concern during a fire situation. Hydrants in these proposed locations would be a challenge to use effectively. In addition, these three hydrants are located in close proximity to the building (approximately 7, 13, and 30 feet from the exterior wall) making them susceptible to damage during a fire event and unsafe to access. Additionally, current hydrant locations leave the west corner of the building vulnerable as there are no nearby hydrants and no roadway to allow access for firefighting and rescue. We recommend adjusting locations to be set back further, at least 50 feet from the building, and installing an access road along the perimeter of the building to improve accessibility by fire apparatus.

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Site/Civil Design Evaluation Weston and Sampson has reviewed the plans and offer the following observations related to the site/civil design features:

1. Fire truck access is only provided to a portion of the front and a portion of the back of the building. It should also be noted that the vehicle access to the back of the building must travel under the building, which is a safety concern during a fire situation.

2. The size of the vehicle used in the “Fire Truck Exhibit” needs to match the Town of Winchester’s Fire Department equipment. This should be verified with the Winchester Fire Department

3. The “Driveway Location Exhibit” indicates there is 106 feet of separation between turning movements. The distance between driveway openings is approximately half of this distance and is shorter than desirable. The developer should demonstrate that stacking of vehicles will not create a problem. The developer should demonstrate that site distance is adequate for all turning movements including vegetation and snow piles.

4. The “Snow Storage Exhibit” indicates designated areas but does not provide quantity. The northwest storage area is located behind a fire hydrant. This area is capable of holding approximately 13,000 cubic feet if piled to 10-feet. This area would reach capacity after only 28-inches of snow assuming plowing of pavement only and 50% compaction. Additional storage locations will likely be required or excess snow will need to be moved off site.

5. The “Loading Exhibit” indicates a truck parked without blocking any other parking spots, however there is a dumpster shown in the same location on the Site plan.

6. The developer should provide a sidewalk to Wainwright Road to accommodate future connection to pedestrian accessible sidewalks.

7. Retaining wall details were not provided. Drains should be provided behind retaining walls and the discharge points identified on the plans. The retaining wall west of the existing home is 11.5 feet tall and is very close to the existing building.

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Weston & Sampson appreciates the opportunity to present our findings. We are available at our earliest convenience to discuss our report. Please contact me if you have any questions. I may be reached at (978) 532-1900 x2280 or elmerd@wseinc.com. Very Truly Yours, WESTON & SAMPSON ENGINEERS, INC.

10/30/2015

XDavid M. Elmer, PE

Vice President

Signed by: David Elmer O:\Winchester\416 Cambridge Street - 40B\Report\Winchester North Peer Review Report.docx

FIGURES

APPENDIX A

HYDRAULIC CAPACITY ANALYSIS