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Home My WebLink About240926 Response #2 Stormwater Peer Review - - 0 GREAT POND ROAD ENVIRONMENTAL September 26, 2024 Ms.Jean Enright, Planning Director North Andover Planning Board 120 Main Street North Andover, Massachusetts 01845 . . North Lake lal Stormwater Peer Revoiew ichew*lck Boat Launch North Andover,, Massachusetts Dear Ms. Enright and Planning Board Members, On behalf of the Town of North Andover(the Applicant), Environmental Partners Group, LLC(EP) has prepared this letter in response to the peer review comments received from Horsley Witten Group (HW) on September 20, 2024. A list of attachments to this letter is provided below. Horsley Witten Group'sfinal open comments are listed below in bold followed by EP's responses in italics. Stormwater Management Design Peer Review 7.b:The Applicant mentions"project compliance with the performance criteria as identified in Section 250-27". However, §250-27 relates to the O&M Plan,while §250-23 relates to redevelopment projects.Attachment 5 provided by the Applicant(North Andover Design and Performance Criteria with Attachments) illustrates how the project complies with Standard 2, but it does not directly reference the stormwater requirements in §250-23. Specifically, §250- 23C provides specific requirements for redevelopment sites such as reducing total phosphorus. HW suggests that the Applicant confirm it is complying with §250-23. Environmental Partners referenced the 2-15-2011 version of the Stormwater Management bylaws located on the North Andover Planning Board webpage link. In review of the updated version for redevelopment projects, we confirm that we are complying with the redevelopment standards of 23C. The project does not propose any new impervious areas. Therefore, the project does not propose to add TSS or total- phosphorus post construction. The proposed bioretention areas will improve the area overall by treating additional impervious areas of the paved right of way on Great Pond Road as an added benefit. Our submission included treatment to show the additional TSS removal outside of our proposed project area. 8.c:The Applicant confirmed that the construction entrance on Sheet C-2 of the permit drawings is at least 30 feet long. However, on Sheet CD-1 the construction entrance detail is Page::'!".i') shown as 15 feet long. HW recommends that the Applicant confirm that the plan and construction detail are consistent. There are no changes to the construction entrance. The construction entrance is 30 ft long as shown on the plan set. The detail shown is a standard typical detail shown as 15"+/-. 9.a: In accordance with §250-27 A.An operation and maintenance plan (O&M Plan)for the permanent stormwater management system is required at the time of application for all projects that include the structural and nonstructural stormwater BMPs.The Applicant has provided a BMP location map and O&M Plan for the Bioretention Areas only. However, an O&M Plan is required for all structural and nonstructural stormwater BMPs, which includes permeable pavers, riprap aprons, and the lined swale. HW recommends that the Applicant provide the O&M Plan for long term functionality of the proposed stormwater system. Please find attached the updated 0&M plan including pavers and rip-rap. 9.b"the Long-Term Operation and Maintenance Plan shall at a minimum include: ... 3.The routine and non-routine maintenance tasks to be undertaken after construction is complete and a schedule for implementing those tasks; ... 6.An estimated operations and maintenance budget". HW recommends that the Applicant include the information noted above to confirm the Town fully understands what is expected for long term maintenance. Please find attached the updated O&M plan. Sincerely, Environmental Partners Group, LLC Ryan J. Paul, PE, CFM Senior Project Manager O: 617.657.0260 E: rjp@envpartners.com Attachments: 1. Revised O&M Plan n v I a IIrt ri e SmC 0 II ENVIRONMENTAL VM PARTNERS OPERATIO N A ND M AINTENA N CE P LAN NORTH LAKE C 0 C C E1W C K BOAT LAUNCH TOWN GF NORTH ANDOVER i o et e:nt i o n Are a s Premature failure of bioretention areas is a significant issue caused by lack of regular maintenance. Ensuring long-term maintenance involves sustained public education and deed restrictions or covenants for privately owned cells. Bioretention areas require careful attention while plants are being established and seasonal landscaping maintenance thereafter.Table 1 shows the bioretention maintenance schedule below. �uiif o Oua i�u� u�li�o uim i i�i of luoi i�o�om o�i oii mi i i m - � s m oio o Ima o Oo '... . ii ii�i of li mi o Activity Time of Year Frequency Inspect and remove trash Year round Monthly Mulch Spring Annually Replace dead vegetation' Spring Annually Prune Spring or Fall Annually Replace entire media and all Late Spring/early Summer As needed vegetation 1. See Planting List in Drawing Plans 2. Paying careful attention to operation and maintenance can extend the life of the soil media. Inspect soil and repair eroded areas monthly. Re-mulch void areas as needed. Remove litter and debris monthly. Treat diseased vegetation as needed. Remove and replace dead vegetation twice per year(spring and fall). Remove invasive species as needed to prevent these species from spreading into the bioretention area. Replace mulch every two years, in the early spring. Upon failure, excavate bioretention area, scarify bottom and sides, replace filter fabric and soil, replant, and mulch.A summary of maintenance activities can be found in Table 1. Because the soil medium filters contaminants from runoff,the cation exchange capacity of the soil media will eventually be exhausted.When the cation exchange capacity of the soil media decreases, change the soil media to prevent contaminants from migrating to the groundwater, or from being discharged via an underdrain outlet. Using small shrubs and plants instead of larger trees will make it easier to replace the media with clean material when needed. Page:!11 1113 f 'm. Cold ClTir'Tiate C&nsideratioIns, Never store snow in bioretention areas. The Operation and Maintenance plan must specify where on-site snow will be stored. All snow dumps must comply with MassDEP'sguidance. When bioretention areas are located along roads, care must be taken during plowing operations to prevent snow from being plowed into the bioretention areas. If snow is plowed into the cells, runoff may bypass the cell and drain into downgradient wetlands without first receiving the required water quality treatment, and without recharging the groundwater. 0�peira't�ioin Itl ii s t o I I a t III o i�i s • Excavation: Excavate and compact the soil sub-grade. • Base Preparation: Place and compact a gravel base, extending beyond the Turfstones by at least 6 inches for residential use and 8 inches for vehicle loads. • Bedding Sand: Spread and screed bedding sand to proper elevations. Ensure uniform moisture content before placing the pavers. • Placement: Lay the Turfstones with a minimum joint spacing of 1/16 inch. Vibration: Use a high-frequency, low-amplitude plate vibrator with a rubber mat to vibrate the Turfstones into the sand. Y1 a'i��in t r"i a in c e I[��Z e g u I a Iir- C I e a Iin III III,i g: • Debris Removal: Sweep or blow off debris like leaves and dirt to prevent clogging2. • Gentle Washing: Use a garden hose with a gentle spray nozzle for cleaning.Avoid pressure washing to prevent damage. Weed C;, IiPm t III ol: • Inspection: Regularly check for weeds and remove them manually or use natural herbicides. III p e ;.1 III" IIr--i A e III,S. "III III"ns: • Drainage Check: Ensure the pavers are draining properly after heavy rains. Address any pooling water by cleaning or replenishing fill material. v III°°°°III Material Mai III"i to IIIo°i a IIP'i c e: • Replenishment: Over time,the fill material (soil or gravel) may displace. Replenish as needed to maintain permeability. r-i o III'-°i( Ice I a r--i a .,,,,,,,Ilr--n e IIr i t: • De-Icing: Use non-abrasive de-icing agents and avoid metal shovels to prevent surface damage. n v I aIIr t i e s m c oIIr v hrif"'ILial • Thorough Check: Conduct a detailed inspection at least once a year to identify and repair any damage. i�� 0 el r'at qi�o r'i • Site Preparation: Clear the area of vegetation and debris. Excavate to the required depth and shape. • Filter Layer: Place a filter fabric or a layer of gravel to prevent soil from moving through the rip-rap. • Placement: Use a well-graded mixture of rock sizes. Place the largest stones at the bottom and work upwards, ensuring a stable and interlocked structure. 1\4 a I r")"t e r"i a in c e II e LA a III I IIr--i p e ct,III o IIr-i s: • Annual Checks: Inspect the rip-rap at least once a year and after major storms to identify any displaced stones, slumping, or erosion at the edges. • Post-Storm Inspections: Check for damage after heavy rains or storms. Promptly repair any damage to prevent further erosion. Weed aIi-id oIiI i t III„ . • Vegetation Management: Remove any weeds or brush that may grow between the rocks to maintain the integrity of the rip-rap. • Cleaning: Remove accumulated sediment and debris to ensure the rip-rap remains effective in controlling erosion. III„ III III III" (-., II,,, , c �Iry i e Ili t: • Damage Repair: If stones are displaced or the filter fabric is exposed, repair these areas immediately to prevent progressive failure. • Replenishment:Add new stones as needed to maintain the structure's effectiveness. n v I a rtIII..i e s m c o IIr P✓1ainte a e u ti g e t (Planr�in` 0nly) �M�� ui ulu li Activity Frequency Replace Plantings $100/ea Mulch $30/<y Grass 10/ry Replace entire media and all vegetation $100/cy Permeable Pavers $20/sf Rip-Rap 8100/cy 12" Drainage Pipe $200/If Drainage Structures $5,000/ea *regular maintenance will be performed with Town forces. rFBENCHMARKI REUSE CLEAN BOULDERS 5'X5'RIP RAP FROM RETAINING WALL. SPLASH PAD DOUBLE SWING GATE SS SIG RESET GUARDRAIL-- REMOVE AND RESET GUARDRAIL REMOVE AND NATIVE TREE VER RESET GUY WIRE 25— BIORETENTION AREA NO.1 RESET MW CO 25-25— ... . . . . . . . . 41- BIORETENTION AREA NO.2 —25 -%T1 AN 2 OHW FF F Z F1 F- 1Z Z FZ FZ 4- -4j FZ 'T Fz -LINED SWA RIPRAP LE FZ r NATIVE -77 0 ONE vvmf ol%,31� 16 u, _N PLANTINGS '--MIN.5'(TYP. BOAT RACKS oU,u SIGN TRAIL +4-PARKING ON (6)8'X20-BOAT RACK T_ I RESET MW COVER _1 _ (2)12'X20'BOAT RACK 4- RESET MW CQ WIR > 'j 8'WIDE BOAT LAUNCH WITH 4�` + 25 z U114L vWky "NO TRAILER ACCESS"SIGN REVETMENT(SEE DETAIL I_1 7. JF 25�No DISTURB ZONE SIGN T SHEET CD-5) (2)LOCKING ++ BOLL,n�RDS' MIN 8'(Ty P.) RECYCLING -1 R36 0' RECEPTACLES 7R54 0' A,\ ONE WAY SIGN OH, 04 0 OHW CHW VV-- 72- -T- ———————— 8'WIDE STONE FILLED PERMEABLE 41 —25_7_7 WITH 12% 25 PAVER BOAT LAUNCH SLOPE(SEE DETAIL SHEET CD-5) NATIVE TREES 7�77 SIGN"HANDICAP WOOD POST WITH(TYP.) EXISTING )��P PARKING" RESET E ROP KIOSKED FENCING E A-N 4 MSE BLOCK WALL VV (SEE DETAIL SHEET CD-5) K —————— BENCHMARKI ———————— ——- REMOVE AND REPLACE SPIKE 01 FENCING(TYP.) EXISTING STONE ROCK BANK ELEV=117.78'1 '6 BENCHMARK ALONG FACE OF WALL SPIKE ELEV=109.32' LEGEND GRAVEL FILLED PAVERS < GRASS FILLED PAVERS BIORETENTION AREA REVETMENT RIP RAP A FLARED END STRUCTURE PLANOVERFLOW STRUCTURE SCALE:1 20' Scale 11. 20' Date JULY 2024 NORTH LAKE COCHICHEWICK BOAT LAUNCH 119 x ENVIRONMENTAL TOWN OF NORTH ANDOVER,MA Sheet No. Job No. 22003302 o 01111",\ M < IN I Designed by THIS LINE IS ONE INCH JLV gw LONG WHEN PLOTTED AT Drawn by FULL SCALE PINK LE ON A 22"X 1 PARTNERS AES FIG. 1 Checked by RJP 34"DRAWING BMP LOCATION MAP Al'Ap x Corniu�u',,y MAR�DATE DESCRIPTION Approved by RJP