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Home My WebLink About210225_1st Peer Review Beechwood Dr - - 25 Beechwood Drive %�. Horsley Wiften Group 0 SUStainable, Ehvirownental Solutions 112 W'at r `tr t-61 Floor-Boston,MBA 02109 .......... February 25, 2021 Ms. Jean Enright, Planning Director Planning Department Town of North Andover 120 Main Street North Andover, Massachusetts 01845 Ref: Initial Stormwater Peer Review Climate-Controlled Self-Storage Beechwood Drive North Andover, Massachusetts Dear Ms. Enright and Board Members: The Horsley Witten Group, Inc. (HW) is pleased to provide the North Andover Planning Board with this letter report summarizing our initial review of the Stormwater Management Report and Site Plans for the proposed Climate-Controlled Self-Storage development on Beechwood Drive, North Andover, MA. The plans were prepared for The Stubblebine Company (Applicant) by TFMoran, Inc. The project proposes the construction of a 3-story, climate controlled self-storage facility, including 23 parking spaces and two driveway entrances on a 2.86-acre lot. The stormwater management includes deep sump catch basins and subsurface infiltration chambers. There is a wetland resource area in the southeastern corner of the site. There is no disturbance proposed within the 25-foot buffer of the resource area and no building proposed within the 50-foot buffer. The proposed development is within the jurisdiction of the North Andover Conservation Commission and will require an Order of Conditions. The following documents and plans were received by HW: • Stormwater Management Report for Climate Controlled Self Storage, Non-Residential Site Plan, Beechwood Drive, North Andover, MA, prepared by TFMoran Inc., dated February 10, 2021 (128 pages); • Special Permit— Site Plan Review—Application, prepared by The Stubblebine Company (5 pages); • Town of North Andover Planning Board —Application for Special Permit, prepared by The Stubblebine Company (3 pages); • Site Development Plans, Climate-Controlled Self-Storage Beechwood Drive, North Andover, Massachusetts, prepared by TFMoran, Inc., dated February 10, 2021, which include: o Cover C-1 o Notes & Legend C-2 o Existing Conditions Plan 1 of 1 o Site Preparation Plan C-3 ors ilt mu. @HorsleyWittenGroupii t iren G,ro.0 P, Inc. Town of North Andover February 25, 2021 Page 2of6 o Site Layout Plan C-4 o Drainage Schedule C-5A o Grading & Drainage Plan C-5 o Utility Plan C-6 o Landscape Plan C-7 o Stormwater Management Plan C-8 o Detail Sheet C-9 — C-15 o Lighting Plan L-1 o Truck Turning Movements Plan T-1 Stormwater Management Design Peer Review HW offers the following overall comments concerning the stormwater management design as per the Massachusetts Stormwater Handbook (MSH) dated February 2008, the North Andover Stormwater Management and Erosion Control Regulations (Stormwater Regulations) adopted February 15, 2011, and the North Andover Stormwater Management and Erosion Control Bylaw (Bylaw). The comments below correlate with the MSH standards and where the more stringent Town requirements are applicable additional comments are noted. 1. Standard 1 states that no new stormwater conveyances (e.g. outfalls) may discharge untreated stormwater directly to or cause erosion in wetlands or waters of the Commonwealth. a. There appears to be a discrepancy on the number of outfalls proposed, the Grading & Drainage Plan indicates two outfalls and the Post-Development Drainage Plan indicates three outfalls. HW recommends that the Applicant verify that the number of outfalls are consistent between the design plans and the Post-Development Drainage Plan. b. HW recommends that the Applicant provide riprap apron sizing calculations for all riprap at proposed outfalls to confirm no erosion will occur. 2. Standard 2 requires that stormwater management systems shall be designed so that post- development peak discharge rates do not exceed pre-development peak discharge rates. a. In accordance with the North Andover Stormwater Management and Erosion Control bylaw, Chapter 240, Section 27 the following amendments are recommended: i. Addition of a summary table including peak discharge rates and total volume of discharge for all modelled storm events to easily evaluate the pre- and post- development values. ii. Amendment of the rainfall data for all modelled storm events to match the values provided in Section B (a). iii. Amendment of the Time of Concentrations to include no more than 50 feet of sheet flow for both pre- and post-development conditions as stated in Section B (11). �"„„ , h iiiii V "7i r .I h,v li i�i ion'" �I ,, I.i��rF ""�MI�� :�n ��l�. I, x ��I,,I� �� ,�� u � ��,�� I, i,m�� a �� , i,� � �, ,. ��µ�, m�� .�_'� ....�'��..� ... III..W µ��I ��"A ��iu ��.�W��'�,� .... �� iu�� W�� mM�'�� ._awl '�,...,� ,� .. ��tl:� .� �..�m.�� .��,-��u��W�..�� . Town of North Andover February 25, 2021 Page 3 of 6 b. There appears to be a discrepancy on the number of infiltration chambers for Stormtech System #1 between the HydroCAD model and the design plans, Sheet C- 19. HW recommends that the Applicant verify the number of chambers and update the plans or calculations accordingly. c. HW recommends that the Applicant verify the chosen flow path for Drainage Area (DA) 2 in the pre-development conditions as the flow path for DA 201 in the post- development conditions appears to be longer and is within the same area as Pre- development DA 2. d. Catch Basin Nodes 214 and 215 in the HydroCAD model do not appear to exist in the design plans. HW recommends that the Applicant verify where these two catch basins are proposed and update the plans or calculations accordingly. e. HW recommends that the Applicant confirm the upper boundary of the catchment area and that the property to the west is not flowing onto the site. f. For documentation purposes of the Post-Development Drainage Plan HW recommends that the area of DA 212 match the area modelled in HydroCAD as well as specifying the location of Pond Node 1. g. To verify that the paved area within DA 212 is draining toward CB 5, HW recommends that the Applicant provide spot grades at the end of the turnaround area in the southeastern driveway. h. For construction purposes, HW recommends that the Applicant list the following items on the plan set for each of the subsurface infiltration systems: • System # • Size and number of chambers • Proposed surface elevation (minimum) • Top of stone elevation • Top of chambers elevation • Bottom of chambers elevation • Bottom of stone elevation • ESHGW 3. Standard 3 requires that the annual recharge from post-development shall approximate annual recharge from pre-development conditions. a. The Applicant has provided a Test Pit Report dated December 5, 2020. Test pits 1 and 2 were conducted within the vicinity of the proposed subsurface infiltration systems. The saturated hydraulic conductivity rate (Ksat) was determined using an Amoozemeter test at Test Pit 1, which is an acceptable method. In accordance with Volume 3, Chapter 1, page 13 of the MSH, "When the "Dynamic Field"Method is used, the exfiltration rate for design purposes must be assumed to be no more than 50% of the in-situ saturated hydraulic conductivity rate at the actual location on site where infiltration is proposed."HW recommends that the Applicant revisit the . 1� �' II( II I� � ,, h� " x��, u,o M � w I„"tl: HIV . , „�11� rc c [s ,,. Town of North Andover February 25, 2021 Page 4 of 6 exfiltration rate used in the HydroCAD modeling calculations to be 50% of the lowest Ksat rate determined in the field. b. In accordance with the MSH, Volume 3, Chapter 1, page 28, a mounding analysis is required when the vertical separation from the bottom of an exfiltration system to seasonal high groundwater is less than four (4)feet and the recharge system is proposed to attenuate the peak discharge from a 10-year 24-hour storm or greater. HW recommends that the Applicant determine if the infiltration chamber designs require a mounding analysis and provide the same as necessary. 4. Standard 4 requires that the stormwater system be designed to remove 80% Total Suspended Solids (TSS) and to treat 1.0-inch of volume from the impervious area for water quality. a. The Applicant has provided water quality volume calculations in the Stormwater Management Report. It appears that the Applicant will meet this criteria however it is not clear how the Applicant calculated the Provided Water Quality Volume. The volume utilized must be the total volume in the infiltration chambers below the outlet elevation. For documentation purposes HW recommends that the Applicant revisit the provided water quality volume and clarify how the values listed were determined. b. The Applicant has included 5% of TSS removal for street sweeping. HW recommends that the Applicant confirm that the street sweeping schedule will be in accordance with the Table provided in Volume 2, Chapter 1, page 9 of the MSH. Furthermore, HW recommends that the Applicant update the Inspection & Maintenance Manual to include the applicable street sweeping schedule. c. The Applicant has proposed a stormwater management system with deep sump catch basins and two subsurface infiltration systems with isolator rows for pretreatment of the parking lot runoff. HW recommends that the closed drainage system be revised to eliminate the catch basin to catch basin configuration. According to the MSH, Volume 2, Chapter 2, page 3 to provide TSS removal the catch basins must be placed offline. Providing manholes between connections is standard engineering practice in Massachusetts. 5. Standard 5 is related to projects with a Land Use of Higher Potential Pollutant Loads (LUHPPL). a. The proposed development is not considered a LUHPPL and therefore, Standard 5 is not applicable to this project. 6. Standard 6 is related to projects with stormwater discharging into a critical area, a Zone 11 or an Interim Wellhead Protection Area of a public water supply. a. The proposed development is not within a critical area, Zone II or an IWPA area and therefore, Standard 6 is not applicable. 7. Standard 7 is related to projects considered Redevelopment. a. The proposed development is not considered redevelopment and therefore, Standard 7 is not applicable. «„ µ N Fi F „ � � . h�� o � �....�,, m.n;'�", h d Y i�I� ��..�.� ; "��' ,I� I�h� I.��I �:�n. I� ,,.I, I,...�,,. �� I� � �� ,�� u � �� i m�� a �� i �,�, ��,�, ��'�� i�� ,� ��µ�, m�� .�_'� ....�'��..� ... III..W µ�� "A ��iu ��.�W��'�,� ...., ��.�� .�iu�� W�� mM�'�� ..�V '�� ,,.. � tl:� .0 �..�m.�� . .� ��u�W W � � ��.�. Town of North Andover February 25, 2021 Page 5 of 6 8. Standard 8 requires a plan to control construction related impacts including erosion, sedimentation, or other pollutant sources. a. The Applicant has provided a Site Preparation Plan. Silt Fence is proposed along the down gradient limit of work. HW recommends that the Applicant add a compost sock, in addition to the siltation fence, where the limit of work is within the 50-foot wetland buffer. b. HW recommends that the Applicant include Catch Basin Protection on all existing catch basins within 100 feet of the construction entrance. c. HW recommends that the Applicant review the required contents and controls of the Erosion and Sediment Control Plan listed in Article VIII, 250-29 and 250-30 of the North Andover Stormwater Regulations and verify all items have been addressed. d. The property will be disturbing more than 1 acre of land and will therefore be required to develop a Stormwater Pollution Prevention Plan (SWPPP) in accordance with the Environmental Protection Agency (EPA) National Pollutant Discharge Elimination System (NPDES) Stormwater Program. HW recommends that the Applicant provide the Town of North Andover with a copy of its SWPPP prior to construction. 9. Standard 9 requires a long-term operation and maintenance (O&M)plan shall be developed and implemented to ensure that stormwater management systems function as designed. a. The Applicant has provided an Inspection and Maintenance Manual. HW recommends that the Applicant review the requirements listed in Article IX, 250-32 of the North Andover Stormwater Regulations and verify all items have been addressed including but not limited to the following: • In accordance with the MSH Vol. 2, Ch. 2, the deep sump catch basins frequency of inspection and cleaning should be increased to four times per year and at the end of the foliage and snow-removal seasons. • In accordance with the MSH Vol. 1, Ch. 1, p. 9, an estimated operations and maintenance budget should be added to the O&M Plan. • A simple plan that illustrates the location of each of the stormwater practices that require inspections should be included. The figure should also include the components of the septic system. • Locations for snow storage. • Signatures of property Owners. 10. Standard 10 requires that an Illicit Discharge Compliance Statement be provided. a. The Applicant has not provided an Illicit Discharge Compliance Statement in the Drainage Report signed by the property owner. HW recommends that the Planning Board or Conservation Commission include a condition of approval requiring an Illicit Discharge Compliance Statement be signed by a representative of The Stubblebine Company prior to land disturbance. � ��,„..., ,W "N' �.' �� i �,,,� �� "�r�, � � h � n.,� ��r q ;��".�� , ,�' "�,� III�� .� �� i� „ �� ,I� �� ,,�� u��,� �� a �I m�� m�I � ��I � � � � � �� ,��, m��, �.��_�'�� ....��'��..��.� ..�. III.�_��I �� A ��.ii� ��L��..��_��,�'�,�..��.. ��. ,, �.ii��_��_�� m��,�'�� .�_�� '��..,�.�,�.��.. �.��tl.� .,�� ._.��.�� .�� u��_�...�� ..�,. Town of North Andover February 25, 2021 Page 6of6 11. Additional Comments: a. The retaining wall along the eastern driveway is over 4 feet high, the design of this wall requires a structural engineer. HW recommends that the Applicant verify it has adequately considered the extent of land disturbance needed to construct the wall. b. HW recommends that the Applicant verify that the 18-inch drainpipe between CB1 and CB2 has adequate separation from the wastewater pipe it goes under. c. Stormtech System #1 includes DM H4 and Inlet 4 that do not appear necessary. HW recommends that the Applicant revisit this structure and verify it is required. Conclusions HW recommends that the Planning Board require that the Applicant provide a written response to address these comments as part of the Board's review process. The Applicant is advised that provision of these comments does not relieve him/her of the responsibility to comply with all Town of North Andover Codes and By-Laws, Commonwealth of Massachusetts laws, and federal regulations as applicable to this project. Please contact Janet Bernardo at 508-833-6600 or at jbernardo@horsleywitten.com if you have any questions regarding these comments. Sincerely, HORSLEY WITTEN GROUP, INC. F Janet Carter Bernardo, P.E. Janelle veary Senior Project Manager Designer � u11,111) m��µ�, m�1 �.�_'� ....1'��..1 ... III..W µ�I�I ��"A ��iu ��.�W��'�,� .... �� iu �� W�� mM�'�� ._�V '�,...,� ,� .. ��tl:� .� �..�m.�� .��,-huvood Dr,idi lo.