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HomeMy WebLinkAbout2022-12-20 Stormwater Review WSP Horsley Witten Group Sustainable Environmental Solutions 112 Water Street-6"door Boston,MA 02109 � 857-263.8193 horsleywitten.com w, October 21, 2022 Ms. Jean Enright, Planning Director North Andover Planning Board 120 Main Street North Andover, Massachusetts 01845 Ref: Special Watershed Permit Peer Review 104 Bonny Lane 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 Watershed Permit Application for the proposed pool construction at 104 Bonny Lane, North Andover, MA. The plans were prepared by Andover Consultants, Inc. on behalf of Patrick J. Gaffny (Applicant). The project proposes the construction of an inground pool with a pervious paver patio. A new chain link fence will be installed around the pool area within the 46,209± square feet parcel. The pool construction is approximately 56.7 feet from the onsite wetland resource area, located in the northwest corner of the site. The proposed work is over 400 feet from Lake Cochichewick, and within the Watershed Protection District. The pool is located within the 100-foot Non- Disturbance and 325 foot Non-Discharge buffer to a wetland resource within the Watershed Protection District. In accordance with §196-4.19. B. of the North Andover Zoning Bylaws, any surface or subsurface discharge proposed within the Non-Discharge Buffer Zone requires a Special Watershed Permit. The following documents and plans were received by HW: • Special Permit-Watershed Permit Application, 104 Bonny Lane, North Andover, MA, signed by Patrick J. Gaffny (2 pages); • Watershed Special Permit Project Description & Supporting Documentation, 104 Bonny Lane, North Andover, MA, prepared by Andover Consultants, Inc., dated March 21, 2022 (5 pages); and • Plan for Proposed Pool, 104 Bonny Lane, North Andover, MA, prepared by Andover Consultants, Inc., dated March 21, 2022 (1 sheet). Stormwater Management Design Peer Review In accordance with §195-4.19. B. (4)All construction in the Watershed Protection District shall comply with best management practices for erosion, siltation, and stormwater control in order to preserve the purity of the groundwater and the lake; to maintain the groundwater table; and to maintain the filtration and purification functions of the land. HorsleyWitten.corn @HorsleyWittenGroup Horsley Witten Group, Inc. Town of North Andover October 21, 2022 Page 2 of 3 HW has the following comments regarding the proposed stormwater management design. 1. The Applicant intends to treat and mitigate stormwater by using porous pavers around the north and west, wetland side of the pool perimeter to filter and infiltrate rain falling on the pool area. The construction of this pool will likely increase peak flow runoff rates by a marginal amount as the porous pavers will mitigate the runoff falling on the patio and the pool will capture the water falling on the pool. 2. The Applicant has proposed a Paver Cross Section Detail on the plan. HW recommends that the Applicant consider substituting No 8 Bedding Aggregate for the bedding sand. HW further recommends that the Applicant call out the size of the aggregate to be used in the 8 inch thick base. 3. HW recommends that the Applicant clearly delineate the limit of disturbance and document whether any trees (greater than 8" diameter) will be removed as part of the project. 4. The Applicant has proposed staked 9-inch straw wattles to provide erosion control surrounding the construction. HW recommends that the Applicant add a silt fence to the straw wattle barrier located within 50 feet of the on-site wetland resource area. 5. HW recommends that the Applicant provide a plan for the re-naturalization of the 350 square foot area in the 25 foot No Disturbance Zone. Specifically, if there will be any seed mix added to the area, if any long-term maintenance is required, or if the area will be left undisturbed. HW recommends that the Applicant confirm that the area does not currently contain any invasive species. 6. HW recommends that the Applicant provide a detail or describe the type of material to be used for the proposed 2-foot-high landscape wall. 7. HW recommends that the Applicant propose slope stabilization practices as need during construction. 8. HW recommends that an Operation & Maintenance (O&M) Plan be provided.to the homeowner for long term maintenance of the porous pavers. 9. HW recommends that the Applicant explain to the Planning Board the methodology for pumping out the pool at the end of the season. Specifically, where will the pool water be pumped to and how will the Applicant confirm that pool chemicals will not be discharged into the resource area. The pool maintenance should be included in the O&M Plan for the owners use. 10. The Applicant intends to remove the fencing that is located on the adjacent lot. HW recommends that the Planning Board confirm that the adjacent property owner is aware of the intended work on its property. KAProjects12021121020 Town of North Andover121020J Bonny Lane\Reports}221021_1stPeerReview Sonny Lane.docx Town of North Andover October 21, 2022 Page 3 of 3 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 jernardo@horsleywitten.com if you have any questions regarding these comments. Sincerely, HORSLEY WITTEN GROUP, INC. Janet Carter Bernardo, P.E. Veronica Seward-Aponte Associate Principal Environmental Engineer KAProjectsi2021t21020 Town of North Andover121020J Bonny LanelReports1221021_1stPeerReview_Bonny Lane.doex Horsley Witten Group AL Sustainable Environmental Solutions 112 Water Street-611 Floor•Boston,MA 02109 857-263-8193•horsleywittan corn November 18, 2022 Ms. Jean Enright, Planning Director North Andover Planning Board 120 Main Street North Andover, Massachusetts 01845 Ref: 2nd Special Watershed Permit Peer Review 104 Bonny Lane 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 second review of the Watershed Permit Application for the proposed pool construction at 104 Bonny Lane, North Andover, MA. The plans were prepared by Andover Consultants, Inc. on behalf of Patrick J. Gaffny (Applicant). The project proposes the construction of an inground pool with a pervious paver patio. A new chain link fence will be installed around the pool area within the 46,209± square foot (sf) parcel. The pool construction is approximately 56.7 feet from the onsite wetland resource area, located in the northwest corner of the site. The proposed work is over 400 feet from Lake Cochichewick, and within the Watershed Protection District. The pool is located within the 100-foot Non- Disturbance and 325-foot Non-Discharge buffer to a wetland resource within the Watershed Protection District. In accordance with §195-4,19. B. of the North Andover Zoning Bylaws, any surface or subsurface discharge proposed within the Non-Discharge Buffer Zone requires a Special Watershed Permit. The proposed project is within the jurisdiction of the North Andover Conservation Commission. The following additional documents and plans were received by HW in response to our October 21, 2022 initial peer review letter: • Letter to North Andover Planning Board, regarding 104 Bonny Lane, North Andover, Mass, prepared by Andover Consultants Inc., dated November 11, 2022 (6 pages); • Letter to North Andover Planning Board, regarding Peer Review for 104 Bonny Lane, North Andover, Mass, prepared by Andover Consultants Inc., dated November 11, 2022 (2 pages); • Plan for Proposed Pool, 104 Bonny Lane, North Andover, MA, prepared by Andover Consultants, Inc., dated March 21, 2022, revised Nov. 8, 2022 (1 sheet); and • Pool and Patio Operation & Maintenance/BMP Plan, 104 Bonny Lane, North Andover, Massachusetts, prepared by Andover Consultants Inc., dated November 8, 2022 (5 pages). HorsleyWi Ito n,corn �n Hors IeyWittenGroup ®Horsley Witten Group, Inc. Town of North Andover November 18, 2022 Page 2 of 4 Stormwater Management Design Peer Review In accordance with §195-4.19. B. (4) All construction in the Watershed Protection District shall comply with best management practices for erosion, siltation, and storm water control in order to preserve the purity of the groundwater and the lake; to maintain the groundwater table; and to maintain the filtration and purification functions of the land. The following comments correlate to our October 21, 2022 initial peer review letter. Follow up comments are provided in bold font. 1. The Applicant intends to treat and mitigate stormwater by using porous pavers around the north and west, wetland side of the pool perimeter to filter and infiltrate rain falling on the pool area. The construction of this pool will likely increase peak flow runoff rates by a marginal amount as the porous pavers will mitigate the runoff falling on the patio and the pool will capture the water falling on the pool. November 18, 2022: No further comment. 2. The Applicant has proposed a Paver Cross Section Detail on the plan. HW recommends that the Applicant consider substituting No 8 Bedding Aggregate for the bedding sand. HW further recommends that the Applicant call out the size of the aggregate to be used in the 8-inch-thick base. November 18, 2022: The Applicant has revised the Permeable Paver Detail as suggested. HW has no further comment. 3. HW recommends that the Applicant clearly delineate the limit of disturbance and document whether any trees (greater than 8" diameter) will be removed as part of the project. November 18, 2022: The Applicant has clarified the limit of disturbance on the plan. It appears that 5 trees will be removed as part of the project. Two 18-inch, one 20 inch, one 24-1nch, and one 30-inch. HW recommends that the Applicant confirm the number of trees to be removed and clarify if the stumps of the trees outside the limit of work will be excavated? 4. The Applicant has proposed staked 9-inch straw wattles to provide erosion control surrounding the construction. HW recommends that the Applicant add a silt fence to the straw wattle barrier located within 50 feet of the on-site wetland resource area. November 18, 2022: The Applicant has added the siltation fence to the erosion control barrier within 60 feet of the resource area. HW has no further comment. 5. HW recommends that the Applicant provide a plan for the re-naturalization of the 350 square foot area in the 25 foot No Disturbance Zone. Specifically, if there will be any seed mix added to the area, if any long-term maintenance is required, or if the area will be left undisturbed. HW recommends that the Applicant confirm that the area does not currently contain any invasive species. November 18, 2022: The Applicant has added a note to the plan stating that the 350-sf disturbed area between the existing fence to be removed and the proposed erosion control barrier shall be seeded with conservation seed mix and allowed to KAProjects12021121020 Town of!North Andover121020J Bonny LanelReportsl221118_2ndPeerReview Bonny Lane.docx ^ 1. Town of North Andover November 18, 2022 Page 3 of 4 re-naturalize. The area should not be mowed or maintained. HW recommends that the Applicant confirm that the area does not currently contain any invasive species. HW further recommends that the Applicant provide the homeowner with literature on invasive plant species and how to mange them properly if observed within the re-naturalized area. 6. HW recommends that the Applicant provide a detail or describe the type of material to be used for the proposed 2-foot-high landscape wall. November 18, 2022: The Applicant has provided a detail of a Modula Block Retaining Wall. HW has no further comment. 7. HW recommends that the Applicant propose slope stabilization practices as needed during construction. November 18, 2022: The Applicant has provided an Erosion Control Blanket Slope Installation detail as suggested. HW has no further comment. 8. HW recommends that an Operation & Maintenance (O&M) Plan be provided to the homeowner for long term maintenance of the porous pavers. November 18, 2022: The Applicant has provided a Pool and Patio Operation & Maintenance/BMP Plan for the homeowners of 104 Bonny Lane. The document describes the need to care properly for the permeable pavers as well as the landscaped areas on the property. The O&M Plan also describes the pool drawdown and maintenance as requested. 9. HW recommends that the Applicant explain to the Planning Board the methodology for pumping out the pool at the end of the season. Specifically, where will the pool water be pumped to and how will the Applicant confirm that pool chemicals will not be discharged into the resource area. The pool maintenance should be included in the O&M Plan for the owners use. November 18, 2022: The Applicant has provided a Pool and Patio Operation & MaintenancelBMP Plan. HW concurs with most of the listed procedures. However, the 0&M Plan states that when applicable the pool water should be discharged over the lawn area. HW recommends that the Applicant install a drywell, outside of the 100-foot buffer to the on-site wetland, that the pool water can slowly be drained into at the end of the season or prior to a sever storm event. Pool water discharging over the lawn may easily migrate into the resource area. 10. The Applicant intends to remove the fencing that is located on the adjacent lot. HW recommends that the Planning Board confirm that the adjacent property owner is aware of the intended work on its property. November 18, 2022: The Applicant has added a note to the plan stating it will coordinate with the adjacent landowner to remove existing fence. HW has no further comment. 11, During the November 1, 2022 hearing a discussion was had regarding the classification of the wetland located on the northwest corner of the parcel. The KAProjed02021121020 Town of North Andover121020J Bonny La nelReporW221118_2nd Pee rReview_8cnny Lane.dou Town of North Andover November 18, 2022 Page 4 of 4 Applicant had stated it believed that the small on-site wetland was isolated but would have the wetland biologist prepare a detailed report. The Applicant provided additional information regarding the drainage pipes located in the small on-site wetland in a letter to the Planning Board dated November 11, 2022. It appears that the on-site wetland discharges into the drainage system in Bonny Lane via a 30-inch reinforced concrete pipe (RCP). The drainage system in Bonny Lane then discharges out a headwall located on 123 Bonny Lane. A channel is located downgradient of the headwall that appears to discharge into Lake Cochichewick. The channel appears to be an intermittent stream and the small on- site wetland would be classified as a bordering vegetated wetland and subject to the Massachusetts Wetlands Protection Act. Conclusions HW recommends that the Planning Board require the Applicant to provide a written response to address the remaining recommendations 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 jernardo@horsleywitten.com if you have any questions regarding these comments. Sincerely, HORSLEY WITTEN GROUP, INC. Janet Carter Bernardo, P.E. Associate Principal K:\Projec1s12021121020 Town of North Andover121020J Bonny Lane]Reports1221118_2ndPee€Review_Bonny Lane.docx i Horsley Witten Group Sustainable Environmental Solutions ' 112 Water Street•811 Floor•Boston,MA 02109 657-263.8193 horsleywitten.corn v , December 14, 2022 Ms. Jean Enright, Planning Director North Andover Planning Board 120 Main Street North Andover, Massachusetts 01845 1 Ref: 3rd Special Watershed Permit Peer Review 104 Bonny Lane 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 third review of the Watershed Permit Application for the proposed pool construction at 104 Bonny Lane, North Andover, MA. The plans were prepared by Andover Consultants, Inc. on behalf of Patrick J. Gaffny (Applicant). The project proposes the construction of an inground pool with a pervious paver patio. A new chain link fence will be installed around the pool area within the 46,209+ square foot (sf) parcel. The pool construction is approximately 56.7 feet from the onsite wetland resource area, located in the northwest corner of the site. The proposed work is over 400 feet from Lake Cochichewick, and within the Watershed Protection District. The pool is located within the 100-foot Non- Disturbance and 325-foot Non-Discharge buffer to a wetland resource within the Watershed Protection District. In accordance with §195-4.19. B. of the North Andover Zoning Bylaws, any surface or subsurface discharge proposed within the Non-Discharge Buffer Zone requires a Special Watershed Permit. The proposed project is within the jurisdiction of the North Andover Conservation Commission. The following additional documents and plans were received by HW in response to our November 18, 2022 second peer review letter: • Letter to North Andover Planning Board, regarding Peer Review for 104 Bonny Lane, North Andover, Mass, prepared by Andover Consultants Inc., dated December 6, 2022 (2 pages); • Plan for Proposed Pool, 104 Bonny Lane, North Andover, MA, prepared by Andover Consultants, Inc., dated March 21, 2022, revised Dec. 6, 2022 (1 sheet); and • Pool and Patio Operation & Maintenance/BMP Plan, 104 Bonny Lane, North Andover, Massachusetts, prepared by Andover Consultants Inc., dated December 6, 2022 (5 pages), Stormwater Management Design Peer Review In accordance with§195-4.19. B. (4)All construction in the Watershed Protection District shall comply with best management practices for erosion, siltation, and Stormwater control in order to HorsleyWitten.corn F?HorsleyWittenGroup Horsley Witten Group, Inc. Town of North Andover December 14, 2022 Page 2 of 4 preserve the purity of the groundwater and the lake; to maintain the groundwater table; and to maintain the filtration and purification functions of the land. The following comments correlate to our October 21 and November 18, 2022 peer review letters. Follow up comments as applicable are provided in bold underlined font. 1. The Applicant intends to treat and mitigate stormwater by using porous pavers around the north and west, wetland side of the pool perimeter to filter and infiltrate rain falling on the pool area. The construction of this pool will likely increase peak flow runoff rates by a marginal amount as the porous pavers will mitigate the runoff falling on the patio and the pool will capture the water falling on the pool. November 18, 2022: No further comment. 2. The Applicant has proposed a Paver Cross Section Detail on the plan. HW recommends that the Applicant consider substituting No 8 Bedding Aggregate for the bedding sand. HW further recommends that the Applicant call out the size of the aggregate to be used in the 8-inch-thick base. November 18, 2022: The Applicant has revised the Permeable. Paver Detail as suggested. HW has no further comment. 3. HW recommends that the Applicant clearly delineate the limit of disturbance and document whether any trees (greater than 8° diameter) will be removed as part of the project. November 18, 2022: The Applicant has clarified the limit of disturbance on the plan. It appears that 5 trees will be removed as part of the project. Two 18-inch, one 20-inch, one 24-inch, and one 30-inch. HW recommends that the Applicant confirm the number of trees to be removed and clarify if the stumps of the trees outside the limit of work will be excavated? December 14, 2022: The Applicant has noted that a 6111 tree will be removed, marked as 20-inches. The Applicant has also confirmed that the stumps of the trees to be removed outside the limit of work will remain and not be excavated. HW has no further comment. 4. The Applicant has proposed staked 9-inch straw wattles to provide erosion control surrounding the construction. HW recommends that the Applicant add a silt fence to the straw wattle barrier located within 50 feet of the on-site wetland resource area. November 18, 2022: The Applicant has added the siltation fence to the erosion control barrier within 50 feet of the resource area. HW has no further comment. 5. HW recommends that the Applicant provide a plan for the re-naturalization of the 350 square foot area in the 25 foot No Disturbance Zone, Specifically, if there will be any seed mix added to the area, if any long-term maintenance is required, or if the area will be left undisturbed. HW recommends that the Applicant confirm that the area does not currently contain any invasive species. November 18, 2022: The Applicant has added a note to the plan stating that the 350-sf disturbed area between the existing fence to be removed and the proposed KAProjocts1202 112 1 02 0 Town of North Andover1210205 Bonny Lane\Reportsi221214_3rdPeerReview BonnyLane.docx Town of North Andover December 14, 2022 Page 3 of 4 erosion control barrier shall be seeded with conservation seed mix and allowed to re-naturalize. The area should not be mowed or maintained. HW recommends that the Applicant confirm that the area does not currently contain any invasive species. HW further recommends that the Applicant provide the homeowner with literature on invasive plant species and how to mange them properly if observed within the re-naturalized area. December 14, 2022: The Applicant has confirmed that the area to be re-naturalized does not currently contain invasive species. HW recommends that the Planninc#,.,,,,,,,_.,_.....,, Board determine if it wants to limit the mowinn and maintenance of this area and include as a condition of approval if applicable. HW notes that the North Andover Conservation Commission may also chop ___. _.. to limit routine maintenance in this area. 6. HW recommends that the Applicant provide a detail or describe the type of material to be used for the proposed 2-foot-high landscape wall. November 18, 2022: The Applicant has provided a detail of a Modula Block Retaining Wall. HW has no further comment. 7. HW recommends that the Applicant propose slope stabilization practices as needed during construction. November 18, 2022: The Applicant has provided an Erosion Control Blanket Slope Installation detail as suggested. HW has no further comment. 8. HW recommends that an Operation & Maintenance (O&M) Plan be provided to the homeowner for long term maintenance of the porous pavers. November 18, 2022: The Applicant has provided a Pool and Patio Operation & Maintenance/BMP Plan for the homeowners of 104 Bonny Lane. The document describes the need to care properly for the permeable pavers as well as the landscaped areas on the property. The O&M Plan also describes the pool drawdown and maintenance as requested. 9. HW recommends that the Applicant explain to the Planning Board the methodology for pumping out the pool at the end of the season. Specifically, where will the pool water be pumped to and how will the Applicant confirm that pool chemicals will not be discharged into the resource area. The pool maintenance should be included in the O&M Plan for the owners use. November 18, 2022: The Applicant has provided a Pool and Patio Operation & MaintenancelBMP Plan. HW concurs with most of the listed procedures. However, the O&M Plan states that when applicable the pool water should be discharged over the lawn area. HW recommends that the Applicant install a drywell, outside of the 100-foot buffer to the on-site wetland, that the pool water can slowly be drained into at the end of the season or prior to a sever storm event. Pool water discharging over the lawn may easily migrate into the resource area. K:\Projectsi2021121020 Town of North Andover121020J Bonny LaneiReports1221214_3rdPeerReview BonnyLane,docx Town of North Andover December 14, 2022 Page 4 of 4 December 14 2022: The Applicant has revised the O&M Plan and added a drywell outside of the 100-foot buffer to be used as needed to drain down the pool. HW has no further comment. 10. The Applicant intends to remove the fencing that is located on the adjacent lot. HW recommends that the Planning Board confirm that the adjacent property owner is aware of the intended work on its property. November 18, 2022: The Applicant has added a note to the plan stating it will coordinate with the adjacent landowner to remove existing fence. HW has no further comment. 11. During the November 1, 2022 hearing a discussion was had regarding the classification of the wetland located on the northwest corner of the parcel. The Applicant had stated it believed that the small on-site wetland was isolated but would have the wetland biologist prepare a detailed report. The Applicant provided additional information regarding the drainage pipes located in the small on-site wetland in a letter to the Planning Board dated November 11, 2022. It appears that the on-site wetland discharges into the drainage system in Bonny Lane via a 30-inch reinforced concrete pipe (RCP). The drainage system in Bonny Lane then discharges out a headwall located on 123 Bonny Lane. A channel is located downgradient of the headwall that appears to discharge into Lake Cochichewick. The channel appears to be an intermittent stream and the small on- site wetland would be classified as a bordering vegetated wetland (BVW) and subject to the Massachusetts Wetlands Protection Act. December 14 2022: The Applicant agrees that the wetland located on the northwest corner of the parcel is a BVW. Stormwater within the BVW can dischar a to the Lake via the existing drainpipes. HW concurs that the proposed pool and patio as designed and maintained will not result in a degradation of the quality or quantity of water in or entering Lake Cochichewick. Conclusions HW is satisfied that the applicant has adequately addressed our comments. 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. Janet Carter Bernardo, P.E. Associate Principal CC: North Andover Conservation Commission KAProjec1s12021121020 Town of North Andover121020J Bonny LanelReports1221214 3rdPeerReview_BonnyLane.doex A daveE I E-,Ist River Place consult€31tts Methuen,kllassnclensetts 01844 Tel.(978)687-3828 ndovercoilsuit:t€tls.com November 11, 2022 North Andover Planning Board C/o Jean.Enright,Planning Director 120 Main,Street North Andover,MA 01845 Rl;: Special Permit Watershed Peer Review 104 Bonny Lane North Andover,Mass Dear Ms, Enright and Board Members: During the Planning Board public hearing held on November 1, 2022, Planning Board Member Mr. Boynton,made an observation of a small channel which discharges to Lake Cochichewick from the general direction of Bonny Lane, Based on this observation, the Board requested the project team investigate, and if possible, determine the genesis of this small channel and determine, if possible,where the on-site wetland drains. Record plans provided by the North Andover Engineering Department for the subdivision titled"Definitive Plan of Hardt Court Estates"prepared by Frank C. Gelinas&Associates dated January 10, 1979 show the drainage system within Bonny Lane is collected by a series of catch basins and manholes which discharged over an existing drainage easement to a headwall located on 123 Bonny Lane. Field observations show that this is where that small channel begins. Additionally, based on field survey, a 30"pipe from the on-site wetland connects to this closed drainage system through an easement on the Applicant property. Additionally, two smaller pipes, a 5"and 12"pipe, discharge from abutting properties into the onsite wetland. The onsite wetland is self-contained as evident by steep topography surrounding and a clear low-lying well-defined wetland area. Based on record plans and field observations, the small channel is a predominantly the result of the existing street stormwater drains within Bonny Lane while the on-site wetland and the two drains which discharge to the wetland from abutting properties also contribute to this street drains. As the proposed project will include a permeable paver patio which will promote the recharge of rain water in addition to the relatively small area of the patio, this project will not result inn the significant degradation of the quality or quantity of water in or entering lake Cochichewick, Attached to this letter are field pictures, aerials, and record plans documenting the above. If you have any questions concerning the above, or require anything further,please feel free to contact nee at your convenience. Sincerely, Andover Consultants Inc. 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T¢pCCt/ fig y� (h{+�• K� S5id 1M + s��k !t� CgC" € :•fit 1 € "� yak: �,r1k 1 I �' Y.} �'Cih, � .� „* '$�,a a "It,� C i ^2�1� `` q�,l�' �„ ' " w ' ���'.;': a (�. (! ,✓S' ?�ii.a �e f � ; L Ark .J.yy aeP I` t rY¢ 'b iV- f} _ 57 04 yA l E'` ti.S1r 4 s� yl Ern -• � � I � $ s 4C, l-: � '� '"��y, e� �`^ /-� a � l�f 7' �s ftA 8r � ,§�..aft� t. a Pool and Patio Operation & MaintenancelBMP Plan 104 Bonny Lane North Andover, Massachusetts November 8, 2022 Prepared for: Patrick Gaffny 104 Bonny Lane North Andover, MA 01845 Prepared By: anclover consultants inc. 1 East River Place Methuen, MA 01844 P:5 UI5 51%daeskeporls%104 Bonny_O&M Manual.doo 104 Bonny Lame North Andover,Mass Project Information Site Address 104 Bonny Lane North Andover,MA 01845 Owner Patrick Gaffey 104 Bonny Lane North Andover,MA 01845 Site Contact Name: Patrick Gaffny Telephone: (978)257-4163 Email: patgaffS@yahoo.com RVIVI-514dnr Vapo,K1038onny_OW Manual.doo 1 104 Bonny Lane North Andover,Mass A. General Operation & Maintenance A.'i Permeable Paver Patio Maintenance The primary maintenance requirement for permeable pavers is to clean the surface drainage voids.Fine debris and dirt accumulate in the drainage openings and reduce the paver's flow capacity. Even though some irreplaceable loss in permeability should be expected over the paver's lifetime,you can increase the longevity of the system by following the maintenance schedule for sweeping and high-pressure washing,restricting the area's use by heavy vehicles,limiting the use of de-icing chemicals and sand,and implementing a stringent sediment control plan. Preventing Clogging of Permeable Paver Surface Areas > Patio areas and/or other areas with permeable pavers shall be cleaned annually with vacuums or hared swept. > Do not allow construction staging,soil/mulch storage,etc. on unprotected pavement surface. > Maintain vegetated areas adjacent to areas with permeable pavers to prevent washout of soil onto surface. > Do not apply any type of sealant to permeable pavers. Removing Snow and Ice > Shovel snow off permeable pavers as necessary. > Do not apply abrasives such as sand or grit on or adjacent to permeable pavers. > Avoid plowing of areas with permeable pavers. Inspecting the System > Inspect areas paved with permeable pavers monthly for the first three months after construction to ensure proper functioning and correct any areas that have settled or experienced washouts. > Inspect areas paved with permeable pavers annually after initial three month period.Annual inspections should take place after large storms,when puddles will make any clogging obvious. Repairing Damages > Do not apply any type of sealant to permeable pavers. > If necessary,add additional aggregate fill material made up of clean sand or gravel. > Damaged interlocking paving blocks should be replaced. P'.52112i-5ildocs5repa�ts4f04 iSonny 0$1'.1 FAanual.doc 2 104 Lonny Lane North Andover,Mass A.2 Pool Maintenance Primary pollutants of concerns in swimming pools are chlorine,bromine or chloramines used as disinfectants. These chemicals,if discharged to a resource area or storm drainage system can have negative impacts on water quality and aquatic life. Storage of Chemicals > Pool chemicals should not be stored outside. Chemical shall be stored inside and according to requirements of chemical provider in order reduce contamination in event of spill. > Spill cleanup materials as recommend by chemical manufacture should be on hand in the event of a spill. Pool Drawdown and Maintenance > The pool shall be equipped with a non-backwash cartridge filter to eliminate the need to discharge pool water into lawn area during regular pool cleaning. > Pool water should not be discharged directly to street or storm drains > Prior to draining of pool,pool water shall be de-chlorinated per state municipal requirements by eliminating chlorine usage for approximately ten days to allow chlorine levels to dissipate or by utilizing sodium thiosulphate or other pool dichlorination chemical approved by DEP and for use in watershed areas. > Pool water should be discharged over the lawn area, away from Lake Cochichewick, to allow for infiltration of water into ground. > When a severe(>100 year storm event)is predicted, the pool water level should be drained to a sufficient level to allow for 8 inches of rain to be collected in the pool. A.3 Vegetated Areas Maintenance Although not a structural component of the drainage system, the maintenance of vegetated areas may affect the functioning of the stormwater management system. This includes the health density of vegetative cover and activities such as the application and disposal of lawn and garden care products, disposal of leaves and yard trimmings and proper aeration of soils. > Inspect planted areas on a semi-annual basis and remove any litter. > Maintain planted areas adjacent to patio to prevent soil washout. > Immediately clean any soil deposited on patio. > Re-seed bare areas;install appropriate erosion control measures when native soil is exposed or erosion channels are fornhing. > Pesticide/Herbicide Usage—Only organic or slow release nitrogen,phosplhorus free products shall be used. Non-organic pesticides and herbicides use is prohibited PAM1-51Woc kfepor[sM4 Bonny_0VJ&lamaWoo 3 104 Benny Lane North Andover,Mass A.4 Long Term Maintenance/ Evaluation Checklist 104 Bonny Lane — North Andover, Mass a� � N � Cr V Qf L L L 0 c ^ a .Q L U. 0 0 O .O 4� E C �+ v 1.+ 0 .0 0 t37 Z M 0 to.v 0 d 0 v v 0 � — 1- O p �� " L) C > a00! a Permeable Vacuum sweep or hand 1X per as Pavers sweep year f f necessar y Pool 1 X per as Maintenanc See requirements above year / / necessar e y Vegetated Repair/re-seed bare spots, 2X per as Areas re-plant as necessary to year necessar prevent erosion y PAMIstika trepoa5u0413 ny_oantinnanuai.aoo 4 104 Bonny Lane North Andover, Mass anclovcr 1 East River Place consultants "Iethuen,Nlassacbusetts 01844 inc, t'el.(978)687-3828 www.:l it;d over•cofi su Ita nts,co nl December 6, 2022 North Andover Planning Board C/o Jean Enright, Planning Director 120 Main Street North Andover, MA 01845 RE: Special Permit Watershed Peer Review 104 Bonny Lane North Andover, Mass Dear Ms. Enright and Board Members.- We are in receipt of a second peer review memorandum prepared by Horsley Witten Group via a letter to the Board c/o of Jean Enright,dated November 18, 2022. Comments previously addressed have been omitted and the remaining comments haven been reproduced below in italics and our response noted below in bold. 3. HW reconrnnends that the Applicant clearly delineate the lintit of disturbance and docuruent whether any trees (greater than 8"dianeter) will be removed as part of the project. November 18, 2022: The Applicant has clarified the lintit of disturbance oil the plant. It appears that 5 trees will be removed as part of the project. Tivo 18-inch, one 20 inch, one 24-inch, and one 30-inch. HW reconinrends that the Applicant confrrrn the number of trees to be removed and clarify if the stunnps of the trees outside the limit of work will be excavated? Response: One additional tree to be removed has been added to the revised plan. The total number of trees to be removed is six and all stumps outside the limit of work will remain and not be excavated. Smaller shrubs/bushes within the limit of work will also be removed as part of the proposed project. 5. HW recornntennds that the Applicant provide a plan for the re-naturalization of the 350 square foot area in the 25 foot No Disturbance Zone. Specifically, if there will be any,seed ruin added to the area, if arty long-term maintenance is required, or if the area will be left undisturbed. HW reconnnends that the Applicant con f rnt that the area does not currently contain any invasive species. November 18, 2022: The Applicant has added a note to the plan stating that the 350-sf disturbed area betiweent the existing fence to be r enuoved and the proposed erosion control barrier shall be seeded with conser-vation seed rnix and allowed to r'e-naturalize. The area should not be nntoived or maintained. HW recon inlennds that the Applicant confr.rrn that the area does not currently contain any invasive species. HTVfi.o-the),recommends that the Applicant provide the homeowner with literature oat invasive plant species and how to manage therm properly if observed within the re-naturalized area. Response: The applicant is agreeable to a condition requiring the area not be mowed or maintained if the Board feels appropriate. The area is currently and landscaped bed and does not contain invasive species, please see pictures of this area attached to this response memo. 9. HW reconunends that the Applicant explain to the Planning Board the methodology for plumping out the pool at the end of the season. Specifically, where twill the pool water be pumped to and how will the Applicant confurrll that pool chemicals will not be discharged into the resource area. The pool maintenance should be included in the O&MPlan for the owners use. November 18, 2022: The Applicant has provided a Pool and Patio Operation &Maintenanrce/BMP Plan. HJV corrcunrs with most of the listed procedures. However; the O&M Plan states that when applicable the pool water Page 1 of 2 C10 Engineers 6 Land Surveyors O Laird Planners P.424121�SItdocsVetters�2022.12-0B_Responso to HW Peet Revr 2.Ax IB(i0\'01 sonsult'aills should be discharged over the lawn area. HW reconnmends that the Applicant install a drywell, outside of the 100 foot buffer to the on-site wetland; that thepool water can slowly be drained into at the end of the seasonn or prior to a severe storm event. Pool water discharging over the lawn may easily migrate into the resource area. Response: The O&M Plan has been revised as suggested to require the when the pool is drained at end of season it is discharged to a drywell located outside of the 100' buffer. A location of the drywell and drywell detail has been added to the revised plan. 11. During the November 1, 2022 hearing a discussion was had regardhig the classification of the wetland located on the northwest corner of the parcel. The Applicant had stated it believed that the small on-site wetland was isolated but would have the wetland biologist prepare a detailed report. The Applicant provided additional information regarding the drainage pipes located in the small on-site wetland in a letter to the Planning Board dated November 11, 2022. It appears that the on-site wetland discharges into the drainage system in Bonny Larne via a 30-inch reinforced concrete pipe (RCP). The drainage system in Bonny Larne then discharges out a headwall located on 123 Bonny Lane. A channel is located downgradient of the headwall that appears to discharge into Labe Cochichewick The chamrel appears to be an intermittent stream and the small on-site wetland would be classified as a bordering vegetated wetland and subject to the Massachusetts YYetlarrds Protection Act. Response: The wetland is flagged was flagged a wetland by Norse Environmental Consultants and a filing with the Conservation Commission will be made following a decision rendered by the Planning Board. What was described at the hearing was a response to the Board's questions regarding the size of the wetland; the response given was to convey it was not a larger wetland mass,but rather a smaller pocket wetland well defined and contained by surrounding higher grades, this wetland would be classified as a Bordering Vegetated Wetland. Upon further research of Town Records and site inspections,we were able to determine that the wetland, along with two pipes that drain into the wetland from off site, and the street drains withing Bonny Lane, discharge to the Lake. Given the small size of the proposed patio, and that it will be a permeable paver patio, and that the pool will discharge to a drywell when water level drawdown is necessary, the proposed project will not result in the significant degradation of the quality of quantity of water in or entering Lake Cochicliewick. If you have any questions concerning the above responses, or require anything fiirther, please feel free to contact me at your convenience. Sincerely, Andover Consultants Inc. Dennis A. Griecci,RE,, LEED AP Enclosures Page 2 of 2 P,12£121-514docs(leners\2022-124s_Response to 1AV P�Rev'�u 2.do Pool and Patio Operation & Maintenance/BMP Plan 104 Bonny Lane North Andover, Massachusetts December 6, 2022 Prepared for.- Patrick Gaffny t04 Bonny Lane North Andover, MA 01845 Prepared By: andover consultants Inc. 1 East River Place Methuen, MA 01844 1110.6.0.1lProjects121121,51Woc VeportsU04 aonny_OW 6lanial.doc 104 Bonny Lane North Andover,Mass Project Information Site Address 104 Bonny Lane North Andover,MA 01845 Owner Patrick Gaffny 104 Bonny Lane North Andover,MA 01845 Site Contact Name:Patrick Gaffny Telephone: (978)257-4163 Email:uatgaff8@yalloo.com ❑anua.,�0��15�,�,-5tldou eporls�t0413cnny_oBh1 Alanual.doc 1 104 Bonny Lane North Andover,Mass A. General Operation & Maintenance A.1 Permeable Paver Patio Maintenance The primary maintenance requirenlent for permeable pavers is to clean the surface drainage voids. piffle debris and dirt accumulate in the drainage openings and reduce the paver's flow capacity. Even though some irreplaceable loss in permeability should be expected over the paver's lifetime,you can increase the longevity of the system by following the maintenance schedule for sweeping and high-pressure washing,restricting the area's use by heavy vehicles,limiting the use of de-icing chemicals and sand,and implementing a stringent sediment control plan, Preventing Clogging of Perineable Paver Surface Areas > Patio areas and/or other areas with permeable pavers shall be cleaned annually with vacuums or hand swept. > Do not allow construction staging,soil/Mulch storage, etc.on unprotected pavement surface. > Maintain vegetated areas adjacent to areas with permeable pavers to prevent washout of soil onto surface. > Do not apply any type of sealant to permeable pavers. Removing Snow and Ice > Shovel snow off permeable pavers as necessary. > Do not apply abrasives such as sand or grit on or adjacent to permeable pavers. > Avoid plowing of areas with permeable pavers. Inspecting the System > Inspect areas paved with permeable pavers monthly for the first three months after construction to ensure proper functioning and correct any areas that have settled or experienced washouts. > Inspect areas paved with permeable pavers annually after initial three month period, Annual inspections should take place after large storms,when puddles will make any clogging obvious. Repairing Damages > Do not apply any type of sealant to permeable pavers. > If necessary,add additional aggregate fill material made up of clean sand or gravel. > Damaged interlocking paving blocks should be replaced. HI0.6.6.IiPrgecis121121-Slltlocslreports4104 Bonny_0864 I, Uanual.doc 2 104 Bonny Lane North Andover,Mass A.2 Pool Maintenance Primary pollutants of concerns in swimming pools are chlorine,bromine or chloramines used as disinfectants. These chemicals,if discharged to a resource area or storm drainage system can have negative impacts on water quality and aquatic life. Storage of Chemicals > Pool chemicals should not be stored outside. Chennical shall be stored inside and according to requirements of chemical provider in order reduce contamination in event of spill. > Spill clean up materials as recommend by chemical manufacture should be on hand in the event of a spill. Pool Drawdown and Maintenance > The pool shall be equipped with a non-backwash cartridge filter to eliminate the need to discharge pool water into lawn area during regular pool cleaning. > Pool water should not be discharged directly to street or storm drains > Prior to draining of pool, pool water shall be de-chlorinated per state municipal requirements by eliminating chlorine usage for approximately ten days to allow chlorine levels to dissipate or by utilizing sodium thiosulphate or other pool dichlorination chemical approved by DBP and for use in watershed areas. > PooI water should be discharged into the drywell slowing over a period of time to allow for recharge of pool water into ground. > When a severe (>100 year storm event)is predicted, the pool water level should be drained to a sufficient level to allow for 8 inches of rain to be collected in the pool. A.3 Vegetated Areas Maintenance Although not a structural component of the drainage system, the maintenance of vegetated areas may affect the functioning of the stormwater management system. This includes the health/density of vegetative cover and activities such as the application and disposal of lawn and garden care products, disposal of leaves and yard trimmings and proper aeration of soils. > Inspect planted areas on a semi-annual basis and remove any litter. > Maintain planted areas adjacent to patio to prevent soil washout, > Immediately clean any soil deposited on patio. > Re-seed bare areas;install appropriate erosion control measures when native soil is exposed or erosion channels are forming. > Pesticide/Herbicide Usage—Only organic or slow release nitrogen,phosphorus free products shall be used. Non-organic pesticides and herbicides use is prohibited 1416.6.0.15P%ecIs424s2151YdocsyepoRs1145F3onny_�&PA 3 104 Bonny Lane North Andover Mass M1ianual.doc A,4 Long Term Maintenance/ Evaluation Checklist 104 Bonny Lane — North Andover, Mass c� as 2 Cr E 0 E 0 �Y ° 0 0 0 MZ a� Q� ��/ V +1+ *Id L O tF, L E .}+ `� Q. Q. �. � �� Permeable Vacuum sweep or hand 1X per as/ / necessar Pavers sweep year Y as PolMaintenance See requirements above 9eear necessar Y y Repair/re-seed bare Vegetated spots, re-plant as 2X per as Areas necessary to prevent year necessar erosion y 151Q.6.0.14Proecls521121-5lldocs>reporls51046onny_O&M 4 104 Bonny Lame North Andover,Mass A9anuat.dac :rndover l r:est River Place coarsuEtarats 'Methuen,ltass:ichusetts 01844 irrc. Tel.(978)687-3828 1 ww'a n(i over'consul tH[1ts.Co Ill November 11, 2022 North Andover Planning Board C/o Jean Enright, Plaiming Director 120 Main Street North Andover, MA 01845 RE: Special Permit Watershed Peer Review 104 Bonny Lane North Andover,Mass Dear Ms. Enright and Board Members: We are in receipt of review conunents from Horsley Witten Group via a letter to the Board c/o of Jean Enright, dated October 21,2022. We have reproduced their conunents in italics and our response noted below in bold. 1. The Applicant intends to treat and mitigate storm water•by using porous pavers around the north and rarest, ivellarnd side of the pool perimeter to filler and infiltrate rain falling on the pool area. The construction of this pool will likely increase peak-flow runoff rates by a marginal amount as the porous pavers will lniligate the nitro(falling on the patio and the pool will capture the walerfalling on thepool. Response: As mentioned above, the proposed patio will be a "permeable"paver patio. The detail has been revised as suggested in comment#l2 below. 2. The Applicant has proposed a Paver Cross Section Detail on the plan. HW recomnnends that the Applicant consider substituting No 8 Bedding Aggregate for•the bedding sand. HW further recommends that the Applicant call out the size of the aggregate to be used in the 8-inch-thick base. Response: The detail for the pavers have been revised as noted and additionally to further promote stormwater infiltration. 3. HW recommends that the Applicant clearly delineate the limit of disturbance arrd docianent whether any trees (greater than 8"diameter) will be removed as part of the project. Response: The limit of disturbance has been demarcated on the revised plan. 4. The Applicant has proposed staked 9-inch straw wattles to provide erosion control surrounding the construction. HW recommends that the Applicant add a silt fence to the straw wattle barrier located within 50 feet of the on-site wellond resourcearea. Response: A silt fence has been added to the straw wattle along the area closest to the on-site resource area along the northern boundary line. 5. HW recommends that the Applicant provide aplan,for the re-natntralization of the 350 square foot area in the 25 foot No Disturbance Zone. Specifically, if there will be any seed mix added to the area, if any long-term maintenance is required, or if the area will be left undisturbed. HW reconnnends that the Applicant con firm that the area does not currently contain any invasive species. Response: A notation has been added to the revised plan specifying a seed juix for revegetation of this previously disturbed no-disturb-zone. 6. HW recommends that the Applicant provide a detail or describe the type of material to be used for the proposed 2,fool-high landscapewall. Page r of Civil Engineo-s et Land Surveyors s Land Manners P:121121-Stlda�JeKers12022•S I.11—Rosponse to HW Peet Nv!ewAd coasul�zia is i 3n. Response: Tile proposed retaining wall will be pre-cast block wall,similar to versa-loc retaining wall, or comparable alternative. 7. HW recwninends that the Applicant propose slope slabilization practices Cis heed during construction. Response: An erosion control blanket(jute mesh) detail has been added to the plans to be used by the contractor if necessary to stabilize slopes. 8. HTV reeonn needs that an Operation &Maintenance (O&M)Plan be provided to the hoieowner for long terns iaintenance of the porous pavers. Response: An Operation& Maintenance Plan has been prepared to instruct homeowner on long term maintenance of permeable paver patio. 9. HW reconnniends that the Applicant eyplain to the Planning Board the inethodology for punipiing out the pool at the end of the season. Specifically, where will the pool water be pionped to and hoiv will the.4pplicant con frni that pool chenticals will not be discharged into the resource area. The pool maintenance should be included in the O&MPlan for the owners use. Response: An operation and maintenance plan has been prepared and submitted with this response memorandum. The pool will utilize a non-backwash cartridge filter which eliminates the need to discharge pool water onto the lawn area during regular pool clearing. Prior to seasonal partial draining of the pool,pool water shall be de-chlorinated per state municipal requirements by eliminating chlorine usage for approximately ten days to allow chlorine levels to dissipate or by utilizing sodium thiosulphate or other pool dichlorination chemical approved by DEP and for use in watershed areas. 10. The Applicant intends to remove the fencing that is located on the adjacent lot.HTY reconutiends that the Planning Board confirin that the adjacent property owner is aware of the intended lvork on its property. Response: The note on the plan has been revised to read "coordinate with adjacent land owner to remove existing fence". If permission is not granted from the abutter, the fence can stay and a new fence rvill be placed along the property line. If you have any questions concerning the above responses, or require anything firrther,please feel free to contact me at your convenience. Sincerely, Andover Consultants Iite. Deruiis A. Griecei,P.E., LEER AP Enclosures Page 2 of 2 P:12721-stdarsle.'Eers12022-11•i 1_Respanse la kMd Peg k.V'KNd-