Loading...
HomeMy WebLinkAboutConsultant Review - 200 CHICKERING ROAD 3/4/1997 F` Tl1® �, 1 EVE ASSOCIATES, INC. March 4, 1997 +' North Andover Conservation Commission North Andover Planning Board 146 Main Street 146 Main Street North Andover, MA 01845 North Andover, MA 01845 Re: 200 Chickering Road, North Andover DEP File#242-856 MHF Design Consultants - Scott Companies Dear Conservation& Planning Board Members: Our firm has been retained by Attorney Mark Johnson on behalf of the Heritage Green Condominium Association for the purpose of providing consulting services in regards to the above-referenced matter. Find attached a report which includes our recommendation to date. We hope this information is helpful to both the Planning Board and Conservation Commission during their deliberations of the respective permits. We expect to have a representative at your meetings. Please feel free to ask any questions of us which you may have about this project. I thank you for having the opportunity to submit this information to you. Sincerely, THOMAS E. NEVE ASSOCIATES, INC. Thomas E. Neve, PE, PLS President, CEO TEN/km Attachment cc: Attorney Mark Johnson #1624JOHNSON.WPS • ENGINEERS • • LAND SURVEYORS • • LAND USE PLANNERS • 447 Old Boston Road U.S. Route #1 Topsfield, MA 01983 (508) 887-8586 FAX (508) 887-3480 Td.loll1 AS a NEVE ASSOCIATES, INC. March 3, 1997 Mr. Mark Johnson, Esq. 12 Chestnut Street Andover, MA 01810 Re: 200 Chickering Road, North Andover DEP File 9242-856 MHF Design Consultants - Scott Companies Dear Mark: As per your instructions, I visited the North Andover Conservation Commission offices on Wednesday, February 19, 1997 and spent time researching, in detail, the file regarding the Request for Determination of Applicability and the Notice of Intent for the above-referenced site. On Wednesday, February 19, 1997 I appeared before the North Andover Conservation Commission and submitted certain verbal evidence into their record regarding my review and concerns. I indicated to the Commission and to the applicants representatives that I would reduce my thoughts to writing for their benefit. The following are my comments to date: 1. The Notice of Intent application indicated the description of work as being "associated site access and parking" for the construction of a 16,900 square foot retail project. By reviewing the plan and understanding the policies of the DEP, this entire project falls under the jurisdiction of the Conservation Commission since the drainage attributes link wetland jurisdiction, .particularly the 100' buffer zone. This policy was reaffirmed when the DEP issued the Stormwater Management Regulations on November 1996. • So I believe an amended description of the project should be submitted by the applicant to indicate all construction and operation which will be subject to this permit. 2. The application also indicated that a.State DPW curb cut permit was applied for relating to projects which will generate more than 1,000 vehicle trips per day. I am working on getting a copy of that curb cut permit, will review same and submit an independent report to you. -ENGINEERS • • LAND SURVEYORS • • LAND USE PLANNERS • 447 Old Boston Road U.S. Route #1 Topsfield, MA 01983 (508) 887-8586 FAX (508) 887.3480 Mr. Mark Johnson, Esq. Page 2 March 3, 1997 3. In my review of the Request for Determination of Applicability (RFD) subfile, I found Mike Howard's (Conservation Administrator) notes and a plan which was marked up by him. The Determination of Applicability was made on a 12/11/96 plan confirming wetland flags #WF 1 through #WF47. Mike Howard's plan indicated that flag #WF22 should be connected to #WF29. He also indicated that the plan should show swales and stream flow. I am not sure that your work was even done or what the final agreement was between the applicant and Mike Howard, however, my examination of the plan filed with the NOI indicates that these reviews were not made. 4. Find attached a letter from the Executive Office of Environmental Affairs (EOEA) dated 12/23/96 regarding the MEPA determination. MEPA did not scope this project with respect to traffic which I feel is unfortunate since it is my opinion that the traffic impacts are significant. The only forum we have to work with now is the DPW on the curb cut permit and the North Andover Planning Board during the Special Permit proceedings. 5. Please find attached a letter dated 12/3/96 from the Division of Fisheries and Wildlife. Although this lot is not contained within an endangered species habitat zone the letter did indicate, "the ruling does not rule out the possibility that more common wildlife or vegetation might be adversely affected by the project, specifically if it will modify currently undeveloped areas". Please be informed that the North Andover Conservation Commission has an expanded resource area with respect to wildlife habitat and I would encourage a closer look at these attributes of the site to determine whether common wildlife vegetation would be adversely affected by the project. 6. The final grading plan calls for a 6' high slope to be built on the Farrwood Avenue side of the project directly adjacent to the property boundary. Although screening is proposed on this embankment, I find it difficult to understand how the buffer will be established long term in order to create an effective buffer on this slope. 7. The drainage system relies on the subsurface detention of storm water in order to mitigate impacts due to certain rainfall events. Careful examination of the analytical aspects of the storm water calculations indicate that they were computed properly. The designer elected to propose 4 underground "infiltrator" systems which will hold 1,100 cubic feet of water per system or 8,228 gallons. The quantity of water will be stored underground in containment structures. There are 4 infiltrator systems numbered 1, 2, 3 & 4. The bottom of these systems are placed close to the seasonal high water table, that is 2.5', 1.25, 2.5' and 1' above the seasonal high water table. In addition, these systems will percolate storm water into the surrounding soils and through a shallow column of soil above the water table, directly into the water table. Included within the hydro calcs the designer has completed a stormwater management form. He has acknowledged that this project is a "high intensity development", however, he fails to recognize that high intensity developments do not allow for infiltration of storm water. In this particular case, untreated storm water will flow directly into the ground water table. There is little separation between the bottom of each system and the seasonal high water table and Mr. Mark Johnson, Esq. Page 3 March 3, 1997 during any moderate rain fall event storm water being detained in each system will slowly percolate through the underlying soils saturating this vertical separation connecting itself to the groundwater table and in effect resulting in no treatment. This infiltration bmp has not been designed in accordance with Standard 5 of the Stormwater Management Policies. We had noticed on the Stormwater Management Form that Standard 5 was left blank and marked "not applicable". We checked Mike Howard's booklet and noted that he had circled this portion of the Stormwater Management Form during his review of the Notice of Intent. I am sure that he questions this same issue. Within the Stormwater Management Report the designer has provided a technical report regarding the infiltrator systems. He admits that only 15% of the pollutants will be removed in the catch basins. The infiltrator detention system is rated to remove 75% to 80% of the pollutants. The major problem with these underground detention systems is that they are very difficult to maintain. The manufacturer recommends annual inspections. I question how the suspended, accumulated pollutants will be cleaned from the underground system. The perforations in the infiltrator units, the stone around the infiltrator units, the stone around the units and the clogged soil will be impossible to clean and maintain. The technical report indicates that oil/grit separators are usually employed to remove heavy solids and hydrocarbons. It further indicates that these separators cannot be by-passed during peak flows. It further suggests that the separators typically only have moderate removing abilities because of the short residence time of the storm water which passes through them. The literature suggests that the inlets must be frequently inspected and maintained. The manufacturer suggests that the infiltrator systems will be rendered useless if poor maintenance is employed. That further suggests that a legally binding maintenance agreement is established with the Town and the Town be given enforcement abilities to insist that the maintenance be performed. In summary, in my professional opinion this underground detention system fails to provide adequate protection of the groundwater. It fails to ensure that once installed this system can be practically maintained and further collectively fails to meet the Stormwater Management Regulations established by the DEP. I hope that the proponent will redesign this stormwater detention system and come up with a program which will meet the Stormwater Management Policies, will ensure that the groundwater will not be polluted and will ensure that the hydrology of the area will not be locally impacted by such large volumes of water being recharged over such a small development. The designer has contended that the subsurface soils are comprised of woodbridge fine loamy sand. The permeability of these types of soils are moderate to moderately rapid in the subsoil which exists to a depth of about 18" below existing grade. However, in the soils beneath the Mr. Mark Johnson, Esq. Page 4 March 3, 1997 subsoil the permeability is slow. The seasonal high water table is at a depth of 1.5'-3' below the ground on an average during the winter and spring months. Test pits dug on the property indicate that the seasonal high water table is somewhat lower than what the soil survey reports indicate and that is not unusual. The important aspects are that the substratum soils or parent material soils are somewhat poorly drained and do not vacate water rapidly. The seasonal high water table will limit the water carrying capacity of the soil as well. Since the subsoil is particularly permeable infiltrated water forced into the ground will be subject to a slow and the parent material restricting to vertical flow. The site slopes from front to back. The infiltrator systems are proposed within the subsoil elevations. Infusion of stormwater into the subsoil layer will create groundwater mounding in this layer and high concentrations of underground water flow will be transported in the subsoil down gradient to abutting properties. The designer should study what affect the infusion of large quantities of stormwater into the subsoil will have on abutting properties. Your client has indicated to me that drainage within the condominium has been an issue and a chronic source of maintenance (i.e. wet basements and damp basement units). A major concern with this project is how the stormwater is being managed and what affect the stormwater will have on the underground groundwater systems which flow through the abutting condominium parcel. Sincerely, _DMA VE ASSOCIATES, INC. Thomas E. Neve, PE, PLS President, CEO TEN/km Attachments #1624 JOHNSONNI'S ' 4 X00 �airj�/� �xeeG; � a� 02202 WIWAM'F.WELD GOVERNOR ARGEO PAUL CELLUCCI Tel: (617) 727-9800 UEUTENANT GOVERNOR Fax: (617).727-2754 TRUDY COXE SECRETARY December 23 , 1996 CERTIFICATE OF THE SECRETARY OF ENVIRONMENTAL AFFAIRS ON THE ENVIRONMENTAL NOTIFICATION FORM PROJECT NAME Old Town Village PROJECT LOCATION North Andover EOEA NUMBER 10967 PROJECT PROPONENT Scott Construction Company DATE NOTICED IN MONITOR November 22, 1996 Pursuant to the Massachusetts Environmental Policy Act (G. L. c . 30, ss-. 61-62H) and Section 11 . 06 of the MEPA regulations (301 CMR 11. 00) , I hereby determine that the above project does not require the preparation of an Environmental Impact Report. This project involves the construction of 16, 900 square feet (sf) of retail space with 8'6 parking spaces on a 6 .2 acre site on the west side of Route 125 immediately south of Farrwood Avenue. The project will include two driveways, utilities, landscaping and a stormwater collection system. The project will require a curb opening permit from the Massachusetts Highway Department (MHD) . It is being reviewed by MEPA because the project is expected to generate more than 1, 000 vehicle trips per day. It also will require local approvals, including an Order of Conditions from the North Andover Conservation Commission. A traffic study prepared for the project indicates that the traffic impacts of the project are minimal. MHD concurs with this opinion. No formal traffic mitigation is required and design details for the curb openings can be developed during the permitting process . 100%P1-=CYr1-F0 PAP=P Commonwealth of*Massachusetts D®v®s®onof 'fe Fisheiries &VOdIN Wayne F. MacCallurn, Director 3 December 1996 Philip E. Koziol MHF Design Consultants, Inc. -i rPi' 2.3 Icc- 12-B Manbr Parkway n rt Salem, NH 03079 7__ 7i DEC 5 19S6 Re: Proposed Retail Development, 200 Chickering Road North Andover, MA NBESP File: 96-1229 Dear Mr. Koziol, Thank you for contacting the Natural Heritage and Endangered Species Program for information regarding state-listed rare species in the vicinity of the project referred to above. At this time we are not aware of any rare plants or animals or exemplary natural communities that would be adversely affected by the proposed project. This review concerns only rare species of plants and animals and ecologically significant natural communities for which the Program maintains site-specific records. This review does not rule out the possibility that more common wildlife or vegetation might be adversely affected by the project, especially if it will modify currently undeveloped areas. Should project plans change, or new rare species information become available, this evaluation may be reconsidered. Please call me at (508)792-7270 x.161 if you have any questions. Sincerely, Hanni Dinkeloo Environmental Reviewer -4 N Natural Heritage & Endangered Species Program Route 135,Westborough,MA 01581 Tel: (508)792-7270 x 200 Fax: (508)792-7275 An Agency of the Department of Fisheries,Wildlife&Environniental Law Enforcement http://www.state.ma.us/dfwele f 11'S0Q'VN -. Ejo 1 VLA C TE March 6, 1997 Kathleen Bradley Colwell Town Planner 146 Main Street North Andover, MA 01845 Re: 200 Chickering Road, North Andover DEP File#242-856 MET Design Consultants - Scott Companies Dear Kathleen: Please find attached two letters; one dated March 3, 1997 and the other dated March 6, 1997. Could you please forward these to John Chessia of Coler& Colantonio for his attention. Also find that we are asking John to provide us with certain correspondence regarding this matter and hope that you will direct him to furnish us with this information. We would be happy to pay the expenses involved in this request. Sincerely, THOMAS E,-N,EVE ASSOCIATES, INC. Thomas E. Neve, PE, PLS President, CEO TEN/km Attachments #1624CHES.WPS ENGINEERS e o LAND SURVEYORS LAND USE PLANNERS 447 Old Boston Road U.S. Route #1 Topsfield, MA 01983 (508) 887-3586 FAX (50€3) 887-3480 THOMASL,NEVE ASSOCIATE 8, ING March 6, 1997 Mr. John Chessia, P.E. Coler& Colantonia 101 Accord Park Drive Suite One Norwell, MA 02061-1685 Re: 200 Chickering Road, North Andover DEP File #242-856 M1-1F Design Consultants - Scott Companies Dear John: Thank you for spending a considerable amount of time on the phone the other day with John Morin from our office, We have been retained by the Heritage Green Condominium Association who abuts the above-referenced project. Our sole mission is to ensure that the federal, state and local regulations and bylaws are being met in the development of this property. At this time we would like to submit our general concerns based on our review of the plans submitted to the Town. We are aware that your office has been involved in the review of this project for several months. We will make every effort to bring our office up to speed with respect to our tasks such that it will not interfere with the Towns ability to efficiently process applications. At this time we ask that you furnish us with copies of your most recent review and possibly the previous review letter and MHF Design Consultants' submittals to you an the issues. We would like information which directly relates to the current proposal being reviewed by you. We are aware that the plan has been changed significantly since the beginning and we are not interested in tracking the history to that extent. We have made an independent inquiry through Kathleen Bradley Colwell, Town Planner, as we assure you will check with her before sending us this information. As John indicated to you by phone, we are quite concerned with the stormwater detention system as proposed for the following reasons: 1. We feel that the system will pollute the groundwater due to the small vertical distance between the system and the groundwater table coupled with the fact that the soils within this vertical distance are poorly drained and will become supersaturated making a direct connection to the groundwater table. ENGINEERS LAND SURVEYORS LAND USE PLANNERS 447 Old Boston Road I.J.S. Route #1 Topsfield, MA 01983 (5078) 887.8586 FAX (508) 887-3480 Mr. John Chessia Page 2 March 6, 1997 2. We are also concerned that the system, as proposed, will surcharge and flow will occur from the catchbasins located on the down stream side of the project. This will result in overland flow of untreated water onto abutting properties and to wetland resource areas. Since no hydraulic grade line information has been submitted this impact cannot be evaluated. 3. Also, close examination of soil type indicates a very pervious subsoil regime, therefore, concentrated flow occurring in this regime will create lateral movement of significant quantities of stormwater which will flow onto abutting properties. If this flow regime encounters foundations or any other attributes on its flowpath the water will create an increased impact with respect to drainage onto abutting properties. We have shared with you our concern that this system cannot be adequately and efficiently maintained and since this property is a privately owned enterprise we feel the Town should pay particular attention to what is being represented to them. The proponent is representing that the system can be maintained; however, they provide no pre- treatment as required by the manufacturer of the infiltrator units. They provide no maintenance manual or inspection protocol and provide no assurance that if the system fails what protection the abutters have. I would expect that you would employ the same standard of care in reviewing private projects which are subject to Special Permits in the same light that you review subdivision roadways and drainage designs. Even though the Town will not inherit the project as they do in subdivisions, the neighbors will inherit any adverse impacts that the project may have if the same standard of care is not taken in the review of drainage and mitigation facilities. I would be happy to discuss these issues with you further and I hope that you will address some of these concerns in your next review letter with the applicant. I appreciate your time and thank you, in advance, for your anticipated cooperation. Sincerely, THOMAS E. ] EVE ASSOCIATES, INC. Thomas E. Neve, PE, PLS President, CEO TEN/km 9 1624CIIES.WPS ,u THOMAS EgNEVE ASSOCIATE , INC. March 4, 1997 North Andover Conservation Commission North Andover Planning Board 146 Main Street 146 Main Street North Andover, MA 01845 North Andover, MA 01845 Re: 200 Chickering Road, North Andover DEP File 9242-856 MHF Design Consultants - Scott Companies Dear Conservation& Planning Board Members: Our firm has been retained by Attorney Mark Johnson on behalf of the Heritage Green Condominium Association for the purpose of providing consulting services in regards to the above-referenced matter. Find attached a report which includes our recommendation to date. We hope this information is helpful to both the Planning Board and Conservation Commission during their deliberations of the respective permits. We expect to have a representative at your meetings. Please feel free to ask any questions of us which you may have about this project. I thank you for having the opportunity to submit this information to you. Sincerely, THOMAS E. NEVE ASSOCIATES, INC. Thomas E. Neve, PE, PLS President, CEO TEN/km Attachment cc: Attorney Mark Johnson #1624JOHNSON.WPS •ENGINEERS - • LAND SURVEYORS • • LAND USE PLANNERS • 447 Old Boston Road U.S. Route #1 Topsfield, MA 01983 (508) 887-8586 FAX (508) 887-3480 �j T O 1 J� ASSOCIATES, INC. March 3, 1997 Mr. Mark Johnson, Esq. 12 Chesinut Street Andover, MA 01810 Re: 200 Chickering Road, North Andover DEP File 9242-856 MHF Design Consultants - Scott Companies Dear Mark: As per your instructions, I visited the North Andover Conservation Commission offices on Wednesday, February 19, 1997 and spent time researching, in detail, the file regarding the Request for Determination of Applicability and the Notice of Intent for the above-referenced site. On Wednesday, February 19, 1997 I appeared before the North Andover Conservation Commission and submitted certain verbal evidence into their record regarding my review and concerns. I indicated to the Commission and to the applicants representatives that I would reduce my thoughts to writing for their benefit. The following are my comments to date: 1. The Notice of Intent application indicated the description of work as being "associated site access and parking" for the construction of a 16,900 square foot retail project. By reviewing the plan and understanding the policies of the DEP, this entire project falls under the jurisdiction of the Conservation Commission since the drainage attributes link wetland jurisdiction, particularly the 100' buffer zone. This policy was reaffirmed when the DEP issued the Stormwater Management Regulations on November 1996. • So I believe an amended description of the project should be submitted by the applicant to indicate all construction and operation which will be subject to this permit. 2. The application also indicated that a State DPW curb cut permit was applied for relating to projects which will generate more than 1,000 vehicle trips per day. I am working on getting a copy of that curb cut permit, will review same and submit an independent report to you. • ENGINEERS • • LAND SURVEYORS • • LAND USE PLANNERS • 447 Old Boston Road U.S. Route #1 Topsfield, MA 01983 (508) 887-8586 FAX (508) 887.3480 Mr. Mark Johnson, Esq. Page 2 March 3, 1997 3. In my review of the Request for Determination of Applicability (RFD) subfile, I found Mike Howard's (Conservation Administrator) notes and a plan which was marked up by him. The Determination of Applicability was made on a 12/11/96 plan confirming wetland flags 9WF 1 through #WF47. Mike Howard's plan indicated that flag #WF22 should be connected to #WF29. He also indicated that the plan should show swales and stream flow. I am not sure that your work was even done or what the final agreement was between the applicant and Mike Howard, however, my examination of the plan filed with the NOI indicates that these reviews were not made. 4. Find attached a letter from the Executive Office of Environmental Affairs (EOEA) dated 12/23/96 regarding the MEPA determination. MEPA did not scope this project with respect to traffic which I feel is unfortunate since it is my opinion that the traffic impacts are significant. The only forum we have to work with now is the DPW on the curb cut permit and the North Andover Planning Board during the Special Permit proceedings. 5. Please find attached a letter dated 12/3/96 from the Division of Fisheries and Wildlife. Although this lot is not contained within an endangered species habitat zone the letter did indicate, "the ruling does not rule out the possibility that more common wildlife or vegetation might be adversely affected by the project, specifically if it will modify currently undeveloped areas". Please be informed that the North Andover Conservation Commission has an expanded resource area with respect to wildlife habitat and I would encourage a closer look at these attributes of the site to determine whether common wildlife vegetation would be adversely affected by the project. 6. The final grading plan calls for a 6' high slope to be built on the Fanwood Avenue side of the project directly adjacent to the property boundary. Although screening is proposed on this embankment, I find it difficult to understand how the buffer will be established long term in order to create an effective buffer on this slope. 7. The drainage system relies on the subsurface detention of storm water in order to mitigate impacts due to certain rainfall events. Careful examination of the analytical aspects of the storm water calculations indicate that they were computed properly. The designer elected to propose 4 underground "infiltrator" systems which will hold 1,100 cubic feet of water per system or 8,228 gallons. The quantity of water will be stored underground in containment structures. There are 4 infiltrator systems numbered 1, 2, 3 & 4. The bottom of these systems are placed close to the seasonal high water table, that is 2.5', 1.25', 2.5' and 1' above the seasonal high water table. In addition, these systems will percolate storm water into the surrounding soils and through a shallow column of soil above the water table, directly into the water table. Included within the hydro calcs the designer has completed a stormwater management form. He has acknowledged that this project is a "high intensity development", however, he fails to recognize that high intensity developments do not allow for infiltration of storm water. In this particular case, untreated storm water will flow directly into the ground water table. There is little separation between the bottom of each system and the seasonal high water table and Commonwealth of Massachusetts Divisionot Fisheffles &VIddleile Wayne F. MacCallum, Director !°"z r L _ 1 3 December 1996 Philip E. Koziol ' MHF Design Consultants Inc. lf y ! 23 cE 'n�- 12-B Manor Parkway Salem, NH 03079 DEC 5 a ,An!^11c:11VIS�c��SUlldt,lS it1C; Re: Proposed Retail Development, 200 Chickering Road North Andover, MA NHESP File: 96-1229 Dear Mr. Koziol, Thank you for contacting the Natural Heritage and Endangered Species Program for information regarding state-listed rare species in the vicinity of the project referred to above. At this time we are not aware of any rase plants or animals or exemplary natural communities that would be adversely affected by the proposed project. This review concerns only rare species of plants and animals and ecologically significant natural I, communities for which the Program maintains site-specific records. This review does not rule out the possibility that more common wildlife or vegetation might be adversely affected by the project, especially if it will modify currently undeveloped areas. Should project plans change, or new rare species information become available, this evaluation may be reconsidered. Please call me at (508)792-7270 x.161 if you have any questions. Sincerely, t � Hanni Dinkeloo Environmental Reviewer ��rx4 Natural Heritage & Endangered Species Program Route 135,Westborough, MA 01581 Tel: (508)792-7270 x 200 Fax: (508)792-7275 An Agency of the Department of Fisheries,Wildlife&Environmental Law Enforcement http://www.state.ma.us/dfwele *a WILLIAM'F.WELD GOVERNOR ARGEO PAUL CELLUCCI Tel: (617)727-9800 UEUTENANT GOVERNOR Fax: (617).727-2754 TRUDY COXE SECRETARY December 23 , 1996 CERTIFICATE OF THE SECRETARY OF ENVIRONMENTAL AFFAIRS ON THE ENVIRONMENTAL NOTIFICATION FORM PROJECT NAME Old Town Village PROJECT LOCATION North Andover. EOEA NUMBER 10967 PROJECT PROPONENT Scott Construction Company DATE NOTICED IN MONITOR November 22, 1996 Pursuant to the Massachusetts Environmental Policy Act (G. L. c . 30, ss-. 61-62H) and Section 11. 06 of the MEPA regulations (3.01_ CMR 11. 00) , I hereby determine that the above project does not require the preparation of an Environmental Impact Report. This project involves the construction of 16, 900 square feet (sf) of retail space with 86 parking spaces on a 6 .2 acre site on the west side of Route 125 immediately south of Farrwood Avenue. The project will include two driveways, utilities, landscaping and a stormwater collection system. The project will require a curb opening permit from the Massachusetts Highway Department (MHD) . It is being reviewed by MEPA because the project is expected to generate more than 1, 000 vehicle trips per day. It also will require local approvals, including an Order of Conditions from the North Andover Conservation Commission. A traffic study prepared for the project indicates that the traffic impacts of the project are minimal. MHD concurs with this opinion. No formal traffic mitigation is required and design details for the curb openings can be developed. during the permitting process. Mn Mark Johnson, Esq. Page 4 March 3, 1997 subsoil the permeability is slow. The seasonal high water table is at a depth of 1.5'-3' below the ground on an average during the winter and spring months. Test pits dug on the property indicate that the seasonal high water table is somewhat lower than what the soil survey reports indicate and that is not unusual. The important aspects are that the substratum soils or parent material soils are somewhat poorly drained and do not vacate water rapidly. The seasonal high water table will limit the water carrying capacity of the soil as well. Since the subsoil is particularly permeable infiltrated water forced into the ground will be subject to a slow and the parent material restricting to vertical flow. The site slopes from front to back. The infiltrator systems are proposed within the subsoil elevations. Infusion of stormwater into the subsoil layer will create groundwater mounding in this layer and high concentrations of underground water flow will be transported in the subsoil down gradient to abutting properties. The designer should study what affect the infusion of large quantities of stormwater into the subsoil will have on abutting properties. Your client has indicated to me that drainage within the condominium has been an issue and a chronic source of maintenance (i.e. wet basements and damp basement units). A major concern with this project is how the stormwater is being managed and what affect the stormwater will have on the underground groundwater systems which flow through the abutting condominium parcel Sincerely, SOMA VE ASSOCIATES, INC. Thomas E. Neve, PE, PLS President, CEO TEN/km Attachments 91624 JOHNSON.WPS Mr. Mark Johnson, Esq. Page 3 March 3, 1997 during any moderate rain fall event storm water being detained in each system will slowly percolate through the underlying soils saturating this vertical separation connecting itself to the groundwater table and in effect resulting in no treatment. This infiltration bmp has not been designed in accordance with Standard 5 of the Stormwater Management Policies. We had noticed on the Stormwater Management Form that Standard 5 was left blank and marked "not applicable".. We checked Mike Howard's booklet and noted that he had circled this portion of- the Stormwater- Management Form during his review of the Notice of Intent. I am sure that he questions this same issue. Within the Stormwater Management Report the designer has provided a technical report regarding the infiltrator systems. He admits that only 15% of the pollutants will be removed in the catch basins. The infiltrator detention system is rated to remove 75% to 80% of the pollutants. The major problem with these underground detention systems is that they are very difficult to maintain. The manufacturer recommends annual inspections. I question how the suspended, accumulated pollutants will be cleaned from the underground system. The perforations in the infiltrator units, the stone around the infiltrator units, the stone around the units and the clogged soil will be impossible to clean and maintain. The technical report indicates that oil/grit separators are usually employed to remove heavy solids and hydrocarbons. It further indicates that these separators cannot be by-passed during peak flows. It further suggests that the separators typically only have moderate removing abilities because of the short residence time of the storm water which passes through them. The literature suggests that the inlets must be frequently inspected and maintained. The manufacturer suggests that the infiltrator systems will be rendered useless if poor maintenance is employed. That further suggests that a legally binding maintenance agreement is established with the Town and the Town be given enforcement abilities to insist that the maintenance be performed. In summary, in my professional opinion this underground detention system fails to provide adequate protection of the groundwater. It fails to ensure that once installed this system can be practically maintained and further collectively fails to meet the Stormwater Management Regulations established by the DEP. I hope that the proponent will redesign this stormwater detention system and come up with a program which will meet the Stormwater Management Policies, will ensure that the groundwater will not be polluted and will ensure that the hydrology of the area will not be locally impacted by such large volumes of water being recharged over such a small development. The designer has contended that the subsurface soils are comprised of woodbridge fine loamy sand. The permeability of these types of soils_are moderate to moderately rapid in the subsoil which exists to a depth of about 18" below existing grade. However, in the soils beneath the NEVE ASS ING Memorandum To: John Chessia, Coler and Colantonio Mike Howard,North Andover Conservation Commission V Kathleen Colwell,North Andover Planning Board Mark Johnson, Esquire ✓ From: Tom Neve Re: 200 Chickering Road-Heritage Green Condominium Association Date: April 9, 1997 I am representing the Heritage Green Condominium Association. I have been asked to review the project for technical compliance. 1. I understand that during their drainage review Coler and Colantonio has required the applicant to conduct percolation tests in locations where they are proposing subsurface disposal of stormwater. Since the infiltrator systems are acting like leaching fields, I would recommend that these tests be conducted in the presence of the Board of Health agent since she is extremely familiar with evaluating soil for the town. 2. I would recommend that maximum high water tables be established as required by the State Environmental Code. I would further recommend that any mitigation system be required to be four feet above the maximum high water table elevation since untreated stormwater will be infiltrating the groundwater system. 3. I would also recommend that perc tests be done in the topsoil and subsoil layers as well as the receiving layer so that groundwater mounding studies can be performed in order to evaluate the impact that the large quantities will have on the abutting properties. Approximately 35,000 gallons of water will be induced into the subsurface soils as a result of the stormwater detention. And I am concerned that the receiving layer(mapped poorly drained by the Soil Conservation Service) will not have sufficient capacity to absorb the stormwater volume, therefore any excess flow would enter the permeable subsoils and create an artificial groundwater gradient which slopes toward the abutting property of the ® ENGINEERS ® LAND SURVEYORS ® ® LAND USE PLANNERS 447 Old Boston Road U.S. Route #1 Topsfield, MA 01983 (508) 887-8586 FAX (508) 887-3480 J. Chessia, M. Howard, K. Colwell Page 2 April 9, 1997 condominium association. Foundation systems of the existing condominiums would intercept any perched water table or any artificial water table created by groundwater mounding in this area. That result could lead to stormwater infiltrating basement systems where these types of problems do not exist today. If the groundwater system is allowed, the applicant should be required to provide an interceptor trench along the property boundary including an impervious barrier on the downstream side of the trench which would eliminate any opportunity for subsurface groundwater flow to create an impact on abutting properties. Where this final interceptor trench would flow to is a further question. I strongly suggest that you pay particular attention to these issues since I don't feel that they have been adequately addressed at this point. Further, the applicant has indicated, which is suppported by the manufacturer's technical data, that these types of systems require agressive maintenance. A bond securing the maintenance, repair and replacement together with a countermeasure plan should be submitted before this agressive system is allowed. I would be happy to discuss this matter further with anyone who has any questions regarding this matter. TEN/ew Tom\1624.doc