Simsbury Design Guidelines September 30, 2011

Appendix A:

Simsbury Center Watershed Planning & Design Framework

Morris Beacon Design 6HF 5HJXODWLQJ3ODQ &KDSWHU6WUHHW)URQWDJHV 

West Seminary

Massaco

Plank Hill

Brook

Owen’s

Hopmeadow Wilcox Station Mall Way

Phelps

Drake Hill

Hopmeadow

Railroad Iron Horse

Phelps Mall Way Mall Wilcox Railroad Iron Horse * * * * * * * * * Simsbury Center Watershed Planning & Design Framework Street Frontage September 26, 2011 Simsbury Center Existing New 6LPVEXU\&HQWHU Road Road data, land use boundaries and categories, and growth Open Site framework legend designations/descriptions are for use as SC-1 Property Line Open Site Building to be Protected an illustrative guide only. Detailed planning and engineering 5HJXODWLQJ3ODQJanuary 4, 2011 Civic Site shall incorporate soils data, topography, land use data, and other SC-2 Street Setback Line Civic Site Building Not Protected relevant base data veri ed by a quali ed professional. HSG C & D Soils Code Studio | Third Coast Design Studio | Urban Advantage | SC-3 Parking Setback Line Existing conditions and regulating plan information is approximate, obtained from Town of Simsbury data Winter and Company | Nelson\Nygaard | W-ZHAPotential Stormwater and Simsbury Center Regulating Plan by Code Studio Receiving Zone SC-4 Simsbury Center Feet N adopted April 4, 2011. FEMA Flood Zone AE SC-5 Proposed Road 0 200 400 600 800 1,000 Soils data obtained from USDA NRCS Web Survey. * (approximate)

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Si m s b u r y Ce n t e r - 1 Si m s b u r y Ce n t e r - 2 High Infiltration Capability High Infiltration Capability Simsbury Center - 1 generally These areas support widespread includes less intense development implementation of block, street, and with increased building setbacks to site scale decentralized infiltration preserve the historic character of BMPs to maximize water quality Hopmeadow Street. Therefore, there treatment and volume recharge, thus may be lower site impervious area reducing land consumption required ratios and more flexibility to devote for larger, centralized structural BMPs. space to natural, vegetated water Simsbury Center -2 Frontage is quantity and quality BMPs. BMPs intended to accommodate more dense should be carefully designed to development, therefore BMPs that do reinforce the historic quality of place not require extensive land area such as in conjunction with neighborhood and permeable pavement systems, green site design. Neighborhood/site design roofs, stormwater harvesting, tree box should prioritize protection of existing filters, underground infiltration systems, mature vegetation. and parking lot / systems provide stormwater function Localized areas with low infiltration and are appropriate to urban context. capacity soils and/or high water table can still support water quality treatment Parks and other open spaces should with “flow-through” BMPs with be graded to provide storage and underdrains, such as green roofs, flow- infiltration. through planters, and tree box filters, to filter and slow runoff velocities. Localized areas with low infiltration Properly designed infiltration BMPs capacity soils and/or high water table such as infiltration trenches, permeable can still support water quality treatment pavement stone reservoirs, and other with “flow-through” BMPs with subsurface systems may provide some underdrains, such as green roofs, flow- peak rate and volume mitigation even through planters, and tree box filters, to in areas of HSG C and D soils. filter and slow runoff velocities. Grading of parks and other open Design of new streets or street retrofits spaces for storage may not be with Simsbury Center - 2 frontage compatible with the historic character should proiritize the needs of retail of Hopmeadow Street. uses with reduced front building setbacks. Design should incorporate New streets or street retrofits with permeable pavement on-street parking Simsbury Center - 1 frontage should spaces, permeable walks, and tree proiritize matching the historic box filters, however bioretention Hopmeadow Street character, and and swales may not be appropriate should incorporate permeable for some conditions as they reduce pavement on-street parking spaces, visability to retail and may hinder permeable walks, tree box filters, pedestrian access from on-street bioretention bump-outs, and water parking. !"#$%&&!'(')*'+&,-&.,,/ quality swales as appropriate to meet 01)2*3+4&%567&8'79'+&8:;++'99'&"'<5+9&&=&&&>>&&& Stormwater Article requirements. !"#$%&&!'(')*'+&,-&.,,/ 01)2*3+4&%567&8'79'+&8:;++'99'&"'<5+9&&=&&&>>&&& ?@@329+;91A'&B;29'+&C@;7 ?@@329+;91A'&B;29'+&C@;7

Si m s b u r y Ce n t e r - 3 Si m s b u r y Ce n t e r - 4 High Infiltration Capability High Infiltration Capability These areas support widespread These areas support widespread implementation of block, street, and implementation of block, street, and site scale decentralized LID BMPs site scale decentralized infiltration to maximize water quality treatment BMPs to maximize water quality and volume recharge, thus reducing treatment and volume recharge, thus land consumption required for reducing land consumption required larger, centralized structural BMPs. for larger, centralized structural Simsbury Center - 3 Frontage, similar BMPs. Simsbury Center -4 Frontage to Simsbury Center -2 Frontage, is is intended to accommodate primarily intended to accommodate more dense residential development, therefore development, therefore BMPs that do stormwater design and BMP selection not require extensive land area such as may require careful integration with site permeable pavement systems, green planning and lotting and coordination roofs, stormwater harvesting, tree box with topography. filters, underground infiltration systems, and parking lot bioretention/bioswale Neighborhood-scale rate and volume systems provide stormwater function mitigation BMPs located at the edges and are appropriate to urban context. of neighborhoods or in adjacent open space may preserve residential urban Parks and other open spaces should design character. be graded to provide storage and infiltration. Parks and other open spaces should be graded to provide storage and Localized areas with low infiltration infiltration. capacity soils and/or!"#$%&&!'(')*'+&,-&.,,/ high water table 01)2*3+4&%567&8'79'+&8:;++'99'&"'<5+9&&=&&&>>&&& can still support water quality treatment Localized areas with low infiltration with “flow-through” BMPs with capacity soils and/or high water table underdrains, such as green roofs, flow- can still support water quality treatment through planters, and tree box filters, to with “flow-through” BMPs with filter and slow runoff velocities. underdrains, such as green roofs, flow- through planters, and tree box filters, to Design of new streets or street retrofits filter and slow runoff velocities. with Simsbury Center - 3 frontage should proiritize the needs of retail Design of new streets or street retrofits uses with reduced front building with Simsbury Center - 4 frontage setbacks. Design should incorporate should meet Stormwater Article permeable pavement on-street parking requirements maximizing incorporation spaces, permeable walks, and tree of LID BMPS including permeable box filters, however bioretention pavement on-street parking spaces, and swales may not be appropriate permeable walks, tree box filters, for some conditions as they reduce bioretention bump-outs, and swales. visability to retail and may hinder !"#$%&&!'(')*'+&,-&.,,/ pedestrian access from on-street 01)2*3+4&%567&8'79'+&8:;++'99'&"'<5+9&&=&&&>>&&& parking. ?@@329+;91A'&B;29'+&C@;7 ?@@329+;91A'&B;29'+&C@;7

Si m s b u r y Ce n t e r - 5 Si m s b u r y Ce n t e r - CIV High Infiltration Capability High Infiltration Capability These areas support widespread Civic site design varies according implementation of block, street, and to specific building use and parking site scale decentralized infiltration requirements, however sites generally BMPs to maximize water quality support implementation of block, street, treatment and volume recharge, thus and site scale decentralized infiltration reducing land consumption required BMPs to maximize water quality for larger, centralized structural BMPs. treatment and volume recharge, thus Simsbury Center -5 Frontage is reducing land consumption required intended to accommodate residential for larger, centralized structural development, therefore stormwater BMPs. Civic sites may accommodate design and BMP selection may require additional innovative stormwater design careful integration with site planning and BMP selection, and potentially and lotting and coordination with may support neighborhood-scale rate topography. and volume mitigation BMPs. Simsbury Center - 5 development Parks and other open spaces should should prioritize the neighborhood- be graded to provide storage and scale strategies in the Site Planning infiltration. and Design Criteria Checklist. Neighborhood-scale rate and volume Localized areas with low infiltration !"#$%&&!'(')*'+&,-&.,,/ mitigation BMPs located at the edges capacity soils and/or high water table 01)2*3+4&%567&8'79'+&8:;++'99'&"'<5+9&&=&&&>>&&& of neighborhoods or in adjacent open can still support water quality treatment space may preserve residential urban with “flow-through” BMPs with !"#$%&&!'(')*'+&,-&.,,/ design character. 01)2*3+4&%567&8'79'+&8:;++'99'&"'<5+9&&=&&&>>&&&underdrains, such as green roofs, flow- through planters, and tree box filters, to Parks and other open spaces should filter and slow runoff velocities. be graded to provide storage and infiltration. Localized areas with low infiltration capacity soils and/or high water table can still support water quality treatment with “flow-through” BMPs with underdrains, such as green roofs, flow- through planters, and tree box filters, to filter and slow runoff velocities. Design of new streets or street retrofits with Simsbury Center - 4 frontage should meet requirements maximizing incorporation of LID BMPS including permeable pavement on-street parking spaces, permeable walks, tree box filters, bioretention bump-outs, and swales. Ot h e r Zo n e s Op e n Sp a c e High Infiltration Capability Potential Stormwater Receiving These areas support strategic Zone implementation of decentralized LID Potential Stormwater Receiving Zones BMPs to maximize water quality are conceptually identified based on treatment and volume recharge. their high infiltration capabilities and Generally, streets and sites not loctaed location near the edges of compact, in designated compact, walkable zones walkable zones or in adjacent open have design flexibility to maximize spaces. Depending on development use of vegetated LID BMPs and can intensity along with soil and accommodate increased volume topographical constraints, these areas recharge requirements. may serve as cost-effective locations for centralized peak rate and volume BMP selection and design should mitigation at the edges of districts be carefully calibrated to the to enable compact development in existing neighborhood context, and the centers. Appropriate buffers to neighborhood/site design should sensitive natural resource areas prioritize protection of existing mature * shall be maintained, and centralized vegetation where appropriate. stormwater mitigation shall be as far Low Infiltration Capability from sensitive water courses as is These areas face greater stormwater practicable. volume mitigation challenges. Decentralized “flow-through” water quality treatment BMPs with Active Open Space underdrains, such as green roofs, flow- Active open spaces accommodate through planters, and tree well filters public use. Active open spaces may be are generally appropriate to filter and designed in whole or in part to provide slow runoff velocities in areas of low mitigation of peak rate and stormwater infiltration capability and high water volume as part of a stormwater master table. Properly designed infiltration plan. BMPs such as infiltration trenches, permeable pavement stone reservoirs, and other subsurface systems Preserve may provide peak rate and volume Preserve areas protect existing natural mitigation even in areas of HSG C and resources from development. D soils. Grading of parks and other open spaces for storage may not be appropriate in areas with low infiltration capacity as public use may be compromised by soggy vegetated areas between larger rain events.