LaPlatte River Watershed Stormwater Infrastructure Study Chittenden County, VT

Transcription

1 LaPlatte Rive Wateshed Stomwate Infastuctue Study Chittenden County, VT June 25, 2010 Pepaed fo: LaPlatte Wateshed Patneship Hinesbug, VT Pepaed by: Milone & MacBoom, Inc. South Bulington, VT

2 Table of Contents Executive Summay... iv 1.0 Poject Intoduction Poject Oveview Poject Need / Histoy of Stomwate Management Wateshed and Subwatesheds Geology Bedock Geology Landfoms Soils Land use / Land cove Wateshed Landuse Impevious Cove Subwateshed Hydology Runoff Analysis Pioitization fom Runoff Analysis Stomwate Infastuctue Mapping Pocedues Shelbune Village Hinesbug Village Chalotte Stomwate Infastuctue Relating Stomwate Scenaio to Existing SGA and Wate Quality Data SGA Data Wate Quality Data Stomwate Teatment Pojects and Geneal Recommendations Poject Identification Summay of Recommended Pojects Geneal Stomwate Recommendations Gowth Cente Consideations Stomwate Utility Consideations LaPlatte Rive Wateshed Stomwate Infastuctue Study i

3 9.0 Refeences Appendix A Town Stomwate Infastuctue Maps Appendix B Impevious Suface Calculation Pocedues LaPlatte Rive Wateshed Stomwate Infastuctue Study ii

4 Acknowledgements This poject was funded by a Vemont Clean and Clea Gant to the Lewis Ceek Association (CC 2009-RCG Andea Mogante of the LaPlatte Wateshed Patneship, in conjunction with Maty Illick of the Lewis Ceek Association, coodinated this poject. Mak Suozzo, a student at the Univesity of Vemont, povided GIS analysis though a sevice leaning component of the NR-243 couse unde diection of Jalath O Neil-Dunne of the Spatial Analysis Lab and pofessos in the College of Engineeing and Mathematical Science. James Pease and Collin Smythe of the Vemont Depatment of Envionmental Consevation Stomwate Section povided poject guidance and technical suppot fo stomwate infastuctue mapping. Pam Bangan of the Chittenden County Regional Planning Commission povided GIS data and poject guidance. Benie Gagnon, Public Woks Diecto fo the Town of Shelbune, contibuted fisthand knowledge of the stomwate infastuctue in Shelbune. Bill Hoadley added knowledge of stomwate outfalls in Shelbune and egional wate quality conditions LaPlatte Rive Wateshed Stomwate Infastuctue Study iii

5 Executive Summay Milone & MacBoom, Inc was etained by the LaPlatte Wateshed Patneship to analyze stomwate impacts on the LaPlatte Rive and tibutaies in Shelbune, Chalotte, and Hinesbug, Vemont. The wok hee includes both GIS analysis and field veification to identify pimay stomwate impacts to wate quality and steam geomophology within the LaPlatte wateshed. Subwatesheds coesponding to steam geomophic assessment eaches wee efined with high esolution topogaphy and field veification of dainage pattens and stomwate infastuctue. These subwatesheds seved as a basis fo the stomwate analysis. Stomwate infastuctue mapping was compiled fo egions of the LaPlatte Rive wateshed in Shelbune, Chalotte, and Hinesbug. This mapping included collection systems, teatment aeas, and outfalls. Data was collected using plans submitted fo use with VT DEC stomwate pemits, a windshield suvey, and collection of GPS infomation on foot in developed village centes. A GIS study was pefomed by a Univesity of Vemont student by subwateshed to estimate elative stomwate isks based on impevious cove, soils, landuse, and unoff volume to taget specific subwatesheds fo mitigation. Subwatesheds wee anked based on pecent impevious cove and estimated unoff volumes. Ranking confimed that the pioity subwatesheds fo focused stomwate mitigation ae within the village centes whee the most land use convesion has taken place. Pioity subwatesheds identified include aeas daining to eaches of the LaPlatte Rive (M04, M06, and M16 village aeas, McCabe s Book (T1.03 in Shelbune Village, the Canal (T4.01, T4.04, and Patick Book (M15.S2 in Hinesbug Village. Results of past steam geomophic assessment and coido planning wee compaed to identified stomwate isks. Seveal of the subwatesheds that anked high in tems of impevious suface and unoff volume also had Poo to Fai geomophic condition (M06, M16, T1.03, T4.01, and T4.04. Many of these subwatesheds, and subwatesheds downsteam of pioity stomwate subwatesheds, had excessive bank eosion. It appeas that stomwate inputs may be contibuting to local steam channel adjustment and channel instability. Steam Habitat condition is Fai to Poo at o downsteam of pimay stomwate inputs. Fo example, on the LaPlatte Rive habitat condition is fai upsteam of each M16 that eceives the majoity of stomwate fom the village cente of Hinesbug, yet the condition educes to Poo downsteam of the stomwate inputs. In Patick Book, uppe eaches wee found to have Good habitat while conditions educed futhe downsteam (T4.02 and T4.01 to Fai to Poo whee stomwate inputs occu. In Shelbune, habitat conditions wee found to be Fai whee the majoity of stomwate inputs occu (T3.01, M LaPlatte Rive Wateshed Stomwate Infastuctue Study iv

6 Wate quality monitoing completed in the LaPlatte Rive and McCabe s Book by the LaPlatte Wateshed Patneship as pat of its Voluntee Monitoing Pogam stating in 2004 (LWP 2008 was eviewed and compaed to the stomwate mapping analysis. Wate quality data have shown that stom events tend to incease concentations of nitogen, phosphous, and suspended solids. Wate quality esults indicate that the LaPlatte Rive may be impacted fom unoff fom the Shelbune Village aea, coesponding to pioity subwatesheds identified in the impevious cove and unoff volume anking. Inceases in suspended sediments, phosphous, and bank eosion downsteam of Hinesbug Village ae possibly a poduct of inceased local flows fom stomwate unoff that ae typically unteated at the cuent time. The wate quality epot notes, Phosphous concentations in McCabe s Book ae significantly impacted by stom unoff fom agicultual land and lage impevious sufaces, as well as by stomwate unoff fom uban/semi-uban aeas in downsteam stations. Sampling on Patick Book showed inceases in tubidity and Total Phosphous between the Mechanicsville Road and Route 116 cossings, suggesting that unoff fom the commecial development may be influencing wate quality. Wate quality data on Mud Hollow and Bingham Book tibutaies show inceased suspended solids and phosphous concentations duing high flows whee lage oad and field ditch netwoks ae the pimay stomwate conveyance mechanisms such as in headwate locations in Chalotte and othe ual locations in the wateshed. Stomwate accumulation aeas and collection systems dischaging within pioity subwatesheds without teatment wee identified fo futue stomwate mitigation pojects. Pojects wee identified pimaily in the village centes. Contibuting dainage aea and amount of impevious suface wee calculated to guide poject implementation. Geneal ecommendations fo stomwate management ae povided based on the esults of this study. These include equiements of smalle scale development to mitigate stomwate and ecommendation of a gowth cente / town village plan fo stomwate. Low Impact Development (LID techniques ae summaized and suggested fo local implementation. These pactices ae small, elatively low cost, and applicable on a popety by popety basis. Cumulatively, small changes to the amount of impevious suface connected to a dainage system have a lage impact. Two specific village neighbohoods ae identified fo possible implementation. Specific popula LID methods ae suggested as possible ways to meet to following stomwate teatment goals. Limit the amount of impevious suface and peseve open space Disconnect impevious sufaces fom collection systems and eceiving wates Peseve ive coido natual stomwate functions Impove stomwate teatment function of oadside ditches LaPlatte Rive Wateshed Stomwate Infastuctue Study v

7 The souces of unegulated and unmitigated stomwate ae substantial in the LaPlatte Rive wateshed and the state. The Laplatte Rive wateshed is not designated as a stomwate impaied wateshed accoding the EPA 303(d list and steps should be taken to impove steam health and avoid a futue impaied designation. Stomwate has a cumulative effect on eceiving wates and should theefoe be examined on a wateshed basis, as is done fo Total Maximum Daily Load allocations in impaied wateways. This poject takes a poactive appoach to examine stomwate isks in the LaPlatte Rive wateshed to impove the condition of eceiving wates and guide futue gowth LaPlatte Rive Wateshed Stomwate Infastuctue Study vi

8 1.0 Poject Intoduction 1.1 Poject Oveview Lewis Ceek Association and LaPlatte Wateshed Patneship (LCA- LWP have completed wate quality and geomophic assessments (VTANR 2009 fo the LaPlatte Rive that suggest significant eosion and phosphous mobilization impacts due to stomwate unoff. Likely stomwate stessos include diect connections to ive channels fom impevious and compacted sufaces, and lage-scale tilled agicultual aeas diectly daining to steam channels. Examination of stomwate outfalls and impacts to the ive channels was identified as a pioity poject in the Steam Coido Plan fo the LaPlatte Rive and Tibutaies in Town of Hinesbug (LWP 2007 and Reaches M6-M11 in Towns of Chalotte and Shelbune (LWP LCA- LWP etained Milone & MacBoom Inc. (MMI to study stomwate infastuctue and inputs to the LaPlatte Rive in Shelbune, Hinesbug, and Chalotte. The objectives of the poject follow. Update and expand existing stomwate infastuctue mapping with available plans and field veification to povide tool fo futue stomwate management. Identify likely stomwate impact locations in the LaPlatte Rive Wateshed using available GIS esouces and updated stomwate infastuctue mapping, and land use egulations. Relate stomwate unoff and infastuctue to peviously collected geomophic, habitat, and wate quality data. Identify potential stomwate design pojects fo implementation. Povide ecommendations fo futhe ive potection planning stategies. Shae evised GIS mapping with poject stakeholdes. GIS files will eside with LCA- LWP, DEC, CCRPC, and the Towns. Many poject patnes have woked with LCA-LWP and MMI to contibute data, analysis, methods, and inteest in poject outcomes. Univesity of Vemont, Spatial Analysis Laboatoy Chittenden County Regional Planning Commission (CCRPC Vemont Depatment of Envionmental Consevation (DEC Stomwate Section DEC Rive Management Pogam Town of Shelbune LaPlatte Rive Wateshed Stomwate Infastuctue Study 1

9 Town of Hinesbug Town of Chalotte 1.2 Poject Need / Histoy of Stomwate Management As land becomes inceasingly compacted, cleaed, and coveed with impevious suface a lage volume of stomwate will un off the land athe than infiltate. Land use convesion away fom natually vegetated condition tends to shoten the amount of time it takes fo wate to tavel to the eceiving body. The inceased volume and shotened time fo wate to each the steam contibute to inceasing peak flood dischages, volumes, and wate suface elevations in the ive. As the flow changes, the channel adjusts to attempt to egain the balance between wate and sediment (Lane Eosion of bed and banks, and downsteam sediment deposition is often associated with channel adjustment. Thesholds of impevious cove below which wate quality and steam conditions deteioate have been found (e.g., Babec, Schulte et al. 2002; CWP 2003; Fitzgeald 2007; Schiff and Benoit Stomwate is egulated by both fedeal and state laws, and municipalities may choose to implement futhe ules. The Vemont Depatment of Envionmental Consevation (DEC Stomwate Section issues pemits fo stomwate unoff fom impevious sufaces, constuction sites, and industial popeties. Vemont began egulating developments that ceated impevious sufaces in the 1970 s. Impevious sufaces ae egulated to comply with Vemont Statute 10 V.S. A These opeational stomwate pemits ae equied if a new o edevelopment poject ceates moe than 1 ace of impevious suface o expands by moe than 5,000 squae feet. If a poject with moe than 1 ace of impevious is located within a stomwate impaied wateshed it is held to a highe standad and must apply fo an Individual pemit, othewise pojects apply fo coveage unde Geneal Pemit To meet Geneal Pemit standads, the site must follow citeia outlined in the 2002 Vemont Stomwate Manual (VTDEC 2002 fo potection of wate quality, goundwate echage, and channel health. Developments that add 1 to 10 aces of impevious cove must detain the 1-yea stom (i.e., channel potection and the 10-yea stom (i.e., ovebank flood potection. Pojects ceating moe than 10 aces of impevious cove equie detention of the 100-yea stom (i.e., exteme flood contol. Some watesheds have been designated as stomwate impaied as listed on the State of Vemont 303(d List (VTDEC Stomwate impaiment equies ceation of a Total Maximum Daily Load (TMDL to set standads fo dischage in the wateshed. Stomwate dischages within watesheds designated as impaied ae equied to meet highe standads and equied to obtain a LaPlatte Rive Wateshed Stomwate Infastuctue Study 2

10 National Pollutant Dischage Elimination System (NPDES Geneal Pemit These ules ae in the pocess of changing, with an incease in standads set to take effect on Octobe 15, Upcoming changes will include standads fo popeties with existing impevious sufaces less than one ace, as pesented in a the Small Sites Guide fo Stomwate Management (VTDEC Cuently the LaPlatte Rive and its tibutaies ae not listed on the 303d list that designates impaied wateways. Shelbune will be affected by some of these moe stingent ules due to the impaiment of Munoe Book. Multiple municipalities in Vemont ae subject to an additional standad based on the fedeal EPA s Phase II Stomwate Rule due to thei size o othe citeia such as containing an impaied wateway. The applicable National Pollutant Dischage Elimination System (NPDES pemit is called the Geneal Pemit fo Small Municipal Sepaate Stom Sewe Systems (MS4. In the LaPlatte Rive wateshed, Shelbune falls unde MS4 juisdiction. MS4 towns ae equied to plan fo: Public Education and Outeach, Public Paticipation/Involvement, Illicit Dischage Detection and Elimination, Constuction Site Runoff Contol, Post-Constuction Runoff Contol, and Pollution Pevention/Good Housekeeping. Specific bounday aeas fo pemit juisdiction ae dawn. MS4 pemit aea in the Town of Shelbune includes the Munoe Book wateshed (a stomwate impaied wateshed and a census-designated ubanized potion of the village cente. Vemont Agency of Tanspotation is pemitted unde the MS4 pogam as a non-taditional system. Constuction sites often have lage aeas of exposed soil that can contibute lage amounts of sediment to eceiving wate bodies duing a stom event. The VTDEC Constuction Stomwate Pemit Pogam addesses stomwate dischage duing constuction. Constuction Geneal Pemit is equied fo sites that distub 1 o moe aces of land. This pemit was ceated by DEC to meet fedeal equiements of the Clean Wate Act unde NPDES. Thee ae thee levels of pemitting equiing inceasing levels of mitigation based on aea distubed, wateshed impaiment, distubance time, slopes and soil eodibility. New and existing industial sites ae equied to obtain a Multi-Secto Geneal Pemit (MSGP. This pemit is a NPDES pemit, also a equiement of the fedeal Clean Wate Act administeed by DEC. The pemit includes a long list of facilities equied to be coveed including many foms of manufactuing, mining, wate and solid waste facilities, tanspotation, mills, among othes. Thee ae stomwate systems that oiginally obtained a pemit, but have let thei pemit lapse. These systems fall unde a special Ophan Stomwate Pogam. This pogam is geaed towad eviewing the stomwate teatment of a subdivision, binging failing systems back into compliance, and issuing a pemit. The pemit obtained would be unde Geneal Pemit Peviously Pemitted Stomwate Dischages to Wates that ae Not Pincipally Impaied, and LaPlatte Rive Wateshed Stomwate Infastuctue Study 3

11 would not be applicable to stomwate impaied watesheds. Systems in this pogam would be tansfeed to the municipality fo contol of the system and futue esponsibility and maintenance. Many souces of unoff ae not coveed by a pemit. Road systems contibute a significant amount of impevious suface and channelization of flow in oadside ditches. State Routes ae coveed unde the VTRANS MS4 pemit, but all local and pivate oads ae uncoveed and have no mitigation unless built ecently enough to fall unde the juisdiction of one of the pemits. Runoff fom ditches is widespead component of ual stomwate unoff in the LaPlatte Rive wateshed. Impevious sufaces ceated befoe the 1970 s when pemitting began. New and edeveloped aeas with less than one ace of impevious suface (unless in stomwate impaied wateshed, in MS4 aea, o industial facility. The souces of non-pemitted and unmitigated stomwate in the LaPlatte Rive wateshed and Vemont ae abundant and widespead. Stomwate has a cumulative effect on eceiving wates and theefoe should be examined on a wateshed basis, such as TMDL allocations fo impaied wateways. In non-stomwate impaied watesheds, non-industial pojects ceating less than 1 ace of impevious suface ae not equied to obtain a stomwate pemit in Vemont (excluding MS4 towns. The fedeal and state pemitting envionment tends to leave most stomwate dischages that ae established incementally in small to modeate pojects non-egulated and unteated. The esponsibility fo maintenance of stomwate infastuctue and level of teatment defaults to the municipalities. Planning is needed to impove the cuent minimal level of teatment and infom the smat gowth movement that is taking place acoss Vemont. Low-impact development should include geen infastuctue to ceate the equied teatment systems to facilitate gowth while minimizing impacts to eceiving wates, ecosystems, open space, and human health. Outeach is needed to incease public awaeness of stomwate impacts and move beyond the taditional expectations to collect stomwate and pass it downsteam as fast as possible, even without any level of teatment o consideation of downsteam impacts. This poject takes a poactive appoach to undestanding and impoving stomwate conveyance and teatment in the LaPlatte Rive wateshed LaPlatte Rive Wateshed Stomwate Infastuctue Study 4

12 2.0 Wateshed and Subwatesheds The LaPlatte Rive uns appoximately southeast to nothwest and dains into Shelbune Bay of Lake Champlain (Figue 1. The LaPlatte Rive wateshed has an aea of appoximately 53 squae miles with contibuting aeas in Hinesbug (46%, Chalotte (30%, Shelbune (17%, Williston (4%, St. Geoge (2%, and Richmond (1%. This study focuses on aeas within Shelbune, Hinesbug, and Chalotte because of thei significant contibuting aeas, pesence of village centes, and existing infastuctue. The LaPlatte Rive is a 5th ode steam when it flows into Lake Champlain. Steam ode (Stahle 1952 is one indicato of the size of a steam. Headwate steams ae 1st ode, when two 1st ode steams meet they fom a 2nd ode steam, when two 2nd ode steams meet they fom a 3d ode steam, and so on. If two steams of diffeent odes join, they etain the highe ode downsteam of the confluence. Stomwate inputs occu at all steam sizes, and accumulate in the downsteam diection. Typical inputs ae fom ditches in ual headwates and ditch/pipe systems nea village centes. Steam geomophic and habitat assessments (VTANR 2009 have been completed fo the LaPlatte Rive Wateshed and povide an undestanding of cuent ive fom and pocesses and how these may have depated fom efeence conditions based on the LaPlatte Rive valley. The geomophic data is useful to guide planning effots fo consevation and estoation. Phase 1 and 2 assessments have been completed fo the LaPlatte Rive eaches M03-M11 and McCabe s Book tibutay eaches T1.02-T1.05 (LWP Phase 2 was also completed fo Hinesbug eaches including M12-M18 and sections of tibutaies including Patick Book, Beeche Hill Book, the Canal, and an unnamed tibutay T3 (LWP Data wee used to ceate a Steam Coido Plan fo the LaPlatte Rive and Tibutaies in Town of Hinesbug (LWP 2007 and Reaches M6-M11 in Towns of Chalotte and Shelbune (LWP These pio studies, available fo download at the LaPlatte Wateshed Patneship website: ( povided infomation fo the cuent study. Subwatesheds, eaches, and segments wee oiginally delineated duing the Phase 1 and 2 assessments. Wateshed divides oiginally delineated using USGS topogaphic maps have been updated whee new high esolution LIDR data aea available (Figue 2. LIDAR data now exist fo 76% of the wateshed, mostly excluding Chalotte. Subwateshed delineations in Chalotte ae not as pecise due to lowe esolution topogaphy available. Stomwate infastuctue was mapped based on plans of state-pemitted systems and field obsevations in village centes (see Section 6.0 fo moe details. Subwateshed delineations wee efined based on the stomwate infastuctue mapping (Figue 3. Field veification of dainage pattens esulted in adjustment of many subwateshed divides. Obsevations of the LaPlatte Rive Wateshed Stomwate Infastuctue Study 5

13 CHURCH HILL RD RIDGEFIELD RD MEADOWSIDE DR N GATE RD S GATE RD HARBOR RD BOSTWICK RD LIMERICK RD Shelbune Bay BAY RD McCabes Book NATURES WY ETHAN ALLEN HWY CHURCH HILL RD MUTTON HILL DR SHELBURNE RD FALLS RD TI LN McCabes Book MOUNT PHILO RD La Platte Rive Mud Hollow Book ACORN LN LIME KILN RD THOMAS RD CLARK RD GUINEA RD VISTA DR Bingham Book Mud Hollow Book HINESBURG RD SOUTHVIEW DR SHELBURNE L aplatte Rive MURPHY RD HEATHER LN SPEAR ST SIMMONS DR POND RD DORSET ST N PASTURE LN HINESBURG RD WEED RD WEED RD SHELBURNE FALLS RD ONEIL RD BLACK DOG LN ST. GEORGE La Platte Rive BALDWIN RD ROUTE 2A FOREST RD HICKORY PL ENMANS RD ROUTE 116 CHARLOTTE RD PLACE RD W CVU RD SILVER ST WILLISTON Patic k Canal OAK HILL RD MARTEL LN LaPlatte Rive SOUTH RD MOUNT PRITCHARD LN POND RD GILMAN RD BEEBE LN Lake Ioquois POND BROOK RD SUNSET LN W ENOS RD FERN RD BUCK HILL RD W ick Book Pat PIETTE MEADOW RD NORTH RD RICHMOND RD TEXAS HILL RD Beeche Hill Book $ RICHMOND LINCOLN HILL RD HAYDEN HILL RD W ONE MILE RD CHARLOTTE HINESBURG OLD ROUTE 116 W VIEW DR SWAMP RD HINES RD Figue 1: LaPlatte Rive Wateshed Roads Towns LaPlatte Rive Wateshed Lakes and Ponds Rive (By Steam Ode Backgound aeial imagey fom 2008 National Agicultue Inventoy Pogam. Roads fom Emegency 911 database obtained fom VCGI.og. Steams fom Vemont Hydogaphy Dataset obtained fom VCGI.og. Wateshed based on HUC- 12 outline, updated whee high esolution topogaphy was availiable by Mak Suozzo and by field veification by Milone & MacBoom, Location Ceated Mach 23, Miles

14 M01 69 aces T aces WILLISTON 4 T aces T aces T aces M aces M aces M aces M aces SHELBURNE ST. GEORGE T aces T aces RICHMOND Reach Subwatesheds (By Data Souce LIDAR Phase 1 T aces M06S aces M aces M aces M08 58 aces M aces M09S aces M12S aces M13S aces T aces T aces T aces Spliced Town Bounday Lake Champlain Rive (By Steam Ode T aces T aces T aces T aces T aces M aces M aces M aces M aces M14 58 aces T aces M aces M15S aces T aces T aces T aces T aces Reach Subwatesheds T aces T aces T2S aces M11S aces T aces M aces LaPlatte Rive Wateshed Stomwate Poject T aces T aces 130 aces T2S aces CHARLOTTE T aces M aces M aces M aces Map By: JSC Date: Januay 2010 Scale: 1 = 4,500' Sheet: Figue 2 81 aces HINESBURG 1233 Shelbune Road, Suite 150 South Bulington, VT Phone: Fax:

15 T aces T aces (0 Adjusted T aces (86.8 Adjusted M01 80 aces (11.3 Adjusted T aces T aces (-84.3 Adjusted M aces (20.1 Adjusted T aces (0.5 Adjusted M aces (6.7 Adjusted M aces (-8.8 Adjusted M aces (2 Adjusted M aces M06S aces M aces (-2 Adjusted M aces M aces M aces M08 58 aces SHELBURNE M aces M09S aces M12S aces ST. GEORGE M13S aces WILLISTON T aces (-21.3 Adjusted T aces T aces T aces T aces RICHMOND 4 Reach Subwatesheds Bounday Field Adjusted Bounday Not Field Adjusted Town Bounday Lake Champlain Rive (By Steam Ode T aces (-1.2 Adjusted T aces T aces (12.7 Adjusted T aces (-20.8 Adjusted T aces (-5.7 Adjusted T aces T2S aces (-4.6 Adjusted T aces (5.7 Adjusted M aces (-8.7 Adjusted M aces (8.7 Adjusted M aces M11S aces M aces M14 58 aces T aces (-17.8 Adjusted M aces (10.3 Adjusted T aces M15S aces M15S aces (20.5 Adjusted M aces M16 96 aces (-0.9 Adjusted T aces (-0.5 Adjusted M aces (0.2 Adjusted T aces (1.2 Adjusted T aces Stomwate Coected Reach Subwatesheds LaPlatte Rive Wateshed Stomwate Poject T aces (11.9 Adjusted T aces (3.3 Adjusted T2S aces T2S aces (-7.1 Adjusted T2S aces (4.6 Adjusted CHARLOTTE T aces M aces M aces M aces Map By: JSC Date: Januay 2010 Scale: 1 = 4,500' Sheet: Figue 3 HINESBURG 1233 Shelbune Road, Suite 150 South Bulington, VT Phone: Fax:

16 ual oad ditch netwok in Chalotte led to efinement of many of the peviously mapped subwatesheds. Stomwate collection systems in the village centes of Shelbune and Hinesbug often did not follow gound topogaphy and esulted in tansfeing collected unoff between peviously delineated subwatesheds (see Section 6.0 fo moe details. Subwateshed divides wee adjusted whee these inte-basin tansfes occued to popely epesent the unoff contibuting to subwateshed and stomwate system outlets. Some subwatesheds wee divided to povide a moe detailed pictue of the stomwate contibutions in village centes. Fo example, each M16 in Hinesbug was split because the lowe section is in the village cente with dense development and multiple stomwate outfalls while the uppe segment is elatively ual. The efined subwateshed delineations impove upon past delineations, ae used as the basis fo analysis fo this study, and should be used fo futue studies in the LaPlatte Rive wateshed. GIS shapefiles of these subwatesheds will be povided to poject patnes fo futue use. 3.0 Geology 3.1 Bedock Geology Wateshed infiltation and aquife stoage chaacteistics ae govened by the undelying bedock geology. Bedock is the paent mateial that makes up ovelying layes. It dictates pesence of aquifes vesus impemeable layes and infiltation chaacteistics of soils. Bedock fomations in the wateshed include dolostones, quatzites, mable, and shales (Figue 4 geneal desciptions of bedock types ae included in Table 1. Table 1: Summay of Bedock Geology in the LaPlatte Rive Wateshed Code Name Aea (aces Pecent Aea (% Ob Bascom Fomation Cch Cheshie Quatzite COcs Claendon Spings Fomation 4, k Cetaceous dikes Desciption Intebedded dolostone, limestone and mable with hoizons of calcaeous sandstone. Feldspa-ich, thin to thick-bedded, white to buff quatzite with agillaceous hoizons. Massively bedded light gay dolomite with numeous vugs and quatz knots on weatheed sufaces, in places disseminated quatz gains ae pesent. Leucophyes and lampophyes vaiable in colo fom black to bick ed. Oc Cutting Dolostone 1, Massively bedded gay dolostone. Cda Danby Fomation 3, Intebedded sandstone and dolostone hoizons. Cdu Dunham Dolostone LaPlatte Rive Wateshed Stomwate Infastuctue Study 9 Cyclically bedded buff to pink coloed dolostone and massively bedded stuctueless buff to white dolostone.

17 Code CZfp Name Aea (aces Pecent Aea (% Faifield Pond Fomation 6, Desciption Light gay to light geen quatz-seicite-chloite phyllite magnetite biotite. Oi Ibeville Shale 1, Black agillaceous shale weathes buff in colo. LAKE Lake Cm CZp Os Lowe unit a gay to white sandstone, often with quatz pebble hoizons; uppe unit intebedded ed sandstone, ed shale and buff coloed dolostone. Monkton Quatzite 4, Pinnacle Fomation 1, Undiffeentiated metageywackes and schists. Shelbune Mable 2, Massively bedded white to gay pinstiped sucosic mable. West of the Champlain Thust the unit is a mottled gay and white limestone fomely temed the Ticondeoga Fomation. Osp Stony Point Shale Black calcaeous fissile shale. Winooski Buff to gay colo, medium- to massively bedded Cw Dolostone 6, dolostone. 3.2 Landfoms Totals: 33, The entie LaPlatte ive wateshed is located within the Champlain Valley biophysical egion of Vemont (Thompson and Soenson This aea was glaciated and coveed at times by both fesh and salt watebodies. The LaPlatte Rive wateshed is dominated by glaciolacustine deposits deposits fom glacies that settled out in lage wate bodies. Sediments deposited afte the melting of glacies have been and continue to be tanspoted and deposited by egional ive systems (LWP The volume and unoff ate within a wateshed ae lagely a function of soil chaacteistics of the aea that in tun diectly elated to the landfoms that they ae associated with. Sand and gavel allow moe pecipitation and unoff to infiltate into the gound than silts and clays. In contast, shallow bedock, compact glacial till, clay, and satuated lowlands limit infiltation and leads to inceased unoff. Glaciolacustine clay deposits with intespesed bedock outcops makes up the majoity of the westen two thids of the wateshed (Figue 5, Table 2. Compacted glacial till and bedock make up most of the easten thid of the wateshed. The pesence of clay and bedock ove much of the LaPlatte Rive wateshed indicates poo dainage and limited potential fo stomwate teatment LaPlatte Rive Wateshed Stomwate Infastuctue Study 10

18 BAY RD LAKE $ k HARBOR RD Oi Shelbune Village BOSTWICK RD Cdu Cm McCabes Book WEBSTER RD FALLS RD McCabes Book MOUNT PHILO RD THOMAS RD Mud Hollow Book SPEAR ST Oc Oc COcs Os HINESBURG RD Cch Ob Os Oc SPEAR ST East Chalotte Village DORSET ST Cda LaP DORSET ST latte Rive Os COcs Cda Cw k Osp SHELBURNE FALLS RD Os COcs kk kos COcs Cda CHARLOTTE RD k CVU RD Patick Book Hinesbug Village SILVER ST POND RD Cw OAK HILL RD CZp CZfp Patick Book Oc COcs Cda Ob NORTH RD Beec he Hill B ook RICHMOND RD CZfp Bingham Book Cw Cm Cdu Osp Osp Figue 4: Bedock Geology of LaPlatte Wateshed Bascom Fomation, Ob Cheshie Quatzite, Cch Claendon Spings Fomation, COcs Cetaceous dikes, k Cutting Dolostone, Oc Danby Fomation, Cda Dunham Dolostone, Cdu Faifield Pond Fomation, CZfp Ibeville Shale, Oi Lake, LAKE Monkton Quatzite, Cm Pinnacle Fomation, CZp Shelbune Mable, Os Stony Point Shale, Osp Winooski Dolostone, Cw The bedock geology dataset includes data that was compiled fom RF 100,000 USGS base maps. The data was ceated unde the auspices of the Vemont Geological Suvey with the assistance of the Infomation Management Section of the Agency of Natual Resouces. Map oiginally ceated by Mak Suozzo as pat of UVM couse NR-243, Decembe 18, Updated by Milone & MacBoom, Inc. Mach 23, Miles

19 $ HARBOR RD BAY RD p dsbc bc BOSTWICK RD Shelbune Village bgm stc t bg McCabes Book t t McCabes Book t bg ps ps t MOUNT PHILO RD ds kt t kt bc Mud Hollow Book bg THOMAS RD Bingham Book LaP latte Rive East Chalotte Village HINESBURG RD ps SPEAR ST kt kt al p DORSET ST wt p ps bg k t Pat ick C anal Patick Book Hinesbug Village p p ps p CVU RD SILVER ST POND RD sw kt OAK HILL RD ps ps RICHMOND RD Beec he Hill B ook kt NORTH RD t t Figue 5: Suficial Geology of LaPlatte Wateshed al, alluvium bc, bouldes in clay bg, beach gavel k, isolated kame kt, kame teace p, swamp, peat and/o muck, bedock exposue stc, silt, silty clay, and clay sw, suface wate bgm, maine beach gavel ds, delta sand ps, pebbly sand psm, pebbly maine sand wt, wave-washed till t, till Location The suficial geology data consists of suficial geologic featues as digitized fom the 1:62, minute seies USGS quadangle map sheets, compiled by The Vemont Geological Suvey Map oiginally ceated by Mak Suozzo as pat of UVM couse NR-243, Decembe 18, Updated by Milone & MacBoom, Inc. Mach 23, Miles

20 Sands and gavels ae mapped in appoximately 8% of the wateshed. This pemeable mateial is impotant as it seves as goundwate infiltation aeas. Pemeable soils located nea village centes ae valuable assets fo infiltation to suppot aquife echage and steam baseflow and fo stomwate teatment. A geen infastuctue ovelay could be ceated to locate and appopiately value these aeas to taget them fo land consevation fo potection of the hydologic cycle and to facilitate smat gowth. Land use in this distict could be anything that does not compact soils o install impevious cove. The teatment of stomwate should be evaluated fo futue development as is cuently done fo siting septic system leach fields. Table 2: Summay of Suficial Mateials in LaPlatte Rive Wateshed Pecent Code Featue Desciption Aea (Aces Aea (% Bedock exposue bedock exposue 3, bgm Champlain Sea deposit maine beach gavel psm Champlain Sea deposit pebbly maine sand t Glacial deposit till 7, k Glaciofluvial deposit isolated kame gavel kt Glaciofluvial deposit kame teace gavel 1, bc Glaciolacustine deposit bouldes in clay 20, bg Glaciolacustine deposit beach gavel ds Glaciolacustine deposit delta sand ps Glaciolacustine deposit pebbly sand stc Glaciolacustine deposit silt, silty clay, and clay wt Glaciolacustine deposit wave-washed till p Pluvial deposit swamp, peat and/o muck al Postglacial fluvial deposit Alluvium, sand and gavel sw Suface Wate suface wate Soils Totals: 33, Soil type stongly influences unoff chaacteistics thoughout a wateshed. Soil types in the wateshed wee detemined fom the NRCS soil suvey fo Chittenden County, Vemont that includes Hydologic Soil Goup (HSG classifications of all soils (Figue 6. The NRCS divides soils into fou hydologic soil goups: A, B, C, o D, depending on thei infiltation capacity the maximum ate wate can ente the soil. A soils ae well-dained and have high infiltation capacity. D soils have the lowest infiltation capacity and geneate the highest unoff ates. Wetlands typically fom in low-gadient aeas with pooly dained soils. Wetlands seve impotant ecosystem functions such as unique habitats and food souces fo fish and wildlife, and LaPlatte Rive Wateshed Stomwate Infastuctue Study 13

21 OA K HIL L D TER R SPE AR ST Shelbune Village ND RI CH S CV D UR ok kc ic Pa t oo k ook i ll B SILV ER ST East Chalotte Village H ud M URG RD HINE S B B o Hinesbug Village CHA RLOTTE RD B w ic k RD lo ol t Pa NORTH RD e latte Ri v FA LL PO ND RD ET ST NE ST k UR SP E A R ook abe s B oo SH EL B DORS La P Mc C Ca Mc sb be MO AS R D a nal THO M RD DOR FALLS RD D ICK R MOUNT PHIL O RD W BO S T ST R RD WE B S RD D SET HARBO R BAY $ B ee c he H Bi ng h am ok Bo Figue 6: Hydologic Soil Goups and Wetlands Soil data wee developed fom mateials used by the Natual Resouce Consevation Sevice (NRCS to pepae the Chittenden County soil suvey. The soil data used wee pepaed by soil scientists as pat of the National Coopeative Soil Suvey. Hydolic soil classifications confom to those used by the National Resouce Consevation Sevice (NRCS and to the Vemont Stomwate Manual. Wetlands fom Vemont Significant Wetlands Inventoy (VSWI updated Febuay Additional wetlands shown ae fom multiple souces and should be used fo planning puposes only. Included ae delineations in Hinesbug fom Aowhead Envionmental completed 2006 (southen pacel and 2009 (village aea extending only to popety bounds of selected pacels. Also included ae genealized and potential wetlands identified by UMASS fo the Town of Hinesbug based on 1993 aeial photogaphy in Map oiginally ceated by Mak Suozzo as pat of UVM couse NR-243, Decembe 18, Updated by Milone & MacBoom, Inc. Apil 14, A C not ated B D wate Vemont Significant Wetlands Wetlands Additional Delineations Miles Location

22 impotant ecosystem sevices such as detainment of suface wate. Wetlands identified in the Vemont Significant Wetlands Inventoy have been ovelaid on the soils map (Figue 6 to show elationship between thei location and HSG. Lage wetlands tend to be found in aeas with C and D soils, and adjacent to steam channels. A highe esolution of wetland delineation is available in Hinesbug based on a past study of potential eceation aeas and has been included in mapping (Figue 6. A small pat of the LaPlatte Rive wateshed has soils that ae suitable fo infiltation (Table 3. The pemeable soils ae geneally located on alluvial deposits in the LaPlatte Rive coido in Hinesbug and Shelbune, and in a noth-south band appoximately following Noth Road and Beeche Hill Book in Hinesbug, South of Lake Ioquois. Given the limited pesence of aeas with high infiltation ates, these locations should be pioitized fo consevation fo stomwate teatment as pat of a geen infastuctue system and fo aquife potection. Table 3: Summay of Soils in LaPlatte Rive Wateshed Hydologic Soil Goup Aea (aces Pecent Aea (% A 1,536 5 B 1,210 4 C 8, D 22, Wate 143 <1 Not Rated Land use / Land cove 4.1 Wateshed Landuse The cuent use o cove of the land influences the hydologic cycle. Land use convesion away fom natual vegetative cove tends to compact soils and ceate impevious sufaces that leads to educed infiltation, educed evapotanspiation, and inceased unoff. Vegetation emoval leads to inceased wateshed expot of sediment and nutients. Land development is also typically associated with a eduction of wateshed stoage. Landuse infomation compiled in 2001 as pat of the National Landcove Dataset was coected by the UVM Spatial Analysis Lab to bette epesent uban aeas. The landuse in the LaPlatte Rive wateshed is pimaily agicultue and foest, with small aeas of uban and esidential uses (Table 4. The easten thid of the wateshed is pimaily foested with some oads, development, wetlands, and suface wates including Lake Ioquois and the impounded section of Patick Book (Figue 7. The westen two thids of the wateshed have a significant amount of LaPlatte Rive Wateshed Stomwate Infastuctue Study 15

23 $ HARBOR RD BAY RD WEBSTER RD OAK HILL RD Shelbune Village BOSTWICK RD FALLS RD SPEAR ST THOMAS RD DORSET ST RICHMOND RD McCabes Book McCabes Book MOUNT PHILO RD Mud Hollow Book HINESBURG RD SPEAR ST LaP DORSET ST latte Rive East Chalotte Village SHELBURNE FALLS RD CVU RD CHARLOTTE RD Pat ick C anal SILVER ST POND RD Patick Book Hinesbug Village NORTH RD Beec he Hill B ook Bingham Book Figue 7: Land Use of Laplatte Wateshed Agicultue Baen Bush Foest Uban Uban-Open Wate Wetland Location Land use data is fom an impoved vesion of NLCD 2001 using ancillay GIS data and Landsat satellite imagey poduced by UVM Spatial Analysis Lab. Map oiginally ceated by Mak Suozzo as pat of UVM couse NR-243, Decembe 18, Updated by Milone & MacBoom, Inc. Mach 24, Miles

24 agicultual land with some aeas of foest. The land use map illustates the oad netwok connecting the village centes in the wateshed. Stomwate contibution was estimated to be 38% fom Agicultual/ Open Space and 62% fom Uban/Developed Land. These contibutions wee estimated using a method outlined in the TMDL fo Munoe Book, an adjacent wateshed (VTDEC Geneally, Agicultue and Baen Land wee lumped into the Agicultue/Open Space categoy and Uban and Uban-Open wee combined in the Uban/Developed Land and othe categoies ae assumed to be in thei natual state with no unnatual impevious sufaces. Aveage values fo impevious suface in each categoy ae used to detemine an estimation of unoff fo each Landuse categoy. Table 4: Summay of Landuse in LaPlatte Rive Wateshed Class Aea (aces Pecent Aea (% Agicultue 13, Baen 4 0 Bush 1,595 5 Foest 13, Uban 2,734 8 Uban-Open 2,075 6 Wate Wetland Impevious Cove As pat of this study an impoved GIS impevious cove laye was ceated at the UVM Spatial Analysis Laboatoy (Appendix B. The impevious cove was calculated using 2008 National Agicultue Imagey Pogam (NAIP imagey and GIS layes of oads and steams. The new impevious cove map is an impoved combined epesentation of oads, buildings, diveways and othe impevious aeas in the wateshed (Figue 8. The LaPlatte Rive wateshed was calculated to be 3.6% impevious suface. Impevious aea was examined by subwateshed to povide an oveview of the steam eaches that ae eceiving unoff fom highe amounts of impevious aea. Thesholds of impevious cove below which wate quality and steam conditions deteioate have been found to ange between 5 and 10 % (e.g., Babec, Schulte et al. 2002; CWP 2003; Schiff and Benoit LaPlatte Rive subwatesheds had low to modeate amounts of impevious cove except at the village centes of Shelbune (M04 = 19.7 %; T1.03 = 19.6 % and Hinesbug (M16 = 14 % that had the highest amount of impevious cove (Figue 9. McCabe s Book subwatesheds in the LaPlatte Rive Wateshed Stomwate Infastuctue Study 17

25 westen section of the wateshed and Patick Book subwatesheds in the easten pat of the wateshed had modeate amounts of impevious cove (4-5 %. The level of connection between impevious cove and steam channel must be consideed to fully undestand the stomwate isks to steams. Impevious cove that conveys stomwate diectly to channels via pipes and shot swales apidly following a stom event pose geate isks to steam health than when the flow is stoed and delayed pio to dischaging to the channel. Although impevious cove tends to be low to modeate in the LaPlatte Rive wateshed, field obsevations indicate that the impeviousness is often located close to the steam channels and that teatment is typically limited o non-existent. Oppotunities exist to mitigate existing unteated stomwate dischage at specific locations eceiving the majoity of unoff fom village centes (see Section 8.0. New stomwate teatment oppotunities ae identified by the poximity of high infiltation sites with pemeable soils (HSG A and B to aeas having dense impevious cove. Impevious cove density was detemined by identifying the numbe of impevious featues (i.e., buildings, oads, and diveways fom the Emegency 911 GIS database pe ace (Figue 10. The numbe of impevious featue point locations wee aveaged ove an aea to detemine density, as descibed in Appendix B. Some aeas in Shelbune and Hinesbug village centes indicate good stomwate teatment potential as high impevious cove density is located close to soils suitable fo infiltation LaPlatte Rive Wateshed Stomwate Infastuctue Study 18

26 HARBOR RD BAY RD $ WEBSTER RD OAK HILL RD Shelbune Village BOSTWICK RD FALLS RD SPEAR ST THOMAS RD DORSET ST RICHMOND RD McCabes Book McCabes Book MOUNT PHILO RD Mud Hollow Book HINESBURG RD SPEAR ST LaP DORSET ST latte Rive East Chalotte Village SHELBURNE FALLS RD CVU RD CHARLOTTE RD Pat ick C anal SILVER ST POND RD Patick Book Hinesbug Village NORTH RD Beec he Hill B ook Bingham Book Figue 8: Impevious Cove fom Imagey Data LaPlatte Rive Wateshed National Agicultue Imagey Pogam (NAIP 2008 imagey data wee used to poduce the impevious cove pesented on this map and visible as backgound images. Nomalized Diffeence Vegetation Index (NDVI values less than wee used to detemine impevious aea. Impevious Cove Location Map oiginally ceated by Mak Suozzo as pat of UVM couse NR-243, Decembe 18, Updated by Milone & MacBoom, Inc. Mach 24, Miles

27 $ HARBOR RD T % T % M01 5.7% T % M02 8.4% T1.03 T % 8.2% T % T % T % T % M03 9.7% Shelbune Village M % McCabes Book T % McCabes Book T % M04 6% M % M06S % MOUNT PHILO RD THOMAS RD T % M05 7.4% M06 4.3% M06 2.4% T2S2.01 0% T2S % T2.02 2% T % M07 4.8% M08 2.8% T2S % T2S % M09 3.7% T % M10 2.8% M09S % M11 3% East Chalotte Village SPEAR ST DORSET ST DORSET ST M12 1.8% M11S % M16 2.7% T4.07 3% M12S % T4.06 T % M13S3.01 5% 2.3% T % SHELBURNE FALLS RD LaPlatte Rive M13 1.7% CHARLOTTE RD M14 1.2% T % T % T % M15S % M15S2.01 T % 2.7% M15 T % M % 14% M16 6.2% SILVER ST OAK HILL RD POND RD Hinesbug Village T % T % Beec he Hill B ook NORTH RD M17 2.6% M18 2.7% RICHMOND RD T % M19 0.1% Figue 9: Pecent Impevious by Subwateshed Aea Data was based on Intepetation of NAIP imagey as seen in Figue 8. Values shown on the map epesent the pecentage of total aea coveed by impevious cove fo each subwateshed. Map oiginally ceated by Mak Suozzo as pat of UVM couse NR-243, Decembe 18, Updated by Milone & MacBoom, Inc. Mach 24, Pecent Impevious > Miles Location

28 HARBOR RD BAY RD $ WEBSTER RD OAK HILL RD Shelbune Village BOSTWICK RD FALLS RD SPEAR ST THOMAS RD DORSET ST RICHMOND RD McCabes Book McCabes Book MOUNT PHILO RD Mud Hollow Book HINESBURG RD SPEAR ST East Chalotte Village LaP DORSET ST latte Rive SHELBURNE FALLS RD CHARLOTTE RD CVU RD P atick Canal Hinesbug Village POND RD Patick Book Beeche Hill Book NORTH RD Bingham Book SILVER ST Figue 10: Density of Impevious Featues Possible Infiltation Site Good (HSG A Impevious density was detemined by point density of featues in the Emegency 911 GIS database including stuctues, oads, and diveways. Points to epesent oads and diveways wee ceated evey 100 linea feet. Infiltation sites ae based on soil classifications of A (Good and B (Aveage using NRCS hydologic soils classificiaion. Aveage (HSG B Impevious Featues pe Ace > 2 Location Map oiginally ceated by Mak Suozzo as pat of UVM couse NR-243, Decembe 18, Updated by Milone & MacBoom, Inc. Mach 24, Miles

29 5.0 Subwateshed Hydology 5.1 Runoff Analysis The amount of unoff geneated fom a pecipitation event o thaw is pimaily a function of wateshed soil types and land cove. As land becomes inceasingly compacted, cleaed, and coveed with impevious suface a lage volume of wate will un off the land athe than infiltate. Land use convesion also tends to shoten the amount of time it takes fo wate to tavel to the eceiving body. The inceased volume and shotened time fo wate to each the steam contibute to inceasing peak flood dischages, volumes, and wate suface elevations in the ive. As the flow changes, the channel adjusts to attempt to egain the balance between wate and sediment (Lane Eosion of bed and banks, and downsteam sediment deposition is often associated with channel adjustment. An estimation of the unoff volume (ace-feet fom each subwateshed was calculated using the Soil Consevation Sevice (SCS, now NRCS unoff cuve numbe method. A ainfall of 2.1 inches associated with the 1-yea, 24-hou duation stom was used fo unoff calculations (VTDEC LaPlatte Rive soils, land cove, and impevious cove maps wee used to develop aea-weighted, composite cuve numbes fo each subwateshed (SCS Cuve numbe assignments wee fine-tuned based on field obsevations. Estimated unoff volumes ae nomalized by wateshed aea, o pesented as the 1-yea unoff depth, in ode to facilitate compaisons between the subwatesheds (Figue 11. Subwatesheds in the village centes of both Shelbune and Hinesbug have the lagest amount of unoff. High unoff volumes wee calculated on the LaPlatte Rive (M04 village section and McCabe s Book (T1.03 in Shelbune Village and the Canal (T4.01 and LaPlatte Rive (M16 village sections in Hinesbug Village. Inceased unoff was anticipated in the village centes, yet the elatively high unoff volumes thoughout the wateshed based on low infiltation capacity associated with the dominance of pooly dained soils is not intuitive. These data suggest that ual stomwate unoff is moe likely to flow to steams and ives than infiltate. The outcome of this analysis futhe illustates the impotance of potecting potential stomwate teatment locations. Upsteam stomwate unoff will influence downsteam locations. Runoff volume estimates pesented do not explicitly conside the timing of unoff o the cumulative effect of unoff fom upsteam wateshed locations. Moe detailed hydology models tavel times and subwateshed position to geneate hydogaphs to show cumulative effects of unoff as it is collected and flows down a ive. This level of modeling equies additional time and infomation and is needed fo poject design and implementation. The detailed influence of existing stomwate infastuctue was also not diectly included in this initial analysis. Runoff cuve numbes assume the pesence LaPlatte Rive Wateshed Stomwate Infastuctue Study 22

30 of some collection systems in uban aeas, but do not include specific stoage and dischage associated with collection and detainment stomwate systems. 5.2 Pioitization fom Runoff Analysis A GIS analysis was pefomed to pioitize subwatesheds fo stomwate mitigation based on existing conditions. A anking was calculated fom pecent impevious cove and unoff volume. Each vaiable was nomalized by the maximum value in the wateshed, summed, and divided by two fo a combined possible ank of zeo to one. A value of one indicates the subwateshed with the highest stomwate theat whee stomwate teatment pojects should be pioitized. The pioitization execise confimed that the village centes subwatesheds should be the focus fo stomwate mitigation (Figue 12, Table 5. Pioity subwatesheds include sections of the LaPlatte Rive (M04 and M06 villages, McCabe s Book (T1.03 in Shelbune Village, and the Canal (T4.01, T4.04 and LaPlatte Rive (M16 village in Hinesbug Village. The Patick Book (M15.S2 eaches wee also identified as high pioity. Table 5: Subwatesheds anked by Stomwate Runoff Risk Phase 2 Reach Steam Aea (aces Pecent Impevious Aea (% Runoff Depth (inches Runoff Rank M04, Shelbune Village Section LaPlatte Rive T1.03, Village Geen Section McCabe Book T4.01 Patick Book Canal M16, Lowe, Saputo Section LaPlatte Rive M15.S2.01, Commece Pak Section Patick Book T1.03, School Steet Section McCabe Book M05 LaPlatte Rive M06, Shelbune Village Section LaPlatte Rive M15S2.01, Ballads Cone Section Patick Book M16, Middle, Silve Steet Section LaPlatte Rive T4.04 Patick Book Possible infiltation sites wee ovelaid on the stomwate theat anking to identify aeas whee soils would be suitable fo infiltation. The potential exists fo infiltation-based stomwate mitigation in select locations in most of the pioity watesheds. These possible teatment sites should be investigated futhe fo veification of infiltation capacity based on soil mapping, poximity to potential development sites, and identification of pacel infomation LaPlatte Rive Wateshed Stomwate Infastuctue Study 23

31 $ HARBOR RD T T M01 80 T T M02 70 T1.03 T M03 72 Shelbune Village M04 90 M04 75 M06 76 M06S M05 81 M06 81 M06 79 M09 80 M09S T T M12S T4.06 T M13S T T McCabes Book FALLS RD THOMAS RD M07 80 M08 64 DORSET ST DORSET ST T T McCabes Book T MOUNT PHILO RD T T T2S T2S T T T2S T2S T M10 80 M11 80 East Chalotte Village SPEAR ST SHELBURNE FALLS RD OAK HILL RD POND RD RICHMOND RD M12 79 M11S LaPlatte Rive M13 79 CHARLOTTE RD M14 79 T T T M15S M15S2.01 T M15 T M Hinesbug Village M16 80 SILVER ST M16 76 T Beec he Hill B ook M17 77 NORTH RD M18 70 T M19 75 Figue 11: Runoff Volume ace-feet / ace Total unoff volumes wee detemined accoding to standad SCS unoff calculations. Cuve Numbes (CN wee detemined fom combination of HSG, landcove, impevious suface and aveaging values ove each subwateshed. Runoff Volume was calculated fo the 1-yea, 24- hou stom event fo Chittenden County (2.1 inches. Subwatesheds ae labeled with CN values used in calculation. Map oiginally ceated by Mak Suozzo as pat of UVM couse NR-243, Decembe 18, Updated by Milone & MacBoom, Inc. Mach 29, Miles Location

32 $ HARBOR RD T T M T M T1.03 T T M Shelbune Village FALLS RD M M M THOMAS RD M06S M M M M M M DORSET ST M09S T T M12S T4.06 T M13S T OAK HILL RD POND RD RICHMOND RD T T T MOUNT PHILO RD HINESBURG RD T T T T2S T M DORSET ST M East Chalotte Village SPEAR ST SHELBURNE FALLS RD M M11S M CHARLOTTE RD M T T M15S M15S2.01 T M15 T M Hinesbug Village M M T T NORTH RD T T T2S T2S T2S T SILVER ST M M M Figue 12: Ranking by Impevious Cove and Runoff Volume Rank Value Possible Infiltation Site Good (HSG A Ranking was based on pecent impevious suface and unoff volume, both nomalized by maximum values. A high values indicate high pecent impevious and/o lage unoff volumes. Infiltation sites ae based on soil classification of A (Good and B (Aveage using NRCS hydologic soils classification Aveage (HSG B Location Map oiginally ceated by Mak Suozzo as pat of UVM couse NR-243, Decembe 18, Updated by Milone & MacBoom, Inc. Mach 29, Miles

33 6.0 Stomwate Infastuctue 6.1 Mapping Pocedues Stomwate infastuctue shown on plans of stomwate pemits on file with the DEC Stomwate Section was digitized into GIS to begin to develop stomwate infastuctue maps. Stomwate infastuctue includes linea featues such as stomwate pipes, swales, and culvets. Point featues such as catch basins, manholes, dop inlets, detention ponds, and outfalls wee also digitized. Methods and map symbols (Figue 13 fo the stomwate infastuctue mostly follows DEC Stomwate Section conventions. Digitized stomwate infomation was added to existing stomwate mapping compiled by the CCRPC in The state-pemitted stomwate systems in Shelbune in the CCRPC GIS database had been field checked by the Shelbune Diecto of Public Woks. Coections based on this field veification have been incopoated into the updated mapping. Newly installed stomwate systems wee also included fom plans available at DEC. Additional field veification was completed via a windshield suvey of the wateshed. Hinesbug and Chalotte did not have stomwate infastuctue mapping in place pio to this poject. Following digitization of DEC stomwate plans, the village centes and aeas of dense development wee exploed on foot and stomwate infastuctue was located with GPS. A windshield suvey of the ual aeas of the wateshed was completed to note geneal unoff pattens and confim oad ditch dainage diections. The cuent stomwate infastuctue maps ae povided with this epot in electonic fomat (Appendix A. The stomwate infastuctue map shows that vey little of the wateshed aea contains infastuctue that falls unde the juisdiction of the state. This even extends to limited egulatoy ovesight in moe developed village centes as infastuctue was in place pio to the stat of pemitting in the 1970 s o some infastuctue does not meet pemitting thesholds (geate than 1 ace of impevious suface, unless in a designated stomwate impaied wateshed whee sticte standads apply. State-pemitted infastuctue conveys stomwate fo appoximately 25% of Shelbune Village (M04, M06, T1.03, 15% of Hinesbug Village (M16, M15S2, T4.01, and 0 % of East Chalotte Village (T2.01. This is an expected finding with so many ual locations, yet highlights the fact that management of stomwate is mostly an issue fo Town s to addess in the LaPlatte Rive wateshed. A desciption of unoff in subwatesheds focusing on stomwate infastuctue follows. The pesence of stomwate collection systems, desciption of dainage aeas, and desciption of dischage locations ae povided to highlight potential mitigation aeas. Developed aeas that have eceived an opeational stomwate pemit unde the juisdiction of the state ae descibed LaPlatte Rive Wateshed Stomwate Infastuctue Study 26

34 as pemitted o egulated, wheeas aeas with no ecod of an opeational pemit ae descibed as non-pemitted o unegulated. Figue 13: Legend showing symbols and stomwate infastuctue categoies fo Figues Shelbune Village Shelbune has a developed cental village suounded by a netwok of esidential neighbohoods intespesed with agicultue fields and tacts of foestland. Stomwate infastuctue is centalized along Route 7 and clusteed aound the village cente (Figue 14. Some neighbohoods in the moe ual sections of Shelbune have stomwate collection systems that can be seen on the full infastuctue map (Appendix A. Shelbune village dains to the lowe sections of the LaPlatte Rive to the east (M4, M6 and McCabe s Book to the west (T1.3. The LaPlatte Rive meets Lake Champlain noth of Shelbune village. Reach M1 is small and ual, and eceives unoff fom Spinnake Lane, a pemitted system, and unegulated unoff fom Bay Road. Moving upsteam, the LaPlatte Rive eceives collected stomwate fom a section of Route 7 (each M2, as well as pemitted and teated unoff fom Athletic Dive and the LaPlatte Rive Wateshed Stomwate Infastuctue Study 27

35 2 LN o o k T * # R ST L D R Ri * # 2 LN FL E Ri v La Pla t te GE US E NE M BUR 2 US E UM UR R * # E LIM HILLS IDE TE RR La K RIC Pl R atte R iv e RD SH EB U EP L DR E DR MIDDLE TER RAC E GREEN HILLS DR KE RT LN OC ST E UPPE R TE RR AC RD 2 R U ER LN RD Shelbune Village Stomwate Infastuctue LaPlatte Rive Wateshed Stomwate Poject AS RIVERVALE RD M THO LN 1233 Shelbune Road, Suite 150 South Bulington, VT ( Fax: ( * # D IE F RD LOW LN * # F BL AC K W IL v Ri SH LL M06S2.01 La P la tt iv e R FU te I IR HI er AIR PARK lat M06 e JOHN ST F Mapped Topogaphy Only LD RD E DR k oo sb RIDG EF IE L ap R U GING WIL D Field Veified # * TE R R AC e ab R O RD T PH IL cc * # 2 2 LOW E R M Subwateshed Bounday * # N LN CO VINGTO LITT LEF IELD DR TI LN * # MO U N DR DR W OOD MA P L E SUR E M05 AD LN LN Y NO U TIM B ER MEADOW R RD SHE L SHE L B U RNE M RD UM LN R FALL S S KE F O ST TC H ER VI LN LL A F e AD RA IL RO VCAO T L ETA DRGE LN SC H O OL S C IR T ABE U R SHE L MC C H ARBOR RD SHE L B URNE M04 W OOD DR 2 CR EE KS 2 2 I D ED R * # * # 2 V ISA DAV PK SHELBURNE SHOPPING CH U R C H ST 2 U 2 T RAC LN HERITAGE Y * # LN 2 2 * # 2 2 U T NN C C RD 2 S E W IR * # LAPLATTE C RR L L TE A KIMB T1.05 D TR T E S R MA DR 2 BA CO N ICK R D 2 BO ST W * # 2 U C * # LN R v NE R UR AT HL E TI C DR U a ENS ID E BUR D e OT R L ap l UUR U R GARD tt e DEP F N DR RV E B HA ab es ACORN LN cc M03 CH ES AP EAKE * # E TURT L M µ DATE: Mach 2010 SCALE: 1 = 1,000' 1,000 Feet SHEET: Figue 14

36 businesses off of Route 7 and a section of unegulated housing without a collection system in the vicinity of Webste Road. A ditch along a section of Route 7 and esidential neighbohoods along Shelbunewood Dive, Gadenside Lane, and Acon Lane cay stomwate to the ive noth of the village (M3. Of these collection systems, only Acon Lane is pemitted and includes teatment. The village is oughly compised of two subwatesheds with the aea to the east of Route 7 daining to the LaPlatte Rive (M04 and the aea to the west daining to McCabe s Book (T1.03. The each M04 subwateshed was divided into two aeas based on vaying land use and stomwate dischage locations. A small tibutay that collects the majoity of the developed land in the subwateshed was split fom the est of M04. This subwateshed eceives unoff fom the village cente including the aea appoximately between Route 7 and Falls Road fom Chuch Steet south to Covington Lane. The neighbohoods in this subwateshed ae olde and mainly constucted pio to statemandated stomwate teatment. The Town holds a pemit fo the nothen pat of Maplewood Dive and Steeplebush Road, but no significant teatment is included in this system. Multiple collection systems compised of catch basins and pipe outfalls without teatment exist in this aea that should be tageted fo impovement. The mostly foested easten potion of the M04 subwateshed daining diectly to the LaPlatte Mainstem was isolated. This subwateshed contains one lage development off of Thompson Road that has a ecent stomwate teatment system and pemit. This subwateshed does have some esidential popeties along Masette Road and LaPlatte Cicle that do not have teatment o state stomwate pemits. Upsteam on the LaPlatte, each M05 has a ual subwateshed to the east of the village with little existing stomwate infastuctue. Although ual with minimal infastuctue, this subwateshed was identified as having a high pecent of impevious cove and unoff potential. Rual development off of Iish Hill Road and Thompson Road does not have stomwate pemits o collection o teatment systems. A small development at the uppe end of the subwateshed, Ceda Ridge Dive does have a pemit held by the Town and teatment. The M06 dainage was boken down to isolate thee subwatesheds with diffeent unoff chaacteistics. The westen section contains a tibutay with a ual wateshed to the east of Thomas Road with little stomwate infastuctue. Anothe divide was made whee the M06.S2.01 tibutay entes the mainstem. This divide sepaates the ual southen section fom the nothwest section with dense esidential development. The developed potion of M06 eceives unoff fom a few olde neighbohoods in the vicinity of John Steet, Littlefield Dive, and Wild Ginge Lane. Teatment ponds exist fo seveal of these systems and a significant LaPlatte Rive Wateshed Stomwate Infastuctue Study 29

37 potion is unde pemits held by the Town. An outfall between John Steet and Littlefield Dive collects oveland and ditch flow fom a section of Mt. Philo Road, as well as effluent fom the teatment pond collecting fom the southen section of Maplewood Dive, Lowe Teace and Wild Ginge Lane. Teatment should be exploed at this outfall to teat the potion of unoff fom Mt. Philo Road. McCabe s Book joins the LaPlatte Rive nea Lake Champlain, and the McCabe s Book wateshed makes up the westen edge of the LaPlatte Rive wateshed. The lowe eaches ae ual with no stomwate infastuctue and include a backwateed section nea the confluence and agicultual land mostly associated with Shelbune Fams. T1.03 extends fom just downsteam of the Town Gaage to upsteam of Heitage Lane. This each was split at the Habo Road cossing due to a lage stomwate collection system enteing on the downsteam side. The collection system that uns down Habo Road collects stomwate fom Shelbune Museum, the Village Geen, businesses on Route 7, pat of the Shelbune Elementay School, and Habo Road. This cuently unteated lage system may have oppotunities fo teatment befoe eaching the outfall. Only the Elementay School has a stomwate pemit. The Town Gaage also dains to this subwateshed and has a pemit held by the Town and teatment in place. Upsteam of Habo Road multiple outfalls exist along McCabe s Book. Many of these ae catch basin and pipe systems in olde esidential neighbohoods that do not appea to have stomwate teatment. They include Heitage Lane, Tacy Lane, Fletche Lane, Stokes Lane, Ceekside Dive, and School Steet. Only Heitage Lane and a section of Tacy Lane have pemits, both held by the Town. Non-pemitted systems should be exploed fo specific impovements that could be made. These steets dain to the McCabe s Book with little available non-wetland space fo systems. The emaining pats of the wateshed in Shelbune include uppe eaches of McCabe s Book and dainage to small tibutaies of the LaPlatte Rive. These aeas ae pimaily ual with little existing development o stomwate infastuctue o stomwate pemits. The Teddy Bea Factoy does have a pemit and is the only additional popety with significant infastuctue. 6.3 Hinesbug Village The potion of the LaPlatte Rive wateshed in Hinesbug is mostly open space o ual esidential. Some of the ual developed aeas have dedicated stomwate collection and teatment systems, but most ely on ditches o oveland flow fo conveyance of suface unoff. The densest development in Hinesbug is in the village cente along Route 116 fom Commece Steet south to the Hinesbug Community School (Figue 15. LaPlatte Rive eaches M LaPlatte Rive Wateshed Stomwate Infastuctue Study 30

38 HAW K LN T4.02 ck B o o k P a t i F F R MU * # U RO 116 TE RCE S MM E O C T S RD HT GE ve F SV LL A Ri Pa tick Ca na l T4.01 M16 IC IG M H EC N RD HE A VI R 2 RD te at R E SH Pl La LD L IL BU 2 AL M FAR RN F Y DR IC W FR E INDC * # * # R O TH * # N U U RY L U ER R LB * # 2 KEL LEYS FIEL D RD R LL A ST E R D LaP C 2 é M E AD * # LYM AN PA * # SILVER ST Mapped Topogaphy Only e FLaPlat te Riv FF 2 F F Hinesbug Village Stomwate Infastuctue 1233 Shelbune Road, Suite 150 South Bulington, VT ( Fax: ( D HIL L Field Veified Subwateshed Bounday OR CH AR F RK RD 2 2 * # LYM A N LN TT E RD FR IENDSHIP Ri ve O CH ARL OW la tte LaPlatte Rive Wateshed Stomwate Poject µ DATE: Mach 2010 SCALE: 1 = 500' 500 Feet SHEET: Figue 15

39 (downsteam/nothen section and M16 (upsteam/southen section eceive unoff fom this aea. At the nothen end of the village, the LaPlatte Rive each M15 emains mostly ual with little existing stomwate infastuctue. Howeve, this each eceives flow fom Patick Book and the Patick Canal that both eceive unoff fom densely developed sections of the village. Patick Book (M15.S2.01 eceives unoff fom NRG, businesses on Commece Steet, a section of Route 116, and pat of Champlain Valley Union High School (CVU. NRG has teatment in place and is pemitted. CVU has multiple detention ponds in place and a state pemit. Runoff fom the easten section of Commece Steet is pemitted and follows a path eithe noth o south to one of two detention ponds. A seies of ditches along Route 116 collects unoff fom the westen section of Commece Steet and business along the easten side of Route 116, including a significant amount of impevious aea befoe dischaging diectly to Patick Book. This nonpemitted collection system should be examined fo teatment pio to outfall. Additional nonpemitted impevious aeas include development and oad unoff along Shelbune Falls Road, CVU Road, Route 116, and Pond Road. Patick Book has been alteed in this aea to include a bypass canal that is consideed as a sepaate steam each (T4.01 that uns paallel to Mechanicsville Road. The canal joins the LaPlatte Rive at the upsteam end of M15. This subwateshed eceives unoff fom pemitted systems in esidential neighbohoods along Thon Bush Road, Village Heights Road, Fedic Way, and pat of the fome Saputo popety. The GIS topogaphy mapped the edge of this subwateshed along the centeline of Fedic Way. Field veification of the stomwate systems showed that unoff fom the entie Fedic Way neighbohood is collected and outed to the detention pond at the southwest cone of the wateshed (Figue 15. Non-pemitted o teated unoff includes multiple businesses and esidences along Route 116 and Mechanicsville Road. Appoximately half of the impevious suface in this subwateshed in non-pemitted. LaPlatte Rive each M16 extends fom the confluence with the Patick Canal, just downsteam of the fome Saputo popety, noth to the confluence with Beeche Hill Book nea Beeche Hill Road. This lage subwateshed was split into thee aeas fo analysis based on vaying land use and stomwate input locations. The downsteam sub-each extends to the Chalotte Road cossing. This aea collects wate though a ditched tibutay that uns along the fome Saputo popety, unde Route 116 and behind the gocey stoe, chuch, and Lyman Meadows neighbohood. A majoity of the village dains to this tibutay, including most of the easten half of Route 116 though the village. Thee is a significant amount of impevious suface associated with the olde development that was not equied to install stomwate teatments that should be examined fo teatment oppotunities. Of the many impevious aeas daining to this tibutay, none include significant teatment and only the Saputo factoy site, Kelley s Field Dive, and Lyman Meadow neighbohood have stomwate pemits. Aeas with lage impevious sufaces LaPlatte Rive Wateshed Stomwate Infastuctue Study 32

40 with no pemits include businesses along Route 116, specifically the gocey stoe, chuch, gas station, dine/ceemee stand, and many esidences. The middle section of M16 includes unoff fom the emaining section of the village, fom Chalotte Road upsteam past Hinesbug Community School. Ditches along Chalotte Road collect wate fom a section of Route 116 with catch basins and pipes. Anothe seies of catch basins and pipes un along the southwest pat of the village and dains to a ditch leading to the LaPlatte Rive downsteam of Silve Steet. Catch basins along Route 116 in font of the Hinesbug Elementay school, and the aea to the east side of Route 116, collect and dischage stomwate nea the cone of Silve Steet and Route 116. Eosion is taking place at this outfall that conveys unteated stomwate to the LaPlatte Rive in a ditch along Silve Steet. This is a pioity teatment location fo Hinesbug Village. Hinesbug Community School has two additional diect dischage locations behind the school. None of the five netwoks descibed in M16 have significant teatment of the stomwate and each should be consideed fo mitigation. The only pemitted system in this subwateshed is the small lowe paking aea on the Hinesbug Community School popety. The westen section of this subwateshed emains mostly in its natual foested state with a few homes and fields. The uppe aea of M16 is ual and mostly compised of agicultual fields and foest. Minimal stomwate infastuctue is in place. Runoff fom oads, agicultual fields, and individual homes is conveyed eithe in ditches o oveland. 6.4 Chalotte Stomwate Infastuctue The potion of the LaPlatte Rive wateshed within the town of Chalotte is ual with a mix of agicultue, foest, and ual esidential land uses. Stomwate infastuctue is minimal consisting of only a few ually located esidential developments. Although had infastuctue such as catch basins and pipes ae limited, the town does have a significant numbe of oadside ditches that collect and convey stomwate unoff fom paved and dit oads, and agicultual fields. Impovement of these netwoks could have substantial impacts on the eceiving wates and will be geneally addessed in late sections of this epot. A study of ual oad ditch netwoks in the egion is being sponsoed by the Lake Champlain Basin Pogam and is slated to begin in Sping of A key outcome of this study is to geneate estimates of sediment and Phosphous loading fom the oad ditch netwoks in all Vemont watesheds daining to Lake Champlain. This infomation will be diectly applicable to undestanding the pimay stomwate theat fom Chalotte, and othe ual aeas, in the LaPlatte Rive wateshed LaPlatte Rive Wateshed Stomwate Infastuctue Study 33

41 7.0 Relating Stomwate Scenaio to Existing SGA and Wate Quality Data 7.1 SGA Data Phase 1 and 2 assessments have been completed fo the LaPlatte Rive eaches M03-M11 and McCabe s Book tibutay eaches T1.02-T1.05 (LWP Phase 2 was also completed fo Hinesbug eaches including M12-M18 and sections of tibutaies including Patick Book, Beeche Hill Book, the Canal, and an unnamed tibutay T3 (LWP Data wee futhe analyzed into a Steam Coido Plan fo the LaPlatte Rive and Tibutaies in Town of Hinesbug (LWP 2007 and Reaches M6-M11 in Towns of Chalotte and Shelbune (LWP 2008, both pepaed by the LaPlatte Wateshed Patneship. These studies collected infomation on steam channel condition that may be elated to stomwate impacts. The Shelbune and Chalotte Coido plan (LWP 2008 identified multiple hydologic stessos that contibute to high stomwate impacts to the channel. These include high oad densities in Shelbune Village, M04, M05, and M06, that leads to lage amounts of impevious cove that has been confimed by mapping fo this study. Bank eosion appeas to be most abundant in subwatesheds with lage amounts of impevious cove and the most identified stomwate outfalls (M06, T1.03, and T1.05. Indicatos of stomwate impacts such as gullies and tibutay ejuvenation wee seen in M06, M09A, M10, and M11. The Hinesbug Coido Plan identified multiple stomwate inputs to the channels and made suggestions that much of the bank eosion may be elated to stomwate unoff (LWP A peliminay suggestion was made to look at implementing a village-wide stomwate appoach to addess smalle popeties that may not be subject to state stomwate pemitting. A few of the watesheds that had a high anking fo isks fom stomwate wee peviously identified to have Poo and Fai geomophic conditions including (M06, M16, T1.03, T4.01, and T4.04 (Table 6. Many of these and downsteam subwatesheds had excessive bank eosion. Steam habitat condition is shown to be Fai o Poo at o downsteam of majo stomwate inputs. In Hinesbug, habitat condition was found to be Fai whee a potion of the village stomwate entes the system (M16, while a Poo habitat conditions was identified downsteam of the village stomwate inputs. In Patick Book, uppe eaches wee found to have good habitat, and downsteam eaches (T4.02 and T4.01 had Fai and Poo conditions whee stomwate inputs occu. In Shelbune, habitat condition was Fai whee the majoity of stomwate inputs occu (T3.01, M LaPlatte Rive Wateshed Stomwate Infastuctue Study 34

42 Table 6: Summay of Steam Geomophic Assessment Data Segment Town Steam Type LaPlatte Rive Wateshed Stomwate Infastuctue Study 35 Depa tue Geomophic Condition Evolution Stage Sensitivity Habitat Condition LaPlatte Rive and Mino Tibutaies M3,M4A Shelbune E5 Dune Ripple Good I High Good M04B Shelbune C4 Riffle Pool Good I High Good M06 Shelbune B4c Plane Bed yes Poo IV High Fai M07 Shelbune B5 Plane Bed Good III Modeate Good M08 Chalotte C4 Riffle Pool Fai IV Vey High Fai M09A Chalotte B4c Plane Bed Fai IV High Fai M09B Chalotte C5 Riffle Pool Fai IV Vey High Good M10 Chalotte C5 Riffle Pool Fai IV Vey High Fai M11 Chalotte B4c Dune Ripple Good I Modeate Good M12 Hinesbug E5 Dune Ripple Good I High Fai M13 Hinesbug E5 Dune Ripple Good I High Fai M14 Hinesbug E5 Dune Ripple Good III High Fai M15A Hinesbug E5 Dune Ripple Fai III Vey High Fai M15B Hinesbug C5c Dune Ripple Fai III Vey High Poo M16 Hinesbug C5 Dune Ripple Fai III Vey High Fai M17 Hinesbug B5c Dune Ripple yes Poo III High Fai M18A Hinesbug C4 Riffle Pool Fai IIC Vey High Good M18B Hinesbug C4 Riffle Pool Poo II Vey High Fai T3.01 Hinesbug E5 Dune Ripple Good III High Fai T3.02 Hinesbug C5 Dune Ripple Good IIc High Fai McCabe's Book T1.02 Shelbune E5 Dune Ripple Good III High Good T1.03 Shelbune E5 Dune Ripple Fai IIc Vey High Fai T1.04A Shelbune N/A N/A N/A N/A N/A N/A T1.04B Shelbune C4 Riffle Pool Fai II Vey High Fai T1.05A Shelbune F4 Riffle Pool yes Poo III Exteme Fai T1.05B Shelbune C5 Dune Ripple Good IIc High Good Patick Book M15S2.01 Hinesbug E4 Dune Ripple Good III High Fai T4.01 Hinesbug C5 Plane Bed Fai II Vey High Poo T4.02 Hinesbug F4 Plane Bed yes Poo III Exteme Fai T4.03 Hinesbug C4 Riffle Pool Fai III Vey High Good T4.04 Hinesbug B4a Step Pool Fai IIc High Good T4.06 Hinesbug C4 Riffle Pool Good III High Good Beeche Hill Book T5.01A Hinesbug E5 Dune Ripple Good IIc High Fai T5.01B Hinesbug E4 Riffle Pool Fai IIc Vey High Fai T5.01C Hinesbug B3 Step Pool Good I Modeate Good T5.01D Hinesbug F4 Plane Bed yes Poo II Exteme Fai

43 7.2 Wate Quality Data Wate quality monitoing has been completed in the LaPlatte Rive and McCabe s Book by the LaPlatte Wateshed Patneship as pat of its Voluntee Monitoing Pogam stating in Data have been compiled and analyzed up though the 2007 monitoing season (LWP Concentations of nitogen, phosphous, and suspended solids inceased with stom events, and concentations of phosphous wee found to be coelated with concentations of suspended solids. This epot includes data fo a elatively shot monitoing peiod, but povides geneal suggestions on wate quality that may be confimed as additional data is collected. Results along the mainstem of the LaPlatte Rive highlighted a few key aeas influenced by stom flows. The suspended sediment concentations incease apidly between the Hinesbug wastewate teatment plant and Leavenswoth Road that have been attibuted to bank eosion. Suspended sediments ae diluted down to the Falls Road and slowly incease again to the mouth of the ive at Lake Champlain. Inceased suspended sediment is thought to be fom stomwate unoff, bank eosion, and channel scou. The stomwate unoff in Shelbune Village is suggested by the LWP peliminay epot to be a possible cause of inceased total Nitogen concentations in the LaPlatte Rive, coesponding to the pioity subwatesheds identified in the impevious cove and unoff volume anking (LWP Past wate quality epoting indicates that Phosphous concentations in McCabe s Book ae significantly impacted by stom unoff fom agicultual land and lage impevious sufaces, as well as by stomwate unoff fom uban/semi-uban aeas in downsteam stations (LWP, These tends geneally apply to suspended sediment and nitogen concentations. Thee wee inceases in total Nitogen, suspended solids, and Phosphous between Bostwick Road and Habo Road. Lage inceases in Phosphous at the Teddy Bea access oad wee attibuted to unoff fom paking aeas and buildings. These wate quality esults indicate that the identified stomwate outfalls at both the Teddy Bea Company and neighbohood upsteam of Habo Road in Shelbune Village should be tageted fo stomwate mitigation. Sampling on Patick Book showed inceases in tubidity and total Phosphous between the Mechanicsville Road and Route 116 cossings. Runoff fom the commecial development may be influencing wate quality. This sampling location is upsteam of the outfall dischaging wate fom Route 116 and the gas station on Commece Road and thus local wate quality may be futhe educed than data suggest. Stomwate outfalls along Patick Book should be tageted fo stomwate teatment LaPlatte Rive Wateshed Stomwate Infastuctue Study 36

44 Mud Hollow and Bingham Book tibutaies wee sampled and showed that when flows ae high the suspended solids and Phosphous concentations ae high. These watesheds ae ual and ae pimaily affected by agicultual field unoff. 8.0 Stomwate Teatment Pojects and Geneal Recommendations 8.1 Poject Identification Stomwate mitigation poject locations have been identified based on the impoved undestanding of the existing conditions of the stomwate system. Subwatesheds with high pecent impevious cove, lage unoff volumes, and known wate quality issues wee tageted fo possible mitigation pojects. Access to soils with good infiltation capacity is also consideed. Stomwate dischage locations establish point souces of pollution on the landscape whee teatment methods can be applied. Addessing point souces is often a moe staight fowad task than dealing with nonpoint souce pollution distibuted acoss the landscape. Potential mitigation pojects ae sited at o nea existing systems and close to poposed gowth cente aeas. In watesheds such as the LaPlatte with concentated village cente aeas with a small amount of stomwate infastuctue in place, multiple landownes, and minimal access to pemeable soils, stomwate teatment and conveyance should be a pimay consideation fo locating futue development and designating gowth centes. Due to the dense natue of development in the village setting, stomwate cumulatively collects fom many landownes and it is difficult o impossible fo each individual to teat stomwate on site. In these densely populated aeas community-based teatment should be planned, implemented, and funded by the town. Potential souces of funding fo community stomwate teatment include ceation of a Stomwate Utility such as in South Bulington, town taxes, o pusuing gant funding. Suggestions and additional infomation fo implementation ae included in Section 8.0. Poject implementation in the aeas geneally identified hee would equie landowne and town paticipation to site a poject on a specific pacel. Futhe analysis and design would be necessay to develop each poject associated with this study and stomwate teatment focused stategy of gowth. LaPlatte Rive M04, Shelbune Village The M04 each subwateshed was boken into two pats. The subwateshed daining the village cente neighbohoods was identified as a pioity wateshed based on impevious suface and unoff volume. This subwateshed is almost entiely developed with olde village neighbohoods LaPlatte Rive Wateshed Stomwate Infastuctue Study 37

45 with stomwate collection systems that lack teatment facilities. Examination of the stomwate infastuctue identifies two main collection systems, each collecting appoximately half of the dainage aea. The easten system collects wate fom Maplewood Dive and Mt. Philo Road, befoe dischaging into a field off of Mt. Philo Road and eventually flowing to the LaPlatte Rive. The dischage location is in a field adjacent to Mt. Philo Road, just noth of Wes Road, whee thee is available space fo stomwate detention and possibly infiltation (Figue 16. A possible teatment location was highlighted nea the Mt. Philo Road fo ease of access and maintenance, although thee ae pemeable soils located in the field fathe to the east nea the woods in the field and in the southen section of the fields behind the homes to the south. This is a walking pak and any teatment implemented would need to be designed to complement the existing eceational uses. Figue 16: Potential Stomwate Teatment Options in Shelbune Village M04 The othe half of the subwateshed collects though a seies of catch basins and pipes to two dischage locations to a small tibutay of the LaPlatte Rive. These outfall locations do not appea to have available space fo end-of-pipe teatment. The potential fo teatment nea these outfalls needs to be exploed futhe. It is ecommended that this neighbohood be tageted fo stomwate eduction methods such as disconnection of impevious cove, use of pevious pavement in the futue, installation of ain gadens, and use of ain baels. Low impact LaPlatte Rive Wateshed Stomwate Infastuctue Study 38

46 development appoaches that amount to decentalized mitigation have been shown to educe stomwate unoff volume and nutient expot (Bedan and Clausen LaPlatte Rive M06, Shelbune Village The M06 each subwateshed was boken into thee pats, the westen section including pat of the village was found to have wate quality, geomophic condition, and impevious cove indicatos of stomwate poblems. Multiple neighbohoods exist in this subwateshed, some of which have teatment in place. A system that collects wate on Mt. Philo Road and dischages between John Steet and Littlefield Dive is a location whee impoved teatment is suggested (Figue 17. This system collects some stomwate teatment pond effluent and pat of the ditches along Mt. Philo Road and leads to a manhole between the neighbohoods. This aea is sloped so a suface detention system would need to be a teaced system to povide multiple stoage cells and adequate esidence times. Othe options include infiltation techniques o impovement of the ditch netwok along Mt. Philo Road to povide teatment befoe enteing the stompipes. Figue 17: Potential Stomwate Teatment Options in Shelbune Village M LaPlatte Rive Wateshed Stomwate Infastuctue Study 39

47 The collection system on John Steet cuently has a gease tap that stomwate passes though befoe dischage to the LaPlatte Rive. This system could be upgaded fo impoved stomwate teatment as a futue poject. Infiltation pactices such as installation of echage galleys o establishment of a stomwate detention pond would be appopiate due to soil types in the aea aound this outfall. McCabe s Book T1.03, Shelbune Village McCabe s Book subwateshed T1.03 was identified as having high impevious cove, lage unoff volumes, and educed wate quality. T1.03 extends fom just downsteam of the Town Gaage to upsteam of Heitage Lane. The system that uns down Habo Road collects stomwate fom Shelbune Museum, the village geen, businesses on Route 7, pat of the Shelbune Elementay School, and Habo Road. This lage system appeas to have oppotunities fo teatment befoe eaching McCabe s Book. Two potential detention aeas ae identified off Habo Road nea Athletic Dive and expanding the existing pond behind the Town Gaage (Figue 18. These locations ae in the vicinity of wetlands and may not have available space fo a lage pond-type teatment option. Thee may be smalle, decentalized teatment altenatives fo stomwate disconnection such as ain gadens at the school. Upsteam of Habo Road, thee ae multiple outfalls along McCabe s Book oiginating fom Heitage Lane, Tacy Lane, Fletche Lane, Stokes Lane, Ceekside Dive, and School Steet. Many of these olde stomwate conveyance systems consist of catch basins and pipes, and do not appea to have teatment facilities. Impovements ae ecommended at any of these outfalls, although the close poximity of outfalls to the ive coido may not allow space fo detention. Low impact development techniques should be applied in this neighbohood to educe stomwate unoff and incease infiltation. A collection system dischaging behind the tennis couts off of School Steet has been tageted fo teatment due to available space at the outfall and the lage contibuting aea. This aea is within a Town Pak and any teatment would need to be designed to complement the existing eceational uses. Subsuface teatment options may be appopiate in this location LaPlatte Rive Wateshed Stomwate Infastuctue Study 40

48 Figue 18: Potential Stomwate Teatment Options in Shelbune Village T3.01 McCabe s Book T1.05, Teddy Bea Factoy, Shelbune The Teddy Bea Factoy popety includes a high pecentage of impevious suface fom buildings, paking lots, and the access oad. This location was identified by the wateshed voluntee wate quality testing as a possible contibuto to lowe wate quality (LWP, A stomwate teatment pond does exist on this popety and has a state stomwate pemit. Futhe investigation is needed to confim wate quality esults and identify possible impovement at the site such as e-outing unoff o inceasing the amount of unoff volume stoed and the duation of stoage. LaPlatte Rive M16, Hinesbug Village LaPlatte Rive each M16 extends fom the confluence with the Patick Canal, just downsteam of the fome Saputo popety, noth to the confluence with Beeche Hill Book. This lage subwateshed was split into thee sections fo analysis based on stomwate type and input locations. The lowe two subwatesheds have been tageted fo stomwate impovement LaPlatte Rive Wateshed Stomwate Infastuctue Study 41

49 A majoity of village dains to the tibutay in the downsteam section of this each, including most of the easten half of Route 116 though the village. Teatment potential exists in this aea. Stomwate could be diveted fom the ditched tibutay into the existing teatment pond that was fomely used by the Saputo factoy (Figue 19. If this pond will not be used fo futue plant opeations it would seve as eady-made stomwate detention. Space fo othe detention aeas exists aound the factoy site that could be eseved fo planned futue uses in the aea and village expansion. Pemeable soils ae mapped in the LaPlatte Rive coido in this aea including the westen half of the factoy site and potions of the fields both to the noth and south of the site which could pesent oppotunities fo infiltation based mitigation. Additional oppotunities fo stomwate inteception ae possible in the collection system upsteam including expanding the cuent ditch in Lyman Pak to enhance stomwate teatment by establishing wide detention aeas. Stomwate entes the ditch systems behind the gas station, chuch, and the gocey stoe at multiple locations and thus small decentalized teatment methods such as ain gadens o infiltation pactices may be appopiate. Minimal, if any, mowing should be pefomed in the swales so thicke vegetation inceases hydaulic esistance slowing flow ate and inceasing etention times. Figue 19: Potential Stomwate Teatment Options in Hinesbug Village Lowe M LaPlatte Rive Wateshed Stomwate Infastuctue Study 42

50 The middle section of M16 includes unoff fom the emaining section of Hinesbug village, fom Chalotte Road upsteam past Hinesbug Community School. This subwateshed was tageted fo teatment due to high pecentage of impevious suface, wate quality poblems downsteam, and local eosion. A multi-celled, teaced detention system is ecommended whee the piped system meets the ditch at the cone of Silve Steet (Figue 20. Multiple detention cells would allow fo inceased etention times on the sloping cone of land. Wate cuently ushes out of the pipe and down the existing steep ditch to the LaPlatte Rive. Ditches along Chalotte Road collect wate fom a section of Route 116 with catch basins and stomwate pipes. The ditch that this system dischages to is a gass swale along the oad that could be impoved into a highe functioning linea ain gaden system. Soils located in the aea indicate that infiltation could be possible in this location. Anothe seies of catch basins along the southwest pat of the village collects unoff along Route 116 in font of the Hinesbug Elementay school and dischages nea the cone of Silve Steet and Route 116. Eosion is taking place at this outfall indicating high stomwate flows. Runoff eventually flows though the ditches along Silve Steet. The teaced ain gaden ecommended in this aea will thus need to be size fo the volume of unoff coming fom this and the peviously mentioned pipe systems. Hinesbug Community School has two dischage points behind the school. Multiple oppotunities exist fo stomwate teatment such as ain gadens o constucted wetlands at the school site (Figue 20. These pojects could benefit local steam health and pesent a hands-on educational oppotunity fo the students at the Hinesbug Community School to lean about stomwate. The tageted outfall collects unoff fom compacted aeas of the lawn and dischages behind the play aea. Roof unoff should be diveted to the ecommended teatment aea. Othe smalle stomwate pojects could be implemented aound the school such as inclusion of ain wate collection baels at the oof downspouts and building of small ain gadens in the median stip in font of the school that ae now dained by catch basins. Disconnection of impevious sufaces o install of infiltation methods ae ecommended fo the paking aeas and the oof that ae now dischaging to the LaPlatte Rive nea the Silve Steet Bidge without teatment. Installation of stomwate teatments may be pusued as pat of the econstuction of the Silve Steet Bidge, scheduled fo LaPlatte Rive Wateshed Stomwate Infastuctue Study 43

51 Figue 20: Potential Stomwate Teatment Options in Hinesbug Village Middle M16 Patick Book M15S02, Hinesbug Village Patick Book (M15.S02.1 was identified as a pioity wateshed fo stomwate teatment based on the anking analysis and specifically pecent impevious suface. Between the local gas station and Patick Book is a piece of open space that could seve as a location fo a stomwate detention pond (Figue 21. A constucted wetland o taditional pond could be built and diectly daining unoff fom the aea could be diveted to the pond via swales o cubing along the back of the paking aeas LaPlatte Rive Wateshed Stomwate Infastuctue Study 44

52 Figue 21: Potential Stomwate Teatment Option in Hinesbug Village Patick Book Patick Canal T4, Hinesbug Seveal of the Patick Canal subwatesheds have been identified as having degaded geomophic condition and ae high pioity fo stomwate mitigation. Much of the development in the lowe each (T4.01 is new and has adequate stomwate teatment. The close poximity of the canal to Mechanicsville Road limits oppotunity fo detention along this degaded each (T4.02. The uppe watesheds have some in-line detention in the fom of ponds and dams. Residential development in the uppe eaches is dispesed and does not have stomwate teatment. One potential teatment location was identified next to Mechanicsville Road at the base of the cemetey (Figue 22. A detention aea at this location could seve as channel oveflow duing stom events and detain unoff fom the cemetey hillside. The location of this detention aea is upsteam of T4.02 that has poo geomophic condition and T4.01 which has significant impevious suface and is theefoe vulneable to stomwate unoff. This site was visited in the field and appeas to be a good location fo a constucted wetland LaPlatte Rive Wateshed Stomwate Infastuctue Study 45

53 Figue 22: Potential Stomwate Teatment Option in Hinesbug Patick Canal 8.2 Summay of Recommended Pojects The ecommended stomwate teatment pojects pesented hee have been tabulated along with elevant stomwate infomation to aid in poject pioitization and futhe poject development (Table 7 and Table 8. Dainage aea and amount of impevious aea daining to each outlet o poject location was identified. An appoximate unoff volume was calculated based on the subwateshed unoff depth and the dainage aea to the outfall LaPlatte Rive Wateshed Stomwate Infastuctue Study 46

54 Table 7: Summay of Suggested Pojects in Shelbune Poject Location Recommendations Popety Owne Pacel ID Mt. Philo Road noth of Wes Road Geen Hills Dive, Timbe Lane, Meadow Lane Aea Neighbohood Mt. Philo Road Dainage, Outfall between John St. and Littlefield Dive Detention in Field Town of Shelbune Rainwate Disconnection / LID Appoaches Install Detention Multiple Pete & Susan Plumb, Town of Shelbune, Fedeick Schmidt & Ann Revtusts, Mak & Judy Willis N/A , , , John Steet Install Infiltation Inge Dybfest Habo Road Collection System, nea Althetic Dive Habo Road Collection System, Detention behind Town Gaage School Steet and Elementay School Heitage Lane, Fletche Lane, Davis Lane, Stoeks Lane, Tacy Lane Aea Neighbohood Divet Pipe Flow to Detention nea Althetic Dive Divet Pipe Flow to Detention behind Town Gaage Install Detention behind Tennis Couts Rainwate Disconnection / LID Appoaches McCabe's Cicle Community Town of Shelbune Town of Shelbune Multiple Investigate and Impove Teddy Bea Factoy Teddy Bea Factoy Teatment Notes: Teddy Bea Factoy Aeas assume all impevious aea on site could be collected. N/A , Steam Reach ID M04, Village M04, Village M06, Village M06, Village T1.03, Nothen T1.03, Nothen T1.03, Southen T1.03, Southen Subwateshed Runoff Ranking Appoximate Dainage Aea to Outlet (aces Appoximate Impevious Aea to Outlet (aces Subwateshed Runoff Depth (inches T LaPlatte Rive Wateshed Stomwate Infastuctue Study 47

55 Table 8: Summay of Suggested Pojects in Hinesbug Poject Location Recommendations Popety Owne Pacel ID Saputo Factoy Site Lyman Meadows Nothen Section Gas Station/Lyman Meadows Chalotte Road Silve Steet and Route 116 Cone Hinesbug Community School Play Aea Hinesbug Community School, Paking Aea Route 116 Cossing ove Patick Book Hinesbug Cemetey, Patick Book Retofit Existing Peteatment Pond / Infiltation Swale Impovement Swale Impovement Swale Impovement, Bioetention, o Infiltation Saputo Cheese USA Inc Andew Buton/ Town of Hinesbug Hat & Mead Inc / Andew Buton Public ROW / Geen Steet LLC. Steam Reach ID M16, Nothen M16, / Nothen M16, / Nothen Road ROW / Detention Town of Hinesbug Bioetention Town of Hinesbug Bioetention o Infiltation Town of Hinesbug M16, Middle M16, Middle M16, Middle M16, Middle Subwateshed Runoff Ranking Appoximate Dainage Aea to Outlet (aces Appoximate Impevious Aea to Outlet (aces Subwateshed Runoff Depth (inches Detention on South side Jolley Associates M15S Patick Book Stowate Oveflow Town of Hinesbug T4.03 & US Reaches Notes: Hinesbug Cemetey site, includes aea fom upsteam subwatesheds that contibute flow to Patick Book at that point LaPlatte Rive Wateshed Stomwate Infastuctue Study 48

56 8.3 Geneal Stomwate Recommendations This study has demonstated that stomwate unoff is an issue within the LaPlatte Rive wateshed. Many of the specific aeas expeiencing the most poblems ae focused in and aound the village centes of Shelbune and Hinesbug. Olde stomwate conveyance systems without any teatment ae now handling inceased volumes of unoff as popeties in village centes conveted land use to impevious cove and the aleady limited infiltation capacity was educed. Data suggest that eceiving wates ae showing signs of impaiment fom stomwate dischage. The aeas that have been identified fo mitigation pojects add teatment to the existing system and seek to expand capacity at the village cente whee gowth is likely to take place since municipal infastuctue (sidewalks, wate and sewe, schools and sevices aleady exist. Although ual aeas do not have the same pemitted development density o amount of impevious cove, stomwate impacts do exist fom field and oad ditch unoff that influences downsteam channels. These aeas will have diffeent appoaches to stomwate mitigation as thee ae not obvious collection systems to taget pojects. Recommended stategies fo impoving wate quality though stomwate teatment. Begin implementation of the pojects identified duing this study to eliminate dischage of unteated stomwate to eceiving wates. Community and school hands-on demonstation pojects ae ecommended to gain public suppot fo minimizing stomwate impacts fom village centes. Requie all popeties submitting an application fo a building pemit to demonstate stomwate mitigation using Low Impact Development (LID techniques. The ultimate goal is mimicking pe-development hydology by educing unoff volume fo futue development (Smith This stategy would specifically taget small developments that ae unde the theshold fo obtaining a state stomwate pemit, but have a cumulative impact by joining the existing stomwate systems with such little teatment facilities. Innovative design appoaches would be equied to size and constuct best management pactices to educe unoff (e.g., Hischman and Collins Fund and implement a low impact development (LID outeach pogam to pomote and suppot single lot-scale stomwate eduction and e-use methods such as ain baels, cistens, and ain gadens. This would include adoption and distibution of an LID guidance manual such as that used by the South Bulington Stomwate Utility (Utility 2009 o VTDEC s The Small Sites Guide fo Stomwate Management (VTDEC An impotant message is that LID techniques educe stomwate unoff (Bedan and LaPlatte Rive Wateshed Stomwate Infastuctue Study 49

57 Clausen 2009, impoves the quality of eceiving wates, is often aesthetically pleasing in village centes, and is cost-effective design appoach (USEPA Building on the findings pesented hee, use stomwate teatment potential to guide futue development and plans fo gowth in the village centes. The potential exists fo infiltation-based stomwate mitigation in select locations in most of the pioity watesheds. These possible teatment sites should be investigated futhe fo veification of infiltation capacity based on soil mapping, poximity to potential development sites, and identification of pacel infomation. Revise planning and zoning odinances to include specific stategies fo stomwate impovement. Ceate a geen infastuctue ovelay distict to eseve pime aeas fo infiltation and goundwate echage based on soils and suficial geology. This type of ovelay would allow fo natual infiltation as well as locations fo sighting engineeed stomwate management aeas. Thee ae many ways to educe and e-use stomwate. A summay of popula appoaches that could be incopoated into standad pactices, maste plans, o municipal code follow. Limit the amount of impevious suface and peseve open space o Cluste development fo to shae dives and oads o Minimizing pavement widths o Reduce setbacks fom popety lines to limit diveway lengths o Reduce necessay popety fontages to educe main oad length pe popety o Encouage minimal distubance pactices duing constuction to peseve natual vegetation, heteogeneous land suface, and soil pemeability o Use pemeable pavement o paves whee possible o Use geen oof tops o Incease infiltation capacity of lawns, spots fields and paks by mowing high and ove seeding bae spots. Disconnect impevious sufaces fom collection systems and eceiving wates o Install ain baels o cistens fo ainwate collection at oof downspouts fo iigation. o Install ain gadens to collect unoff fom diveways and medians. Technical guidance fo design and building is povided by the Vemont Rain Gaden Manual ceated by the Winooski Natual Resouce Consevation Distict (Distict Assistance is also available though UVM extension sevices. o Install infiltation systems such as infiltation tenches, basins, o undegound galleys whee soils ae pemeable LaPlatte Rive Wateshed Stomwate Infastuctue Study 50

58 o Eliminate use of cubing whee possible to pomote oveland flow of unoff fom impevious sufaces. Peseve ive coido natual stomwate functions o Restict new development fom designated floodplain aeas. These aeas ae citical fo wate stoage duing flood events and sediment and nutient emoval. o Maintain and expand vegetated buffes to filte stomwate unoff. Impove stomwate teatment function of oadside ditches o Encouage natual vegetation fo eduction of wate velocity, impoved settling of solids, and eduction of eosion. o Include small depessions to pomote settling of solids and collection of gavel in oad unoff. o Install sediment foebays and check dams whee appopiate along existing ditches to incease wate stoage, pomote infiltation, and allowing settling of solids. o Stone lined ditches aise wate tempeatues due to sun exposue and ultimately aise tempeatues in steams that is hamful to many aquatic species. Impove stomwate unoff fom agicultual aeas o Encouage landownes to take advantage of USDA fencing and buffe pogams to potect ipaian aeas. o Pomote soil potection using cove cops and othe methods. o Reduce pollutant load fom fields. Futue consideations fo the Towns. Thee is value in planning fo stomwate mitigation on a wateshed and town-wide basis instead of a site by site level as equied by cuent state egulations. How can this moe efficient level of planning be incopoated into policy? The benefits of being poactive in mitigating effects of stomwate ae numeous and moe economical in the long un. Could implementation of a stomwate management plan avoid state and fedeal mandated egulation? Minimizing ecological impacts in the wateshed should be a pioity fo towns. Ou health and that of the ecosystem depend on it. Should a geen infastuctue ovelay be ceated to conseve infiltation aeas and descibe thei pioity fo stomwate mitigation and goundwate aquife echage? LaPlatte Rive Wateshed Stomwate Infastuctue Study 51

59 Due to the ual natue of the towns, development is often dispesed and small scale. Should new development of this type be equied to meet a town stomwate teatment standad? How easily can the town implement low-impact design appoaches? Ae the costs and benefits fo stomwate dischage appopiately shaed between ual and uban aeas? Would the town foste patneship with LaPlatte Wateshed Patneship to facilitate outeach to popety ownes to povide education and technical advice on impoved stomwate management? Many municipalities ae moving towads toughe development standads whee athe than no incease in peak flow ate no incease in stomwate unoff volume leaving the site is allowed. Is this standad a fai buden on futue development? Roadside ditches contibute unteated stomwate diectly to steams in the majoity of the wateshed. Is thee a way to taget specific aeas fo impovement duing scheduled ditch maintenance? Will the town agee to change ditch pactices to impove stomwate teatment and fomalize these appoaches in a policy? 8.4 Gowth Cente Consideations The Town of Shelbune has taken steps to implement stomwate impovement stategies as pat of MS4 pemit equiements. A floodplain ovelay has been incopoated into municipal zoning that includes steam buffes and stomwate ovelay disticts (Figue 23. Details and standads fo stomwate teatment have been included in the Town Public Woks Specifications. The Town has passed a Stomwate Odinance. All of these steps have woked towads impoved stomwate teatment and potection of the ive coidos. The Town of Shelbune s stomwate ovelay distict includes the majoity of the developed aea in and aound the village cente that has been discussed as high isk in this study. It equies that any new o edevelopment poject exceeding 10,000 squae feet (appoximately ¼ ace may be subject to individual pemit equiements fom the DEC Wate Quality Division. The focus on stomwate has been on developed aeas with designated stomwate impaied ives. This epot illustates the need fo pevention of futue impacts and povides suggestions fo efinement of the designated stomwate ovelay distict to peseve impotant infiltation aeas o potect open space LaPlatte Rive Wateshed Stomwate Infastuctue Study 52

60 The Hinesbug Zoning disticts include a Village Gowth Aea (Figue 24. This Gowth Aea designates a significant amount of cuently undeveloped land to be pat of futue development. These aeas ae within many subwatesheds that wee identified to be stomwate hot spots including LaPlatte Rive (M16 and Patick Book and Canal (M15.S02, T4.01, T4.02. The Patick Book and Canal eaches have aleady been identified as contibuting to degaded conditions in the LaPlatte Rive each (M15. Steam buffes have been included as pat of the designated Gowth Aea. These buffes begin to set pioity fo steam functions and decease pollutants in unoff, but may benefit fom being extended to include moe of the adjacent aeas shown to have high infiltation capacity to suppot cuent and futue stomwate teatment. It is ecommended that the Hinesbug Village Gowth aea be efined based on a village-wide stomwate management plan. This plan would stategize mitigation of cuent stomwate poblems and set guidance fo futue development. Mitigation of stomwate unoff fom public infastuctue would be addessed in the plan. A few aeas with soils conducive to infiltation should be designated fo infiltation type stomwate teatment and be incopoated in site planning. Chalotte emains mostly ual within the LaPlatte Rive wateshed. Town zoning designated most of the aea as ual (Figue 25. Consevation aeas show steam buffes and a few lage aeas adjacent to steams. East Chalotte village, including a small section of Village Commecial zoning is included in the wateshed. This aea of concentated development is located at the headwates of a few tibutaies that appea to have adequate open space to povide stomwate teatment befoe dischage to a eceiving wate LaPlatte Rive Wateshed Stomwate Infastuctue Study 53

61 FARM BARN LN DUCK POND RD BEACH RD COL FLETCHER RD QUAKER SMITH PT RD HIGH ACRES FARM DR PHEASANT HILL RIDGE LAKE RD BARN VIEW RD BOSTWICK FARM RD PHEASANT HILL RD CRABAPPLE DR N GATE RD HARBOR RD LIMERICK RD POPLAR DR HAWTHORN DR WAKE ROBIN DR S GATE RD WAKE ROBIN LN BAY RD DEPOT RD RIDGEFIELD RD T1.04 S RIDGE RD TURTLE LN DAVIS AV FLETCHER LN HERITAGE LN REDSTONE DR CREEKSIDE DR SCHOOL ST T1.05 Shelbune Bay M01 M02 T1.01 T1.02 T1.03 STOKES LN TRACY LN MCCABE CIR SHELBURNE MUSEUM SPINNAKER LN ATHLETIC DR HILLSIDE TERR CYNOSURE DR FALLS RD KIMBALL TERR GREEN HILLS DR YACHT HAVEN DR VILLAGE VALE DR SHELBURNE MUSEUM 2 OCKERT LN COTTAGE LN MEADOW LN MARSETT RD TI LN AIR PARK RD POINT VIEW DR M03 LaPlat BACON DR MOUNT PHILO RD MARINERS WY BAYFIELD DR HOES LN M06S2.01 SHELBURNE RD BOURGEA LN te Rive LaPlatte Rive SHELBURNEWOOD DR CHURCH ST WES RD TIMBER LN MAPLEWOOD DR STEEPLEBUSH RD COVINGTON LN MAPLE LEAF LN WINTER HAVEN RD CHESAPEAKE DR MARINERS COVE UNKNOWN HARVEST LN JOHN ST CROWN RD LITTLEFIELD DR WILD GINGER LN BAYVIEW LN LOWER WEBSTER RD SHELBURNE SHOPPING PK RAILROAD LN UPPER TERRACE DR LAPLATTE CIR MIDDLE TERRACE DR LOWER TERRACE DR EDWARD DR MCDONALD FARM RD CROWN RD DREW LN WEBSTER RD M04 LaPlatte Rive DEER RUN DR FARMSTEAD DR ACORN LN GARDENSIDE LN LaPlatte Rive M05 M06 RIVERVALE RD LaPlatte Rive GOBBLER LN EXECUTIVE DR EXECUTIVE DR Subwateshed Bounday Stomwate Ovelay Floodplain Ovelay Rual Residential RED CEDAR LN WHITE CEDAR LN Village Residential Museum WRIGHT RD WITCH HAZEL RD LONGMEADOW DR RICHMOND DR Munoe Book FIELDSTONE WY BLACK WILLOW LN THRUSH WY QUAIL WY FOX RUN RD ADDIE LN NORTHSIDE DR CARDINAL WY PARTRIDGE WY EXECUTIVE DR MUNROE DR THOMPSON RD HAWLEY RD Munoe B VISTA DR OLD STAGE LN IRISH HILL RD LaP Village Cente Mixed Use Shelbune Falls Mixed Use STONEGATE LN latte R ive ook CEDAR RIDGE DR WILDWOOD CT Mixed use WILDWOOD DR WEBSTER LN PIERSON DR LOGAN CT Commece & Industy POTTER PL BOULDER HILL DR MORSE DR COLLAMER CIR Munoe Book KELADY DR SPEAR ST MAECK FARM RD TRILLIUM LN RAVINE CT Commece & Industy South Consevation Wate COLLAMER CT NASHVILLE RD BRENTWOOD DR THOMAS RD M07 LaPlatt e Rive BISHOP RD S PASTURE RD EUSTACE LN SOUTHVIEW D M08 PEEPER POND LN BOSTWICK RD ETHAN ALLEN HWY McCabes Book Shelbune Village Zoning Disticts SOARING HAWK LN µ ,000 2,000 Feet 1233 Shelbune Road, Suite 150 South Bulington, VT ( Fax: ( LaPlatte Rive Wateshed Stomwate Poject DATE: Mach 2010 SCALE: 1 = 1,000' SHEET: Figue 23

62 Rual Residential 1 (noth of gowth cente Commecial Village NW Village NE Residential 1 Village Commecial Rual Residential 1 (east of gowth cente Industial 4 Industial 3 Agicultual (west of gowth cente Village W N S E 1: inch = 900 feet Feet Hinesbug Village Gowth Aea Zoning Disticts Adopted by Selectboad May 4, 2009 Effective May 25, 2009 map date 5/14/2009 by Hinesbug Planning/Zoning Office Agicultual (south of gowth cente Residential 2

63 RIDGEFIELD RD GREEN HILLS D LAKE RD BOSTWICK RD CRABAPPLE DR LIMERICK RD BOSTWICK FARM RD WAKE ROBIN DR POPLAR DR HAWTHORN DR WAKE ROBIN LN REDSTONE DR CROSSWIND DR S RIDGE RD NATURES WY SHELBURNE RD CYNOSURE DR F F OCKERT LN McCabes Book MAPLEWOOD DR UPPER TERRACE DR MIDDLE TERRACE DR TI LN T1.06 LOWER TERRACE DR COVINGTON LN F WILD GINGER LN LITTLEFIELD DR AIR PARK RD M06S2.01 MCDONALD FARM RD F RIVERVALE RD GOBBLER LN WITCH HAZEL RD LaP latte Rive SOARING HAWK LN THOMAS RD LIME KILN RD EUSTACE LN M07 M08 PEEPER POND LN EATHER LN SOUTHVIEW DR RABBIT RD SIMMONS DR HAYTUMBLE RD LaPlatte Rive T2.01M09 M10 M09S3.01 M09S3.02 SHELBURNE WEED RD CROW HILL RD ETHAN ALLEN HWY McCabes Book T1.07 T1.08 MOUNT PHILO RD M06S2.02 CLARK RD T2.03 T2.02 Mud Hollow Book PLOUFFE FARM LN SHELBURNE HINESBURG RD WIDOW IRISH RD SUMMERFIELD RD APPLE RIDGE RD FROGS END WEED RD SHELBURNE FALLS RD TAPROOT FARM LN SANCTUARY LN SNOW DRIFT LN MCGUIRE PENT RD LaPlatte Rive RIVERVIEW DR DORSET ST WHISPERING MEADOWS CARPENTER RD M11 M12 M11S4.01 N PASTURE LN BOUTIN RD TH 42 ONEIL RD M12S5.01 HINESBURG LEAVENSWORTH RD F FERRY RD Thop Book PATTON WOODS Thop Book FOX RUN RD ROOT RD STONE WALL LN COMMON WY WILDWOOD W T1.09 BOWN LN COL WILLIAMS WY RIDGE RD WESLEY DR CHURCH HILL RD CHARLOTTE RED TAIL LN PALMER LN HIGBEE RD EAST THOMPSONS POINT RD MUSEUM RD MUTTON HILL DR MUTTON HILL RD TAVERN RD WESTGATE RD HOMESTEAD DR SUTTON PL T2.07 PEASE MOUNTAIN RD LUCYS LN CANNON POINT RD LOWER OLD TOWN TRL 1233 Shelbune Road, Suite 150 South Bulington, VT ( Fax: ( McCabes Book McCabes Book Kimball Book T2.06 STOCKBRIDGE RD SPLIT ROCK RD UPPER OLD TOWN TRL T2S2.02 FIRE POND RD T2S2.03 Kimball Book QUARTER MILE RD ONE MILE RD GUINEA RD T2.05 T2S2.01 SFN MOUNTAINS EDGE Bingham Book Mud Hollow Book HALF MILE RD Bingham Book T2.04 T2S1.01 T2S1.02 Bingham Book Bingham Book T2S1.03 Chalotte Village Zoning Disticts DOLLIVER DR LaPlatte Rive Wateshed Stomwate Poject SPEAR ST BINGHAM BROOK RD MEADOWSIDE DR MURPHY RD SHEEHAN GREEN BEVERLYS PL JACKSON HILL RD TENNEYS MEWS MORNINGSIDE DR ASHE RD UPPER MEADOW LN VALLEY VIEW DR NIGHT RUN RD WOODLAND WY PRINDLE RD Lewis Ceek NORTH OLDE CARRIAGE RD Lewis Ceek SAWMILL RD HINESBURG RD SOUTH OLDE CARRIAGE RD BEAN RD BITTERSWEET LN Subwateshed Bounday Lewis Ceek GAREN RD Commecial/Light Industial Consevation East Chalotte Village Rual Shoeland Lewis Ceek OAK HILL RD ROSCOE RD CHARLOTTE RD BLACK DOG LN RED TRUCK LN BURRITT RD MAGIC HILL RD DRINKWATER RD Lewis Ceek Shoeland Seasonal Home Management Village Commecial West Chalotte Village TOAD RD µ 0 1,000 2,000 4,000 Feet DATE: SHEET: Octobe 2010 SCALE: Figue 25 1 = 3,500'