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HomeMy WebLinkAboutCorrespondence Miscellaneous 1/28/2002 ;~~9~;.(',~~;.~\ ':~(~", "~""'.'+ '0)' . t\fl'<':~::O~0i!.~: ...=:z \ ,.\:"...,,/,'j \,<' '+"'// .' "',-:_~...;./,-' '~L~~2-" ~Oregon John A. Kit.>:h<1bl'r, .\<1.0., C""ernnr Department of Environmental Quality 811 SW Sixth Avenue Portland, OR 97204-1390 (503) 229-5696 TTY (503) 229-6993 March 1,2001 Mr. Charles Davis, Water Quality Program Manager Springfield Utility Board ~ h 202 South 1St Street Springfield, Oregon 97477 RECEIVED -1-"'Zg.,=:DL Re: City of Springfield Source Water Assessment Completion By: CAJ~ av-~ Dear MyBllvis: ,As you know, the Springfield Drinking Water Protection Plan was certifi(;d by the 'Oregon Depanment of Environmental Quality (DEQ) on November 29,1999. The Springfield Plan addressed the groundwater component of wells determined to be '"groundwater under the direct influence, of surface water" (referred to as '"GWUDI"). At that time, we indicated to you that the surface water component can be done as a supplement to that plan in order to meet the requirements of the Safe Drinking Water Act's Source Water Assessments. At the request of Nancy Moreno, this letter is meant to help clarifY what needs to be done to complete your Assessment. The con'3'dera,;on of surface water source areas and zones of groundwater contrib, :l'on during th jeli:l~ation process is termed "conjunctive delineation", Conjunctive delineati'''ls for water systems that are under the direct influence of surface wateri:dude the watersned supplying the surface water body, This is important because the pmrq:iing of wells in the vicinity of surface water may induce infiltration of the surface water into the groundwater and subsequently into the water supply from the welL In Oregon, there are 25 systems that have already been identified as GWUDI by the Oregon Heaith Division, The delineation of these groundwater systems need to be supplemented with a delineation of the entire watershed area upstream of the intersection of the surface water body with the drinking water protection area for the groundwater system. For a GWUDI system such as Springfield's, Oregon DEQ delineates the entire watershed area upstream of the intersection and provides the water system with a map of the delineated watershed, The limited resources for conducting the Assessments do not allow time for DEQ to determine the sensitive areas or conduct the inventories in these watersheds (except for the small public water systems), We recommend that you determine the sensitive areas, and limit your inventory of '"potential contaminant sources" (PCS) to within those sensitive areas. F~-' "-'r' DEQ-I 2 I am attaching a brief description of how we determine the sensitive areas within watersheds for surface water intakes. You may use these guidelines, or choose other areas in the watershed you feel are more appropriate to inventory because r:hey are considered sensitive, The most important sensitive area will likely be the areas adjacent to the .. surfa,ce wat.er body,,.In t.heAssessments for surface water intakes, we use a distance of l' I OOO.feet for.. detertnining-sensitive areas'adjacent to streams, reservoir/lake shorelines, , and all perenriialtribui'aries, We recommend that you 'extend the 1000-foot setback upstream Of the intake to the distance equivalent to an 8-hour time-of-travel (TOT) for that'stre~' system, We feel that this is the most sensitive area in a watershed that could impact a GWUDI system, To assist you with the inventory, DEQ will provide you with a list of those PCS that are considered high risks of transmitting microorganisms or toxics from spills or releases within the watershed. I have attached the "Short List" of PCS that we consider to present the highest potential risks to the surface water component of a GWUDI system. DEQ, will also provide a query of the regulatory databases :vir:hin the watershed that can be used to help identify PCS on the "Short List", Of coUrse, you can enhance or improve your Assessment by adding additional PCS within the watershed if you feel it is appropriate. i Once you have completed the basic inventory by locating the PCS on the watershed map, you can submit this with a letter as a supplemi:mtto the Springfield Plan. We will send a letter. acknowledging the completion of the Assessment. You'll need to make the Assessment results available to the public. This will complete your requirement for an Assessment under the, Safe Drinking Water Act. Please don't hesitate to call me if you need moreinfOlmation, I can be reached at 503- 229-5413. For inventory questions, you can contact'Rachel Burr in our Eugene office at 541-686-7838 x264, and for groundwater protection technical assistance, you can call Julie Harvey at 503-229-5664, Sincerely, ~ ee Ste art Drinking Water Protection Coordinator Water Quality Division Attachmeny- Cc: Dennis Nelson, Oregon Health Division !.; It :. '~:' MORENO Nancy From: Sent: To: Subject: STEWART.Sheree@deq:state,or,us Monday, January 28, 2002 1 :51 PM NancyLM@subutil,com RE' Surface Water Delineation Hi Nancy What you've described is the delineation and inventory of the watershed supplying the sand filter 'intake', This is the equivalent of a source water assessment and we have reviewed the submittals you described, It is an adequate assessment, but since there is no formal process for DEQ approval of a voluntary assessment, I can only tell you it is adequate per our assessment process, (In fact, there is no need for DEQ to formally approve any Source Water Assessment performed on a system that is installed after June 1999,) For purposes of creating an addendum to your Drinking Water Protection Plan, you can use the assessment as a starting point because the delineation and inventory is accurate, So no approval from DEQ for a "surface water addendum" is necessary prior to the new system going on line, The DHS Health Division is the Oregon agency that regulates the installation and startup of a public water system, The sanitary survey may meet all their requirements, You need to check with them about the requirements and find out the process for granting approval of the SUB plans for installation and startup, The Health Division Drinking Water Section can be reached at 503-731-4010, Hope this heips, -----Original Message----- From: MORENO Nancy [mailto:NancyLM@subutil.coml Sent: Thursday, January 24, 2002 12:43 PM To: STEWART Sheree Subject: Surface Water Delineation Sheree: , It was good to finally meet you in person today, The following is a summery of what I verbally requested this morning, As you are aware, SUB intends to put a new slow sand filter system (currently under construction) on-line in the fall of 2002, Water from both wells and the Middle Fork Willamette River will be added to the filter beds ' at that time, In preparation for this addition of surface water to our drinking water resource, SUB prepared a Sanitary Survey (Potential Pollution Source Inventory) and submitted it to the Oregon Department of Human Services last June, DEQ was also sent a copy, This survey report contains the delineations of the area of contribution (entire MFW watershed) and a smaller area designated as the management area, This management area was determined on the basis of a suggested 1,000 foot setback and 8-hour time of travel upstream from SUB's intake on the river. ' 1 ~.~ - ~ The survey within the management area also identified Potential Contaminant Sources based on DEQ's "Short List of PCS's for the Surface Water Component of GWUDI Systems", When the delineations for groundwater protection associated with Springfield's DWPP was aproved by DEQ, we received both a certificate and a formal letter of DEQ/Health Dept. approval. According to our conversation, no such certification is necessary or available for a surface water resource, It is uncertain if the surface water addendum to the current DWPP needs to be approved by DEQ and/or the City of Springfield prior to going on-line with the new slow sand filter system, SUB would like to have a formal letter from DEQ stating all these facts, This letter will be used for.the purpose of documenting status during the procedures for formal City of Springfield approval of the addendum to the current Drinking Water Protection Plan, DEQ will be provided a copy of this addendum, Thanks, Nancy 2 .. . ~.. -L \ Assessments for Surface Water Systems Watershed Delineation For surface water sources, the drinkil)g water protection area delineation process begins by identifying the watershed, The surface water delineation will include the entire watershed area upstream of the public water system ,intake structure. up to the boundary of the state border. This area will be determined by identifying the perimeter of the catchment basin that provides water to the surface water intake. For intakes on canals or irrigation ditches (open-air conveyances). the delineation will be done from the point of use at the treatment facility. The watershed of the stream source intake will be fully delineated as well. The section of any open-air conveyance from the stream source to the treatment facility will be treated as a stream segment and delineated as such. Where water is diverted from one watershed to another, the delineation of source areas will include all applicable watersheds. streams, etc. After delineating the entire watershed, DEQ will identify "sensitive areas" within the watershed. The sensitive areas within a drinking water watershed will include both setbacks and other natural! man-made factors that increase the risk of contamination of the surface water, The result will be the identification of a subset of the entire watershed where the water bOdy is most susceptible to contamination, Sensitive Area Setbacks The first sensitive area is a setback using a consistent 1000' distance from the water body, This is an arbitrary distance selected to designate an area where there are higher risks of contamination by spills or other releases. The 1000' sensitive area setbacks are intended to identify those areas that present higherrisks simply d(Je to their proximity to the water body. The sensitive area setbacks, will be identified as a minimum of 1000' from centerline of the intake stream and all perennial tributaries within the delineated watershed. Sensitive area setbacks for a reservoir or lake would include a minimum of 1000' around the water body and a minimum of 1000' from centerline of streams and all perennial tributaries flowing into the water body. These sensitive area setbacks can be larger based on site-specific data and time-of.. travel calculations performed by the public water system. The proposed sensitive area setbacks involve using a horizontal distance, but a slope distance can also be calculated as needed for site-specific analysis, x For very large watersheds. the sensitive area setbacks may' be limited to a minimum distance equivalent to an 8-hour time of travel (TOT) to the intake. Eight hours should provide adequate response time to protect the integrity of the public water system intake after a spill or release at any crossing or discharge ,point to the stream, For the few larger river systems in Oregon with intakes, this means the sensitive area setbacks will extend to approximately 15 miles upstream of the intake. J, For intakes on canals or irrigation ditches (open-air conveyances). the sensitive areas will include a 1000' setback from the conveyance and all streams in the watershed for the natural stream intake, High Soil Erosion Potential The soil erosion potential will be determined by combining the effects of slope and the soil erodibility factor ("K-factor"), Slopes within a watershed are evaluated using the SSURGO data set. The slope for a map unit is a weighted average of the average slope. The soil erodibility factor is available in the SSURGO database and quantifies the susceptibility of soil particles to detachment and movement by water including the,effects of rainfall, runoff, and infiltration. The K factor Used is a 'weighted average of only the value for the surface layer of the map unit. In the watershed, soils with "high" erodibility ratings were mapped as sensitive areas. Soils..that c1assi(y as "high" include soil with slopes greater than 30% and K-factors greater than 0,25, This rating system is based on the Revised Universal Soil Loss Equation from the USDA Agricultural Research Service as defined in the State of Washington's Standard Methodology for Conducting Watershed Analysis (1993). High Permeability Soils Soils identified in the U. S, Ge%gica/ Survey geologic map of Oregon GIS layer as Recent Alluvial Deposits (Oal) will be mapped as sensitive areas due to the high potential for groundwater recharge adjacent to the stream, Alluvial deposits are typically very high permeability soils. These areas may be sources for rapid infiltration of contaminants to groundwater and subsequent discharge to a stream or lake/reservoir. High Runoff Potential The potential for high runoff rates was evaluated using the SSLJRGO (Soil Survey , Geographic Database) data sets from the Natural Resources Conse';vation Service. Class D soils, which are defined as soils with very slow infiltration rates were mapped as sensitive areas within the boundaries of the DWPA, A Class D soil is typified as clayey, has high water table, or is shallow to an impervious layer, Soils with these characteristics would have the potential for rapid runoff and subsequent transport of sediments and possible contaminants to the surface water body supplying the public water system, High Rainfall/Irrigation Sensitive areas attributable to high rainfall and/or irrigation areas will be identified using average annual precipitation data from Oregon Climate Service.( 1961 - 1990) , and irrigation/water rights data from Oregon Water Resources Department Water Rights database and mapping application. High rainfall or irrigation rates may increase the likelihood .of transport of sediments and possible contaminants to the surface water body, Transient Snow Zone Sensitive areas attributable to the transient snow zone will be identified using the available GIS data sets. In the Oregon Coast range, for example. the transient snow zone is defined as 1500 feet; in the Cascades the transient snow zone is defined as 2000 feet, These areas are typically very vulnerable to quiCk snowmelt r 1- :. .1'.::-'" '1 events, which increase the likelihood of transport of sediment's to the surface water bOdy. The sensitive areas are those where potential contamination sources or land use activities have a greater potential to impact the water supply, There are several issues to take into account when establishing these sensitive areas, It is important to note that some of these factors may be limited by available data or require additional research. In using GIS to delineate the sensitive areas within the watershed, the availability of data atappropriate scales is of major concern. As we have discussed in the past, the objective in determining the sensitive areas for surface water sources is to produce meaningful information to the community and public water system that is useful in developing protection strategies, This will ' involve working with the public water system and other resources in the community to use a procedure that is appropriate for that site-specific system, while consistent' with what is done in similar watersheds elsewhere. The final watershed map for each public water system intake will include identification of all sensitive areas within the wiltershed, This subset of the entire watershed will enable the communities and responsible agencies to focus protection efforts in susc'eptible areas, We have received many requests from public water systems and community officials to provide the delineation maps and inventories, Both DEQ and OHD's staff are working out the glitches to make this a solid, beneficial program for public water systems and Oreg'on communities, We are committed to meet the 3,5-year timeframe for completing the 2000 assessments that need to be done, , If you'd like to discuss the revisions to the SW A'F:, please feel free to contact us, If there's a substantial amount of interest in discussi0,g the issues. we can always re- convene the committee and discuss it as a group, Although we are moving forward with the assessments. we still welcome your input at any time. Please feel free to call us: Sheree Stewart 503-229-5413 ' Dennis Nelson 541-726-2587 We will be sending out'updates to you on the program as we progress, We sincerely appreciate your help in developing Oregon's approach for conducting the assessments. Identifying Sensitive Areas for Surface Water Intake Watersheds . After delineating the entire watershed, DEQ identifies the "sensitive areas" within the watershed. The objective in determining the sensitive areas for surface waler sources is to produce reliable information to the community and public water system that is useful in developing and prioritizing protection strategies. The list of the sensitive areas to be identified within drinking water watersheds was defmed by the DEQ , advisory committee as the procedures were develop~d-i~~-; th~-Z;S'~~;c~ W-;Uer-Assessment Plan"), The sensitive areas within a drinking water watershed includes both setbacks (land adjacent to stream) and other natural factors that increase the risk of contamination of the surface water. The result is an identification of a subset'oftheentire watershed. The sensitive areas are those where potential comamination sources or land use activities. if present, have a greater potential {O impact the water supply. In establishing sensitive areas in a watershed, there are several limiting factors to take into account. In using a Geographic Information System (GIS) to delineate the sensitive areas within the watershed, DEQ typically uses GIS layers and other natural resource agency data sets. Not all areas of the state have been mapped for the natural resource parameters of interest orat the level of detail ideal for this type of analysis, The availability of data at appropriate scales is'also a potential limitation. The sensitive area mapping may be limited simply by the lack of readily available data, and conducting additional res"arch is not possible within the time frame allowed to do this assessment. DEQ staff seeks to obtain the kst available information for each water system as' the source water assessment is perform'~d. There are four individual characteristics that determine the sensitivity of areas within the drinking water watersheds in the Source Water Assessment Plan procedures for Oregon water systems, A brief description of the sensitive area characteristics and the sources of the GIS data are included below, ~ ~ Sensitive Area Setbacks The fIrst sensitive area is a setback using a consistent 1000' (about 300 meters) distance from the ~ ... 4~, ~ ,water body. The 1000' sensitive area setbacks are intended to identify those areas where there are ~. '.... -'higher risks of contamination by spills or other releases, simply due to their proximity to the water ~ body, The sensitive area setbacks are identified as a minimum of 1000' from centerline of the '-> intake stream and ail perennial tributaries within ttie delineated drinking water watershed. The r ~ distance ot 1000' was based on EPA national guidance for the distance to conduct the potential contamination source inventories adjacent to streams. "~<'J ~ y bP-I' ~ High Soil Erosion Potential The soil erosion potential is determined by combining the effects of slope and the soil erodibility factor ("K-factor"), Slopes within a watershed are evaluated using the 1:24,000 SSURGO (Soil Survey Geographic Database) data sets from the Natural Resources Conservation Service. The slope for a map unit is a weighted average of the average slope. The soil erodibility f~ctor is also available in the SSURGO database and quantifies the susceptibility of soil particles to detachment and movement by water including the.effects ofrainfalL runoff, and infiltration, The K-factor used is a weighted average of only the value for the surface layer of the map unit. In the watershed, only soils with "high" erodibility ratings were mapped as sensitive areas. Soils that classiry as "high" include soil with slopes greater than 30% and K-factors greater than 0,25, This rating system is based on the Revised Universal Soil Loss Equation from the USDA Agricultural Research Service as defined in the Washington's Standard Methodology for Conducting ~hed Analysis (Washmgton Forest Practices 'Board, 1993), --, / , .------/ I J-'U f" :',~', - ~-. " \High Permeability Soils SOils IdentIfied In the US Geological Survey geologiC map of Oregon Q~~.I':Ye':.(1 500.000 scale) as Recent Alluvlal Deposits (Qal) are mapped as sensitive Oleas due to the high potentIal for vbl- :sk~ ~ ~ . ;. groundwater recharge adjacent to the stream. Alluvial deposits are typically very high penneability soils, These areas may be very vulnerable to rapid infiltration of contaminants to groundwater and subsequein discharge to a stream or lak~/reservoir. ~ High Runoff Potential The potential for bigh runoff rates was evaluated using the 1 :24,000 SSURGO (Soil Survey Geographic Database) data sets from the Natural Resources Conservation Service, Class D soils, which are defmed as soils with very slow infiltration rates were mapped as sensitive areas within the boundaries of the drinking water protection area-. Map units are assigned to hydrologic groups based on their majority component. A Class D soil is typified as clayey, has a high water table, or an impervious layer occurs at a shallow depth, Soils witl\ these characteristics would have the potential for rapid runoff and subsequent transport of sediments and possible contaminants to the l. surface water body supplying the public water system, ' /""Additional Sensitive Areas 'I There may be other natural characteristics within a watershed that can be mapped as sensitive. Modifying the list of sensitive areas in this assessment cdn be done by the public water svstem or . th~ community by identifying resources -and procedures that are appropriate for the indiv~idual system, For example, the local community may choose t6 add "transient snow zones", high rainfall areas, 'and landslide/debris-flow hazards to the sehsitive areas within their watershed, Due to time constraints, these additional areas will not be mapped by DEQ as part of this source water assessment, but can be added by the local community before developing a protection plan, ~, Transient snow zones are typically defined as areas aboJ 1500 feet ii: the Oregod C_oEt Range, or above 2000 feet in the Cascades, In some watersheds, th~se areas may be subject tfrapid snowmelt or rain-an-snow events which increase the likelihood of tmnsport of sediments to the surface water bodies in the watershed. Areas of high rainfall or irrigation rates may increas~ the likelihood of transport of sediments and possible contaminants to the surface water body, These areas can-be identified using average annual precipitatiori data from Oregor} Climate Service (years 1961 through 1990) and irrigation/water rights dat~ from Oregon Water Resources Department's water rights database, Mapping the high ri,sk landslide and debris-flow areas can also be useful for evaluating sediment risks from natural hazards within a drinking water , watershed, The Department of Forestry has recently conipleted GIS-based landslide and debris flow maps for western Oregon (Website address: http://vJww,odfstate,or.us/gis/debris,html), ....... . I. I The fmal watershed map for each public water system intake inC:h.ides a composite of all sensitive areas identified within the watershed. This composite or overlay win e~able the communities and responsible agencies to focus future protection efforts in these sensitive areas.. J ~~, ~ ~iY ?