preliminary hydrology, floodplain, and water quality technical … · 2016-06-07 · water from the...

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| Civil Engineering | Water Resources | Environmental Compliance | Geotechnical Engineering | 1

Memorandum

Date: August 3, 2015

To: Keith D. Rhodes, PE – T.Y. Lin International

From: Andrew Chin / Analette Ochoa, P.E. – WRECO

Subject: South County Corridor Project – Preliminary Hydrology, Floodplain, and Water Quality Technical Memo

INTRODUCTION Scope of Services This memorandum is prepared in support of the Feasibility Study for the South County Corridor (SCC) Project (Project). The memorandum evaluates the potential floodplain impacts and mitigation measures, if needed, for the Project, and documents the preliminary water quality assessment and possible minimization measures to reduce the potential impacts to water quality from the Project. Project Description The SCC is a planned east-west four-lane divided expressway connecting State Route 99 (SR 99) to Interstate 5 (I-5) in the southern portion of Stanislaus County and bypassing the cities of Patterson and Newman. The SCC Feasibility Study will analyze potential traditional and multi-modal corridor alignments that will enhance the east-west transportation link for all travel modes in southern Stanislaus County. Key goals of the Feasibility Study are as follows:

• Provide an efficient movement of goods and people for all modes of travel statewide • Improve safety through the roadway widening and improvements, limiting access to the

expressway facility and divided traffic lanes • Enhance local, regional and statewide connectivity • Improve air quality and noise • Promote an increase of local and regional investments • Promote the support of General Plans applicable within the Project limits • Assess the feasibility including planned land use, transportation and environmental issues • Develop Project development and implementation strategies

Figure 1 is an aerial map showing the Project study area, and Figure 2 is a map identifying the existing SCC and proposed SCC alternative alignments. Project Need Stanislaus County is a vital hub for the movement of agricultural (farm to market) and other goods, both locally grown/produced and those that pass through the region, which links northern and


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southern California as well as the Bay Area. The lack of an efficient and direct travel route between SR 99, SR 33, and I-5 in the southern part of Stanislaus County has become a pressing concern to the region. Of primary concern is the amount of regional and interregional traffic generating congestion within the Patterson city limits and surrounding areas. This traffic congestion, noise, and related safety issues are of a larger concern to the region, which depends on an efficient and safe transportation system to deliver manufactured and agricultural goods both regionally and inter-regionally. In addition, the centrally located nature of Stanislaus County has made it an ideal location for the distribution of goods through the Central Valley. The SCC will be key to the continued success of these industries. The existing corridor is part of the 39.7 mile County Route J17 (CR J17) established in 1960 that runs through Stanislaus and Merced counties. The section of CR J17 (Sperry Road, E. Las Palmas Avenue, and W. Main Street) between SR 99 and I-5 functions as an agricultural trade corridor that extends 18 miles between the cities of Turlock and Patterson. This section of CR J17 is generally a two-lane highway through rural areas, although the facility has four-lane segments within the city limits of Turlock and three-lane segments within the city limits of Patterson. East Las Palmas Avenue on the east side of town has 100 year old palm trees that prevent widening of the road. Trucks experience approximately 10 traffic signals along Sperry Road, East Las Palmas Avenue, and West Main Street to get from I-5 to SR 99. Because Patterson is becoming a west side hub for commerce distribution, the existing corridor route is heavily used and is often congested.


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Figure 1. SCC Study Area Map


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Figure 2. SCC Project Map Source: TY Lin International


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PHYSICAL SETTING Regional Hydrology Runoff within the Project area drains to local ditches, creeks, streams and waterways that eventually outfall to the San Joaquin River. The river extends approximately midway between SR 99 and I-5 and flows from south to north through the Project study area. The California Department of Transportation “Water Quality Planning Tool” identifies the Project area east of the San Joaquin River as being within the San Joaquin Valley Floor hydrologic unit, Turlock hydrologic area, hydrologic sub-area number 535.50. The areas west of the river are identified as being within the Delta-Mendota Canal hydrologic unit, Patterson hydrologic area, and hydrologic sub-area 541.10. The tool further identifies multiple sub-watersheds within the Project area, which are labeled in Figure 3. Creek, Stream, and River Crossings There are three primary creeks that extend through the Project study area. These creeks originate from the mountain ranges west of I-5 and generally flow in a northeastern direction until they converge with the San Joaquin River. Figure 4 identifies the creeks and the San Joaquin River in relation to the SCC. Del Puerto Creek is the most northern creek that partially runs parallel to Zacharias Road; SCC routes 1 and 2 would cross this creek. Salado Creek runs parallel to Ward Avenue through the City of Patterson; SCC routes 3, 9, and 21 would cross this creek. Orestimba Creek runs parallel to Crows Landing Road within the Project study area; none of the SCC routes are expected to cross over the creek, but runoff from SCC route 25 may potentially discharge to this creek. In addition to these major creeks, there are various local and regional canals, aqueducts, and laterals that cross through the Project study area. These drainages either direct water from or discharge to the San Joaquin River. The water from these drainages serves the local agriculture and residences in the area. The California Aqueduct runs parallel to northbound I-5 on the east side. The aqueduct conveys water from the Sierra Nevada Mountains and Northern California to Southern California. The aqueduct provides both drinking water and irrigation water throughout the state. The aqueduct is operated and maintained by the California Department of Water Resources. The existing and proposed SCC will cross over the aqueduct, likely via clear-span bridges. The Delta-Mendota Canal runs parallel to the California Aqueduct to the east. The canal conveys water from the Sacramento-San Joaquin Delta to the Mendota Pool, located at the border of Madera and Fresno counties, northeast of the City of Mendota. The water is used primarily for irrigation. The canal is operated and maintained by the United States Bureau of Reclamation and the San Luis Delta Mendota Water Authority. The existing and proposed SCC will cross over the aqueduct, likely via clear-span bridges.


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Figure 3. Sub-watershed Map Source: Caltrans


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Figure 4. Receiving Water Map Source: Google


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Topography The study area consists of flat topography with a slight rise in elevation in the west, near I-5. The elevation range is approximately 40 feet to 200 feet, with the San Joaquin River being the lowest and I-5 being the highest. Grassland and farmland are the dominant habitats throughout the area. Soils and Groundwater The Preliminary Geotechnical Technical Memo prepared for the Project (WRECO, 2015) discusses in detail the soil, groundwater, and geologic characteristics of the Project area. The following discussion summarizes general soil and groundwater information as it relates to the potential for implementation of stormwater treatment measures, specifically the potential for the existing soils to infiltrate runoff and groundwater depth. The United States Department of Agriculture Natural Resources Conservation Service’s Web Soil Survey identifies a wide range of soils within the study area. The majority of these soils are classified as being within hydrologic soil group (HSG) C, with HSGs B and D occurring the second most. Soils along the San Joaquin River are primarily HSGs A and A/D, with smaller portions consisting of HSG C/D. Figure 5 is an overview map showing the alignments and HSGs, and attached to this memorandum is the Web Soil Survey breakdown of acres and percentage of Project study area within each HSG. HSG A soils have a high infiltration rates and consist mainly of deep, well drained to excessively drained sands or gravelly sands. HSG B soils have a moderate infiltration rates and consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. HSG C soils have a slow infiltration rates and consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. HSG D soils have a very slow infiltration rate, and consist chiefly of clays that have a high shrink-swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. Dual classes (A/D, B/D, or C/D) are only assigned to soils that in their natural condition are in HSG D, where the first letter represents drained areas and the second represents undrained areas. Based on the State Water Resources Control Board’s (SWRCB) GeoTracker Groundwater Ambient Monitoring and Assessment (GAMA), monitoring wells in the study vicinity indicate an average depth to water of 23.88 feet below ground surface (bgs) in the western portion and 17.50 feet bgs in the eastern portion of the Project study area.


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Figure 5. Soil Map Source: Natural Resources Conservation Service & Google


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Climate and Precipitation The climate of Stanislaus County (within San Joaquin Valley) is classified as mild Mediterranean, with warm semi-arid to arid conditions. There is one wet season during the year, with 90 percent of the precipitation occurring from October through April. Snow in the valley is infrequent, and occurs once in about every seven years. Precipitation ranges from 5 to 7 inches annually in the San Joaquin Valley, and from 7 to 12 inches annually on the surrounding terraces, foothills, and mountains. In the San Joaquin Valley, the last frost in spring is generally in February or early March and the first frost in fall is late in November or early December. In the mountains, the last frost typically in spring is early in May and the first frost in fall for some areas is early in October. Land Use Figure 4 shows the existing and proposed SCC routes overlaid on aerial mapping. The existing SCC is a connector from between SR 99 and I-5 with the surrounding land use being predominantly agricultural, except where the SCC crosses through the urban areas of Turlock and Patterson. The proposed SCC routes avoid the urban areas of Turlock and Patterson and extend through agricultural land. The proposed routes generally traverse along existing streets; however, there are locations where existing agricultural lands will be disturbed or removed to place the SCC. All the proposed SCC routes will cross the San Joaquin River, so there is expected bridge work where the SCC crosses the river. Other creeks, streams and waterways cross the proposed alignments, which may result in the need to construct bridge or culvert structures at these crossings. FLOODPLAIN Regulatory Setting The Federal Emergency Management Agency (FEMA) is the nationwide administrator of the National Flood Insurance Program (NFIP), which is a program that was established by the National Flood Insurance Act of 1968 to protect lives and property, and to reduce the financial burden of providing disaster assistance. Under the NFIP, FEMA has the lead responsibility for flood hazard assessment and mitigation, and it offers federally backed flood insurance to homeowners, renters, and business owners in communities that choose to participate in the program. FEMA has adopted the 100-year floodplain as the base flood standard for the NFIP. FEMA is also concerned with construction that would be within a 500-year floodplain for proposed projects that are considered “critical actions,” which are defined as any activities where even a slight chance of flooding is too great. FEMA issues the Flood Insurance Rate Maps (FIRMs) for communities that participate in the NFIP. These FIRMs present delineations of flood hazard zones. In California, nearly all of the State’s flood-prone communities participate in the NFIP, which is locally administered by the California Department of Water Resources’ (DWR) Division of Flood Management. Under California’s NFIP, communities have a mutual agreement with the State and Federal government to regulate floodplain development according to certain criteria and standards, which are further detailed in the NFIP.


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In addition FEMA, the Central Valley Flood Protection Board has jurisdiction over the San Joaquin River. Crossings or development within the river and its floodplain must comply with Central Valley Flood Protection Board’s regulations and requirements. FEMA Floodplains The FEMA FIRMs were researched for floodplain information within the Project study area (Figure 6). The existing West Main Street/Las Palmas Avenue roadway extends through the San Joaquin River floodplain. This floodplain is identified as Zone A, which represents areas that are subject to inundation by the 100-year flood event where no base flood elevations have been determined. Del Puerto Creek, which extends through the northern end of the Project study area, and Orestimba Creek, which extends through the southern end of the Project study area, are identified as Zone AE. This zone represents areas that are subject to inundation by the 100-year flood event determined by detailed methods. Much of the city of Patterson is identified as Zone X (shaded), which designates areas within the 500-year floodplain. There are other areas throughout the southern portion of the feasibility study area that are designated as Zone AO and Zone X (shaded). These areas are located predominantly adjacent to and surrounding the Southern Pacific Railroad; these floodplain areas are associated with named and unnamed channels, canals, and laterals. Zone AO represents areas that are subject to inundation by the 100-year flood event with flood depths between 1 and 3 feet. All other areas not identified as Zone A, Zone AE, Zone AO, or Zone X (shaded), are classified as Zone X (unshaded). Zone X (unshaded) designates areas determined to be outside of the 500-year floodplain.


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Figure 6. Floodplain Map Source: FEMA & Google


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Floodplain Impacts The potential risk associated with the implementation of the proposed Project includes but is not limited to: 1) change in land use, 2) change in impervious surface area, 3) fill inside the floodplain, or 4) change in the 100-year water surface elevation. The Project has the potential to support incompatible base floodplain development that will encourage, allow, serve, or otherwise facilitate incompatible base floodplain development, such as commercial development or urban growth. Table 1 identifies the approximate number of miles and percentage of each alignment segment crossing a 100-year floodplain. Widening, realignment, or modification of the existing SCC, or the construction of new segments of roadway, has the potential to result in additional fill and increases to floodplain water surface elevations. There would be expected fill within the floodplains where the proposed SCC routes propose widening of existing roadways or construction of new roadways along existing floodplains. Fill within the floodplains may also occur where bridge structures would not be able to clear span floodplain, so footings, piers, and abutments would be placed within the creeks and floodplain. Segments of the proposed SCC would also extend longitudinally to the normal direction of the floodplain, which would result in a longitudinal encroachment of the floodplain. Floodplain Avoidance, Minimization, and/or Mitigation Measures Executive Order 11988 (Floodplain Management) directs all federal agencies to avoid, to the extent possible, long- and short-term adverse impacts associated with the occupancy and modification of floodplains, and to avoid direct and indirect support of floodplain development wherever there is a practicable alternative. If the preferred alternative involves significant encroachment onto the floodplain, the final environmental document (final environmental impact statement or finding of no significant impact) must include:

• The reasons why the proposed action must be located in the floodplain, • The alternatives considered and why they were not practicable, and • A statement indicating whether the action conforms to applicable State or local floodplain

protection standards. Avoidance, minimization, and mitigation measures would be considered to reduce or maintain the existing 100-year floodplain characteristics. The measures to address impacts to the crossings over the San Joaquin River and its floodplain would be required to comply with the Central Valley Flood Protection Board’s regulations and requirements. While all the SCC alignments would potentially impact the San Joaquin floodplain, alternative alignments would be considered to avoid other floodplain areas. Efforts to avoid, minimize, or mitigate unavoidable floodplain impacts could include balancing the amount of proposed fill and cut, or designing retention or detention basins to maintain the existing floodplain characteristics. Structures within a floodplain or SCC segments that longitudinally encroach onto a floodplain would be designed, at a minimum, to meet the FEMA design criteria and performance standards. Within Caltrans right-of-way, the Federal Highway Administration and Caltrans standards would be used. The Project is also within the Mid-San


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Joaquin River Region, and the development within this region must comply with the Regional Flood Management Plan for the Mid-San Joaquin River Region (November 2014). Local and Regional Investment Local and regional investment would be limited where the proposed SCC alignment has the potential to impact a floodplain. Based on the information shown on Table 1, many of the alignment segments extend through a floodplain. Selection of a preferred segment of alignment should consider potential floodplain impacts and efforts to avoid, minimize, and/or mitigate these impacts. Where floodplains can’t be avoided, measures to minimize or mitigate floodplain impacts could include proving extended areas of cut to balance proposed fill within the floodplain, constructing the roadway or bridges to clear-span the floodplain, placing local or regional floodplain basins, or selecting a combination of alignments that would further minimize floodplain impacts. These measures to address floodplain impacts could result in areas where development is either prevented because the level of impacts are too great and can’t be design or cost effectively mitigated, or made more expensive because additional design measures are necessary to restore the floodplain or mitigate impacts. Impacts to San Joaquin River floodplain are unavoidable whether considering the existing alignment or any of the proposed SCC alignment segments that cross the San Joaquin River. However, the amount of impacts can be reduced if a segment that generally crosses the San Joaquin River floodplain perpendicularly is selected (e.g. the existing alignment, or proposed segments 7, 11, and 12), instead of segments that traverses the floodplain (e.g. segments 6 and 8) or cross diagonally through the floodplain (e.g. segments 25 and 26) are selected. Generally, any selected alignment would result in some level of impact to a floodplain; however, the selection of segments for an alignment can be made to minimize floodplain impacts, this includes considering segments that are located outside of a 100-year floodplain, such as segments 22 and 23 connecting to I-5, segment 9 between the City of Patterson and San Joaquin River, and segments 15-18 and 29-30 connecting to the City of Turlock.


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Table 1. Miles of Alignment Segment Crossing a 100-Year Floodplain

A AEAE

floodwayAH AO

Existing 3.3 0.1 3.4 6.7 51%1 0.1 0.1 1.0 1.2 3.1 39%2 0.2 0.1 1.0 1.3 3.4 38%3 0.3 0.3 5.2 6%4 0.9 0.9 1.9 47%6 4.7 4.7 6.4 73%7 2.6 2.6 5.4 48%8 4.1 4.1 5.7 72%9 0 3.0 0%11 3.0 3 3.0 100%12 2.6 0.5 3 7.3 41%13 0.7 0.7 5.1 14%14 0.4 0.4 3.5 11%15 0 1.0 0%16 0 5.8 0%17 0 2.0 0%18 0 1.0 0%21 2.5 2.5 9.0 28%22 0 1.8 0%23 0 1.8 0%25 1.0 0.1 1.1 7.0 16%26 2.1 2.1 2.1 100%27 0.7 0.7 2.4 29%28 0.5 0.5 3.3 15%29 0 1.0 0%30 0 1.0 0%

100-Year Floodplain Zone (miles)Segment

No.

Total Miles within 100-Year

Floodplain

Length of Segment

(mile)

% Segment within 100-Year

Floodplain

WATER QUALITY Regulatory Setting In 1972 Congress amended the Federal Water Pollution Control Act, making the addition of pollutants to the waters of the United States from any point source unlawful unless the discharge is in compliance with a National Pollutant Discharge Elimination System (NPDES) permit. Known today as the Clean Water Act (CWA), Congress has amended it several times. In the 1987 amendments, Congress directed dischargers of stormwater from municipal and industrial/construction point sources to comply with the NPDES permit scheme. The objective of the CWA is “to restore and maintain the chemical, physical, and biological integrity of the Nation’s waters.”


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California’s Porter-Cologne Act, enacted in 1969, provides the legal basis for water quality regulation within California. This Act requires a “Report of Waste Discharge” for any discharge of waste (liquid, solid, or gaseous) to land or surface waters that may impair beneficial uses for surface and/or groundwater of the State. It predates the CWA and regulates discharges to waters of the State. Waters of the State include more than just waters of the United States, like groundwater and surface waters not considered waters of the United States. Additionally, it prohibits discharges of “waste” as defined and this definition is broader than the CWA definition of “pollutant.” Discharges under the Porter-Cologne Act are permitted by Waste Discharge Requirements (WDRs) and may be required even when the discharge is already permitted or exempt under the CWA. The SWRCB and Regional Water Quality Control Boards (RWQCBs) are responsible for establishing the water quality standards (objectives and beneficial uses) required by the CWA, and regulating discharges to ensure compliance with the water quality standards. This Project is located within the Central Valley RWQCB jurisdiction. Section 402(p) of the CWA requires the issuance of NPDES permits for five categories of stormwater dischargers, including municipal separate storm sewer systems (MS4s). The U.S. EPA defines an MS4 as “any conveyance or system of conveyances (roads with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, human-made channels, and storm drains) owned or operated by a state, city, town, county, or other public body having jurisdiction over stormwater, that are designed or used for collecting or conveying storm water.” The cities of Patterson and Turlock are identified as Phase II MS4 and must comply with the SWRCB’s Waste Discharge Requirements (WDRs) for Storm Water Discharges from Small Municipal Separate Storm Sewer Systems (MS4s) (General Permit) (Order No. 2013-0001-DWQ). Caltrans is identified as an MS4 under the NPDES Statewide Storm Water Permit for State of California Department of Transportation (Order No. 2014-0077-DWQ); the permit covers all Caltrans rights-of-way, properties, facilities, and activities in the state. Under Section 401 of the CWA, any project requiring a federal license or permit that may result in a discharge to a water of the United States must obtain a 401 Certification, which certifies that the project will be in compliance with State water quality standards. A 401 permit certification would likely be required for this Project and would be obtained from the Central Valley RWQCB. Water Resources Environment Beneficial Uses of Receiving Water Bodies Beneficial uses are the identified existing and potential resources, services, and qualities of aquatic systems. Protection and enhancement of existing and potential beneficial uses are the primary goals of water quality planning, and are critical to water quality management in California. The Water Quality Control Plan (Basin Plan) for the California Regional Water Quality Control Board, Central Valley Region, Fourth Edition (October 2011) identifies beneficial uses for surface waters based on hydrologic unit, and also identifies beneficial uses for the California Aqueduct and Delta-Mendota Canal (Table 2).


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Water Quality Objectives Water quality objectives are narrative and numerical objectives that define appropriate levels of environmental quality and to control activities that can affect aquatic systems. The Basin Plan identifies the water quality objectives established for inland surface waters within the region. Objectives are provided for: bacteria, biostimulatory substances, chemical constituents, color, dissolved oxygen, floating material, methylmercury, oil and grease, pH, pesticides, radioactivity, salinity, sediment, settleable material, suspended material, taste and odors, temperature, toxicity, and turbidity. Possible Pollutants Affecting Water Quality Section 303 of the CWA provides water quality standards, criteria, and guidelines for all surface waters of the United States. The SWRCB and RWQCBs assess water quality monitoring data for the State’s surface waters to determine if they contain pollutants at levels that exceed protective water quality standards. If these standards are exceeded, the impaired water is placed on the state’s 303(d) List. The impaired waters identified on the 303(d) List within the Project study are listed in Table 3. Placement of a water body on the 303(d) List initiates the development of a Total Maximum Daily Load (TMDL). TMDLs are regulatory efforts that work toward reducing the amount of a pollutant entering a water body to meet water quality standards. TMDLs are approved for chlorpyrifos within Orestimba Creek below Kilburn Road, and boron and chlorpyrifos within San Joaquin River from the Merced River to Tuolumne River. While the estimated TMDL completion dates for many of the pollutants listed in Table 3 have passed, these TMDLs are still not approved and are going through the study and approval process.


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Table 2. Beneficial Uses for Waters within Hydrologic Units 535 and 541

Water Body M

unic

ipal

and

D

omes

tic

Supp

ly Agriculture Industry Recreation

Freshwater Habitat

Migration Spawning

Wild

life

Hab

itat

Nav

igat

ion

Irri

gati

on

Wat

erin

g

Pro

cess

Serv

ice

Supp

ly

Pow

er

Con

tact

Can

oein

g an

d R

afti

ng

Oth

er

Non

cont

act

War

m

Col

d

War

m

Col

d

War

m

Col

d

Surface Waters (Creeks, Streams, and

Rivers) P E E E E E E E E E E E

California Aqueduct E E E E E E E E E

Delta-Mendota Canal E E E E E E E

Notes: P = Potential Beneficial Use E = Existing Beneficial Use

Source: Central Valley RWQCB


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Table 3. Project Receiving Water Bodies 303(d) List Summary

Water Body Pollutant Source TMDL

Completion Date

Del Puerto Creek

Bifenthrin Agriculture 2010 Chlorpyrifos Agriculture 2008 Diazinon Agriculture 2008 Dieldrin Agriculture 2021 Dimethoate Agriculture 2021 Diuron Agriculture 2021 Escherichia coli (E. coli) Source Unknown 2021 Pyrethroids Agriculture 2010 Salinity Source Unknown 2021 Sediment Toxicity Agriculture 2021 Unknown Toxicity Source Unknown 2021 pH (high) Source Unknown 2021

Harding Drain

Chlorpyrifos Agriculture 2008 DDE (Dichlorodiphenyldichloroethylene)

Source Unknown 2021

E. coli Source Unknown 2021 Hexachlorobenzene/ HCB Source Unknown 2021 Lindane/gamma Hexachlorocyclohexane (gamma-HCH)

Agriculture 2021

alpha.-BHC (Benzenehexachloride or alpha-HCH)

Agriculture 2021

Orestimba Creek (above Kilburn Road)

Azinphos-methyl (Guthion) Agriculture 2008 Chlorpyrifos Agriculture 2008 DDE Agriculture 2011 DDT (Dichlorodiphenyltrichloroethane)

Agriculture 2011

Diazinon Agriculture 2008 Dieldrin Agriculture 2011 Dimethoate Agriculture 2021 E. coli Source Unknown 2021 Sediment Toxicity Agriculture 2021 Unknown Toxicity Agriculture 2021



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Table 2. Project Receiving Water Bodies 303(d) List Summary (continued)

Water Body Pollutant Source TMDL

Completion Date

Orestimba Creek (below Kilburn Road)

Azinphos-methyl (Guthion) Agriculture 2008

Chlorpyrifos Agriculture Approved

Dec. 20, 2006 DDD (Dichlorodiphenyldichloroethane)

Agriculture 2011

DDE Agriculture 2011 DDT Agriculture 2011 Diazinon Agriculture 2008 Dieldrin Agriculture 2021 Dimethoate Agriculture 2021 Diuron Agriculture 2021 E. coli Source Unknown 2021 Malathion Agriculture 2021 Sediment Toxicity Agriculture 2019 Unknown Toxicity Agriculture 2019

Salado Creek

E. coli Agriculture Urban Runoff /Storm Sewers

2021

Salinity Agriculture Urban Runoff /Storm Sewers

2021

San Joaquin River (Merced River to Tuolumne River)

Boron Agriculture Approved

Feb. 8, 2007

Chlorpyrifos Agriculture Approved

Jan. 1, 2007 DDE Agriculture 2011 DDT Agriculture 2011 Electrical Conductivity Agriculture 2021 Group A Pesticides Agriculture 2011

Mercury Resource Extraction

2012

Temperature, water Source Unknown 2021 Unknown Toxicity Source Unknown 2019 alpha.-BHC (Benzenehexachloride or alpha-HCH)

Source Unknown 2022



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Temporary Water Quality Impacts and Avoidance, Minimization, and/or Mitigation Measures During construction, the Project has the potential for temporary water quality impacts due to soil disturbance activities, which includes grading activities, trenching, removal of existing vegetation, and other construction-related activities. These soil disturbance activities can cause increased erosion and transport of pollutants to nearby creeks and storm drains from stormwater runoff from the Project. Generally, as the disturbed soil area increases, the potential for temporary water quality impacts also increases. This Project would disturb one acre or more of soil and would thereby be subject to the SWRCB’s National Pollutant Discharge Elimination System (NPDES) General Permit for Storm Water Discharges Associated with Construction and Land Disturbance Activities (Order No. 2012-0006-DWQ), or Construction General Permit (CGP). The CGP has varying monitoring, sampling, and reporting requirements for projects based on a calculated risk level. There are three risk levels, 1, 2, and 3, where requirements increase with numerical risk level. A project risk level is determined from the receiving water and sediment risks. The receiving water risk for this Project is considered low because none of waters within the study area:

• Have the combined existing beneficial uses of cold freshwater habitat, fish spawning, and fish migration,

• Have an approved TMDL implementation plan for sediment, or • Are on the 303(d) List for sedimentation/siltation

The sediment risk factor is calculated from the product of the rainfall runoff erosivity factor (R), the soil erodibility factor (K), and the length-slope factor (LS). The R factor can’t be determined because the construction schedule is not known. The K factor was determined from the Web Soil Survey; the K factor map is attached to this memorandum. The K value within the study area ranges from 0.02 within areas within and near the San Joaquin River to 0.49 within areas of east of the river. The LS factor was determined from the Caltrans Water Quality Planning Tool (Figure 7), and ranges from 0.11 within the valley floor to 5 in the mountain areas of I-5. Because the R factor can’t be determined, it is not known if the Project has a low, medium, or high sediment risk. Based solely on the low receiving water risk, this Project can’t be classified as risk level 3. The Project may be risk level 1 if it is sediment risk is calculated to be low, or risk level 2 if the sediment risk is calculated to be medium or high. The factors used to determine the Project risk level would be further refined during later phases of the Project. Risk level 1 and 2 projects are subject to construction site best management practice (BMP) implementation and visual monitoring requirements. Additionally, risk level 2 projects are subject to monitoring and sampling requirements, and compliance with Numeric Action Levels for pH and turbidity. The risk level determination and compliance with risk level requirements will be documented in the Storm Water Pollution Prevention Plan that would be developed and approved prior to the start of construction.


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Figure 7. LS Map Source: Caltrans


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Permanent Water Quality Impacts and Avoidance, Minimization, and/or Mitigation Measures Stormwater Treatment Roadway runoff has the potential to affect receiving water quality. The nature of these impacts depends on the uses and flow rate or volume of the receiving water, rainfall characteristics, and roadway characteristics. Generally, roadway stormwater runoff has the following pollutants: total suspended solids, nitrate nitrogen, total kjeldahl nitrogen, phosphorous, ortho-phosphate, copper, lead and zinc. The pollutants are dispersed from combustion products from fossil fuels and the wearing of brake pads and tires. The added impervious area is directly related to the potential permanent water quality impacts. This Project would be required to design and implement stormwater treatment measures to treat runoff and decrease the amount of pollutants discharging to downstream receiving waters. The MS4 General Permit requires road projects that create and/or replace 5,000 square feet or more of impervious surface to implement low impact development measures that treat stormwater, preferably through infiltration, evapotranspiration, and/or bioretention. The Caltrans NPDES Permit requires highway facilities that create one acre or more of new impervious surface to implement stormwater treatment measures, preferably through infiltration, harvest and re-use, evapotranspiration, or other methods that capture and treat stormwater runoff. For improvements within the Project study area that are not covered under the MS4 General Permit or Caltrans’ NPDES Permit, stormwater treatment is required under the post-construction standards of the CGP. Hydromodification Management The Project has the potential to alter the existing terrain, modify the vegetation and soil characteristics, introduce impervious surfaces, and alter the condition of stream channels through straightening, deepening, and armoring. These changes affect hydrologic characteristics in the watershed and affect the supply and transport of sediment in the stream system (hydromodification). The impacts of hydromodification include, but are not limited to, increased bed and bank erosion, loss of habitat, increased sediment transport and deposition, and increased flooding. This Project is required to evaluate potential hydromodification impacts to receiving waters. The Project must consider hydromodification management or runoff reduction measures to address increases in runoff flow and volume due to the impervious area created. Hydromodification management is required by both the MS4 General Permit and Caltrans’ NPDES Permit because the SCC improvements would create and/or replace one acre or more of impervious surface and increase impervious surface area over the pre-project condition. Runoff reduction is required under the post-construction standards of the CGP for areas not covered under the MS4 General Permit and Caltrans’ NPDES Permit. Hydromodification management measures for areas covered under the MS4 General Permit should be designed so post-project runoff does not exceed the estimated pre-project flow rate for the 2-year, 24-hour storm. Hydromodification requirements of the Caltrans NPDES Permit are based on a risk-


Phone: 925.941.0017 Fax: 925.941.0018

www.wreco.com


based approach that determines the level of design and appropriate measures through assessment of pre-project channel stability and risk to existing or proposed highway structures from the increase of impervious surface runoff. Runoff reduction for areas covered under the CGP are achieved through the use of non-structural or structural measures that replicate the pre-project water balance for the smallest storms up to the 85th percentile storm event and preserve the pre-construction drainage density. Local and Regional Investment All the proposed SCC alignments would likely disturb one acre or more of soil and require compliance with the CGP and implementation of construction site BMPs, so local or regional investment or cost implications in relation to construction stormwater compliance would generally be consistent for each of the proposed alignments. Local and regional investment would be limited where the proposed SCC alignment has the potential to encounter soil properties that would increase the cost of providing stormwater treatment or hydromodification management, predominantly where adequate infiltration is not provided by the native soils (i.e. soils within HSG C or D). In these areas where native infiltration is not achieved, additional efforts to provide adequate infiltration and stormwater treatment may be necessary, including amending soils or placing engineered soils with an underdrain system to promote infiltration and retention of runoff. To provide hydromodification management where infiltration is not feasible, use of structural measures, such as detention basins with an outlet control or underground storage may be required. These additional design efforts to meet stormwater and hydromodification management requirements could result in areas where development is either prevented because implementing measures to provide treatment or hydromodification management measures are not feasible or made more expensive as a result of needing additional engineered measures to achieve stormwater treatment and hydromodification management. Generally, within the Project study area, soils east of the San Joaquin River are classified are classified as within HSG C, so additional efforts to achieve infiltration of runoff would likely be necessary. However, both the existing SCC and proposed segment 16 extend through areas within HSG A, so infiltration measures should be placed in these areas and runoff directed to these areas. Soils immediately surrounding the San Joaquin River are within HSG A, so if feasible and where there would be no impacts to the river’s existing characteristics or from overflow from the river during storm events, stormwater and hydromodification management measures should be prioritized. Soils west of San Joaquin River are generally within HSG C and D, where infiltration measures using native soils are not feasible. There some areas within and surrounding the City of Patterson that area within HSG B. The western extents of segments 3, 4, 12, and 13 and the existing SCC along Sperry Avenue extend through this HSG B area. Portions of segments 21 and 25 also extend through areas within HSG B. These segments or portions of segments should be considered for their potential beneficial cost saving through the use of soils that provide native infiltration. While any proposed alignment and the existing alignment would require some level of engineering methods to achieve treatment and hydromodification management, there is the potential to select segments that are more effective at providing treatment and hydromodification management using native soils and not


Phone: 925.941.0017 Fax: 925.941.0018

www.wreco.com


requiring the design and construction of engineered method to meet stormwater treatment and hydromodification management requirements. ATTACHMENTS

• Soil Data o Hydrologic Soil Group Map o K Factor Map

REFERENCES California Department of Transportation. Water Quality Planning Tool.

<http://svctenvims.dot.ca.gov/wqpt/wqpt.aspx>. (Last accessed March 2015).

California Department of Water Resources. (November 2014). Regional Flood Management Plan for the Mid San Joaquin River Region.

California Regional Water Quality Control Board, Central Valley Region. (October 2011). The Water Quality Control Plan (Basin Plan) for the California Regional Water Quality Control Board Central Valley Region, Fourth Edition, The Sacramento River Basin and the San Joaquin River Basin.

Federal Emergency Management Agency. (2008). Flood Insurance Rate Map for Stranislaus County, California and Incorporated Areas. Map Number 06099C0515E. Panel 515 of 1075.]







Phone: 925.941.0017 Fax: 925.941.0018

www.wreco.com











National Geographic Holdings. (2001). TOPO! ® Version 2.6.8.

State Water Resources Control Board. GeoTracker Groundwater Ambient Monitoring & Assessment. < http://geotracker.waterboards.ca.gov/gama/>. (Last Accessed March 2015)

State Water Resources Control Board. (July 2012). National Pollutant Discharge Elimination System (NPDES) General Permit for Storm Water Discharges Associated with Construction and Land Disturbance Activities. Order No. 2012-0006-DWQ, NPDES No. CAS000002.

State Water Resources Control Board. (July 2014). National Pollutant Discharge Elimination System (NPDES) Statewide Storm Water Permit for State of California Department of Transportation (Order No. 2014-0077-DWQ).


Phone: 925.941.0017 Fax: 925.941.0018

www.wreco.com


State Water Resources Control Board. (February 2013). Waste Discharge Requirements (WDRs) for Storm Water Discharges from Small Municipal Separate Storm Sewer Systems (MS4s) (General Permit). Water Quality Order No. 2013-0001-DWQ, General Permit No. CAS000004.

United States Department of Agriculture, Natural Resources Conservation Service. Web Soil Survey. <http://websoilsurvey.sc.egov.usda.gov/App/HomePage.htm>. (Last Accessed March 2015).

WRECO. (June 2015). South County Corridor Project – Preliminary Geotechnical Technical Memo.

Hydrologic Soil Group—Eastern Stanislaus Area, California; and Stanislaus County, California, Western Part

Natural ResourcesConservation Service

Web Soil SurveyNational Cooperative Soil Survey

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4133

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652000 656000 660000 664000 668000 672000 676000 680000 684000 688000 692000 696000

652000 656000 660000 664000 668000 672000 676000 680000 684000 688000 692000 696000

37° 35' 15'' N12

1° 1

7' 2

2'' W

37° 35' 15'' N

120°

46'

12'

' W

37° 19' 8'' N

121°

17'

22'

' W

37° 19' 8'' N

120°

46'

12'

' W

N

Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 10N WGS840 10000 20000 40000 60000

Feet0 3000 6000 12000 18000

MetersMap Scale: 1:210,000 if printed on A landscape (11" x 8.5") sheet.

MAP LEGEND MAP INFORMATION

Area of Interest (AOI)Area of Interest (AOI)

SoilsSoil Rating Polygons

A

A/D

B

B/D

C

C/D

D

Not rated or not available

Soil Rating LinesA

A/D

B

B/D

C

C/D

D


Soil Rating PointsA

A/D

B

B/D

C

C/D

D


Water FeaturesStreams and Canals

TransportationRails

Interstate Highways

US Routes

Major Roads

Local Roads

BackgroundAerial Photography

The soil surveys that comprise your AOI were mapped at 1:24,000.

Please rely on the bar scale on each map sheet for mapmeasurements.

Source of Map: Natural Resources Conservation ServiceWeb Soil Survey URL: http://websoilsurvey.nrcs.usda.govCoordinate System: Web Mercator (EPSG:3857)

Maps from the Web Soil Survey are based on the Web Mercatorprojection, which preserves direction and shape but distortsdistance and area. A projection that preserves area, such as theAlbers equal-area conic projection, should be used if more accuratecalculations of distance or area are required.

This product is generated from the USDA-NRCS certified data as ofthe version date(s) listed below.

Soil Survey Area: Eastern Stanislaus Area, CaliforniaSurvey Area Data: Version 9, Sep 18, 2014

Soil Survey Area: Stanislaus County, California, Western PartSurvey Area Data: Version 9, Sep 25, 2014

Your area of interest (AOI) includes more than one soil survey area.These survey areas may have been mapped at different scales, witha different land use in mind, at different times, or at different levelsof detail. This may result in map unit symbols, soil properties, andinterpretations that do not completely agree across soil survey areaboundaries.

Soil map units are labeled (as space allows) for map scales 1:50,000or larger.

Date(s) aerial images were photographed: May 12, 2010—Jul 25,2013

The orthophoto or other base map on which the soil lines werecompiled and digitized probably differs from the backgroundimagery displayed on these maps. As a result, some minor shiftingof map unit boundaries may be evident.

Hydrologic Soil Group—Eastern Stanislaus Area, California; and Stanislaus County, California, Western Part



3/26/2015Page 2 of 10

Hydrologic Soil Group

Hydrologic Soil Group— Summary by Map Unit — Eastern Stanislaus Area, California (CA644)

Map unit symbol Map unit name Rating Acres in AOI Percent of AOI

CcA Columbia fine sandyloam, 0 to 1 percentslopes

A/D 176.3 0.2%

CeA Columbia loam, 0 to 1percent slopes

A/D 1,156.1 1.2%

CfA Columbia silt loam, 0 to 1percent slopes

A/D 24.6 0.0%

ChA Columbia silt loam,moderately deep overfresno soils, slightlysaline-alkali, 0 to 1percent slopes

C/D 25.7 0.0%

CkA Columbia silt loam,moderately deep overtemple soils, 0 to 1percent slopes

C/D 5.9 0.0%

CmA Columbia silt loam,moderately deep overtemple soils, slightlysaline, 0 to 1 percentslopes

C/D 148.4 0.2%

CoA Columbia silty clay loam,slightly saline, 0 to 1percent slopes

A/D 325.4 0.3%

CpA Columbia soils, 0 to 1percent slopes

A/D 240.5 0.3%

CsB Columbia soils,channeled, 0 to 8percent slopes

A/D 761.7 0.8%

DeA Delhi loamy sand, 0 to 3percent slopes, MLRA17

A 2,178.5 2.3%

DeB Delhi loamy sand, 3 to 8percent slopes

A 5.7 0.0%

DgA Delhi loamy sand, siltysubstratum, 0 to 3percent slopes

A 124.7 0.1%

DhA Delhi sand, 0 to 3 percentslopes, MLRA 17

A 74.8 0.1%

DhB Delhi sand, 3 to 8 percentslopes, MLRA 17

A 20.0 0.0%

DmA Dinuba fine sandy loam,0 to 1 percent slopes

C 472.0 0.5%

DrA Dinuba sandy loam, 0 to1 percent slopes

C 5,608.1 5.9%

Hydrologic Soil Group—Eastern Stanislaus Area, California; and Stanislaus County, California,Western Part



3/26/2015Page 3 of 10



DsA Dinuba sandy loam,shallow, 0 to 1 percentslopes

C 64.5 0.1%

DtA Dinuba sandy loam,deep, 0 to 1 percentslopes

A 406.6 0.4%

DwA Dinuba sandy loam,slightly saline-alkali, 0to 1 percent slopes

C 9,505.0 10.0%

DxA Dinuba sandy loam,moderately saline-alkali, 0 to 1 percentslopes

C 16.3 0.0%

DyA Dinuba sandy loam,shallow, slightly saline-alkali, 0 to 1 percentslopes

C 670.6 0.7%

DzA Dinuba sandy loam, verypoorly drained variant,slightly saline- alkali, 0to 1 percent slopes

C 45.0 0.0%

FrA Fresno fine sandy loam,moderately saline-alkali, 0 to 1 percentslopes

D 32.9 0.0%

FsA Fresno fine sandy loam,strongly saline-alkali, 0to 1 percent slopes

D 210.9 0.2%

FtA Fresno sandy loam,slightly saline-alkali, 0to 1 percent slopes

D 1,192.2 1.3%

FuA Fresno sandy loam,moderately saline-alkali, 0 to 1 percentslopes

D 1,052.6 1.1%

FwA Fresno-Dinuba sandyloams, strongly salinealkali, 0 to 1 percentslopes

D 766.4 0.8%

GsA Greenfield sandy loam, 0to 3 percent slopes

A 78.9 0.1%

HdA Hanford sandy loam, 0 to3 percent slopes

A 135.6 0.1%

HdC Hanford sandy loam, 8 to15 percent slopes

A 21.2 0.0%

HddA Hanford sandy loam,poorly drained variant,0 to 1 percent slopes

A/D 92.8 0.1%

HdmA Hanford sandy loam,moderately deep oversand, 0 to 3 percentslopes

A 23.4 0.0%




3/26/2015Page 4 of 10



HfA Hilmar loamy sand, 0 to 1percent

C 10,220.4 10.8%

HfdA Hilmar loamy sand,deep, 0 to 1 percentslopes

A 367.1 0.4%

HkaA Hilmar loamy sand,poorly drained, slightlysaline-alkali, 0 to 1percent slopes

C/D 32.4 0.0%

HkbA Hilmar loamy sand,slightly saline-alkali, 0to 1 percent slopes

C 3,632.9 3.8%

HmA Hilmar sand, 0 to 3percent slopes

C 386.6 0.4%

MdA Madera sandy loam, 0 to2 percent slopes

D 67.3 0.1%

RkA Rossi clay loam,moderately saline-alkali, 0 to 1 percentslopes

D 349.7 0.4%

Rr Riverwash 87.3 0.1%

TbA Temple loam,overwashed, 0 to 1percent slopes

C/D 24.9 0.0%

TcA Temple loam,overwashed, slightlysaline, 0 to 1 percentslopes

C/D 925.3 1.0%

TeA Temple silty clay, slightlysaline, 0 to 1 percentslopes

C/D 128.8 0.1%

TgA Temple silty clay loam, 0to 1 percent slopes

C/D 22.7 0.0%

ThA Temple silty clay loam,slightly saline, 0 to 1percent slopes

C/D 478.2 0.5%

TkA Temple silty clay loam,moderately saline, 0 to1 percent slopes

C/D 408.5 0.4%

TpA Traver sandy loam,slightly saline-alkali, 0to 1 percent slopes

B 96.6 0.1%

TrA Traver sandy loam,moderately saline-alkali, 0 to 1 percentslopes

B 250.7 0.3%

TuA Tujunga loamy sand, 0 to3 percent slopes

A 387.4 0.4%

W Water 445.0 0.5%




3/26/2015Page 5 of 10



WaA Waukena fine sandyloam, slightly saline-alkali, 0 to 1 percentslopes

C 511.7 0.5%

WbA Waukena fine sandyloam, moderatelysaline-alkali, 0 to 1percent slopes

C 3,052.1 3.2%

WcA Waukena fine sandyloam, strongly saline-alkali, 0 to 1 percentslopes

C 454.9 0.5%

WdA Waukena sandy loam,slightly saline-alkali, 0to 1 percent slopes

C 430.8 0.5%

WeA Waukena sandy loam,moderately saline-alkali, 0 to 1 percentslopes

C 11.6 0.0%

WrA Whitney and Rocklinsandy loams, 0 to 3percent slopes

C 8.1 0.0%

Subtotals for Soil Survey Area 48,443.9 51.2%

Totals for Area of Interest 94,657.5 100.0%

Hydrologic Soil Group— Summary by Map Unit — Stanislaus County, California, Western Part (CA642)


100 Capay clay, 0 to 2percent slopes

C 3,966.7 4.2%

101 Capay clay, wet, 0 to 2percent slopes

D 7,038.7 7.4%

102 Capay clay, loamysubstratum, 0 to 2percent slopes

C 2,405.1 2.5%

106 Capay clay, 0 to 2percent slopes, rarelyflooded

C 1,479.2 1.6%

116 El Solyo silty clay loam, 0to 2 percent slopes,rarely flooded

C 293.2 0.3%

120 Vernalis-Zachariascomplex, 0 to 2percent slopes

C 1,909.5 2.0%

121 Vernalis loam, wet, 0 to 2percent slopes

C 286.0 0.3%

122 Vernalis loam, 0 to 2percent slopes

B 3,094.9 3.3%

123 Vernalis clay loam, wet, 0to 2 percent slopes

C 414.0 0.4%




3/26/2015Page 6 of 10



125 Vernalis clay loam, 0 to 2percent slopes

C 3,621.5 3.8%

126 Vernalis-Zachariascomplex, 0 to 2percent slopes, rarelyflooded

C 410.2 0.4%

127 Vernalis loam, 0 to 2percent slopes, rarelyflooded

B 1,611.4 1.7%

128 Water 619.1 0.7%

130 Stomar clay loam, 0 to 2percent slopes

C 2,405.8 2.5%

131 Stomar clay loam, wet, 0to 2 percent slopes

D 685.1 0.7%

140 Zacharias clay loam, 0 to2 percent slopes

C 2,141.5 2.3%

141 Zacharias clay loam,wet, 0 to 2 percentslopes

C 1,749.9 1.8%

142 Zacharias gravelly clayloam, 0 to 2 percentslopes

C 1,571.3 1.7%


C 243.2 0.3%


C 259.9 0.3%

146 Zacharias clay loam, 0 to2 percent slopes,rarely flooded

C 713.6 0.8%

147 Zacharias gravelly clayloam, 0 to 2 percentslopes, rarely flooded

C 829.1 0.9%

150 Columbia fine sandyloam, 0 to 2 percentslopes, occasionallyflooded

A 42.1 0.0%

151 Columbia complex, 0 to 2percent slopes,occasionally flooded

A 56.3 0.1%

153 Columbia fine sandyloam, channeled,partially drained, o to 2percent slopes,frequently flooded

A 903.7 1.0%

157 Columbia complex, 0 to 2percent slopes, rarelyflooded

A 69.1 0.1%

159 Columbia complex, 0 to 2percent slopes,frequently flooded

A 220.5 0.2%




3/26/2015Page 7 of 10



160 Merritt silty clay loam,partially drained, 0 to 2percent slopes,occasionally flooded

C 437.6 0.5%

170 Dospalos-Bolfarcomplex, 0 to 2percent slopes,occasionally flooded

C 507.4 0.5%

175 Dospalos-Bolfarcomplex, 0 to 2percent slopes, rarelyflooded

C 113.5 0.1%

176 Dumps 77.3 0.1%

180 Dello fine sandy loam,channeled, 0 to 2percent slopes,frequently flooded

A 146.1 0.2%

190 Clear Lake clay, drained,0 to 2 percent slopes,occasionally flooded,MLRA 17

D 282.0 0.3%

195 Clear Lake silty clay,drained, 0 to 2 percentslopes, MLRA 17

D 69.1 0.1%

200 Veritas sandy loam, 0 to2 percent slopes,rarely flooded

A 169.3 0.2%

210 Cortina gravelly sandyloam, 0 to 5 percentslopes, rarely flooded

A 294.2 0.3%

245 Bolfar-Columbiacomplex, 0 to 2percent slopes, rarelyflooded

C 196.6 0.2%

246 Bolfar-Columbiacomplex, 0 to 2percent slopes,occasionally flooded

C 276.8 0.3%

253 Chaqua-Arburuacomplex, 8 to 15percent slopes

C 46.2 0.0%

255 Calla-Carbona complex,30 to 50 percentslopes

C 1,212.8 1.3%

270 Elsalado fine sandyloam, 0 to 2 percentslopes, rarely flooded

B 355.3 0.4%

271 Elsalado loam, 0 to 2percent slopes, rarelyflooded

B 577.6 0.6%

272 Elsalado loam, wet, 0 to2 percent slopes

B 159.6 0.2%




3/26/2015Page 8 of 10



273 Elsalado fine sandyloam, 0 to 2 percentslopes

B 477.5 0.5%

274 Elsalado loam, 0 to 2percent slopes

B 1,124.8 1.2%

281 Carbona clay loam, 2 to8 percent slope

C 32.5 0.0%

301 Damluis clay loam, 2 to 8percent slopes

C 107.6 0.1%

303 Damluis gravelly clayloam, 2 to 8 percentslopes

C 98.3 0.1%


C 139.1 0.1%

330 Pedcat clay loam, 0 to 2percent slopes, rarelyflooded

D 211.2 0.2%

500 Wisflat-Arburua-SanTimoteo complex, 30to 50 percent slopes

D 59.9 0.1%


D 0.7 0.0%






3/26/2015Page 9 of 10

Description

Hydrologic soil groups are based on estimates of runoff potential. Soils areassigned to one of four groups according to the rate of water infiltration when thesoils are not protected by vegetation, are thoroughly wet, and receive precipitationfrom long-duration storms.

The soils in the United States are assigned to four groups (A, B, C, and D) andthree dual classes (A/D, B/D, and C/D). The groups are defined as follows:

Group A. Soils having a high infiltration rate (low runoff potential) when thoroughlywet. These consist mainly of deep, well drained to excessively drained sands orgravelly sands. These soils have a high rate of water transmission.

Group B. Soils having a moderate infiltration rate when thoroughly wet. Theseconsist chiefly of moderately deep or deep, moderately well drained or well drainedsoils that have moderately fine texture to moderately coarse texture. These soilshave a moderate rate of water transmission.

Group C. Soils having a slow infiltration rate when thoroughly wet. These consistchiefly of soils having a layer that impedes the downward movement of water orsoils of moderately fine texture or fine texture. These soils have a slow rate of watertransmission.

Group D. Soils having a very slow infiltration rate (high runoff potential) whenthoroughly wet. These consist chiefly of clays that have a high shrink-swellpotential, soils that have a high water table, soils that have a claypan or clay layerat or near the surface, and soils that are shallow over nearly impervious material.These soils have a very slow rate of water transmission.

If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter isfor drained areas and the second is for undrained areas. Only the soils that in theirnatural condition are in group D are assigned to dual classes.

Rating Options

Aggregation Method: Dominant Condition

Component Percent Cutoff: None Specified

Tie-break Rule: Higher




3/26/2015Page 10 of 10

K Factor, Rock Free—Eastern Stanislaus Area, California; and Stanislaus County, California, Western Part



3/26/2015Page 1 of 9

4133

000

4137

000

4141

000

4145

000

4149

000

4153

000

4157

000

4161

000

4133

000

4137

000

4141

000

4145

000

4149

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4153

000

4157

000

4161

000

652000 656000 660000 664000 668000 672000 676000 680000 684000 688000 692000 696000

652000 656000 660000 664000 668000 672000 676000 680000 684000 688000 692000 696000

37° 35' 15'' N12

1° 1

7' 2

2'' W

37° 35' 15'' N

120°

46'

12'

' W

37° 19' 8'' N

121°

17'

22'

' W

37° 19' 8'' N

120°

46'

12'

' W

N

Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 10N WGS840 10000 20000 40000 60000

Feet0 3000 6000 12000 18000

MetersMap Scale: 1:210,000 if printed on A landscape (11" x 8.5") sheet.

MAP LEGEND MAP INFORMATION

Area of Interest (AOI)Area of Interest (AOI)

SoilsSoil Rating Polygons

.02

.05

.10

.15

.17

.20

.24

.28

.32

.37

.43

.49

.55

.64


Soil Rating Lines.02

.05

.10

.15

.17

.20

.24

.28

.32

.37

.43

.49

.55

.64


Soil Rating Points.02

.05

.10

.15

.17

.20

.24

.28

.32

.37

.43

.49

.55

.64


Water Features

Streams and Canals

TransportationRails

Interstate Highways

US Routes

Major Roads

Local Roads

BackgroundAerial Photography

The soil surveys that comprise your AOI were mapped at1:24,000.

Please rely on the bar scale on each map sheet for mapmeasurements.

Source of Map: Natural Resources Conservation ServiceWeb Soil Survey URL: http://websoilsurvey.nrcs.usda.govCoordinate System: Web Mercator (EPSG:3857)

Maps from the Web Soil Survey are based on the Web Mercatorprojection, which preserves direction and shape but distortsdistance and area. A projection that preserves area, such as theAlbers equal-area conic projection, should be used if moreaccurate calculations of distance or area are required.

This product is generated from the USDA-NRCS certified data asof the version date(s) listed below.

Soil Survey Area: Eastern Stanislaus Area, CaliforniaSurvey Area Data: Version 9, Sep 18, 2014

Soil Survey Area: Stanislaus County, California, Western PartSurvey Area Data: Version 9, Sep 25, 2014

Your area of interest (AOI) includes more than one soil surveyarea. These survey areas may have been mapped at differentscales, with a different land use in mind, at different times, or atdifferent levels of detail. This may result in map unit symbols, soilproperties, and interpretations that do not completely agreeacross soil survey area boundaries.

Soil map units are labeled (as space allows) for map scales1:50,000 or larger.

Date(s) aerial images were photographed: May 12, 2010—Jul25, 2013

The orthophoto or other base map on which the soil lines werecompiled and digitized probably differs from the backgroundimagery displayed on these maps. As a result, some minor shiftingof map unit boundaries may be evident.

K Factor, Rock Free—Eastern Stanislaus Area, California; and Stanislaus County, California, Western Part



3/26/2015Page 2 of 9

K Factor, Rock Free

K Factor, Rock Free— Summary by Map Unit — Eastern Stanislaus Area, California (CA644)


CcA Columbia fine sandyloam, 0 to 1 percentslopes

.24 176.3 0.2%

CeA Columbia loam, 0 to 1percent slopes

.24 1,156.1 1.2%

CfA Columbia silt loam, 0 to 1percent slopes

.24 24.6 0.0%

ChA Columbia silt loam,moderately deep overfresno soils, slightlysaline-alkali, 0 to 1percent slopes

.49 25.7 0.0%

CkA Columbia silt loam,moderately deep overtemple soils, 0 to 1percent slopes

.49 5.9 0.0%

CmA Columbia silt loam,moderately deep overtemple soils, slightlysaline, 0 to 1 percentslopes

.49 148.4 0.2%

CoA Columbia silty clay loam,slightly saline, 0 to 1percent slopes

.24 325.4 0.3%

CpA Columbia soils, 0 to 1percent slopes

.24 240.5 0.3%

CsB Columbia soils,channeled, 0 to 8percent slopes

.24 761.7 0.8%

DeA Delhi loamy sand, 0 to 3percent slopes, MLRA17

.15 2,178.5 2.3%

DeB Delhi loamy sand, 3 to 8percent slopes

.15 5.7 0.0%

DgA Delhi loamy sand, siltysubstratum, 0 to 3percent slopes

.15 124.7 0.1%

DhA Delhi sand, 0 to 3 percentslopes, MLRA 17

.02 74.8 0.1%

DhB Delhi sand, 3 to 8 percentslopes, MLRA 17

.02 20.0 0.0%

DmA Dinuba fine sandy loam,0 to 1 percent slopes

.24 472.0 0.5%

DrA Dinuba sandy loam, 0 to1 percent slopes

.20 5,608.1 5.9%

K Factor, Rock Free—Eastern Stanislaus Area, California; and Stanislaus County, California,Western Part



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DsA Dinuba sandy loam,shallow, 0 to 1 percentslopes

.28 64.5 0.1%

DtA Dinuba sandy loam,deep, 0 to 1 percentslopes

.20 406.6 0.4%

DwA Dinuba sandy loam,slightly saline-alkali, 0to 1 percent slopes

.24 9,505.0 10.0%

DxA Dinuba sandy loam,moderately saline-alkali, 0 to 1 percentslopes

.24 16.3 0.0%

DyA Dinuba sandy loam,shallow, slightly saline-alkali, 0 to 1 percentslopes

.28 670.6 0.7%

DzA Dinuba sandy loam, verypoorly drained variant,slightly saline- alkali, 0to 1 percent slopes

.24 45.0 0.0%

FrA Fresno fine sandy loam,moderately saline-alkali, 0 to 1 percentslopes

.32 32.9 0.0%

FsA Fresno fine sandy loam,strongly saline-alkali, 0to 1 percent slopes

.32 210.9 0.2%

FtA Fresno sandy loam,slightly saline-alkali, 0to 1 percent slopes

.32 1,192.2 1.3%

FuA Fresno sandy loam,moderately saline-alkali, 0 to 1 percentslopes

.32 1,052.6 1.1%

FwA Fresno-Dinuba sandyloams, strongly salinealkali, 0 to 1 percentslopes

.32 766.4 0.8%

GsA Greenfield sandy loam, 0to 3 percent slopes

.32 78.9 0.1%

HdA Hanford sandy loam, 0 to3 percent slopes

.17 135.6 0.1%

HdC Hanford sandy loam, 8 to15 percent slopes

.17 21.2 0.0%

HddA Hanford sandy loam,poorly drained variant,0 to 1 percent slopes

.17 92.8 0.1%

HdmA Hanford sandy loam,moderately deep oversand, 0 to 3 percentslopes

.17 23.4 0.0%




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HfA Hilmar loamy sand, 0 to 1percent

.24 10,220.4 10.8%

HfdA Hilmar loamy sand,deep, 0 to 1 percentslopes

.24 367.1 0.4%

HkaA Hilmar loamy sand,poorly drained, slightlysaline-alkali, 0 to 1percent slopes

.24 32.4 0.0%

HkbA Hilmar loamy sand,slightly saline-alkali, 0to 1 percent slopes

.24 3,632.9 3.8%

HmA Hilmar sand, 0 to 3percent slopes

.05 386.6 0.4%

MdA Madera sandy loam, 0 to2 percent slopes

.37 67.3 0.1%

RkA Rossi clay loam,moderately saline-alkali, 0 to 1 percentslopes

.32 349.7 0.4%

Rr Riverwash .02 87.3 0.1%

TbA Temple loam,overwashed, 0 to 1percent slopes

.37 24.9 0.0%

TcA Temple loam,overwashed, slightlysaline, 0 to 1 percentslopes

.37 925.3 1.0%

TeA Temple silty clay, slightlysaline, 0 to 1 percentslopes

.28 128.8 0.1%

TgA Temple silty clay loam, 0to 1 percent slopes

.37 22.7 0.0%

ThA Temple silty clay loam,slightly saline, 0 to 1percent slopes

.37 478.2 0.5%

TkA Temple silty clay loam,moderately saline, 0 to1 percent slopes

.37 408.5 0.4%

TpA Traver sandy loam,slightly saline-alkali, 0to 1 percent slopes

.24 96.6 0.1%

TrA Traver sandy loam,moderately saline-alkali, 0 to 1 percentslopes

.24 250.7 0.3%

TuA Tujunga loamy sand, 0 to3 percent slopes

.15 387.4 0.4%

W Water 445.0 0.5%




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WaA Waukena fine sandyloam, slightly saline-alkali, 0 to 1 percentslopes

.28 511.7 0.5%

WbA Waukena fine sandyloam, moderatelysaline-alkali, 0 to 1percent slopes

.28 3,052.1 3.2%

WcA Waukena fine sandyloam, strongly saline-alkali, 0 to 1 percentslopes

.28 454.9 0.5%

WdA Waukena sandy loam,slightly saline-alkali, 0to 1 percent slopes

.28 430.8 0.5%

WeA Waukena sandy loam,moderately saline-alkali, 0 to 1 percentslopes

.28 11.6 0.0%

WrA Whitney and Rocklinsandy loams, 0 to 3percent slopes

.24 8.1 0.0%



K Factor, Rock Free— Summary by Map Unit — Stanislaus County, California, Western Part (CA642)


100 Capay clay, 0 to 2percent slopes

.20 3,966.7 4.2%

101 Capay clay, wet, 0 to 2percent slopes

.20 7,038.7 7.4%

102 Capay clay, loamysubstratum, 0 to 2percent slopes

.20 2,405.1 2.5%

106 Capay clay, 0 to 2percent slopes, rarelyflooded

.20 1,479.2 1.6%

116 El Solyo silty clay loam, 0to 2 percent slopes,rarely flooded

.37 293.2 0.3%

120 Vernalis-Zachariascomplex, 0 to 2percent slopes

.28 1,909.5 2.0%

121 Vernalis loam, wet, 0 to 2percent slopes

.32 286.0 0.3%

122 Vernalis loam, 0 to 2percent slopes

.32 3,094.9 3.3%

123 Vernalis clay loam, wet, 0to 2 percent slopes

.28 414.0 0.4%




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125 Vernalis clay loam, 0 to 2percent slopes

.28 3,621.5 3.8%

126 Vernalis-Zachariascomplex, 0 to 2percent slopes, rarelyflooded

.28 410.2 0.4%

127 Vernalis loam, 0 to 2percent slopes, rarelyflooded

.32 1,611.4 1.7%

128 Water 619.1 0.7%

130 Stomar clay loam, 0 to 2percent slopes

.32 2,405.8 2.5%

131 Stomar clay loam, wet, 0to 2 percent slopes

.32 685.1 0.7%


.32 2,141.5 2.3%

141 Zacharias clay loam,wet, 0 to 2 percentslopes

.32 1,749.9 1.8%


.28 1,571.3 1.7%


.28 243.2 0.3%


.32 259.9 0.3%

146 Zacharias clay loam, 0 to2 percent slopes,rarely flooded

.32 713.6 0.8%

147 Zacharias gravelly clayloam, 0 to 2 percentslopes, rarely flooded

.28 829.1 0.9%

150 Columbia fine sandyloam, 0 to 2 percentslopes, occasionallyflooded

.24 42.1 0.0%

151 Columbia complex, 0 to 2percent slopes,occasionally flooded

.24 56.3 0.1%

153 Columbia fine sandyloam, channeled,partially drained, o to 2percent slopes,frequently flooded

.24 903.7 1.0%

157 Columbia complex, 0 to 2percent slopes, rarelyflooded

.24 69.1 0.1%

159 Columbia complex, 0 to 2percent slopes,frequently flooded

.24 220.5 0.2%




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160 Merritt silty clay loam,partially drained, 0 to 2percent slopes,occasionally flooded

.37 437.6 0.5%

170 Dospalos-Bolfarcomplex, 0 to 2percent slopes,occasionally flooded

.20 507.4 0.5%

175 Dospalos-Bolfarcomplex, 0 to 2percent slopes, rarelyflooded

.24 113.5 0.1%

176 Dumps 77.3 0.1%

180 Dello fine sandy loam,channeled, 0 to 2percent slopes,frequently flooded

.20 146.1 0.2%

190 Clear Lake clay, drained,0 to 2 percent slopes,occasionally flooded,MLRA 17

.20 282.0 0.3%

195 Clear Lake silty clay,drained, 0 to 2 percentslopes, MLRA 17

.24 69.1 0.1%

200 Veritas sandy loam, 0 to2 percent slopes,rarely flooded

.24 169.3 0.2%

210 Cortina gravelly sandyloam, 0 to 5 percentslopes, rarely flooded

.17 294.2 0.3%

245 Bolfar-Columbiacomplex, 0 to 2percent slopes, rarelyflooded

.32 196.6 0.2%

246 Bolfar-Columbiacomplex, 0 to 2percent slopes,occasionally flooded

.32 276.8 0.3%

253 Chaqua-Arburuacomplex, 8 to 15percent slopes

.37 46.2 0.0%

255 Calla-Carbona complex,30 to 50 percentslopes

.32 1,212.8 1.3%

270 Elsalado fine sandyloam, 0 to 2 percentslopes, rarely flooded

.28 355.3 0.4%

271 Elsalado loam, 0 to 2percent slopes, rarelyflooded

.43 577.6 0.6%

272 Elsalado loam, wet, 0 to2 percent slopes

.43 159.6 0.2%




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273 Elsalado fine sandyloam, 0 to 2 percentslopes

.28 477.5 0.5%

274 Elsalado loam, 0 to 2percent slopes

.43 1,124.8 1.2%

281 Carbona clay loam, 2 to8 percent slope

.24 32.5 0.0%

301 Damluis clay loam, 2 to 8percent slopes

.24 107.6 0.1%


.24 98.3 0.1%


.24 139.1 0.1%

330 Pedcat clay loam, 0 to 2percent slopes, rarelyflooded

.37 211.2 0.2%


.28 59.9 0.1%


.28 0.7 0.0%



Description

Erosion factor K indicates the susceptibility of a soil to sheet and rill erosion bywater. Factor K is one of six factors used in the Universal Soil Loss Equation (USLE)and the Revised Universal Soil Loss Equation (RUSLE) to predict the averageannual rate of soil loss by sheet and rill erosion in tons per acre per year. Theestimates are based primarily on percentage of silt, sand, and organic matter andon soil structure and saturated hydraulic conductivity (Ksat). Values of K range from0.02 to 0.69. Other factors being equal, the higher the value, the more susceptiblethe soil is to sheet and rill erosion by water.

"Erosion factor Kf (rock free)" indicates the erodibility of the fine-earth fraction, orthe material less than 2 millimeters in size.

Rating Options

Aggregation Method: Dominant Condition

Component Percent Cutoff: None Specified

Tie-break Rule: Higher

Layer Options (Horizon Aggregation Method): Surface Layer (Not applicable)




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preliminary hydrology, floodplain, and water quality technical … · 2016-06-07 · water from the...

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