Memorandum
J:\27679000_SD Stormwater\TO-54 SW OM Support\FY 2013\014 Work in Progress\Task 08 - Gen. & LosPen Mitigation\Task 081 - Conceptual Mitigation Plan\PQ Conceptual Plan\Appendices - Same for both sites\Appendix B - JD\JD Memo 04-15-13.docx
Date: April 29, 2013 To: Mark Tucker From: Julie Stout and Sundeep Amin Subject: Jurisdictional Delineations for Proposed Mitigation Sites within
Los Peñasquitos Canyon Preserve The purpose of this memo is to document the methods and results of the delineation and jurisdictional determination conducted at two potential mitigation sites within Los Peñasquitos Canyon Preserve (Figures 1 and 2). The purpose of the delineation was to identify and map the location and extent of the limits of local, state, and federal jurisdictional waters of including wetlands that would fall under the jurisdiction of the U.S. Army Corps of Engineers (Corps), California Department of Fish and Wildlife (CDFW), Regional Water Quality Control Board (RWQCB), California Coastal Commission (CCC), and the City of San Diego. The current Arid West Regional Supplement and Rapanos/Carabell guidance (Rapanos) were applied to the methods and results of this study when relevant. This wetland study also evaluated the extent of waters of the State that may fall under the jurisdiction of the California Department of Fish and Wildlife pursuant to Section 1602 of the Fish and Game Code of California (Streambed Alteration Agreements) or the Porter-Cologne Act regulating waste discharge into waters of the State. This report is for use in the verification process with Local, State and Federal regulators and is intended to be submitted to the regulatory agencies for review and verification. Methods Site visits were conducted by URS biologists Julie Stout and Catherine MacGregor on April 4, 2013 and Julie Stout and Sundeep Amin on April 19, 2013. The initial site visits included vegetation mapping of the mitigation areas plus a 150-foot buffer and compilation of a plant species list. Areas with hydrophytic plant species were examined more closely to determine the wetland boundary. Initial delineation was conducted visually based on vegetation indicators. A three parameter wetland delineation was conducted in accordance with the 1987 Corps Manual and 2006 Arid West Supplement. Wetland waters of the U.S. were sampled using the general methodology detailed in the 1987 U.S. Army Corps of Engineers Wetland Delineation Manual (Corps Manual) for wetlands less than 5 acres in size. Sample points were chosen based on vegetation community mapping and considered visible transitions in vegetation composition and topographical changes. Additional soil pits were created to further document the wetland and upland conditions on site during the subsequent site visit and confirm wetland conditions in the southeastern corner of the site. The definition of the growing season and the basis of determining and recording indicators for hydrophytic vegetation, hydric soils, and wetland hydrology was the 2008 Regional Supplement to the Corps of Engineers Wetland Delineation Manual: Arid West Region (Version 2.0) (Arid West Supplement). Both the Corps Manual and Arid West Supplement were used for the determination and evaluation of any normal circumstances, atypical situations, and problem area wetlands. All Corps and CDFW jurisdictional areas were also assumed to be under the jurisdiction of the RWQCB and the CCC.
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J:\27679000_SD Stormwater\TO-54 SW OM Support\FY 2013\014 Work in Progress\Task 08 - Gen. & LosPen Mitigation\Task 081 - Conceptual Mitigation Plan\PQ Conceptual Plan\Appendices - Same for both sites\Appendix B - JD\JD Memo 04-15-13.docx
Results El Cuervo al Oeste-The western mitigation area included both upland and wetland areas within the current mitigation site boundary (Figure 1). Freshwater marsh and disturbed wetland overlapped the southwestern and southeastern portions of the proposed mitigation area. The riparian vegetation associated with Los Peñasquitos Creek is considered to be to be jurisdictional wetlands for all agencies. A summary of the delineation results and determinations El Cuervo al Oeste is provided in Table 1 below.
Table 1. Summary of Delineation Results and Jurisdictional Determinations for El Cuervo al Oeste
JDSP No. Hydrophytic Vegetation Hydric Soils Wetland Hydrology Jurisdictional
Wetland (Y/N)
1 - - - N 2 x x x Y 4 - N 5 x x x Y 6 x x x Y 7 - - - N
El Cuervo del Sur-The southern mitigation area included both upland and wetland areas (Figure 2). The site is surrounded to the North and West by riparian and wetland vegetation. A small patch of wetlands was mapped within the western boundary. This area meets the state definitions of wetlands and is assumed to be Corps jurisdictional under the PJD approach. A summary of the delineation results and determinations for the El Cuervo del Sur is provided in Table 2 below.
Table 2. Summary of Delineation Results and Jurisdictional Determinations for El Cuervo del Sur
JDSP No. Hydrophytic Vegetation Hydric Soils Wetland Hydrology Jurisdictional
Wetland (Y/N)
3 - - - N 8 x - - Y 4 - - - N
Recommendations It is recommended that the downstream boundary of both mitigation areas be revised to avoid wetland impacts. Suggested boundary revisions are shown on Figures 1 and 2.
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SOURCES: Site Boundary, Buffer, Vegetation, Utility Right of Way, JDSP, Boring (URS, 2013). Aerial Imagery (SanGIS, 2012). Soil (SSURGO, USDA, 2007).
JURISDICTIONAL DELINEATIONEL CUERVO AL OESTE
CITY OF SAN DIEGO
CREATED BY: LR
PM: BE PROJ. NO: 27679954.08300FIG. NO:
1SCALE: 1" = 90' (1:1,080)
45 0 45 90 Feet
OSCALE CORRECT WHEN PRINTED AT 11X17
DATE: 5/9/2013
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SOURCES: Site Boundary, Buffer, Vegetation, Utility Right of Way, JDSP, Boring (URS, 2013). Aerial Imagery (SanGIS, 2012).Soil (SSURGO, USDA, 2007).
JURISDICTIONAL DELINEATION
EL CUERVO DEL SUR
CITY OF SAN DIEGO
CREATED BY: LR
PM: BE PROJ. NO: 27679954.08300
45 0 45 90 Feet
ODATE: 10/24/2013
Proposed Mitigation Site Boundary
Suggested Boundary Revision
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El Cuervo Mitigation Site
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SCALE: 1" = 90' (1:1,080)SCALE CORRECT WHEN PRINTED AT 11X17
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SOURCES: Survey Points, Borings,Cross Sections (URS, 2013). Aerial Imagery (Microsoft, 20100503).
SURVEY LOCATIONSLOS PEÑASQUITOS CREEK
CITY OF SAN DIEGO
CREATED BY: PM
PM: BE PROJ. NO: 27679954.08300
FIG. NO:1SCALE: 1" = 350' (1:4,200)
175 0 175 350 Feet
OSCALE CORRECT WHEN PRINTED AT 11X17
DATE: 4/19/2013
Legend!( Survey Location
! A Boring
Cross Section
Mitigation Area
20
25
30
35
40
45
50
55
60
0 100 200 300 400 500 600
ELEV
ATION (F
T)
STATION (FT)
FIGURE 2. LOS PENASQUITOS CREEKEL CUERVO AL OESTE ‐ SECTION A‐A
FIELD SURVEY CROSS‐SECTION 2 ‐ HEC‐RAS CROSS‐SECTION 4677.59
Field Survey Existing Ground Existing 2‐ft Contours Surveyed Water Surface Elevation Winter High Water Mark (March 2013) Storm Event Water Surface Elevation
Water depth in section was too deep to survey. No information within the stream.
Approximate Boring (B05) Location
Parking Lot
Extent of Existing Riparian Vegetation
Existing SDG&E AccessRoad Location
Soil Removal/Excavating Grade
Proposed Baseline Grading
Mitigation Area
Note(s): Plot contains significant vertical exaggeration in scale.Cross‐Section plotted from left to right looking in the downstream (westerly) direction.Water surfaces shown are preliminary only. Calculations were based on the Manning's Equation and preliminary survey data .
25 Yr WSE
10 Yr WSE
5 Yr WSE
2 Yr WSE
30
35
40
45
50
55
60
65
70
75
80
70 170 270 370 470 570 670 770 870
ELEV
ATION (F
T)
STATION (FT)
FIGURE 3. LOS PENASQUITOS CREEKEL CUERVO DEL SUR ‐ SECTION B‐B
FIELD SURVEY CROSS‐SECTION 2 ‐ HEC‐RAS CROSS‐SECTION 7566.95
Existing 2‐Ft Contour Field Survey Existing Ground Surveyed Water Surface Elevation Winter High Water Mark (March 2013) Storm Event Water Surface Elevation
Stopped Field Survey. Due to dense vegetation.
Approximate Boring (B02) Location
Mitigation Area
Note(s): Plot contains significant vertical exaggeration in scale.Cross‐Section plotted from left to right looking in the downstream (westerly) direction.Water surfaces shown are preliminary only. Calculations were based on the Manning's Equation and preliminary survey data .
25 Yr WSE10 Yr WSE
5 Yr WSE2 Yr WSE
Proposed Baseline Grading
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