09_NCS000250_ROSS program development planning document

OTETRA TECH
To: Brian Lipscomb, Andy McDaniel,
Ryan Mullins,
NCDOT Highway Stormwater
Program
From: Peter Cada, Jason Wright
One Park Drive, Suite 200 • PO Box 14409
Research Triangle Park, NC 27709
Tel [phone] • Fax [phone]
MEMORANDUM
Date: 02/05/2018
Subject: NCDOT Retrofit Site Program
Framework Recommendations
Project R-4436, 34625.1.1, LSC 7000016984
Number: Tt# 100-IWM-T36943.05
Tetra Tech has been contracted by NCDOT to assist the agency in the development and implementation
of the BMP Retrofits Program and RetrOfit Site Selection (ROSS) program to facilitate compliance with its
NPDES permit. NCDOT's permit requires that a minimum of fourteen (14) potential retrofit projects be
identified per year for a total of seventy (70) retrofits completed over the five (5) year term of the permit.
The goal of this Task (Task 05) is to minimize delays in the pre -construction phase of the Retrofit Project
Cycle so that NCDOT stays in compliance. This memorandum details a proposed program framework for
the NCDOT Hydraulics Unit that can be used to guide multiple, synchronous workflows of the BMP
Retrofits and ROSS Programs working from an initial state-wide retrofit identification through subset
creation, prioritization within the subset, field assessment of subset selections, and final selection for the
subsequent construction phase of the Retrofit Project Cycle (survey, design, and construction). Included
in the overall program framework are recommendations on how and when to employ Private Engineering
Firms (PEFs) to perform:
• Creation and testing of a Retrofit Site Selection Tracking System (ROSS Tracking System).
• Desktop analyses to create Retrofit Investigation Areas (RIAs) for the entire State.
o Extents of each RIA may contain multiple retrofit opportunities (ROs).
• Desktop screening of NCDOT-provided subset of statewide RIAs.
• Field Assessment of NCDOT-selected subset of RIAs.
• (Eventual) construction phase efforts of select retrofit opportunities.
NTETRA TECH 1 Task Order #5

February 5, 2018
A visual schematic of the recommended work flow is provided below in Figure 1 (does not include the
effort to create an online ROSS Tracking System), where multiple workflows can be going on
simultaneously, but in different Steps, starting with Step 1.0 and ending in Step 3.5 (or Step 3.0, in some
cases). It is recommended that the ROSS Tracking System be created and tested prior to Steps 1.0
through 3.5 as shown in Figure 1 below (a more detailed version of this schematic with annotated text
descriptions of each step is available as Appendix A).
Step 0.5 PEF identifies RIAs statewide for
To be done population of NCDOT-housed GDB 4 AGOL
only once...
and ArcG15 Online (AGOL) r
NC
NCDOT selects HUC12(s) and DOT
Step 1.0 provides subset of RIAs and Existing G D B
SCMs to selected PEF for Step 1.54
Step 1.5 PEF performs desktop review of all
®� RIA(s) within selected HUC12(s)
7s�elect
AGOL
NCAs for
Step 2.0 fielEF �� • • •
Survey123
1
Step 2.5 PEF performs field review Nc
DOT
�j GDB
AGOL
Step 3.0 NCDOT loads to
Step 3.5 AGOL/ROSS - Survey, Design & Construct -
selects subset Track in ROSS/AGOL System
Figure 1. Workflow Schematic of Recommended Retrofit Program Framework
OTETRA TECH 2 Task Order #5

February 5, 2018
The development of the Retrofit Site Selection (ROSS) Tracking System will enable NCDOT to store,
review, revise, and display information related to Stormwater Control Measure (SCM) retrofit opportunities
across the state. Detailed in this section are recommendations for software, workflow, and database
system design and management that will allow NCDOT to maximize the potential of an online, database -
driven system with a user-friendly interface. The objective of the ROSS Tracking System is to create
consistency for all users from system inception (i.e., RIA and RO creation); into the prioritization, field
assessment, and selection stages; to the final stages of SCM design and construction; and continued
tracking of pre- and post -constructed SCM retrofit opportunities across the state.
The software packages recommended for NCDOT's ROSS Tracking System are:
• Survey123 for ArcGIS
• ArcGISOnline's Web Applications
Survey123 for ArcGIS and ArcGISOnline (AGOL) have been leveraged by numerous organizations —from
small to large —across the country that want to store and manage geospatial and associated tabular data,
while allowing multiple, synchronous user input and/or viewing by desktop users as well as from (and
during) field assessments (Figure 2). A mock-up example of the different user interfaces (mobile and
desktop) is provided in Figure 3.
Ask Questions � Get Answers iviaKe uecli fl }rt�i
(design & Publish) (Collect Data) (View & Analyse)
AGOL
® AE.
AGOL
Survey123 .
9
O
Survey123 •. • • •
Figure 2. Workflow Schematic of Proposed ROSS Tracking System Leveraging Survey123 and AGOL
OTETRA TECH 3 Task Order #5

February 5, 2018
Survey123 for ArcGIS
NCDOT ROSS Tracking System I u
� ar�
0
eaor�
AGOL Desktop Interface
Figure 3. Mock-up Example of Collector App and AGOL interfaces Linkage
Survey123 for ArcGIS allows the capture data anytime and anywhere, even when temporarily working
"offline". It can work on smartphones, tablets (iPad, etc.), laptops, or desktops as a native app or in a
browser, providing simple and intuitive form -centric data gathering solutions that allow the creation,
sharing, and analysis of data (even in real-time if desired). Field survey forms can be designed with
predefined questions that use logic and provide easy -to -fill answers (even allowing embedded audio and
images, and multiple languages other than English). Field personnel can use Survey123 on nearly any
device with which they are familiar, requiring little training, to report detailed information yielding
significant cost (and time) savings over prior paper -based workflows.
Just as important, Survey123 for ArcGIS enables geolocation of collected and updated GIS data,
including digitization while in the field. Survey123 for ArcGIS creates a combination that can provide map -
driven data collection (and revision/update) through a map -driven mobile form that is simple to use but
still leverages advanced mapping capabilities.
As for AGOL's role in the recommended ROSS Tracking System, NCDOT will be able to leverage its
existing relationship and enterprise account with ESRI to develop an AGOL-centered database and easy -
to -use interface that provides the powerful behind -the -scenes database infrastructure needed to meet
NCDOT storage and analysis objectives. AGOL provides NCDOT with a commercial "off -the -shelf" cloud
GIS solution that allows the users to create, manage, and store maps and applications. It is mobile ready
and is secure, reliable, and scalable over time to meet evolving needs.
2.1 FIELD ASSESSMENT FORM - SURVEY123
As previously mentioned, the field assessment portion of the recommended Retrofit Program Framework
will require a template that will lead to consistent outcomes —for PEFs to understand and use with ease,
but also to ensure that NCDOT receives consistent deliverables from PEFs regardless of where and when
field assessments occur across the state. A field assessment form template (in MSWord) has already
been created (see Appendix B for example of completed form) which can easily be used within
Survey123 to assist with Step 2.5, and subsequent steps of the recommended Retrofit Program
Framework seen in Figure 1.
OTETRA TECH 4 Task Order #5

February 5, 2018
Through consultations with the NCDOT Hydraulics Unit 3 different types of RIAs were identified:
1. NCDOT Facility/Yard Areas
2. NCDOT implicit/explicit outfalls
3. "Major" NCDOT Intersections
RIA's for the NCDOT facilities/yards are more easily identifiable in that these locations are relatively well
known and many of these will have Stormwater Pollutant Prevention Plans (SP3) that can significantly
increase the ability to easily identify retrofit opportunities. Each of these unique areas can be considered
an RIA in conjunction with any other peripheral NCDOT road right of way (ROW) areas.
For creation of the other two RIA types it is recommended that a PEF perform a series of geospatial (GIS)
steps to create polygons for the entire state. This state-wide coverage can be merged with the extents of
NCDOT facilities/yards for subsequent NCDOT considerations and possible PEF review.
3.1 NCDOT IMPLICIT/EXPLICIT OUTFALLS
NCDOT has two different GIS point coverages which identify 1) Explicit Outfalls, locations of NCDOT
outfalls that have been field -verified, and 2) Implicit Outfalls, locations where NCDOT road polyline layers
cross Hydro24k stream lines. These two point layers can be leveraged to create a RIA polygonal dataset
by buffering the points 400 feet in all directions. An iterative review of different buffer distances was
performed with desktop review of buffer outputs in different locations across the state where more than
400 feet tended to be too great —combining more implicit outfalls into one RIA than desired —and less
than 400 feet tended to not provide enough area for consideration by PEFs during the desktop review. An
example of the 400-ft buffer step output is provided in Figure 4.
NZV .1p. f
Legend
expucm outrans ®- - e
Implicit Outtalk Gdt��
Hydro24k Streams ®ID
_ a4
B.Ivin Ave er Sun6ialC 5. rn Rd' ��� e 9 a
a�'a'vn 4ve
O
E n,im p5t F.rrdl Rd by
n�c�1
E o' I iio 9HL .�s7 �
2� P• c
V �
syo sR os. rHecr� µadn aM
ph_ 2T un pry St VF� zi A � 9 9}Esn kM1e 4 a ) n�Y _ eeet aPffit4 area
rvry
Figure 4. Example of RIAs created by buffering Explicit and Implicit outfall points by 400 feet.
OTETRA TECH 5 Task Order #5

February 5, 2018
3.2 "MAJOR" NCDOT INTERSECTIONS
"Major" NCDOT Intersections are proposed for RIA development in that they should be only those areas
where major intersections of non -local, NCDOT roads cross over/under, or have intersections, with other
roads that are also considered to be non -local NCDOT roads (i.e., all Functional Classes except "7",
which are considered "Local" roads). These types of intersections tend to have larger areas of impervious
available for possible treatment by proposed SCM retrofits, as well as have greater ROW area than
smaller road crossings with the potential to have sufficient size for conveyance and/or treatment of
stormwater runoff draining from NCDOT jurisdictional areas. Recommended GIS steps to be taken to
create RIAs for these "Major" NCDOT intersections would leverage the "NCDOTRouteCharacteristics"
statewide GIS data.
The first step is to subset the "NCDOTRouteCharacteristics" data set into unique Functional Classes (i.e.,
using the "FuncClass" attribute of this NCDOT geospatial dataset) for all Functional Classes ranging from
1 to 6. Iterative geospatial analyses to identify where these 6 different subset of Functional Class road
types intersect should be performed with an output as a point feature class. An example of how these
Functional Class road types look in the Falls Lake Watershed in Figure 5.
N Leasburg Roxboro Legend
Falls Lake Watershed
NCRouteCharacteristics
Functional Class
oxford - Interstate (Class = 1)
Timberlake Major Collector (Class = 5)
Hurdle Mills Minor Arterial (Class =4)
Minor Collector (Class = 6)
- PA-FrwyExp (Class = 2)
Rougemont PA-Other(Class = 3)
/ Stem Local (Class = 7)
Bahama
Butner
Creedmoor
Franklinton
Efland
Hillsborough
1
_ Gorman )
Youngsville
i
Durham
Wake Forest
Bethesda
J�J�� Rol`esville
Carrboro _ --- _ ___ \ Lassiter
Chapel Hill - Meuse
l
Figure 5. Functional Class Subset Example — Falls Lake Watershed
OTETRA TECH 6 Task Order #5

February 5, 2018
Next, a polygonal dataset should be created from the "intersection points" by buffering the points 300 feet
in all directions. An iterative review of different buffer distances was performed with desktop review of
buffer outputs in different locations across the state where more than 300 feet tended to be too great —
combining more than one intersection into one RIA— and less than 300 feet tended to omit important
ramp and intersection open space areas that tend to be valuable for consideration of individual ROs in
subsequent review steps. An example of this 300-ft buffer step's output within the same extent as Figure
4 (northeast Durham) is provided in Figure 6.
As can be seen in Figure 6, there are some areas of larger intersections (e.g., 1-85 and US-70
intersection) where the 300-ft buffer does not include the entire intersection area and its related road
ROWs; however, if the buffer distance was increased other identified intersections would begin to merge
into one long polygon covering several RIAs, which should be considered as separate RIAs in
subsequent steps. Also, for subsequent prioritization and tracking purposes each polygon was assigned
the "highest -order" Functional Class (e.g., FuncClass = 1, i.e., interstate, is the highest possible "order")
of an intersection or group of intersections. This can also be found in Figure 6 as the numbered labels for
each "Major" NCDOT Intersection RIA.
Finally, these polygons can be merged with the other two RIA types to provide a single, comprehensive
RIA polygonal GIS layer to serve as a guide for subsequent steps (see example in Figure 7). This single
RIA layer can then be given other, multiple attributes through spatial join steps to inform NCDOT's
subsequent decision making processes —number or outfalls (explicit/implicit), road characteristics (e.g.,
number of lanes), number and characteristics of bridges, and parcel/ownership information (if available).
Legend
® "Major" NCDOT Intersection RIA
NCRouteCharacteristics
Functional Class
Interstate (Class = 1)
Major Collector (Class = 5)
- MinorArlerial(Class =4)
Minor Collector (Class = 6)
PA-FrwyExp (Class = 2)
PA -Other (Class = 3)
Local (Class = 7)
Eeri, HERE, DeLo , Mspmy l ndi.,( Ope Streetivlep -n trib�t ra and the GIS user
Figure 6. Example Outputs from of "Major" NCDOT Intersection Locations -- 300-ft Buffering Step
OTETRA TECH 7 Task Order #5

February 5, 2018
Legend
4
♦ Explicit Outfalls
1
11Implicit Outfalls
ImMerged RIAs
5
NC RouteC haracteristics
5
Functional Class
Interstate (Class = 1)
- PA-FrwyExp (Class = 2)
PA -Other (Class = 3)
Minor Arterial (Class = 4)
- Major Collector (Class = 5)
Minor Collector (Class = 6)
Local (Class = 7)
5
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0
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5
®
®
®
5
3
(D®
3
1
1
0
2
4
4 4
2
3 4 4
2
Esri. HERE, OeLorme. Mapmylndia, ©
OpenstreetMap
contributors, and the GIS use
unity
Figure 7. Example Outputs from Merging of the three different RIA types into one coverage.
NCDOT will select one or more HUC-12(s) that meet the agency's current objective(s) for further
investigation by a PEF under Step 1.5 of the proposed Retrofit Program Framework —"Desktop Review".
The area of these selected HUC-12(s) can be further refined to include or exclude certain areas and/or
RIA types that help NCDOT's meet particular objective(s). Because all RIA's will include road
characteristics (e.g., number of lanes) and other attribute information it will be important for NCDOT to
communicate guidance/preferences to the PEF what types of RIA's should have a higher priority (e.g.,
intersections with outfalls, intersections in general, etc.) to be reviewed under a given task order. For
example, based on the methodology described above for the Falls Lake watershed 1,641 unique RIAs
were identified, of which 270 are from "Major" NCDOT intersections (black areas in Figure 8) and 226
contain explicit outfalls (red areas in Figure 8) —but 39 of the explicit outfall locations are co -located with
"Major" NCDOT intersections. Providing guidance —or a subset of RIAs within selected HUC-12s (e.g.,
selection of only those intersections co -located with explicit outfalls)—to the PEFs for Step 1.5 may help
to expedite the completion of the next step (1.5) and subsequent Framework steps.
OTETRA TECH 8 Task Order #5

February 5, 2018
F�
• •t • • i
1 t 40
` A, I
Fsri
Legend
_ RIA Explicit Outfalls - Falls Lake
RIA Implicit Outfalls - Falls Lake
RIA"Major" NCUOT Intersections
i1UC12s - Falls Lake Watershed
Figure 8. Spatial Composition of Example Outputs of different RIA types — Fall Lake Watershed
The boundaries of the RIAs within a subset selected by NCDOT for review by a PEF (i.e., Step 1.5 of the
Retrofit Program Framework —"desktop review") should be refined (expanded and/or clipped) by the PEF
as appropriate as a part of the review process. This may include the use of local/regional data (e.g.,
LiDAR-derived contours, parcel boundaries, local infrastructure coverages) that might inform more
accurate delineations of ROW boundaries, which might also provide other ancillary but pertinent
information to be identified by PEFs as a part of Step 1.5. These refined boundaries can then be used
under Step 2.5—"Field Review" —where another refinement of RIA boundaries should be made during
field review, while also delineating RO footprint and drainage area boundaries.
PEFs should also provide the following information for each RIA as a part of the desktop review of
subset(s) provided to them by NCDOT:
• Possible installation of multiple retrofit SCMs (Y/N)
• Presence of existing SCMs (Y/N)
• Utility (e.g., storm water, sanitary sewer, water supply) information available in GIS format (Y/N)
OTETRA TECH 9 Task Order #5

February 5, 2018
o If utility data is not available in GIS format:
■ Apparent surface channels (Y/N)
■ Apparent storm water inlets (Y/N)
• Manhole Access locations, indicating underground utility(ies)
• Parcel boundary/information available in GIS format (Y/N)
• Approximate distance to nearest 303(d), i.e., impaired waterways (feet)
o To be done along contours/terrain, not Euclidean (i.e., straight line) distance.
Just as with the "Selection of HUC12(s) — Step 1.0", NCDOT will select several RIAs that meet the
agency's objective(s) at that time for further investigation by a PEF under Step 2.5 of the proposed
Retrofit Program Framework —"Field Review". This is another opportunity for NCDOT to provide direction
for the types and locations of RIAs for a given set of HUC12(s) to include or exclude certain areas and/or
RIA types that help NCDOT's meet particular objective(s). The attributes detailed above as to be provided
as a part of Step 1.5 (Desktop Review of RIA Subset) can be leveraged by NCDOT to make the decisions
on which RIAs to select for subsequent field review and consideration.
A subset of RIAs will be provided to PEFs for field review planning and execution. As previously
mentioned, RIA boundaries should be refined (expanded and/or clipped again, if needed) as appropriate
as a part of the field review process. These revisions should be made based on field observations, along
with delineation of RO footprint(s) and associated drainage area boundaries.
A field assessment sheet template (see Appendix B) should be provided to PEFs in an electronic format
(e.g., Survey123, iForm, i.e., whichever software is ultimately selected by NCDOT to accompany the
AGOL-database management system) with limitations to each question/response field so that NCDOT is
guaranteed to receive consistent and complete, minimum data required from PEF field review efforts. As
previously discussed, it is proposed that ESRI Collector App and associated functionalities be embedded
within the electronic form allowing spatial collection of data, and associated tabular data (e.g., RO
footprint and drainage area, photograph locations and associated notes).
PEFs should provide at least one completed electronic form for each RIA provided to them by NCDOT,
along with any relevant digitized features such as storm water inlets, outlets, etc. (e.g. see Appendix B,
map on second page) even if no potential ROs were identified within that particular RIA. An electronic
form, delineation of both footprint and drainage area boundaries, recommended RO types, and
photographic documentation should be completed for each RO identified by the PEF within each RIA.
All of this information and data will be submitted to and reviewed by NCDOT (and refined by the PEF as
needed) before acceptance into the ROSS tracking system and further consideration.
OTETRA TECH 10 Task Order #5

February 5, 2018
NCDOT will select ROs that have been reviewed through the Desktop and Field Review processes and
accepted/uploaded into the ROSS tracking system for the final stage — design and construction. Once a
RO is selected a field (e.g., named design stage (Y/N)) should be modified as appropriate for tracking
purposes. NCDOT will provide one or more selected ROs to PEFs for the final stage.
PEFs will plan and schedule field surveys (e.g., geotechnical, cadastral/elevation) that are required to
recommend the type(s) of SCMs appropriate for a unique RO location. A review of PEF-selected SCM
type(s) should be done by NCDOT before initiation of the conceptual design process. A 30% complete
conceptual design for each RO should be provided to NCDOT for internal review and approval. Finally, a
100% design should be provided to NCDOT for approval before construction planning and subsequent
construction begins.
OTETRA TECH 11 Task Order #5

February 5, 2018
Step 0.5 PEF identifies RIAs statewide for
population of NCDOT-housed GDB AGOL
any oncTo be e and ArcGIS Online (AGOQ
NC
NCDOT selects HUC12(s) and
Step 1.0 provides subset of RIM and Existing G°
SCMs to selected PEF for Step 1.54
,tep 1. PEF performs desktop review of all
RIA(s) within selected HUC12(s)
I
Step 2.0 NCDOT select RIAs for .
field review by PEF 0- lie
Survey123 � 11
try T
Step AGOL �11 N PEF performs field review
® G
AGOL
+I r
Step 3.0 NCDOT loads to
Step 3.5 AGOL/ROSS- Survey, Design& Construct -
selects subset Track in ROSS/AGOL System
Step 0.5 —Private Engineering Firm (PEF) performs automated geospatial
orates= to icen-ry Are= Cf Igte•est "0'1. i e.. _nicue -e-r-it-in.—tigation areas
AIAs). -c•t� e erti•e sta-: usirg malic t a-J _Rs•Iir t Cut-sllsNCDOT
fac Lies'aarcls, a J a su,set _ac::•, Lnu r:arsei.ii.ns. De rahle ,. ill 6e a
oc , :•nal :C3 a,e, tc NCDCT f•:•r I:•-Jirg tc f.CCCT's A•sG15 Cnl ire
alatform. e:"erc es:h SIH has o uIc.e I' ,asing -_C1_ C•_, e.g.,
"0'3202C_043S "3SC, 3C1G4C3 2 . anc sa -n A cai- to bestoredin a
NCDOT GDB along with existing SCMs for subsequent viewing purposes.
Step 1.0 — NCDOT selects HUC12(s) for consideration of Step 1.5 to
meet current objective(s).
Step1'1 —PEF(sltaskec'+.ore•:ie;ra'IRIA;s;tr'thiiFJC12;s}
selected by NCDOT. De',.erables III be uodated GCB lave Ifsubset of
state; :rith oopula-eb attriMes such az %'Y-N-`la-�, of e ea -etc j for
attributes such as "av ailaole stag'ng area forested "adlacent
sensitik.:e properties",exis=i )g SCM", "utility rc rlict", "pr :ate
road/driveway access", "historic areas", etc.
Step 2.0 - NCDOTselects RIA(s) forfield assessments by PEFs.
- PEFisI use S.ir;ey123, ESRI Colle-or.4pp, a-d ArcGIS
OnL ne f;..GOLj 'terfaces a -d f e c assessme -template to assess
selectee R19,N in .he fie d. Syste n .-,III need to be se tc to allow
multiple;>1i potential •etro"it recc-iriendatic for each R A, where
the secc•d etro-itldenti-ied t-e-ield�yaPEF +,:ilautorratically
be assigned a value such as "03020201040312", and so on.
Step 3.0-Once NCDOT reviewoffield assessment iscomplete and
approved, NCDOT uplcads to ROSS/AGOL System. When appropriate,
NCDOT selects and pr•o: ides retrofitjsl for field surveys, design and
construction and pro,,'cles to PEF.
Steu 3.5 - PEF �er-o ms f eld survey, geotech. survey, design and
construction=o retrof'_is;•,pro%.`c"e,detailed soa_ia'and-a'Dulardata
to NCDCT for RCS5;AGOLsystem tracking (at minimum, change field
from "No" to "Yes" under "Designed", "Implemented" Attributes).
OTETRA TECH 12 Task Order #5

February 5, 2018
SCM Retrofit Field Evaluation Form (Page 1 of 2)
Field Crew - Name(s): Peter Cada, Jesse Phillips
Date: 12-27-2017 Time: 2:15 p.m.
Company Name: Tetra Tech, Inc.
Site ID: 030202010304-1-1
Site Location: I-85 and I-70 Interchange (West of Durham - Exit 170)
Site Description: Long eroding gully formed at pipe outlet from storm water
City/County: Orange County
system draining the majority of I-85 impervious surface east of the I-85 and 70
Location Description: North side of I-85 to the east of the
Interchange and crossing of Rhodes Creek.
beginning of Exit 170.
Draw Drainage Area & Flow Patterns. Comment on any features (culvert/road crossings, inaccurate contours, new construction, etc.) on map
below.
Soil Characteristics (circle all that apply): ❑Sand ❑ Silt 0 Clay 0 Rock
Depth to Water Table: Unknown
Adjacent Land use: Forest
Conflicts with Existing Utilities (circle one)? ❑ Yes 0 No
Configuration (circle one): 0 Online ❑ Offline
If yes, list utility conflicts: none apparent
Located in Floodplain? ❑ Yes ® No
Receives Flow from Offsite? 0 Yes ❑ No
Requires Divergence of Stormflows (circle one)?
El Yes 0 No
Evidence of Hydric Soils and/or Standing Water? ❑ Yes ® No
Access and/or Staging Constraints (circle one)?
El Yes 0 No
If yes, Explain:
If yes, ex lain constraints:
Slopes in Potential BMP footprint: ❑ Low (0-5°/u) 0 Moderate (6-10%) ❑ High (>10%)
Slopes in Area Surrounding BMP footprint: ❑ Low (0-5%) 0 Moderate (6-10%) ❑ High (>10%)
Outfall Location(s)? (describe and mark on map below if applicable) If possible, note elevation difference between inlet(s) and outlet(s). North
side of I-85 southbound, east of off -ramp, at western end of guardrail, just west of NCDOT Explicit Outfall with Object_12 = 155, located on
unnamed tributary to Rhodes Creek, north -side of I-85.
Concrete ditch(es)? ❑ Yes 0 No, How Man ? Condition: Good / Fair (Cracking) / Poor (Total Failure/Eroding soil)
Outfall Type (e.g. channel, catch basin, pipe, etc.) Pipe to Gully
Outfall Condition: ❑ Good ❑ Fair 0 Poor
Drainage Structure Depth (if applicable): Not Applicable
Outfall condition notes: Deep gully with apparent, recent
erosion of banks and bed. Trees and rocks preventing wide -
Pipe and/or Channel Dimensions: 12" RCP
scale bank failure.
Is there potential to adjust the existing storm drain configuration and/or existing drainage patterns to increase the impervious area contributing
to a facility at this location? If yes, explain: Yes, install curb and gutter along the north -side shoulder to route northern half of crowned highway
lanes to location of outfall, at least along the highway section with existing guardrail.
Land Use Downstream of Outfall: Forest, State Park
Existing encroachments into ROW?❑ Yes 0 No
Roadway Type: Interstate 85
If yes, describe ROW encroachments:
Posted Speed Limit: 65 mph
Illicit Discharge/Illegal Dump Site (circle one)? ❑ Yes 0 No
Assess impact of SCM construction and maintenance on adjacent property owners (e.g. conflicting easement uses, SCM may raise concerns over
noise, safety, and/or general quality of life, etc.): None.
Other Constraints not already covered (bedrock, heavily wooded area, etc.): potential bedrock and larger, well -established trees within proposed
BMP footprint.
Proposed BMP type(s): Based on the results of the field evaluation, what is the recommended BMP type? Select from the list below and make
a sketch on the field map or site drawing (Mark all that are feasible):
Structural
Non-Structural/Distributed
O Level spreader 0 Preformed scour hole/plunge pool O Swirl concentrator
O Riparian Buffer
O Dry detention basin O Wet detention basin O Concrete Ditch Conversion
O Catch basin insert/inlet filter
O Infiltration trench O Stormwater wetland O Sidewalk bioretention
O Compost Seeding
O Bioswale O Infiltration Basin O Suspended sidewalk
O Permeable pavement
O Bioretention/Filtration O Filter Strip O Wet vault
Other:
O Sand Filter O Bio-embankment O Tree box
O Treatment Swale 0 Step Pool Stormwater Conveyance O Permeable Pavement/Pavers
OTETRA TECH 13 Task Order #5

February 5, 2018
SCM Retrofit Field Evaluation Form (Page 2 of 2)
PHOTO NOTES
Photo1: See Attached. Detailed Photo
Photo2:
Photo3:
Photo4:
Photos:
Photo7:
Legend
0 Tt-Verified Inlet
- Tt-Verified Outlet
d Tt-Assumed SW Pipe
Existing SCM
G Verified Outfall
Implicit Outfall
Upperl'alls_Streams
_ Preliminary SCM Footprint
OPreliminary SCM Drainage Area
S_FLD_HAZ_AR
0.2 PCT ANNUAL
Dhn+n to
OTETRA TECH 14 Task Order #5