SW4240703_Design Calculations_20241031

Project Information Complete this sheet if required by your reviewing authority.
Contact them for any questions. Grey boxes/text are optional.
SNAPv4.2.0 LOCATION
Project Name(optional): Cane Creek Phase 8 Parcel ID(optional):
Submission Date(optional): 10/31/2024 date Nutrient Management Watershed: Jordan Lake menu
Local Jurisdiction/Reviewing Agency: menu Subwatershed: Haw River menu
Project Latitude Coordinates(optional): N Phosphorus Delivery Zone: Jordan-050050 menu
Project Longitude Coordinates(optional): W Nitrogen Delivery Zone: Jordan-050050 menu
PROJECT DETAILS
Development Land Use Type: Single Family Residential menu Disturbed Area: 399,445 ft2
Part of Common Development Plan? yes y/n Project Activity: New Development menu
Designated Downtown Area? yes yin Project Drains to SA Waters? no yin
Public Linear Road/Sidewalk Project? no y/n Pre-Project Land Use: fallow/open menu
Project Owner Type: (Private menu Project Description(optional):
STORM WATER DETAILS
(Falls ONLY)Onsite Reduction%Req. % Project Uses LID/Runoff Volume Match? no yin
Existing BUA/Development Onsite? yes yin Local Gov't nutrient req's same as State? yes y/n
Local Gov't cutoff date for Existing BUA: date Project Drains to Regional SCM? no yin
Nitrogen Export Rate Target: 3.80 lb/ac/yr Total Nitrogen Offset Credits Needed: lb/yr
Phosphorus Export Rate Target: 11.43 lb/ac/yr Total Phosphorus Offset Credits Needed: lb/yr

SNAP v4.2.0
Project Area and Offsite Land Cover Characteristics Precipitation suer City
Station:
Copy r 'aste VALUES ONLY for Best Results Click here to scroll down to error messages on this sheet.
I PROJECT AREA LAND COVERS TN EMC (mg/L) TP EMC (mg/L) Pre-Project Area (ft2) Post-Project Area (ft2) Change pre-to-post(ft2)
Roof 1.18 0.11 116,331 116,331
Roadway 1.64 0.34 20,677 79,330 58,653
Parking/Driveway/Sidewalk 1.42 0.18 0
Protected Forest 0.97 0.03 588,274 487,400 -100,874
Managed Pervious/Landscaping 2.48 1.07 1,312,049 1,205,313 -106,736
Offsite or Existing Roof 1.18 0.11 0
Offsite or Existing Roadway 1.64 0.34 0
Offsite or Existing Parking/Driveway/Sidem 1.42 0.18 0
Offsite Protected Forest 0.97 0.03 0
Offsite Managed Pervious 2.48 1.07 0
CUSTOM LAND COVER 1 _ 0
CUSTOM LAND COVER 2 0
CUSTOM LAND COVER 3 0
LAND TAKEN UP BY SCM 1.18 0.11 32,626 32,626
Total (Regulated & UnReg)Area 1,921,000.00 1,921,000.00
Project (Regulated)Area 1,921,000.00 1,921,000.00

SCM Characteristics
Stormwater Control Measure(SCM)Characteristics Click here to eo cc Click here to eo cc Click here to eo back to the
Copy&Paste VALUES ONLY 5CM101's land Cover Data Click here to review Errors Summary Data
SNAP v4.2.0
Nu Best Resolts \\ 11��
I Catchment SCM 101 I meu:to 10'2 /103 • 201 I DM' , 202 I Dr""' >203 301 � 302 303 401 4042 I Dr''t' > 403 501 � 502 k2
Type of SCM Dry pond Dry Pond Dry Pond r P
Hydrologic sail group at SCM location B B B
SCM Description
la Design Storm Size(inches/24hrs)
I. Percent of Full Size 100% 10D% 10D%
■ %Annual Effluent 80% 0% 0% 80% 0% 0% 80% 0% 0% 0% 0% 0% 0% 0%
I. %Annual Overflow 16% 0% 0% 16% 0% 0% L 16% 0% 0% 0% 0% 0% 0% 0%
■ %Annual ET/Infiltrated 4% 0% 0% 4% 0% 0% 4% 0% 0% 0% 0% 0% 0% 0%
I. Custom%Annual Effluent
■ Custom%Annual Overflow
I.Custom%Annual ET/Infiltrated
■ SCM Effluent TP EMC(mg/L) 0 0.22 0.00 0.00 0.22 0.00 0.00 0.22 0.00 0.00 0.00 0.00 0.00 0.00 0.00
I. SCM Effluent TN EMC(mg/L) 1.33 0.00 0.00 1.33 0.00 0.00 1.33 0.00 0.00 0.00 0.00 0.00 0.00 0.00
■ Custom Effluent TP EMC 1
F Custom Effluent TN EMC
SCM Land Cover TP EMC(mg/L) 0.11 0.00 0.00 0.11 0.00 0.00 0.11 0.00 0.00 0.00 0.00 000 0.00 0.00
1 SCM Land Cover TN EMC(mg/L) 1.18 0.00 0.00 1.18 0.00 0.00 1.18 0.00 0.00 0.00 0.00 000 0.00 0.00
This SCM Drains to Numbered SCM 0 0 0 0 0 0 0 0 0 0 0 0 0
Catchment Routing
Catchments Draining to Catchments Draining to Catchments Draining to Catchments Draining to Catchments Draining to Catchments Draining to Catchments Draining to Catchments Draining to Catchments Draining to Catchments Draining to Catchments Draining to Catchments Draining to Catchments Draining to Catchments Draining to
SCM 101 SCM 102 SCM 103 SCM 201 SCM 202 SCM 203 SCM 301 SCM 302 SCM 303 SCM 401 SCM 402 SCM 403 SCM 501 SCM 502
Catchment no no
Catchment ` ilm = a
Catchment no no _
Catchment no no no _
Catchment no no no
Catchment no no no
Error Check-Missing SCM'
■' Error Check-Min/Max Size:
Error Check-Hydrology:
Error Check-Missing SCM Info:
Error Check-Drainage Data w/o SCM:
Error Checks-SCM Type:
um. lot 102 103 201 202 203 un 302 303 COI 402 403 Sm
SCM Drainage Area Land Covers Area Draining Directly to Area Draining Directly to Area Draining Directly to Area Draining Directly to Area Draining Directly to Area Draining Directly to Area Draining Directly to Area Draining Directly to Area Draining Directly to Area Draining Directly to Area Draining Directly to Area Draining Directly to Area Draining Direc%to Area Draining Direct%to
SCM 101(ft2) SCM 102(ft2) SCM 103(ft2) SCM 201(ft2) SCM 202(ft2) SCM 203(ft2) SCM 301(ft2) SCM 302(ft2) SCM 303(ft2) SCM 401(ft2) SCM 402(ft2) SCM 403(ft2) SCM 501(ft2) SCM 502(ft2)
Roof 17,442 61,047 17,442
Roadway 17,100 25,697 30,078
Parking/Driveway/Sidewalk
Protected Forest 8,455 10,792 20,890
Managed Pervious/Landscaping _ 154,873 515,209 160,231
Offsite or Existing Roof _
Offsite or Existing Roadway _
Offsite or Existing Parking/Driveway/Sidewalk
Offsite Protected Forest _
Offsite Managed Pervious
CUSTOM LAND COVER 1
CUSTOM LAND COVER 2
CUSTOM LAND COVER 3
LAND TAKEN UP By SCM 11,626 12,722 8,278
TOTAL AREA DRAINING TO SCM(ft): 209,496 0 0 625,467 0 0 236,919 0 0 0 0 0 0 0
CATCHMENT AREA(ft): 209,406 625,467 236,919 0 0

Nutrient Export Summary SNAP v4.2.0
Landcover Et SCM Data Review
Errors/Advisories Errors/Advisories
Avg Annual precip(in)= 46.62 SCM Area(ftZ)= 32,626
Total(Regulated+
Unregulated)Area(ftZ)= 1,921,000 SCM Treated Area(ft2)= 1,071,882
Project(Regulated)
1,921,000 Catchment Routing: No errors
Area(le)=
Net BUA(Project Area Treating Runoff from
174,984 Net BUA indicates new development or expansion. no
BUA only ftZ)= Existing BUA or Offsite:
Custom Landcovers are no Disturbed Area(ftZ)= 399,445
present:
Total Nitrogen Export Target 167.ss Total Phosphorus Export Target 63.06
Scaled to Project Area(lb/yr): Scaled to Project Area(lb/yr): I
Total Area Total Area Project Area Total Area Project Area Total Area Project Area
Project Area Total Area Project Area
(Onsite+ Post-Project Post-Project Post-Project Post-Project Post-Project Post-Project
Nutrient Export Summary Offsite) (Onsite Only) before before Post-Project Post-Project SCM-Treated SCM-Treated Untreated Untreated
Pre-Project Pre-Project Treatment Treatment after Treatment after Treatment Area Only Area Only Areas Areas
Area(All Landcover Types)(acres) 44.1001 44.1001 44.1001 44.1001 44.1001 44.1001 24.6070 24.6070 19.4931 19.4931
Percent Built-Upon Area(BUA)(%) 1% 1% 10% 10% 10% I 10% 16% 16% 3% 3%
Built-Upon Area(BUA)(sqft) 20,677 20,677 195,661 195,661 195,661 195,661 168,806 168,806 26,855 26,855
Annual Runoff Volume(fts/yr) 400,906 400,906 1,059,928 1,059,928 1,025,021 1,025,021 792,065 792,065 232,956 I 232,956
Annual Runoff%Change 164% 164% 156% 156%
Total Runoff Change(cuft/yr) 659,021 659,021 624,115 MOM
Total Nitrogen EMC(mg/L) 1.95 1.95 1.54 1.54 1.40 1.40 1.36 1.36 1.52 1.52
Total Nitrogen Load Leaving Site(lb/yr) 48.78 48.78 101.65 I 101.65 89.40 89.40 67.32 67.32 22.08 22.08
Total Nitrogen Loading Rate(1b/ac/yrJ_ 1.11 1.11 2.31 2.31 2.03 2.03 2.74 2.74 1.13 1.13
Total Nitrogen%Change Pm-to-Post 108% 108% 83% 83%
Total Nitrogen Change(lb/yr)Pre-to-Post 52.87 52.87 40.61 40.61
Total Phosphorus EMC(mg/L) 0.68 0.68 0.35 0.35 0.27 0.27 0.24 0.24 0.37 0.37
Total Phosphorus Load Leaving Site(lb/yr) 16.98 16.98 23.27 23.27 17.31 17.31 11.86 11.86 5.45 5.45
Total Phosphorus Loading Rate(Ib/ac/yr) 0.38 0.38 0.53 0.53 0.39 0.39 0.48 0.48 0.28 0.28
Total Phosphorus%Change Pre-to-Post 37% 37% 2% 2%Total Phosphorus Change(Ib/yr)Pre-to-Post 6.29 6.29 0.33 0.33
SCM/CLatchment Summary
SCM ID and Type volume TN Reduction TP Reduction TN Out Reduction(%) (%) (%) Out
(Ibs/ac/yr) (Ibs Out/
o TP Falls Lake ONLY:Onsite Reduction Compliance Check
Catchment 1 4.22% 14.06% 29.74% 3.10 0.54 II Nitrogen II Phosphorus
101:Dry Pond 4.22% 14.06% 29.74% 3.10 0.54 Onsite%Reduction Requirement
102:NA 0.00% 0.00% 0.00% _ 0.00 0.00 Export Target Scaled to Area(lb/yr) 167.58 63.06
103:NA _ 0.00% 0.00% 0.00% 0.00 0.00 Export Load Post-Project Before Treatment _101.65 23.27
Catchment 2 4.22% 15.68% 35.50% 2.41 0.43 Total Reduction Need(lb/yr)
201:Dry Pond 4.22% 15.68% 35.50% 2.41 0.43 Onsite Reduction Need(lb/yr)
202:NA _ 0.00% 0.00% _ 0.00% 0.00 _ 0.00 Onsite Export Target(Ib/yr)
203:NA 0.00% 0.00% 0.00% 0.00 0.00 Project Area Post-Project After Treatment 89.40 17.31
Catchment 3 4.22% 15.96% _ 32.22% 3.27 _ 0.57
301:Dry Pond 4.22% 15.96% _ 32.22% 3.27 _ 0.57
302:NA 0.00% 0.00% 0.00% 0.00 _ 0.00
303:NA 0.00% 0.00% 0.00% 0.00 0.00
Catchment 0.00% 0.00% 0.00% 0.00 0.00
401:NA 0.00% 0.00% 0.00% 0.00 0.00
402:NA 0.00% 0.00% 0.00% 0.00 0.00
403:NA 0.00% 0.00% 0.00% 0.00 0.00
Catchment 5 0.00% 0.00% 0.00% 0.00 0.00
501:NA 0.00% 0.00% 0.00% 0.00 0.00
502:NA 0.00% 0.00% 0.00% 0.00 0.00
503:NA 0.00% 0.00% 0.00% 0.00 0.00
Catchment 6 0.00% 0.00% 0.00% 0.00 0.00
601:NA 0.00% 0.00% 0.00% 0.00 0.00
602:NA 0.00% 0.00% 0.00% 0.00 0.00
603:NA 0.00% 0.00% 0.00% 0.00 0.00
1

Nutrient Management Strategy Watershed - Nutrient Offset Credit Reporting Form
SNAP v4.2.0
Please complete and submit the following information to the local government permitting your development project
to characterize it and assess the need to purchase nutrient offset credits. Contact and rule implementation
information can be found online at:
http://deq.nc.gov/about/divisions/water-resources/planning/nonpoint-source-management/nutrient-offset-information
PROJECT INFORMATION
Applicant Name:
Project Name: Cane Creek Phase 8
Project Address:
Date: (mm/dd/yyyy) Development Land Use Type: Single Family Residential
County: Project Activity Type: New Development
Project Area (sqft): 1,921,000 Project Latitude: 0.000000
Post-Project Built-Upon Area%: 10.19% I Project Longitude: 0.000000
WATERSHED INFORMATION
Nutrient Management Watershed: Jordan Lake N Target Export Rate(Ib/ac/yr): 3.80
Subwatershed: Haw_River P Target Export Rate(Ib/ac/yr): 1.43
Nitrogen Delivery Zone: Jordan-050050 Nitrogen Delivery Factor: 71%
Phosphorus Delivery Zone: Jordan-050050 Phosphorus Delivery Factor: 67%
PERMANENT NUTRIENT OFFSET REQUEST
Post-Project Nitrogen Calculations-Projects with No Offsite or Built-Upon Area
(Where
(A) (B) I (C) (D) (F) (G) Applicable)
TN Permanent Total TN
TN Untreated TN Export TN Treated TN Remaining Additional
TN Delivery Offsets Permanent
Load(Ib/yr) Target Load Load(Ib/yr) Reduction Local Gov't
Factor(c/o) Required Offsets to
(Ib/yr) Need(Ib/yr) (Ib/yr) Offsets(Ib/yr) Buy(Ib/yr)
101.7 167.6 89.4 0.0 ' 71.0% 0.0 0.0 1
Post-Project Phosphorus Calculations-Projects with No Offsite or Built-Upon Area
(A) (B) (C) (D) (F) (G) (Where
Applicable)
TP Permanent Total TP
TP Untreated TP Export TP Treated TP Remaining TP Delivery Offsets Additional I Permanent
Load(Ib/yr) Target Load Load(lb/yr) Reduction Local Gov't
Factor(%) Required Offsets to
(Ib/yr) Need(Ib/yr) (Ib/yr) Offsets(Ib/yr) Buy(Ib/yr)
23.3 63.1 17.3 0.0 I I 67.0% 0.0 0.0 I
LOCAL GOVERNMENT AUTHORIZATION
Local Government Name:I
Staff Name: Phone:
Staff Email: Date:
Local Government Authorizing Signature: