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Drainage Reports - 03/03/2014
1 1 AThis Drainage Report is consciously provided as a POF. Please consider the environment before printing this document in ib entirety. When a hard copy is absolutely necessary, we recommend double -sided printing. ' Northern Englneering.com // 970.221.4158 February 21, 2014 City of Ft. Collins pro d Plans Approved By Date 3 _3 -1 FINAL DRAINAGE REPORT OLD TOWN FLATS Fort Collins, Colorado Prepared for: Brinkman Development, LLC . 3003 East Harmony Road, Suite 300 Fort Collins, Colorado 80528 Prepared by: (NORTHERN ENGINEERING 200 South College Avenue, Suite 10 Fort Collins, Colorado 80524 Phone: 970.221.4158 F. 970.221.4159 waw.nonhernengneedngoam Project Number: 379-039 1 I NORTHERN ENGINEERING February 21, 2014 City of Fort Collins Stormwater Utility 700 Wood Street Fort Collins, Colorado 80521 RE: Final Drainage Report for Old Town Flats Dear Staff: IF ADDRESS: PHONE:970.221.4158 WEBSI 200 S. College Ave. Suite 10 TE: WEBSIrthernengineering com Fort Collins, C080524 FAX.970.221.4159 Northern Engineering is pleased to submit this Final Drainage Report for your review. This report accompanies the Final Plan mylar submittal for the proposed Old Town Flats development. This report has been prepared in accordance with the Fort Collins Stormwater Criteria Manual (FCSCM), and serves to document the stormwater impacts associated with the proposed Old Town Flats housing project. We understand that review by the City of Fort Collins is to assure general compliance with standardized criteria contained in the FCSCM. If you should have any questions as you review this report, please feel free to contact us. Sincerely, NORTHERN ENGINEERING SERVICES, INC. Nicholas W. Haws, PE LEED Vice President pp -�'4 JJk- Andrew Reese Project Engineer ' NORTHERN ENGINEERING TABLE OF CONTENTS ' I. GENERAL LOCATION AND DESCRIPTION......................................................... 1 II. DRAINAGE BASINS AND SUB-BASINS............................................................. 5 III. DRAINAGE DESIGN CRITERIA......................................................................... 6 ' IV. DRAINAGE FACILITY DESIGN.......................................................................... 8 V. CONCLUSIONS.............................................................................................10 References............................................................................................................. 11 APPENDICES: APPENDIX A — Hydrologic Computations APPENDIX B — Hydraulic Computations B.1 — Hydraulic Computations ' B.2 — Detention Facilities APPENDIX C — Water Quality Design Computations APPENDIX D — Erosion Control Report ' APPENDIX E — Standard Operating Procedures (SDP's) References MAP POCKET: ' C700 — Drainage Exhibit EX1 — Existing Drainage Exhibit I 1 11 1 1 1 1 1 ,V I NORTHERN ENGINEERING Old Town Flats I. GENERAL LOCATION AND DESCRIPTION A. Location 1. Vicinity Map LOCATION Figure 1 — Vicinity Map 2. The Old Town Flats project site is located in the Northeast quarter of Section 11, Township 7 North, Range 69 West of the 6" Principal Meridian, City of Fort Collins, County of Larimer, State of Colorado. 3. The project site (refer to Figure 1) is bordered to the north by vacant property; to the south by Maple Street (100' ROW); to the east by an existing public alley (20' Right - of -Way); and to the west by Mason Street (100' ROW). 4. There are no major drainageways within or adjacent to the site. Page11 1 1 1 1 NORTHERN ENNINEERINQ B. Description of Property 1. Old Town Flats is comprised of ±0.87 acres. 2. The site is currently unoccupied, vacant land. Old Town Flats ' 3. The existing groundcover consists of grasses and gravel. The existing on -site runoff generally drains from the southwest -to -northeast east across flat grades (e.g., ' <2.00%) into the existing alley. From there it is directed to an existing inlet via a concrete pan, at which point the drainage continues through an existing storm system down College Avenue to Willow Street, and on to the Cache La Poudre River. The ' existing concrete pan and area inlet are encompassed by an existing 10' drainage easement (Rec. #2004-0002334) on Lot 10, Block 23. 4. A soils report (Project No. 1132055 1 Date: July 30, 2013) was completed by Earth ' Engineering Consultants, LLC. The report contains the results of a complete geotechnical subsurface exploration as well as pertinent geotechnical ' Page12 ' NORTHERN ENGINEERING L Old Town Flats recommendations. According to the summary of findings presented in the aforementioned report, a surficial layer of gravel, asphaltic concrete, topsoil/landscape material or concrete was observed through the site at the boring location. An approximate 1-112 to 4-foot layout of fill material was encountered immediately beneath the surface materials. Native cohesive to slightly cohesive sandy lean clay and/or clayey sand subsoils were encountered at approximate depths of 2 1/2 to 4 feet below site grades." 5. There are no major drainageways within or adjacent to the project site. ' 6: "The -proposed Old Town Flats *development will consist of a single residential building: -- Other proposed improvements include: a new concrete and permeable Modular Block Paver (MBP) parking area and landscaping. ' 7. The proposed land use is residential, multi -family dwelling. This is a permitted use in the Downtown District (D). 1 1 I ' Page13 1 1 1 1 INORTHERN ENGINEERING C. Floodplain 1. The subject property is not located in a FEMA regulatory or City of Fort Collins designated Floodplain. In particular, the project site is not located within a FEMA designated 100-year floodplain per Map Number 08069CO979H (Effective date: May 2, 2012). JOINS PANEL M77 l�I�llj p� F a aFy NAP SCALE 1"=880' s ZONE AE 0 500 fOD� �re�._"WmOc ... .... 6iNE 0 4 p - YMX4 W/NX P t e FIRM w�'s'^• ��'by.�re s*nEE <� mom', FLOOR INSURANCE RATE MAP '9Wo m LARLMERCOUNTV, x COLORADO AVOINCOHPOAAiFDAPiA3 C wRLonorlM�..g ' mmurmi uecn aw -..,. �VENVE ayd` xLLN79 � e eve ma..a.. �+ IUPNUY9FR ®'�� NOIOWRNI �' G 1uP REN9Eo LL0480 mnx J''. NNYt,nn ICI I.S�v1 EneM1aCwr.��n� OVVE S1PEE Figure 4 — FEMA Firmette (Map Number 08069C0979H) Page14 ' NORTHERN ENGINEERING ' Old Town Flats II. DRAINAGE BASINS AND SUB -BASINS A. Major Basin Description ' 1. Old Town Flats is located within the City of Fort Collins Old Town major drainage basin. Specifically, the project site is situated in the north -central portion of this major drainage basin. This basin is located in north -central Fort Collins and has a drainage ' area of approximately 2,120 acres, including approximately 400 acres of the Colorado State University campus. The Old Town major drainage basin generally drains from west to east. It receives some runoff from the Canal Importation Basin directly west of Old Town. Most of the runoff from the Old Town major drainage basin drains into the ' Poudre River. "- B. Sub -Basin Description 1. The outfall for the project site is an existing area inlet located just west of College Avenue between Cherry Street and Maple Street. The existing area inlet is ' encompassed by an existing 10' drainage easement (Rec. #2004-0002334) on Lot 10, Block 23. 2. The existing subject site can be defined with one (1) sub -basin. Refer to the Existing Drainage Exhibit for additional information. • Sub -basin EX1 delineates the proposed project site, which was used to ' approximate the 2- and 100-year existing runoff. The existing site runoff generally drains from southwest -to -northeast into the existing alley along the eastern boundary of the site. 3. The project site does not receive notable runoff from contiguous off -site properties. I 1 Page15 1 ,y (NORTHERN ENGINEERING III. DRAINAGE DESIGN CRITERIA Old Town Flats A. There are no optional provisions outside of the FCSCM proposed with Old Town Flats. ' B. The overall stormwater management strategy employed with Old Town Flats utilizes the "Four Step Process" to minimize adverse impacts of urbanization on receiving waters. The following is a description of how the proposed development has incorporated each step. I 1 1 7 Step 1 — Employ Runoff Reduction Practices. The first consideration taken in trying to reduce the stormwater impacts of this development is the site selection itself. By choosing an already developed site with public storm sewer currently in place, the burden is significantly less than developing a vacant parcel absent of any infrastructure. Old Town Flats aims to reduce runoff peaks, volumes and pollutant loads from frequently occurring storm events (i.e., water quality (i.e., 801h percentile) and 2-year storm events) by implementing Low Impact Development (LID) strategies. Wherever practical, runoff will be routed across landscaped areas or Modular Block Pavers (MBPs). This LID practice reduces the overall amount of impervious area, while at the same time Minimizing Directly Connected Impervious Areas (MDCIA). The combined LID/MDCIA techniques will be implemented, where practical, throughout the development, thereby slowing runoff and increasing opportunities for infiltration. Step 2 — Implement BMPs That Provide a Water Quality Capture Volume (WQCV) with Slow Release. The efforts taken in Step 1 will help to minimize excess runoff from frequently occurring storm events; however, urban development of this intensity will still have stormwater runoff leaving the site. The primary water quality treatment will occur in the Modular Block Paver (MBP) section in sub -basin A. Step 3 — Stabilize Drainageways. As stated in Section 1.B.5, above, there are no major drainageways in or near the subject site. While this step may not seem applicable to Old Town Flats, the proposed project indirectly helps achieve stabilized drainageways nonetheless. Once again, site selection has a positive effect on stream stabilization. By developing an infill site with existing stormwater infrastructure, combined with LID and MDCIA strategies, the likelihood of bed and bank erosion is reduced. Furthermore, this project will pay one-time stormwater development fees, as well as ongoing monthly stormwater utility fees, both of which help achieve Citywide drainageway stability. Step 4 — Implement Site Spec'dic and Other Source Control BMPs. This step typically applies to industrial and commercial developments. C. Development Criteria Reference and Constraints 1. The subject property is not part of any Overall Development Plan (ODP) drainage study or similar "development/project" drainage master plan. 2. The site plan is constrained on two sides by public streets, as well as by existing undeveloped and developed sites along the remaining two sides. As previously mentioned, the drainage outfall for sub -basin A is an existing area inlet located just west of College Avenue between Cherry Street and Maple Street on Lot 10. 3. Peak runoff from the project site during the 2-year event will remain unchanged and will decrease during the 100-year storm event. During the 2-year storm event, runoff Page16 NORTHERN ENGINEERING Old Town Flats will remain at ±0.82 cfs; and during the 100-year storm event runoff will decrease ' from ±3.91 cfs to ±0.82 cfs. D. Hydrological Criteria ' 1. The City of Fort Collins Rainfall Intensity -Duration -Frequency Curves, as depicted in Figure RA-16 of the FCSCM, serve as the source for all hydrologic computations ' associated with the Old Town Flats development. Tabulated data contained in Table RA-7 has been utilized for Rational Method runoff calculations. 2. The Rational Method has been employed to compute stormwater runoff utilizing ' coefficients contained in Tables RO-11 and RO-12 of the FCSCM: - - 3. The Rational Formula -based Federal Aviation Administration (FAA) procedure has ' utilized for detention storage calculations. 4. Two separate design storms have been utilized to address distinct drainage scenarios. ' The first event analyzed is the "Minor," or "Initial" Storm, which has a 2-year recurrence interval. The second event considered is the "Major Storm," which has a 100-year recurrence interval. ' E. Hydraulic Criteria ' 1. The drainage facilities proposed with the Old Town Flats project are designed in accordance with criteria outlined in the FCSCM and/or the Urban Drainage and Flood Control District's (UDFCD) Urban Storm Drainage Criteria Manual. ' 2. As stated in Section I.C.1, above, the subject property is not located in a FEMA regulatory or a City of Fort Collins designated floodplain. ' F. Floodplain Regulations Compliance 1. As previously mentioned, this project is not subject to any floodplain regulations. G. Modifications of Criteria 1. No modifications are requested at this time. H. Conformance with Low Impact Development (LID) 1. 15,852 sf of paving is proposed with this project, and of the total, 5,275 sf is proposed to be Modular Block Pavers (MBPs). This means that ± 34% of the paved areas in the project are pervious, exceeding the minimum requirement of 25%. ' 2. The total project area is 38,050 sf. Of that area, 34,884 sf will be treated by LID techniques, primarily Modular Block Pavers (MBPs). This means that ± 92% of the site will be treated by LID -type technology, exceeding the minimum requirement of 50%. ' Page17 ,y NORTHERN ENGINEERING ' Old Town Flats IV. DRAINAGE FACILITY DESIGN ' A. General Concept ' 1. The main objective of the Old Town Flats drainage design is to maintain existing drainage patterns, while not adversely impacting adjacent properties. ' 2. No notable off -site runoff passes directly through the project site. 3. A list of tables and figures used within this report can be found in the Table of Contents at the front of the document. The tables and figures are located within the sections to which the content best applies. - 4. The project site has been divided into four (4) drainage sub -basins, designated as sub - basins A, B, C, D and OS1. The drainage patterns anticipated for each basin are further described below. Sub -Basin A ' Sub -basin A encompasses ±90 percent of the total site area. This sub -basin is comprised of roof area, landscaping and the on -site parking area. This parking area will be a mix of concrete and Modular Block Pavers (MBPs). Detention will be ' provided within in the MBPs (WSEL100.re,r=4975.6±). This basin will release at an adjusted 2-year rate of 0.54 cfs through an orifice plate. An outlet orifice cap located on the east wall of the proposed drain basin will be used to control the flow rate. Sub -Basin B Sub -basin B is a relatively small basin (0.02 acre) that is comprised of landscaping. ' The developed runoff will follow the historic drainage path north and then east at rates significantly less than the existing condition. The 100-year developed runoff (Q1oo=0.04 cfs), for sub -basin B, was subtracted from the total 2-year existing release ' rate (Q100=0.82 cfs). Sub -Basin C Sub -basin C encompasses the western edge of the project site along the Mason Street frontage. It is comprised of public sidewalks and landscaping. The developed runoff will drain into Mason Street and flow north. The 100-year developed runoff (Qioo=0.12 cfs), for sub -basin C, was subtracted from the total 2-year existing release ' rate (Q100=0.82 cfs). Sub -Basin D Sub -basin D encompasses the southern edge of the project site along the Maple Street frontage. It is comprised of public sidewalks and landscaping. The developed runoff will drain into Maple Street and flow east. The 100-year developed runoff (Q100=0.12 cfs), for sub -basin D, was subtracted from the total 2-year existing release rate (Q100=0.82 cfs). Sub -Basin OS1 Sub -basin OS1 is an off -site basing along Mason Street adjacent to the northwest corner of the project. It is comprised of public sidewalks, public roadway and railroad tracks. The developed runoff will in Mason Street and will now be intercepted by an area inlet. From there, stormwater will be conveyed to the existing curb inlet located ' Page18 ' NORTHERN ENGINEERING Old Town Flats just south of the railroad tracks, at which point the drainage will continue to follow its historic drainage path to a storm drain on the west side of the railroad tracks and then north to the Poudre River. The 100-year developed runoff (Q,.=0.74 cfs), for sub - basin OS1, was not subtracted from the total 2-year existing release rate since the ' runoff did not originate on -site. A full-size copy of the Drainage Exhibit can be found in the Map Pocket at the end of this report. B. Specific Details ' 1. The release rate for the undeveloped land (pre=development) was established by calculating the 2-year peak runoff rate for the entire project area. The total establishes the overall maximum allowable release rate, 0.82 cfs, from the project site. The allowable release rate of 0.54 cfs utilized in the FAA procedure detention storage computations (Refer to Appendix B for these calculations) and was established by subtracting the total undetained release of 0.31 cfs (0.04 cfs +0.12 cfs+0.12 cfs) from the overall maximum ' allowable release rate. 2. The FAA method was used to size the on -site pond for quantity detention. ' Calculations for this area, based on the characteristics of sub -basin A and adjusted release rate, indicate a detention volume of 6,670 cu. ft. This ' includes 849 cu. ft. of Water Quality Capture Volume (WQCV). During water quality events the water quality capture volume will release over 12-hours. There is no -infiltration accounted for with this design. 3. The storage volume available within the reservoir area (i.e., No. 57 and No. 2 open -graded aggregate) of the MBP section is ±7213 cu. ft. at WSEL 4975.65. The 100-yr WSEL is 4975.43. The MBP section is designed with an increased No.2, open -graded aggregate, material depth in order to provide storage for storm events in excess of the water quality (801h percentile) storm event. ' 4. A Drain Basin is located at the downstream end of the landscape island. This basin will have an orifice cap installed on the east wall that will limit the release from the site to the maximum allowable release rate (0.54 cfs). 5. All roof drain downspouts will discharge into the MBP section. 6. The emergency spill path will be from the landscaping island into the existing alley, where flows will proceed along the historic path north along the alley and east to the existing area inlet. I ' Page19 NORTHERN ENGINEERING Old Town Flats V. CONCLUSIONS A. Compliance with Standards 1. The design elements comply without variation, and meet all LID requirements. 2. The drainage design proposed with Old Town Flats complies with the City of Fort Collins Master Drainage Plan for the Old Town Basin. 3. There are no regulatory floodplains associated with the Old Town Flats development. 4. The drainage plan and stormwater management measures proposed with the Old Town Flats project are compliant with all applicable State and Federal regulations governing stormwater discharge. B. Drainage Concept 1. The drainage design proposed with this project will effectively limit potential damage associated with its stormwater runoff. Old Town Flats will detain for the pervious area converted to impervious areas to release at the 2-year existing rate during the 100- year storm. 2. The proposed Old Town Flats development will not impact the Master Drainage Plan recommendations for the Old Town major drainage basin. Page110 (NORTHERN ENGINEERING References Old Town Flats 1. City of Fort Collins Landscape Design Guidelines for Stormwater and Detention Facilities, November 5, 2009, BHA Design, Inc. with City of Fort Collins Utility Services. 2. Fort Collins Stormwater Criteria Manual, City of Fort Collins, Colorado, as adopted by Ordinance No. 174, 2011, and referenced in Section 26-500 (c) of the City of Fort Collins Municipal Code. 3. Subsurface Exploration Report Block 23 — Phase I, July 30, 2013, Earth Engineering Consultants, LLC (Project No. 1132055). 4. Soils Resource Report for Larimer-County Area, Colorado, Natural Resources Conservation - Service, United States Department of Agriculture. 5. Urban Storm Drainage Criteria Manual, Volumes 1-3, Urban Drainage and Flood Control District, Wright -McLaughlin Engineers, Denver, Colorado, Revised April 2008. Pagel11 APPENDIX A HYDROLOGIC COMPUTATIONS N.,th.,.F..i.en,i.a.com//970.221.4159 \R 6 �0 q= § } \E � 3 \}0 B G \,s LAJ o u |lkkt�s° w, k"6!`-e 2 - � 77) R \ 2§* LAJ . \%k ®00 F a ��\ K - 2 = 2 Lu ) {fL9o(s 0t u� 3 ! 1 i 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 i C N Y .. i c o v a o u ` N LL 2, E Y O a O 6 ii m � Y c O a o. 3 1V Y > mJr u` O J O L � E O o o O � E n � S c e Q (� LOMN V { p J i? O W � e yC U x S o « Y a u LL J T N N s O (7 l0 U O II o O =s � ao 0 o tl Y 4 e V N II N o XO O N N S 0 QLLLL a L 0 / 0 _ ))2 }�#/ # {i{ 7:7_k q o - \ �A§ ; J � ct \ § © 2 Lw \ 16 § ) _- �| ! § f \� 2 ;- _- w ! a i §) EXISTING RUNOFF SUMMARY TABLE 1 1 1 1 TOTAL 10-yr 100-yr DESIGN BASIN 2-yr Tc Oz 4to 4too REA 02 1 0to 0too POINT ID (min) (cfs) (ds) Ids) (Acres) (min) (min) EX1 EXl 0.87 0.50 1 0.50 0.63 15.4 15.4 12.2 0.82 1.39 3.91 D:IPmjects1379-0391DminagelHydmiogy1379-039_Rationa/ Calcs_Existing.x/sxlSummaty Table \\ 2 \ /[](/)f/§§ o « , \ ]!\ |�! }|)§-666;6 �)� 0�}E C5006do \ / §20m § &§,|]\000000 M 0 § « }!0 000000 Q • $ #! _ :_} - })\ �;e;R /)\2|2 �){ k \t( k)\ //f// j)\ /§77§§ &.; . a ��) 2 12 § = 2 o - � }�(�\} at � /::::;,::• }!»5; }j))/)\/) k / 3 ! ! § a = OOOOO c o o �' E .. ici ui ui ui ui ^ 'E -. 0000 o o vi ui ui ui N f=o� o z E ^0000 � ¢ n 4 ry vi ui ui ui ui O d � d m � V C 0 zzzz 0 0 Q q - .-� U ^ 00000 U ; >� h0000 O �0000 ILL Y > xUe 0 0 0 0 0 N -0000 �/7 J 2 OF c O Q Q Q Q Q E ni z z z z o =>� -0000 0000 y 2 O 00000 V 00000 O N O O O o � J K p m E 00000 Ll Q ✓ = Fo m m II 1m c� E 0 0 0 0- C _ B o m innn q a e " ry E 0 000.E �ryNo$ n J Ly aoou = n $ o LU 00000 W O O Z 4 J O�OOO�D g{ C 5 1� ti •-� (7 t J a 'So,N�' og000 0 =S 0 T O 0 N 0 h N o ry � �� u.y II 00000 W O S LV o n .q rn o+ m o+ o+ � ai � U.N. II 00000 U S S N N S O u F O U 0 O N N ya^ ram. -JE O0: d JY Y�1 O zzzz O O O O z > > V H O c N E o LL 4 Y 6 m U O O O 07 Y 0 j m ~II = m:� A �rD_D a am000 002 3 e0 h O N N O LL O n 0 0 0 0 C N O O O M V LL C7 O N N LL N � � ? c 0 t W OOON a � � O Q ii m ^ N 0 p On OU lT Cn lT M � OU lT m e u U n CO CO CO n CO o oq n a''- E a vvvv c M in in mmmmm cq cq O O �,_ C N N N N N _ w y q O yy y • ep O O�OIN O V (sK a U o ..000.. moo 4zi opNN NN V N W M V 00000 J R U M 9 OY e pINV n�Y � ~00 B 4 Y a SYYuNc T C 00000 .E'_o A �ri �ri iri iri �ri O g o � x w LL U T C .-i 0000 m "1 U 00 O 0o T ^' 000 O N � E in vi Ln Lo ui 0 E = m .d. W 0 0 0 0 U q 00600 U p U R QQ](i o w 0 � N DEVELOPED RUNOFF SUMMARY TABLE TOTAL 10-yr 100-yr DESIGN BASIN 2-yr T. Oz Om Omo AREA C z C 10 C ioo T ` T ` POINT ID (min) (cfs) (cfs) (cfs) (acres) min min A A 0.80 0.83 0.83 1.00 5.1 5.1 5.0 1.89 3.23 7.97 B B 0.02 0.15 0.15 0.19 5.0 5.0 5.0 0.01 0.02 0.04 C C 0.03 0.31 0.31 0.39 5.0 5.0 5.0 0.03 0.05 0.12 D D 0.02 0.49 0.49 0.62 5.0 5.0 5.0 0.03 0.05 0.12 OS1 OSt 0.07 0.95 0.95 1.00 5.0 5.0 5.0 0.20 0.34 0.74 D:IPmjectsU79-0391DminagetHydmlogy1379-039_Rationl-Calcs_Pmposed.xisxlSummary Table I 1 1 1 11 APPENDIX B HYDRAULIC COMPUTATIONS B.l — Storm Sewers B.2 — Detention Facilities •f 4. I �A'SA5/fl 11` �l l Y i rj Y � Nnrthcrn Ennineerinn.c.. 11 970.221 A7 58 APPENDIX B.l STORM SEWERS worry Head /1 970.221.4158 Y N T_ N 0 7 C'1 N C O a E z 2 N Cl) E N 0 N LL N a 1-0 1 H 1 0 u m c n m 0 d 0 0 0 N m C C O OJz W N 4 m C O m O m �? o m n J C7 N N N - O i x O R V Z QO m m m J N e in O n O <n O m N � n m7 m m m cWx m r m m N m T c o m I0 o m m t CC m m o J m � m A U U U c . t J m t2 t2 m m C IJ. G N N N O Z LL 0 4V O O O E � N 0 J N v C E m n o E n n n w 0 a a a IL N u m W F o p JZ O b C O m O p o 0 0 J O O O e W� x o c O rn a x t o � C J e C9 O M G G C N O p r N N J > N N w m'Y a a a m o o jt� o 0 0 E w d m ao ri m > N V N p _ � O N N L Q N ar o c c E K m m N J o s J n � n � m m C m > n n n 5 ami x o v e 1D rn m C N _ Yf M W o a O O N O 0 sm at o r N m O O t ci O O O O a E m O m — m n C LD Q N N N 11 G Q w o 0 o m O $ m p U p N lh (I N II O r �- 02^ N m rn rn p _a mr 00 E U Y o E y v < v o J O m E N N 10 F oJi Q N t c N N N m m C N — y Li C 0o N 7 a Z J 0 o g $ g O ri � r c o gg v e a v v v h0 S' e:u, [-�MV'13 N ul 'Aul 1n0 FgMvwitiloll u� Z :ul N N 8 N A ul lip S R L y L :ul Ix N S N n J W i i i i J N = ul Q VE.. IIeAnO 0 > m m < m v m v rn c rn o e W 1 1 1 *A.c OW ED PvI ~ Peep a , ED (lor cr.WW M Prme[nen I I li�iOL 1 _ N APPENDIX B.2 E Oplgp9 Dpirm.ee ROMm! P.Guvp Nu,n.l YMlel Lv� Dlr ED p7 DETENTION FACILITIES NorthernEneineerine.rnm // 97n 721.41 SR N NQRTHERN Project Location: Calculations By: _ Pond No.: February 21, 2014 Design Storm 1.. Required Detention Volume Developed "C' = I WQCV 849 ft° Area IA)= 08S acres Quantity Detention 6670 It' Max Release Rate = 0.54 CIS Total Volume fe Total Volume iC+R Ft.Collins Inflow Storage Time Time 100-yr Q100 (Runoff) Outflow Detention Intensity Volume (Release) Volume Volume Old Town Flats D.lPmiectsl379-0391Drainagel0etemionl379-039 Detention.xtsml (NORTHERN E NGINFFR INC Old Town Flats Stage - Storage Calculation Project Number: Project Location: Calculations By: A Reese Pond Na.: I' a 1'.V r.IC Required Volume Date: February 21, 2014 Water Surface Elevation (WSE) Design Point Design Storm Require Volume= 849 ft3 Design Storm 100-yr Required Volume= 6670 fe Void Ratio 40% Required Material Volume 16675 WSEL�ft. Minimum Contour Maximum Contour Incremental Volume Cummulative Volume Conic (X-values) 11. n3 4,971.93 4.972.18 4,96 4.96 4,972.18 4,972,43 94.82 99,78 4,972.43 4,972.68 567.25 667,03 4,972.68 4,972.93 1104.12 1771.15 4,972.93 4,973.18 1407.4 3178.55 4,973.18 4,973.43 1 1499.37 1 4677.92 4,973.43 4,973.68 1501.23 6179.15 4,973.68 4,973.93 1502.41 7681.56 4,973.93 4.974,18 1503.58 9185.14 4,974.18 4,974.43 1504.75 10689.89 4.974.43 4,974.68 1505.93 12195.82 4.974.68 4,974.93 1507.1 13702.92 4,974.93 4,975.18 1508.27 15211.19 4.975.18 4.975.43 1509.45 18720:84 4.975.43 4.975.68 1510,62 18231.26 4,975.68 4.975.93 1511,8 19743.06 4,975.93 4,976.18 1 1512,97 1 21256.03 4,976.18 1 1 4,976.43 1 1514,14 1 22770.17 4,976.W 4,976.00 4,975.50 4,975.00 4,974.50 N 4,974.00 4,973.50 0 4,973.00 4,972.50 4,972.00 4,971.50 0 5000 10000 15000 20000 25000 Cummuladve Volume, cu. It. 0: I Pmiects 1379-03910rainagelDetention 1379.039_Detention.xism I ORIFICE RATING CURVE Pond Outlet 100- r Orifice PROJECT: Old Town DATE: February 8v: A. Reese Flats 21, 2014 ORIFICE RATING Orifice Dia (in) Orifice Area (so Orifice invert (ft) Orifice Coefficient 3.2500 0.0576 4971.91 0.65 Stage FT Outlet Release CFS 4971.91 0.00 4972.00 -' 1.00 4972.10 0.00 4972.20 0.12 4972.30 0.15 4972.40 0.18 4972.50 0.20 4972.60 0.22 4972.70 0.24 4972.80 0.26 4972.90 0.28 4973.00 0.29 4973.10 0.31 4973.20 0.32 4973.30 0.34 4973.40 0.35 4973.50 0.36 4973.60 0.37 4973.70 0.39 4973.80 0.40 4973.90 0.41 4974.00 0.42 4974.10 0.43 4974.20 0.44 4974.30 0.45 4974.40 0.46 4974.50 0.47 4974.60 0.48 4974.70 0.49 4974.80 0.50 4974.90 0.51 4975.00 0.52 4975.10 0.53 4975.20 0.53 4975.30 0.54 4975.40 0.55 4975.50 0.56 4975.60 0.57 4975.70 0.57 4975.80 0.58 4975.90 0.59 4976.00 0.60 4976.10 0.61 4976.20 0.61 4976.30 0.62 4976.40 0.63 APPENDIX C ' WATER QUALITY DESIGN COMPUTATIONS [1 I I I I 11 I I I I I North ernEnaineerine.rom It 970.221.4158 1 1 1 1 t A. Reese ruary 21, 2014 REQUIRED STORAGE & OUTLET WORKS: BASIN AREA = 0.800 <-- INPUT from impervious calcs BASIN IMPERVIOUSNESS PERCENT = 75.91 <-- INPUT from impervious cake BASIN IMPERVIOUSNESS RATIO = 0.7591 <-- CALCULATED Drain Time (hrs) 12 <-- INPUT Drain Time Coefficient 0.8 <-- CALCULATED from Figure Table 3-2 WQCV (watershed inches) = 0.244 <-- CALCULATED from Figure EDB.2 WQCV (ac-ft) = 0.016 <-. CALCULATED from UDFCD DCM V.3 Section 6.5 Adjusted WQCV (ac-ft) = 0.0195 <-- CALCULATED (20% Sedimentation Accumulation) WQ Depth (ft) = 0.700 <-- INPUT from stage -storage table AREA REQUIRED PER ROW, a Orl = 0.076 <-- CALCULATED from Figure EDB-3 dia (in) = 1/3 <-- INPUT from Figure 5 number of rows = 2 t (in) = 0.500 <-- INPUT from Figure 5 number of rows = 1.000 <-- CALCULATED from WQ Depth and row spacing 1 1 1 1 1 » APPENDIX D EROSION CONTROL REPORT North ern Enaineerinn.mm 11 970.221A159 ' NORTHERN FNGINEERINO Old Town Flats EROSION CONTROL REPORT 1 A comprehensive Erosion and Sediment Control Plan (along with associated details) has been included with the final construction drawings. It should be noted, however, that any ' such Erosion and Sediment Control Plan serves only as a general guide to the Contractor. Staging and/or phasing of the BMPs depicted, and additional or different BMPs from those included may be necessary during construction, or as required by the authorities having ' jurisdiction. It shall be the responsibility of the Contractor to ensure erosion control measures are ' properly maintained and followed. The Erosion and Sediment Control Plan is intended to be a living document, constantly adapting to site conditions and needs. The Contractor shall update the location of BMPs as they are installed, removed or modified in conjunction with construction activities. It is imperative to appropriately reflect the current site conditions at all times. The Erosion and Sediment Control Plan shall address both temporary measures to be implemented during construction, as well as permanent erosion control protection. Best ' Management Practices from the Volume 3, Chapter 7 — Construction BMPs will be utilized. Measures may include, but are not limited to, silt fencing and/or wattles along the disturbed perimeter, gutter protection in the adjacent roadways and inlet protection at existing and ' proposed storm inlets. Vehicle tracking control pads, spill containment and clean-up procedures, designated concrete washout areas, dumpsters, and job site restrooms shall also be provided by the Contractor. 1 n 1 Grading and Erosion Control Notes can be found on Sheet C001 of the Utility Plans. The Final Utility Plans will also contain a full-size Erosion Control Plan as well as a separate sheet dedicated to Erosion Control Details. In addition to this report and the referenced plan sheets, the Contractor shall be aware of, and adhere to, the applicable requirements outlined in any existing Development Agreement(s) of record, as well as the Development Agreement, to be recorded prior to issuance of the Development Construction Permit. Also, the Site Contractor for this project may be required to secure a Stormwater Construction General Permit from the Colorado Department of Public Health and Environment (CDPHE), Water Quality Control Division — Stormwater Program, before commencing any earth disturbing activities. Prior to securing said permit, the Site Contractor shall develop a comprehensive StormWater Management Plan (SWMP) pursuant to CDPHE requirements and guidelines. The SWMP will further describe and document the ongoing activities, inspections, and maintenance of construction BMPs. APPENDIX E STANDARD OPERATING PROCEDURES (SOPS) REFERENCES 1 1 1 1 1 1 NorthernEnaineerina.com 11 970.221.4159 STANDARD OPERATING PROCEDURES (SOPS) A. Purpose In order for physical stormwater Best Management Practices (BMPs) to be effective, proper maintenance is essential. Maintenance includes both routinely scheduled activities, as well as non -routine repairs that may be required after large storms, or as a result of other unforeseen problems. Standard Operating Procedures (SOPS) should clearly identify BMP maintenance responsibility. BMP maintenance is typically the responsibility of the entity owning the BMP. Identifying who is responsible for maintenance of BMPs and ensuring that an adequate budget is allocated for maintenance is critical to the long-term success of BMPs. Maintenance responsibility may be assigned either publicly or privately. For this project, the privately owned BMPs shown in Section B below are to be maintained by the property owner, homeowner's association (HOA), or property manager. B. Site -Specific SOPS The following stormwater facilities contained within Old Town Flats are subject to SOP requirements: - Directly Connected Downspouts - Permeable Modular Block Pavers (MBPs) - Storm Drains and Tree Roots The location of said facilities can be found on the Utility Plans and, Landscape Plans for Old Town Flats. Inspection and maintenance procedures and frequencies, specific maintenance requirements and activities, as well as BMP-specific constraints and considerations shall follow the guidelines outlined in Volume 3 of the Urban Drainage and Flood Control District (UDFCD) Urban Storm Drainage Criteria Manual. SOP Maintenance Summary Table t Stormwater Facility / Ownership / BMP Responsibility UDFCD Maintenance Reference Directly Connected Roof Private Gutters and Downspouts Permeable Modular Block Private Pavers (MBPs) Perforated Subdrain Private Follow guidelines for Roof Gutters and Downspouts Follow guidelines for Permeable Modular Block Pavers (Chapter 6 — Section 11.0) Refer to Section 5: Maintenance from Permeable Interlocking Concrete Pavements, 4th Edition (PICP Follow applicable guidelines for Perforated Subdrain ' The complete UDFCD BMP maintenance references listed above, except for the roof gutters and downspouts, can be found in Chapter 6 of Volume 3. Applicable BMP maintenance excerpts can be found at the end of this document. 1 I Directly Connected Downspouts ' Many of the downspouts connect directly to the storm drain system. The following SOP generally applies to all direct downspout connections, and more specifically to those which drain directly to the reservoir areas beneath the Modular Block Pavers. At each of these connections, the downspout discharges to a perforated drain basin. The drain basins ' discharge directly to the MBP reservoir. The drain basins are designed to prevent debris and sediment from entering the MBP reservoir area. Debris and sediment compromise the functionality and effectiveness of the system. Routine Maintenance Table for Directly Connected Downspouts Required Action Maintenance Objective Frequency of Action ' Inspect the downspout and basin to Inspections ensure the system functions as it was Routine designed. Repair or replace damaged ' downspouts as needed. Sediment, Debris Remove debris and litter from the basin. Routine —just before annual storm seasons (i.e., and Litter removal Remove sediment from the sump. April/May); at the end of storm season after leaves ' have fallen; and following significant rainfall events. 1 lJ IJ L 1 Permeable Modular Block Pavers (MBPs) There is one large MBP sections associated with the project serving a critical role in the drainage system. These systems provide storage and important water quality benefits. Proper maintenance is critical to ensure lasting performance and integrity of the system. The more frequent and diligent the routine maintenance procedures are, the more likely it is to avoid and/or postpone significant repair and replacement actions. Such major remedies would include removal of the surface pavers to access (and potentially replace) the underlying sub -base material and/or underdrain pipes should either become clogged or otherwise fail to function properly. For additional information on the maintenance of the Modular Block Pavers, refer to Section 5: Maintenance from Permeable Interlocking Concrete Pavements, 4" Edition (PICP Manual) by the Interlocking Concrete Pavement Institute. Routine Maintenance Table for Permeable Pavement Systems Required Action Maintenance Objective Frequency of Action Inspect the pavement condition and Inspection observe infiltration either during a rain At least annually. event or with a garden hose to ensure that water infiltrates into the surface. Debris Removal, Use a regenerative air or vacuum sweeper As necessary - the frequency depends on use types Sweeping and to maintain infiltration rates. Replace infill ( foot traffic only versus vehicle traffic) and Vacuuming aggregate as needed. patterns as well as specific site conditions such as tributary basin characteristics. DO NOT apply sand to the MBP surface. Snow Removal Mechanical snow and ice removal should As necessary. be used. If the surface is completely clogged and Full and Partial rendering minimal surface infiltration rate, Replacement of restoration of surface infiltration can be the Pavement or achieved by removing the first /2 to 1 inch Infill Material of soiled aggregate infill material with a vacuum sweeper. Refill the openings with clean aggregate infill materials. Routine — Annual inspection of hydraulic and structural facilities. Also check for obvious problems during routine maintenance visits, especially for plugging of outlets. Trash Enclosure Should stormwater leach out pollutants Leakage, or other from the trash enclosure area, or should As necessary, based on routine observation and Surface other similar contaminants collect in the inspection by the professional property Contamination/ paver joint filler aggregate, said material management and maintenance contractor. Pollution shall be removed and properly disposed of, and replaced with new infill aggregate. Perforated Subdrain Maintenance Plan The perforated subdrain system storm drain outfall at the bottom of the Modular Block Paver (MBP) system is critical to the overall function of the paver subbase. As such, special maintenance has been identified to ensure these perforated drain systems perform as they were designed. Routine Maintenance Table Required Action Maintenance Objective Frequency of Action Use a video camera to inspect the condition of the perforated drain pipes. Inspection Cleanout pipes as needed. If the integrity Every two to five years. of the pipe is compromised, then repair the damaged section(s). BMP Maintenance ' 11.0 Permeable Pavement Systems The key maintenance objective for any permeable pavement system is to know when runoff is no longer rapidly infiltrating into the surface, which is typically due to void spaces becoming clogged and requiring sediment removal. This section identifies key maintenance considerations for various types of permeable pavement BMPs. 11.1 Inspection Inspect pavement condition and observe infiltration at least annually, either during a rain event or with a garden hose to ensure that water infiltrates into the surface. Video, photographs, or notes can be helpful in measuring loss of infiltration over time. Systematic measurement of surface infiltration of pervious concrete, Permeable Interlocking Concrete Pavers (PICP), concrete grid pavement, and porous asphalt' can be accomplished using ASTM C 1701 Standard Test Method for Infiltration Rate of In Place Pervious Concrete. t Porous asphalt is considered a provisional treatment BMP pending performance testing in Colorado and is not included in this manual at the present time. November 2010 Urban Drainage and Flood Control District Urban Storm Drainage Criteria Manual Volume 3 PJ 6-15 L BMP Maintenance ' 11.2 Debris Removal, Sweeping, and Vacuuming • All Pavements: Debris should be removed, routinely, as a source control measure. Typically, sites ' that require frequent sweeping already plan for this activity as part of their ongoing maintenance program. For example, a grocery store may sweep weekly or monthly. Depending on the season, city streets also may have a monthly plan for sweeping. This is frequently performed with a broom ' sweeper such as the one shown in Photo 6-4. Although this type of sweeper can be effective at removing solids and debris from the surface, it will not remove solids from the void space of a permeable pavement. Use a vacuum or regenerative air sweeper to help maintain or restore infiltration. If the pavement has not been properly maintained, a vacuum sweeper will likely be ' needed. • PICP, Concrete Grid Pavements (with aggregate infill), Pervious Concrete, and Porous ' Asphalt': Use a regenerative air or vacuum sweeper after any significant site work (e.g., landscaping) and approximately twice per year to maintain infiltration rates. This should be done on a warm dry day for best results. Do not use water with the sweeper. The frequency is site specific ' and inspections of the pavement may show that biannual vacuuming is more frequent than necessary. After vacuuming PICP and Concrete Grid Pavers, replace infill aggregate as needed. 11.3 Snow Removal ' In general, permeable pavements do not form ice to the same extent as conventional pavements. Additionally, conventional liquid treatments (deicers) will not stay at the surface of a permeable ' pavement as needed for the treatment to be effective. Sand should not be applied to a permeable pavement as it can reduce infiltration. Plowing is the recommended snow removal process. Conventional plowing operations should hot cause damage to the pavements. ' PICP and Concrete Grid: Deicers may be used on PICP and grid pavers; however, it may not be effective for the reason stated above. Sand should not be used. If sand is accidently used, use a vacuum sweeper to remove the sand. Mechanical snow and ice removal should be used. ' • Pervious Concrete: Do not use liquid or solid deicers or sand on pervious concrete. Deicers can damage the concrete and sand will reduce infiltration. Mechanical snow and ice removal should be used. 1 • Porous Asphalt': Use liquid or solid deicers sparingly; mechanical snow and ice removal is preferred. Do not apply sand to porous asphalt. 11.4 Full and Partial Replacement of the Pavement or Infill Material ' PICP and Concrete Grid: Concrete pavers, when installed correctly, should have a long service life. If a repair is required, it is frequently due to poor placement of the paver blocks. Follow industry guidelines for installation and replacement after underground repairs. If surface is completely clogged and rendering a minimal surface infiltration rate, restoration of surface infiltration can be achieved by removing the first '/z to I inch of soiled aggregate infill ' Porous asphalt is considered a provisional treatment BMP pending performance testing in Colorado and is not included in this manual at the present time. ' 6-16 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 ' Chapter 6 BMP Maintenance ' material with a vacuum sweeper. After cleaning, the openings in the PICP will need to be refilled with clean aggregate infill materials. Replacement of the infill is best accomplished with push brooms. ' Porous Gravel: Remove and replace areas of excessive wear or reduced infiltration as needed. The frequency is dependent on site characteristics including site uses, vegetation, and materials. 1 ' 12.0 Underground BMPs ' Maintenance requirements of underground BMPs can vary greatly depending on the type of BMP. Frequent inspections (approximately every three months) are recommended in the first two years in order ' to determine the appropriate interval of maintenance for a given BMP. This section provides general recommendations for assorted underground BMPs. For proprietary devices, the manufacturer should provide detailed maintenance requirements specific for the BMP. ' 12.1 Inspection All Underground BMPs: Inspect underground BMPs at least quarterly for the first two years of ' operation and then twice a year for the life of the BMP, if a reduced inspection schedule is warranted based on the initial two years. Specifically look for debris that could cause the structure to bypass water quality flows. Strong odors may also indicate that the facility is not draining properly. Inspection should be performed by a person who is familiar with the operation and configuration of the BMP. • Inlet Inserts: Inspect inlet inserts frequently; at a minimum, inspect after every storm event ' exceeding 0.6 inches. Removal of flow blocking debris is critical for flood control. 12.2 Debris Removal, Cartridge Replacement, and Vacuuming ' • All Underground BMPs: Follow the manufacturer's recommended maintenance requirements and remove any flow blocking debris as soon as possible following inspection. 11 3 Porous asphalt is considered a provisional treatment BMP pending performance testing in Colorado and is not included in this manual at the present time. November 2010 Urban Drainage and Flood Control District 6-17 Urban Storm Drainage Criteria Manual Volume 3 BMP Maintenance 13.0 References CONTECH Stormwater Solutions. 2007. StormFilter Inspection and Maintenance Procedures. www.contech-cpi.or 1. Koski, T. and Skinner, V. 2003. Colorado State University Extension. Fact Sheet no.7.202, Lawn Care. littp://www.ext.colostate.edu/pubs/garden/07202.htm]. Law, N.L., K. DiBlasi, and U. Ghosh. 2008. Deriving Reliable Pollutant Removal Rates for Municipal Street Sweeping and Storm Drain Cleanout Programs in the Chesapeake Bay Basin. Center for Watershed Protection. Prepared for U.S. EPA Chesapeake Bay Program Grant CB-973222-01: Ellicott City, MD. www.cpw.or=. M Wright Water Engineers, Inc., Wenk Associates, Muller Engineering Company, Inc., Matrix Design ' Group, and Smith Environmental. 2004. City and County of Denver Water Quality Management Plan. Denver, CO t6-18 Urban Drainage and Flood Control District November 2010 Urban Storm Drainage Criteria Manual Volume 3 ICPI »KINGCONCRET PAVEMENT INSfrrUTE Inspector's Guide for PICP Installation & Maintenance The following is a PICP inspector's guide for project construction and maintenance written to a municipal inspector. The checklist is developed from the ICPI PICP manual and the PICP certificate course. Please keep in mind that ICPI recommends that PICP construction specifications include a method statement. Among many things, the method statement requires a pre -construction conference to where the project inspector(s) needs to be present. ICPI recommends that the inspector of construction of PICP be certified as Certified Compliance Inspector of Stormwater (CCIS) or Certified Erosion, Sediment, and Stormwater Inspector (CESS W I) and have familiarity with Stormwater Pollution Prevention Plans (SWPPP). Construction Inspection Checklist ' Pre -construction meeting ❑ Walk through site with builder/contractor/subcontractor to review erosion and sediment control plan/stormwater pollution prevention plan or SWPPP) ' ❑ Determine when PICP is built in project construction sequence; before or after building construction, and measures for PICP protection and surface cleaning ❑ Aggregate material locations identified (hard surface or on geotextile) 1 r Sediment management ❑ Access routes for delivery and construction vehicles identified ❑ Vehicle tire/track washing station (if specified in E&S plan/SWPPP) location/ maintenance Excavation ❑ Utilities located and marked by local service ❑ Excavated area marked with paint and/or stakes ❑ Excavation size and location conforms to plan Sediment management ❑ Excavation hole as sediment trap: cleaned immediately before subbase stone placement and runoff sources with sediment diverted away from the PICP, or ❑ All runoff diverted away from excavated area ❑ Temporary soil stockpiles should be protected from run-on, run-off from adjacent areas and from erosion by wind. ❑ Insure linear sediment barriers (if used) are properly installed, free of accumulated litter, and built up sediment less than 1 /3 the height of the barrier. ❑ No runoff enters PICP until soils stabilized in area draining to PICP Foundation walls ❑ At least 10 ft (3 m) from foundation walls with no waterproofing or drainage ❑ At least 100 ft (30 m) from water supply wells ❑ Soil subgrade: rocks and roots removed, voids refilled with permeable soil ❑ Soil compacted to specifications (if required) and field tested with density measurements per specifications ❑ No groundwater seepage or standing water. If so dewatering or dewatering permit may be required. 1 1 1 1 t Geotextile (if specified) ❑ Meets specifications (nonwoven recommended) ❑ Placement and down slope overlap (min. 2 ft or 0.6 m) conform to specifications and drawings ❑ Sides of excavation covered with geotextile prior to placing aggregate base/subbase ❑ No tears or holes ❑ No wrinkles, pulled taught and staked Impermeable Liner (if specified) ❑ Meets specifications (woven recommended) ❑ Placement, field welding, and seals at pipe penetrations done per specifications Drain pipes/observations wells ❑ Size, perforations, locations, slope, and outfalls meet specifications and drawings ❑ Verify elevation of overflow pipes Subbase, base, bedding and jointing aggregates ❑ Sieve analysis from quarry conforms to specifications ❑ Spread (not dumped) with a front-end loader to avoid aggregate segregation ❑ Storage on hard surface or geotextile to keep sediment -free ❑ Thickness, placement, compaction and surface tolerances meet specifications and drawings Edge restraints ❑ Elevation, placement, and materials meet specifications and drawings Permeable interlocking concrete pavers ❑ Meet ASTM/CSA standards (as applicable) per manufacturer's test results ❑ Elevations, slope, laying pattern, joint widths, and placement/compaction meet drawings and specifications ❑ No cut paver subject to tire traffic is less than 1 /3 of a whole paver ❑ All pavers within 6 ft (2 m) of the laying face fully compacted at the completion of each day ❑ Surface tolerance of compacted pavers deviate no more than t3/8 (t 10 mm) under a 10 ft (3 m) long straightedge Final inspection ❑ Surface swept clean ❑ Elevations and slope(s) conform to drawings ❑ Transitions to impervious paved areas separated with edge restraints ❑ Surface elevation of pavers 1/8 to 3/8 in. (3 to 10 mm) above adjacent drainage inlets, concrete collars or channels (for non-ADA accessible paths of travel); to %a in. or 6 mm (for ADA accessible paths of travel) ❑ Lippage: no greater than 1/8 in. (3 mm) difference in height between adjacent pavers ❑ Bond lines for paver courses: f% in. (fl5 mm) over a 50 ft (15 m) string line ❑ Stabilization of soil in area draining into permeable pavement (min. 20 ft (6 m) wide vegetative strip recommended) ❑ Drainage swales or storm sewer inlets for emergency overflow. If storm sewer inlets used, insure properly protected. ' ❑ ❑ Runoff from non -vegetated soil diverted from PICP surface Test surface for infiltration rate per specifications using ASTM C1701 Minimum 100 in./hr recommended 1 PICP In-service Inspection Checklist ❑ 1 to 2 times annually (typically spring/fall): vacuum surface, adjust vacuuming schedule per sediment loading and/or any sand deposits from winter t ❑ Winter: Remove snow with standard plow/snow blowing equipment; monitor ice on surface for reduced salt use than typically used on impervious pavements ❑ Water ponding on surface immediately after a storm (paverjoints or openings severely loaded with sediment): test surface infiltration rate using ASTM C 1701. Vacuum clean to remove surface sediment and soiled aggregate (typically %z to 1 in. or 13-25 mm deep), refill joints with clean ' aggregate, sweep surface clean and test infiltration rate again per C 1701 to minimum 50% increase Annual Inspection ' ❑ ❑ Replenish aggregate in joints if more than %z in. (13 mm) from chamfer bottoms on paver surfaces Inspect vegetation around PICP perimeter for cover & soil stability, repair/replant as needed ❑ Inspect and repair all paver surface deformations exceeding 1/2 in. (13 mm) ❑ Repair pavers offset by more than 1/4 in. (6 mm) above/below adjacent units or curbs, inlets etc. ' ❑ Replace cracked paver units impairing surface structural integrity ❑ Check drains outfalls for free flow of water and outflow from observation well after a major storm H 1 [1 1- I Ci 1 1 F I 1 1 1 PICP Maintenance Checklist This can be included in the above agreement or used separately to manage in-service PICP. PICP In-service Inspection Checklist 0 1 to 2 times annually (typically spring/fall): vacuum surface, adjust vacuuming schedule per sediment loading and/or any sand deposits from winter O Winter: Remove snow with standard plow/snow blowing equipment; monitor ice on surface for re- duced salt use than typically used on impervious pavements O As needed, indicated by water ponding on surface immediately after a storm (paverjoints or open- ings severely loaded with sediment): test surface infiltration rate using ASTM C1701. Vacuum to remove surface sediment and soiled aggregate (typically 1/2 to 1 in. or 13-25 mm deep), refill joints with clean aggregate, sweep surface clean and test infiltration rate again per C1701 to minimum 50% increase or minimum 10 in./hr (250 mm/hr). Annual Inspection O Replenish aggregate in joints if more than 1/2 in. (13 mm) from chamfer bottoms on paver surfaces O Inspect vegetation around PICP perimeter for cover & soil stability, repair/replant as needed O Inspect and repair all paver surface deformations exceeding 1/2 in. (13 mm) O Repair pavers offset by more than Va in. (6 mm) above/below adjacent units or curbs, inlets etc. O Replace cracked paver units impairing surface structural integrity O Check drains outfalls for free flow of water and outflow from observation well after a major storm Permeable Interlocking Concrete Pavements 81 1 1 1 1 MAP POCKET DR1 - OVERALL DRAINAGE EXHIBIT NorthernEnaineerina.com // 970.221.4159 NORTH 20 0 20 Po 50 F•t �REO Na a00Y T9N __ �— ___ �— _� _ 1 n IN LE[20 - _ cwmcT 10%� LEGEND: �' n. 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