CMG GardenNotes #268 Irrigation Management Worksheet: Lawn In-Ground Sprinkler System Check-Up

Transcription

1 CMG GardenNtes #268 Irrigatin Management Wrksheet: Lawn In-Grund Sprinkler System Check-Up Name: This activity is a check-up n an in-grund lawn sprinkler system. If yu dn t have access t an in-grund sprinkler system fr the activity, please cntact the instructr fr an alternative activity. T cmplete the irrigatin check-up, yu will need the fllwing items: 6, identical straight-sided, flat bttm cans r cups (d nt use tuna r ther shrt cans) Watch Ruler Clred flags r ther marking tls (screwdrivers r sticks) t mark sprinkler heads by zne (helpful) Calculatr Screwdriver and/r sil prbe Why d an irrigatin check-up Fr mst residents, attentin t irrigatin efficiency has the greatest ptential fr water cnservatin f all the principles f water wise landscaping. In the typical hme yard, extra attentin t irrigatin system design, maintenance, and management will reduce water use by 20% t 70%; 40% being average. The purpse f a lawn irrigatin check-up is a systematic evaluatin f the irrigatin system design, maintenance, and management. It will identify areas where adjustments will make a minr r majr impact n water cnservatin and lawn quality. Run times fr each sprinkler zne will be calculated based n the precipitatin rate f each zne. The check-up is nly a tl t help the gardener identify where the system is wrking adequately and where adjustments need t be made. Actual water cnservatin cmes as findings are incrprated.

2 Nte: Carry ut a nrmal watering the day befre ding the check-up. Step 1 Visually evaluate the lawn 1. Hw des the lawn lk? Green (high input lawn) Thick Weed free Green (mderate input lawn) Thin Few weeds Green (lw input lawn) Weedy Dry spts: % f lawn Dry/Drmant 2. Sil cnditins 1. Stick a screwdriver in the grund t get a sense abut sil cmpactin. The ease r difficulty at which the screwdriver can be pushed int a mist sil gives a grasp f sil cmpactin. 2. If pssible, use a sil prbe t get a sense n sil texture, cmpactin, sil layers, rting depth, and thatch layer. Nte: On cmpacted r rcky sil, it may impssible t push a sil prbe int the sil. On extremely cmpacted sils, it may even be impssible t push a screwdriver int the sil. Sil cmpactin Little t n cmpactin (screwdriver/prbe readily ges in) Mderate cmpactin (screwdriver/prbe hard t push in) Severe cmpactin (screwdriver/prbe extremely difficult t impssible t push in) Aeratin needed t increase infiltratin Sil texture Carse texture (sandy) Mderate texture (lamy) Fine texture (clayey) Sil prfile Changes in sil texture evident Hardpan layer Evidence f drainage prblems (such as surface pling) Thatch layer Less than 1/2 inch Greater than 1/2 inch Aeratin needed t manage thatch Runff ptential Lw ptential High ptential (use cycle and sak applicatin) Due t slpe Due t sil cnditins (cmpactin and clayey sils) Due t heavy thatch

3 3. Current irrigatin pattern During the summer (July/August) the lawn is typically watered (days) fr minutes During the typical July/August weather, the lawn can g days between irrigatin befre getting dry. Multiply the number f days (maximum) between summer irrigatins by 0.20 t estimate the water hlding capacity fr the sil and rting depth at this site. This is the maximum amunt f water t apply per irrigatin. days x 0.20 inches = inches per irrigatin (maximum) 4. Ntes Step 2 Current Cntrller Settings Recrd current settings frm the cntrller including watering days, start time(s) and run times. Nte Precipitatin rates and inches applied may be calculated later. This will be used t dcument water saving ptential frm the check-up. Cntrller is set fr (mnth). Table: Step 4 Current Setting and Inches Applied Zne Zne Identity Watering day(s) Start time(s) Run time Precipitatin Rate Inches Applied

4 Step 3 Identify and Evaluate Irrigatin Znes A. Identify the lcatin f each sprinkler head in each zne (a grup f sprinkler heads that cme n at the same time). Using difference clrs f landscape flags r ther marking devices (like screwdriver r stick pushed in the grund near each head) is helpful. Sprinklers may need t be turned n t find and identify sprinkler heads by zne. B. Evaluate the fllwing hydrzne layuts Step 3. Irrigatin Znes OK Cncept incrprated Minr Benefits received with minr adjustments r implementatin Majr Benefits received with majr adjustments r implementatin Nt applicable t site Irrigatin Znes 1. Lawn znes separate frm flwer and shrub bed znes 2. Lawn areas zned by irrigatin demand (i.e., high input, mderate input, and lw input areas n separate irrigatin znes) 3. Zne by expsure (i.e., extreme expsures, full sun, partial shade, full shade, and slpes n separate irrigatin znes) 4. Drip r bubblers used in flwerbeds, shrub beds, small fruits, and vegetable gardens 5. Design avids sprinkler irritatin n small, irregular shaped areas (generally areas less than 10 feet wide) C. If design des nt meet this criteria, cnsider upgrading the irrigatin system. D. Ntes:

5 Step 4 Evaluate sprinkler perfrmance Turn n sprinklers and evaluate sprinkler perfrmance as utlined belw, repeating steps fr each zne. A. Design criteria fr even water distributin 1. Head t head cverage Des the water frm each head reach neighbring heads? [The Science f Gardening, page 620] Table 4a1 Head t Head Cverage NO = adjustments needed* * In sme situatins adjusting heads r changing nzzles may crrect the prblem. In ther situatins, the system design may need t be up-graded fr water cnservatin. 2. Lined-ut Are sprinkler heads lined-ut alng the edge f nn-irrigated areas (watering frm the utside in)? [The Science f Gardening, page 620] Table 4a2 Lined-ut NO = upgrade needed* * If n, cnsider upgrading the sprinkler system fr imprved water cnservatin. 3. Head layut Are sprinkler heads arranged in triangle and square patterns, aviding pentagn patterns? [The Science f Gardening, page 621] Table 4a3 Head Layut NO = upgrade needed* * If n, cnsider upgrading the sprinkler system fr imprved water cnservatin.

6 4. Zne unifrmity Are all head in a zne the same brand and type? Table 4a4 Zne Unifrmity NO = adjustments needed* * In sme situatins, replacing heads may crrect the prblem. In ther situatins, the system design may need t be up-graded fr water cnservatin. 5. Pressure Is there a mist clud arund sprinkler heads? [The Science f Gardening, page 621] Table 4a5 Pressure / Mist Clud NO = adjustments needed* * A mist clud indicates excessive pressure. Lwer pressure t cnserve water. In sme situatins, this may invlve installatin f an in-line pressure regulatr. 6. Ntes/Cmments B. Maintenance criteria fr even water distributin 1. Delivery arc Fr each head des the delivery angle need adjustments (t avid spraying the sidewalk, driveway, r ther areas utside the zne)? [The Science f Gardening, page 621] Table 4b1 Delivery Arc N = OK Yes = adjustments needed Identify heads needing adjustments

7 2. Vertical adjustment D heads need adjustment t vertical (straight up and dwn)? [The Science f Gardening, page 622] Table 4b2 Vertical adjustment N = OK Yes = adjustments needed* Identify heads needing adjustments * Heads ff vertical will distrt the delivery pattern. Adjust t vertical t cnserve water. 3. Height Is nzzle releasing water abve grass height? [The Science f Gardening, page 622] Table 4b3 Height N = adjustments needed* Identify heads needing adjustments * When water desn t clear grass height, distributin pattern may be distrted. Raise head. 4. Wrn Nzzles Lk at the fan created by the water spray fr each head. Is it unifrm arund the arc? This is rather difficult t evaluate by line f sight. [The Science f Gardening, page 622] Table 4b4 Wrn Nzzles N = adjustments needed* Identify heads needing adjustments * Replace wrn nzzles t imprve distributin pattern.

8 5. Replace leaky valves In the irrigatin valve, the rubber diaphragm that actually turns water n and ff ages ver time. Valves that d nt shut-ff cmpletely need the diaphragm r entire valve replaced. [The Science f Gardening, page 622] Table 4b5 Leaky Valves Valve nt leaking = OK Valve leaking = needing replacement 6. Evaluate dry spts If the zne has a dry spt, place sme cans n the dry spt and n the green areas. After running the sprinkler fr their nrmal time, cmpare the amunt f water received in each can. [The Science f Gardening, page 622] Table 4b6 Evaluate Dry Spt N dry spts Dry spt(s) receiving less water than the green areas 1 Dry spt(s) receiving similar amunts f water as green areas 2 1 When the amunt f water received in dry area cans is significantly less than the green area cans, pr water distributin is a primary cntributr. Evaluate irrigatin design and maintenance issue. 2 When the amunt f water received in bth the green area cans and dry area cans is similar, the prblem is nt directly related t sprinkler perfrmance. Evaluate ther grwth factrs, including sil cmpactin, thatch, runff, insect r disease prblems, etc. Adjusts identified in step 4 need t be perfrmed befre cntinuing t step 5. Step 5 Perfrm precipitatin rate (catch can) test Perfrm a precipitatin rate test (catch can test) fr each zne, recrding the precipitatin rates in Run Time Table. [The Science f Gardening, page 631] Precipitatin Rate (Catch Can Test) T d the calculatins yu will need 6 identical, straight-sided, flat bttm, cans r cffee mugs such as sup cans, fruit r vegetable cans, r cffee cans. (D nt use shrt cans like tuna cans as they are t shallw and water may splash ut.) Yu will need a ruler, a watch, and paper/pen t recrd yur findings.

9 Steps a. Place 6 identical, straight-sided, flat bttm cans r cffee mugs randmly arund the area between sprinkler heads in the zne. b. Turn n the sprinklers fr exactly 10 minutes. c. Pur all the water int ne can. d. With a ruler, measure the depth f the water in the can. This is yur precipitatin rate in inches per hur. e. Write dwn the rate fr each zne in Table: Step 8 f. Repeat steps 1-5 fr each irrigatin zne. Nte: if the amunt f water in sme cntainers is significantly mre r less than thers, it indicates that the system is prly designed r head(s) are malfunctining. Table 5 Precipitatin Rate Precipitatin Rate (inches/hur) Step 6 Calculate system run times fr each zne A. Wrking dwn thrugh the table, calculate the run time per irrigatin. Table 6a Run Times 1. Histrical Summer ET amunt f water t apply 1.5 /week 2. Precipitatin Rate inches/hur frm catch can test, Table 5, Rw 2 3. Run time per week (July/August) Based n Precipitatin Rate fr the zne (line 3), lk this up frm Table 50-2 (page 612) r Table 52-1 (page 632). 4. Number f irrigatins/week Refer t Step 1-3 abve 5. Run time per irrigatin Cnvert the Run Time per Week (line 4) t Run Time per Irrigatin using table 50-3 (page 612) r Table 52-2 (page 633)

10 B. Adding Cycle and Sak Mst clayey and/r cmpacted sils cannt absrb water as quickly as sprinklers apply it. Many clayey sils, typical f the Frnt Range, absrb abut ¼ inch f water per hur. Therefre, the mst effective watering schedule n these sils wuld be t set each zne t deliver n mre than ¼ inch per cycle with multiple cycles. Fr example, if the lawn is t have ½ inch f water, set cntrller t apply ¼ inch and cycle back an hur later t apply the secnd ¼ inch. If the lawn was t have ¾ inch, set the cntrller t apply ¼ inch per cycle with 3 cycles. Sak and cycle is particularly helpful n slpes t avid wasteful surface runff. Use Table 50-4 (page 613) r Table 52-3 (page 633) t determine if Cycle and Sak is desired. Table 6b Cycle and Sak 1. Need fr Cycle and Sak? Yes/N 2. Run Time Per Irrigatin frm Table 6a, Line Number f cycles frm Table 50-4 (page 613) r Table 52-3 (page 633) 4. Run Time Per Cycle Divide Run Time per Irrigatin (line 2) by Number f Cycles (line 3) Step 7 Start time(s) a. Determine the first start time Mst cmmunities suggest nighttime irrigatin, between 9 p.m. and 9 a.m. Winds are typically less in the early mrning, and evapratin lss will be lwer. Hwever, many cmmunities experience peak water use frm 4 t 6 a.m. as many sprinklers cme n, s remember that the irrigatin windw is 9 t 9, nt just 4 in the mrning. Enter yur first start time int Table 7 Start Time(s), rw 1

11 b. Adding additinal start times fr Cycle and Sak (if needed) 1. Add all the Run Time per CYCLE tgether. 2. Cycle Time Rund this up t the next ¼ r ½ hur (depending n what start time intervals are used in yur cntrller start ptins). This is the time t run thrugh all the znes. Add this t Table 7-Start Time(s), Rws 2 and 4 belw. Or add 1 hur if the ttal run time is less than 60 minutes. 3. Add this t the first start time fr the secnd start time. Recrd yur secnd start time in Table 7-Start Times) Rw 3, Start Time Likewise, if a third cycle is needed, add this t the secnd start time t get the third start time. Recrd this in Table 7-Start Times) Rw 5, Start Time 2. Table 7 Start Time(s) 1. Start time 1 2. Ttal cycle time 3. Start time 2 (if needed) [add line 1 t line 2] 4. Ttal cycle time 5. Start time 3 (if needed) [add line 3 t line 4] Step 8. Set the Cntrller fr July/August Run Time 1. Set the run times fr each zne as listed in Table 6a, line 6 if Cycle and Sak is nt used, r Table 6b, line 4 if Cycle and Sak is used. 2. Set the start time(s) as given in Table 7-Start Time(s) Step 9. Seasnal Adjustment A simple way t adjust fr the seasn is t use the Percent Key fund n mst cntrllers. Fr Late April and early Octber, set the percentage t 50% Fr May/June and September, set the percentage t 67% An alternative methd is t repeat Step 6 t 8 fr the spring/fall seasn.

12 Step 10. Fine-Tune t Match Site Specific Needs These textbk figures are a gd start pint in irrigatin management. Hwever, any scheduling methd will need fine-tuning t match the actual water need f the site based n the expsure, wind, heat, and shade. This is dne by careful bservatin f the lawn. When adjusting all znes, the Percent Key n mst cntrllers makes an easy methd t fine-tune fr the actual site by adjusting the percentage up/dwn in 10% increments, as needed. It can als be dne by adjusting the run time f each zne up/dwn in 10% increments, as needed. When adjusting a single zne, adjust the run time fr that zne up/dwn in 10% increments, as needed. In the typical summer weather, if the lawn starts t becme dry between irrigatins, increase the run time in 10% increments, as needed. By experience, it is easy t fine-tune each irrigatin zne. In multiple days f unseasnably ht weather, dry spts shuld begin t pp up if the cntrller if precisely fine-tuned. In unseasnably ht weather, if dry spts d nt pp up, the lawn is being verwatered. Cut back the time in 10% increments, as needed t fine-tune each zne. The fllwing guidelines may help yu understand sme needs fr adjustments: In full shade (nt under a large tree), water use (ET) culd be 30% less. In ht and/r windy sites, water use (ET) culd be 20% t ver 50% higher. In the rting area f large shade trees, water use (ET) culd be 30% t 50% higher. Authr: David Whiting, Extensin Cnsumer Hrticulture Specialist (retired), Clrad State University Extensin. Revisin: Kurt M. Jnes, Chaffee Cunty Extensin Directr (9/2017). Clrad Master Gardener GardenNtes are available nline at Clrad Master Gardener training is made pssible, in part, by a grant frm the Clrad Garden Shw, Inc. Clrad State University, U.S. Department f Agriculture and Clrad cunties cperating. Cperative Extensin prgrams are available t all withut discriminatin. N endrsement f prducts mentined is intended nr is criticism implied f prducts nt mentined. Cpyright Clrad Master Gardener Prgram, Clrad State University Extensin. All Rights Reserved. This CMG GardenNtes may be reprduced, withut change r additins, fr nnprfit educatinal use. Revised: September, 2017