Sports Turf Drainage Q+ A with Barry Pace of M J Abbott Ltd
Following on from our successful TurfChat evening on Sports Turf Drainage with Barry Pace, contracts manager at MJAbbotts. Barry answered not far off 20 questions on all thing’s drainage, from winter sports pitches to cricket squares.
Q1- We’ve recently ‘moved’ pitches on site, and like many have drainage problems. Clay just under the surface and we’re mulling on what might be the best option to drain. No easy access to mains drainage?
Based on the assumption you are clay based with no option to drain water downwards to soakaway and if you have no Mains Drainage available to connect to normally the first option is to look for a ditch outfall if any exist on the site or around your boundary. If there is no ditch could the levels of the site allow an attenuation area or crate system to be made in a low corner allowing the pitch areas to be drained off.
Cautionary Point 1: You are really heading in to needing some professional advice from a Drainage Consultant if there are no obvious existing outfalls and should consider this as your first port.
Cautionary Point 2: The above suggestions could have serious legal/financial implications if you get them wrong and cause a problem elsewhere, please refer to the point above.
Q2- Our outfield at is probably like most, saturated, some of our drains are not working and we’ve even re-laid a section 50mts..how best can we go forward to rectify that problem and also what’s the best solution for aerating the outfield and cost?
We then dug down to about 12-14″ and laid pipe bedding and piping on top then filled with pipe bedding to just under the soil and turf, then we put the sods back on top.This led to a point off the field where it could run to
This sounds exceptionally shallow to be any use other than to move surface water away from a very small catchment, if there is little or no sand or fine gravel around it I am not surprised it has filled with fines, even given the Terram. which I hate personally
That will be your best current option, locate the outfall and work your way back up. it is likely silting has started at either a ditch, chamber or a problem such as tree roots
Q3- When fitting a new drainage system do you have to ask permission for an outflow to flow into a stream etc?
It does depend on the site but it is prudent to assume that any outlet will require permission unless it is existing one and even then, they may well require additional works to mitigate flows by attenuating water in peak weather, this is one of the problems with putting a cost on a system without full knowledge as you are never sure what the EA or others will require once involved as each location can be so variable in terms of catchment and outfall load downstream.
Q4- What materials would you advise to back fill with? Barry in what regard
- Again, a couple of factors, location and availability is one, Sport is another, timing of installation as at construction stage it tends to be sand to surface over gravels but in established turf a rootzone over gravel would be used to sustain growth after.
Current specs generally call for a 2-6mm clean aggregate then either a standard sport grade rootzone or sand, working on the bridging factors of each preventing the sand/rootzone dropping in to the gravel.
You can use a larger gravel ie 4-10mm or a 10-20mm if locally more available/economical but you would ideally need to use blinding or intermediary layer between the gravel and sand/rootzone to prevent migration in to the larger pore size.
Q5- How much aggregate/ sand if the drain is 2 ft deep?
Again, location and sport dependant but between 100 and 300 of sand or growing media and then 5oo to 300 of gravel, your trench width dictates the tonnage per metre. Work out the cubic metres of any drain for its gravel (Length by Width by Depth in M) and times by (material dependant again) between 1.5 and 1.7 tons per cubic metre and for Sand/Rootzone the same but cube x 1.7 to 1.8 ton.
Note 1, if buying in bulk loads its rounded up to per 20t or 27t loads needed, if in bags add a couple for wastage.
Note 2, Having enough to finish is key….
Q6- What could we expect from an audit of an existing drainage system?
Good question this one, so I would want to know what, if anything is in place already and its effectiveness, what outfalls are available and, back to the permission q, what is permitted in terms of discharge, next would-be soil type, anticipated usage, i.e., how well do you require it to perform and maintenance levels
Q7- We are based on a heavy clay soil, we spike, slit regularly and verti-drain twice a year. What else could we to help within a minimal budget?
If you have any existing drainage show it some love…. clean out chambers, clean ditches and if possible, check they are running well. unfortunately, anything else requires prayer and budget
Q8- What is your preferred, sand or gravel bands as secondary drainage option?
It really depends on the soil type and location/weather. They all work well if you do not have Shrinky clay then you need to budget for lots of topping up. Sand Grooving tends to give a more intense coverage.
Q9- How long would you expect a secondary drainage system to work effectively?
First, with topdressing… anything up to 10 to 15 years. No topdressing and overplay in poor conditions… 6 months or less
Q10- What’s your thoughts on Lytag use instead of gravel and the type of cost savings?
Lytag is a reputable product, lightweight and if enough is required gives good value. Can be expensive in comparison if you’re buying bags rather than bulk. The current lean of the industry to use 2-6mm gravels in specifications means it tends to get pushed out for use at our level, but I have put plenty in Greens and pitch areas through a Bander Hopper over the years to give a god 3 or 45 years use.
Q11- We have heavy clay just below the surface. No drainage but are considering mole ploughing as an option for a couple of years. Any thoughts?
I love a mole plough… Make sure you know your levels and falls, set in to a ditch or fresh drain if possible and keep good lines. Timing for surface traction and not damage is paramount and there is an old saying… don’t mole Shrinky clay past Christmas unless you want big cracks…
Q12- I’ve read that vertidraining is not necessarily a good thing on heavy clay. Do you have a view?
Timing is everything and by that I do not mean the date, vertidrain in wrong conditions and you will either bounce or be like a fork in butter and let more water hold in the profile.
Q13- What membrane other than Terran would you recommend between gravel and root zone?
Most good sport aggregate suppliers will be able to ensure materials are compatible, again this is why industry has predominantly used 2-6mm of late
Q14- Pitches with a primary drainage system, what are the pros and cons of adding a secondary drainage system?
A Primary Drainage System will give you X in terms of performance/drainage capabilities which depending on soil type will allow x hours use.
- A Primary Drainage System of 3m centres will remove water quicker than a system with 5m or 7m or 10m centres but all limited the inherent abilities of the soil type and age of the system.
- A Secondary System will remove water from the surface far quicker due to the increased intensity of drainage channel and invariably will allow a surface to be more playable in wetter conditions and playable more quickly. In theory this leads to better sward and soil conditions allowing more usage.
Conversely if you require more out of a surface in terms of playing time you need to look to improving its ability to drain invariably adding Secondary Drainage. More efficient drainage, more manageable a surface, more potential for usage.
Downside for a good many site, especially in drier parts of the country is that the surface invariably through dressing and drain intensity can become too dry and droughted in prolonged dry periods causing sward stress and potential loss through weakness. So the ability to irrigate should be a key part of the decision and budgeting process but unfortunately often is not….
The increased intensity of any system and addition of sand can also lead to nutrient leaching and additional pest and disease pressure, the unfortunate yin to the yang of performance.
Q15- Without putting you on the spot Barry, roughly what kind of cost per meter for piped drainage?
Ok, location is everything, materials cost more depending on the distance to haul, the amount of drainage to be installed will affect the rate. is the material to be removed form site or not massively affects the rate, do you need to install attenuation or outfalls again all affect the rate. so basically, I can’t really tell you as EVERY job is specific… Still can’t tell you Brian…
Q16- How vital is topdressing to maintain a primary or secondary drainage system?
Topdressing is ESSENTIAL to ensure a ‘clean’ connection is maintained from the surface to the drainage to ensure optimum performance
Q17- Hi Barry, we have a football pitch which was drained three years both primary and secondary drainage was installed and we have topdressed and verti-drained annually. Since then, 4/5 wet areas have appeared.
What should we be looking at to rectify the problem?
Unfortunately many projects over time have spent on something they cannot then sustain, a very difficult balance for most grass roots to achieve but it sounds like here that from what you are saying you are doing all you should be. It is important to find out where the water is sitting in these areas, is it on the surface or are the drains not working to depth.
A simple careful open up of the area to look below the surface should be your first point. If the drains are holding water to depth then there may be an issue with pipes, a connection may have failed or a blockage occurred, these things do happen but shouldn’t. If water is sitting in the Secondary drains then the connection to the Primary or compatibility of the materials should be checked.
If the water is sitting on the surface then the compatibility of the sand you are applying should be checked, the timing of aeration (see above) checked to see it has opened the soil up to drain not caused it to hold water by ‘potting’ if conditions were wet or that one pitch in conditions to make a Turfies toes curl hasn’t smeared the surface badly at some point.
Most reputable companies would offer support and should review what has been done but you should be ready to be fully open to them in terms of what has or hasn’t happened maintenance wise… we can often tell.
Really enjoyed the hour, whilst some of the questions can be fairly commonly asked to us working in sport construction, the information for those seeking answers or direction is clearly key but maybe it is lacking in availability, especially to help them just see where they need to head next to improve a surface.
Unfortunately, drainage improvements come at an often-significant cost and unless you are blessed with free draining soils invariably as weather patterns change and rainfall intensity increases the need for quicker or more efficient surface water removal is becoming paramount where performance and playability is required.
Every site is different and will have, especially as increased restrictions on watershed come to fore, site specific requirements and costs that will need to be covered.
A big thank you to Barry for taking the time out to host, the Sports Turf Drainage Q+A on TurfChat and we hope you found this summary of the evening of some help.
Big Well Done to Tom Banks , who won the below goodies for the best question of the evening.